Patterns of Somatic Diagnoses in Older People with Intellectual Disability: A Swedish Eleven Year Case Control Study of Inpatient Data

Transcription

1 Journal of Applied Research in Intellectual Disabilities 2017, 30, Published for the British Institute of Learning Disabilities Patterns of Somatic Diagnoses in Older People with Intellectual Disability: A Swedish Eleven Year Case Control Study of Inpatient Data Magnus Sandberg, Gerd Ahlstr om and Jimmie Kristensson Department of Health Sciences, Faculty of Medicine, Lund University, Lund, Sweden Accepted for publication 6 October 2015 Background Knowledge about diagnoses patterns in older people with intellectual disabilities is limited. Methods The case group (n = 7936) comprised people with intellectual disabilities aged 55 years and older. The control group (n = 7936) was age matched and sex matched. Somatic inpatient diagnoses ( ) were collected retrospectively. Results Several diagnoses were in several years significantly more common in the case group, particularly infections [odds ratio (OR) ]; nervous system (OR ); respiratory (OR ) and genitourinary diseases ( ); injuries, unspecified symptoms (OR ); and external causes of morbidity (OR ). The oldest in the case group had significantly less occurrence of tumours (OR ), cardiovascular (OR ), and musculoskeletal diseases (OR ) than controls. Conclusions Older people with intellectual disabilities have higher numbers of some diagnoses, but lower numbers of others. Further research on the reasons for the unique pattern of diagnoses in this group is required. Keywords: aged, case-control studies, diagnosis, inpatient, intellectual disability, register studies, retrospective studies Introduction In recent decades, life expectancy in people with intellectual disabilities and in the general population has increased (Coppus 2013). This is attributed to medical, social (World Health Organization 2000), nutritional (Coppus 2013) and lifestyle advances (Blackman 2007). The proportion of people aged 65 years and older with intellectual disabilities has greatly increased, and it has been reported that the present generation of older people with intellectual disabilities is the first to reach older age (Bigby 2007; Blackman 2007). There are studies indicating that in people with intellectual disabilities, ageing appears to occur at an earlier chronological stage, and with a higher prevalence of diseases and health problems related to ageing compared with the general population of the same age (Kapell et al. 1998; Haveman et al. 2010). Dementia is a health issue commonly related to intellectual disabilities. Strydom et al. (2010) reviewed studies that investigated dementia in older adults with intellectual disabilities. The prevalence rates for populations with intellectual disabilities not related to Down s syndrome were inconsistent, with some studies reporting rates comparable to that in the general population, and others reporting a higher prevalence than in the general population (Strydom et al. 2010). However, it has been reported that people with intellectual disabilities have a 2.5-fold greater frequency of health problems compared with the general population (McCarron et al. 2013). There are a substantial number of reviews and studies that have reported higher rates of diagnoses and health problems in people with intellectual disabilities compared with a population without intellectual disabilities. For example, in people with intellectual disabilities, higher rates have been found for epilepsy (Coppus 2013), obesity (Evenhuis et al. 2001; de Winter et al. 2012; Coppus 2013), vision and hearing impairment (Kapell et al. 1998; Haveman et al. 2011; Coppus 2013), gastro-oesophageal 2015 The Authors. Journal of Applied Research in Intellectual Disabilities published by John Wiley & Sons Ltd /jar This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

2 158 Journal of Applied Research in Intellectual Disabilities reflux and esophagitis (Evenhuis et al. 2001), nonatherosclerotic heart disease (Kapell et al. 1998), thyroid disease (Kapell et al. 1998; Coppus 2013), osteoporosis (van Schrojenstein Lantman-De Valk et al. 1997; Center et al. 1998) and cardiovascular diseases (CVD) (Draheim 2006). In contrast, some studies reported a lower frequency of hypertension (Kapell et al. 1998; Janicki et al. 2002), hyperlipidaemia and adult-onset diabetes (Janicki et al. 2002) in people with intellectual disabilities. Earlier onset of the normal ageing process could be a reason for a higher prevalence of diagnoses and health problems in people with intellectual disabilities compared with the general population. However, there could also be other reasons. A high prevalence of specific diseases may be related to the syndromes associated with intellectual disabilities, or to lifestyle and environmental issues (Evenhuis et al. 2001). For example, a high prevalence of heart disease may be related to a sedentary lifestyle, high body mass index and lack of exercise. Evenhuis et al. (2012) stated that apart from people with Down s syndrome who experienced early sensory loss and dementia, there were no signs that normal ageing occurred prematurely in people with intellectual disabilities. As many people with intellectual disabilities are residents of institutions, they are at greater risk of infectious diseases such as Helicobacter pylori infection, hepatitis B and tuberculosis (Haveman et al. 2010). Accurate diagnosis of people with intellectual disabilities may also be difficult. For example, Merrick et al. (2004) reported a decrease in the prevalence of CVD with increasing cognitive severity and suggested that a lower prevalence of some diseases or conditions could be explained by underdiagnoses. Some of the studies reporting prevalence of disease and health problems in people with intellectual disabilities have investigated the prevalence in all ages, not only those regarded as old. However, many of these studies were small in scale and lacked a control group or were cross-sectional. Lin et al. (2011) noted that there was limited information available on the health status of people with intellectual disabilities, including how health status changed with increasing age and whether the onset of age-related diseases occurred earlier in the life cycle. This highlighted a need for larger scale studies investigating disease and health problems in people with intellectual disabilities compared with the general population. The aim of this study was therefore to investigate patterns of somatic inpatient ICD-10 diagnoses in older people with intellectual disabilities in relation to age over an 11-year period and to compare these diagnoses patterns with people without intellectual disabilities in the general population. Methods Study design This study used a eleven year, retrospective, population register-based, case control design. The study was performed in accordance with the Helsinki Declaration (World Medical Association 2013). Data were anonymized and did not contain any information linking data to any individual. The study design meant that the present authors were not able to obtain informed written consent from the participants. However, information about the study and how to withdraw from it was advertised in two major newspapers in Sweden, one of which was a national newspaper distributed by the Swedish National Association for Persons with Intellectual Disability (FUB). The study was approved by the Regional Ethical Review Board in Lund (diary no 2013/15). Setting About 18% of Sweden s population, approximately 1.8 million people, are aged 65 years or older (Lennartsson & Heimerson 2012). Sweden has one of the highest average life expectancies in the world. In 2011, the average life expectancy was 83.7 years for women and 79.8 for men (Danielsson & Talb ack 2012). In Sweden, healthcare and social services are based on a welfare system funded mainly by taxes (Anell et al. 2012) and are regulated by the Health and Medical Services Act (SFS 1982:763), the Act concerning Support and Service for Persons with Certain Functional Impairments (SFS 1993:387), and the Social Services Act (SFS 2001:453). Healthcare and social services are provided at different administrative levels. Municipalities provide healthcare and social services to older people and people with special needs at a local level, either at home or in special accommodation/ group homes. County councils provide healthcare, treatment and specialized medical care in outpatient and inpatient facilities, and rehabilitation and home nursing care at a regional level (Anell et al. 2012). All healthcare and social services are registered in public national registers, with mandatory participation by all county councils and municipalities. The National Patient Register (NPR), related to the Health and Medical Services Act (SFS 1982:763),

3 Journal of Applied Research in Intellectual Disabilities 159 contains registration information for all inpatient care and outpatient specialist care and includes details such as diagnoses, hospital/clinic and whether the admission was unplanned/planned. All support and services for older people regulated by the Social Services Act (SFS 2001:453) are recorded in another national register. This includes information about services provided, amount of services and the municipality that provided the services. All support and services provided according to the Act concerning Support and Service for Persons with Certain Functional Impairments (SFS 1993:387) are also recorded in a national register (including the services provided, the amount of services and the municipality that provided the services). This register also contains three group classifications, or personae, for the impairment of the service user: personae 1, people with intellectual disabilities from birth or an early age, are autistic or have a condition resembling autism; personae 2, people with considerable and permanent intellectual functional impairment after brain damage in adulthood, the impairment being caused by external force or physical illness; and personae 3, people with some other lasting major physical or mental functional impairment manifestly not due to normal ageing that causes considerable difficulties in daily life, and a need for extensive support and services (SFS 1993:387). Study populations The case group comprised people with intellectual disabilities aged 55 years and older living in Sweden. The age of 55 years was chosen because the ageing process can start earlier in people with intellectual disabilities (World Health Organization 2000). This group was identified from the National Board of Health and Welfare s register of people that received support and social services (according to SFS 1993:387), and included all people who fulfilled the age criteria and were registered as personae 1 (i.e. people with intellectual disabilities from birth or an early age are autistic or have a condition resembling autism) in A control group consisting of people without intellectual disabilites was selected through matching by birth year and sex from the Swedish National Population Register (Wilen & Johannesson 2002). The matching was performed by Statistics Sweden (2014). In total, individuals were included in the study, the case group and the control group each had 7936 participants. If a person was identified as a case that individual could not also be matched as a control. Material Anonymized inpatient data for individuals in the two groups were collected from the NPR at the National Board of Health and Welfare for the 11-year period from 1 January 2002 to 31 December Variables included were primary and secondary diagnoses, injury codes, date of registration and medical activity code. Anonymized identity codes were used when matching case and control data from the inpatient database. Inpatient diagnoses were registered at discharge and followed the International Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) (World Health Organisation 2015). The ICD translates diagnoses of diseases and other health problems from words into an alphanumeric code (World Health Organisation 2015). The ICD-10 contains 21 chapters, subdivided into homogeneous blocks of three-character categories, that is, one letter and two digits (e.g. I48 is atrial fibrillation and flutter). Most of the three-character categories are subdivided by means of a fourth numeric character after a decimal point, also called four-character subcategories (e.g. I48.2, chronic atrial fibrillation). For each NPR registration, it is possible to record one primary and up to 21 secondary diagnoses. The only exception is Chapter XX in the ICD-10 that includes codes for external causes of morbidity and mortality. These are not divided into primary or secondary diagnoses; instead, up to five such codes can be registered as injury codes in the NPR. An individual might have several registrations for one in-hospital period because of changes in ward during the hospital stay. The primary code is assumed to be the main reason for the registration. The NPR also categorizes registrations as somatic or psychiatric care, including the clinic to which the individual had been admitted (registered as a medical activity code). This study only used registrations in inpatient somatic care; registrations in inpatient psychiatric care will be published in a future paper. In this study, the diagnoses were dichotomized as present or not present for each year. This means that a diagnosis was registered as present once each year regardless of how many times in that year that particular diagnosis was registered and regardless if it was a primary or a secondary diagnosis. The present authors analysed somatic inpatient ICD-10 registrations at chapter and three-character category levels. Statistical analysis Four age groups were created (<60, 60 64, and 70 years) based on the age distribution of the study population as at 31 December The groups consisted

4 160 Journal of Applied Research in Intellectual Disabilities of 5118 (32.2%), 4194 (26.4%), 3272 (20.6%) and 3288 (20.7%) individuals, respectively, with equal numbers for each age group in the case and control groups. The number of individuals with at least one registered diagnoses in a chapter for was calculated. Diagnoses registered in the Factors influencing health status and contact with health services chapter (Ch. XXI) were not included in the analysis as these did not reflect diseases or health problems. Diagnoses chapters Pregnancy, childbirth and the puerperium (Ch. XV), Certain conditions originating in the perinatal period (Ch. XVI) and Codes for special purposes (Ch. XXII) were not presented, as there was a low number of diagnoses in (n < 15) for both the case and control groups. The three most common three-character categories for each chapter were determined for the case group and compared with the control group. Differences between the intellectual disability and control groups were compared using logistic regression, with ICD-10 chapters and three-character categories as dependent variables and group (case or control) as the independent variable. Odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for each comparison. Differences over time were investigated with the chi-squared test for trend (Altman 1991) for each age group (intellectual disability and control groups). This test allows comparisons of proportions among groups (in this case, the years form the groups); when a straight line is fitted to the proportions, any observed trend that is significantly different from a horizontal line is a linear trend (Altman 1991, p. 262). For all comparisons, a P- value of <0.05 was regarded as statistically significant. Results The mean age of the study sample (n = ) was 65 years, and 7222 (45.5%) were women. The study sample accounted for a total of somatic inpatient registrations during the study period; with the intellectual disability group accounting for and the control group for 9660 registrations. In total, 1052 different three-character categories (ICD-10 classifications) were registered throughout the 11-year period. The number of individuals with at least one diagnosis in an ICD-10 chapter during the 11 years differed significantly between the intellectual disability and control groups, with higher numbers in the case group for all chapters except Diseases of the circulatory system (Ch. IX) and Diseases of the musculoskeletal system and connective tissue (Ch. XIII), for which the control group had significantly higher numbers (Table 1). Table 1 also presents the number of the most common three-character categories in each ICD-10 chapter for the intellectual disability group with respect to the control group. The case group had a significantly higher number in most three-character categories, but there were several diagnoses where the difference was not significant (Table 1). There were also some threecharacter categories where the control group had a significantly higher number of diagnoses: Disorders of vestibular function (H81), Essential (primary) hypertension (I10), Atrial fibrillation and flutter (I48), Coxarthrosis (M16), Gonarthrosis (M17) and Pain in throat and chest (R07) (Table 1). For 14 of the 18 ICD-10 chapters presented in Table 1, the number of individuals with at least one diagnosis in each of these chapters for each of the 11 years investigated is shown in Table 2a,b. The other four chapters are presented in text only. Chapter I: certain infectious and parasitic diseases, A00 B99 There were higher numbers of these diagnoses in the intellectual disability group than in the control group for all years, especially for those aged <60, and (Table 2a). There were significant differences for 6 of the study years for these three youngest age groups, and in 2 years in those aged 70 (Table 2a). There was a significant increase over time in all age groups in both the case and control groups (Table 3). Chapter II: neoplasms, C00 D48 For neoplasms, there were non-significant differences between the case and control groups in all study years for those aged <60, and 65 69, except in 2009 for those aged years (Table 2a). For those aged 70, there were a significantly higher number of diagnoses in the control group for the years and 2012 than in the case group (Table 2a). There was a significant linear increase over time in all age groups in the case and control groups (Table 3). Chapter III: diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism, D50 D89 Primary or secondary diagnoses in this chapter were more common in those aged <60, and in

5 Journal of Applied Research in Intellectual Disabilities 161 Table 1 Number of individuals in case (n = 7936) and control groups (n = 7936) with at least one diagnosis (ICD-10 diagnoses chapters), and the three most common three-character categories in the case group in each chapter for ICD-10 chapter Intellectual disabilities, n (%) Control group, n (%) P-value OR 95% CI Ch. I certain infectious and parasitic diseases, 669 (8.4) 272 (3.4) < A00 B99 A41 other sepsis 157 (2.0) 67 (0.8) < A46 erysipelas 113 (1.4) 33 (0.4) < B96 other specified bacterial agents as the cause of 130 (1.6) 59 (0.7) < diseases classified to other chapters Ch. II neoplasms, C00 D (5.3) 523 (6.6) < C18 malignant neoplasm of small intestine 26 (0.3) 33 (0.4) C50 malignant neoplasm of breast 106 (1.3) 101 (1.3) C54 malignant neoplasm of corpus uteri 33 (0.4) 28 (0.4) Ch. III diseases of the blood and blood-forming 439 (5.5) 213 (2.7) < organs and certain disorders involving the immune mechanism, D50 D89 D50 iron deficiency anaemia 162 (2.0) 59 (0.7) < D62 acute post-haemorrhagic anaemia 54 (0.7) 43 (0.5) D64 other anaemias 210 (2.6) 79 (1.0) < Ch. IV endocrine, nutritional and 1142 (14.4) 862 (10.9) < metabolic diseases, E00 E90 E03 other hypothyroidism 238 (3.0) 114 (1.4) < E11 non-insulin-dependent diabetes mellitus 541 (6.8) 373 (4.7) < E87 other disorders of fluid, electrolyte and 166 (2.1) 72 (0.9) < acid base balance Ch. V mental and behavioural disorders, F00 F (22.9) 326 (4.1) < F79 unspecified mental retardation 779 (9.8) 2 (0.0) < F84 pervasive developmental disorders 276 (3.5) F89 unspecified disorder of psychological 270 (3.4) development Ch. VI diseases of the nervous system, G00 G (17.9) 327 (4.1) < G40 epilepsy 1023 (12.9) 46 (0.6) < G45 transient cerebral ischaemic attacks and 90 (1.1) 97 (1.2) related syndromes G80 cerebral palsy 218 (2.7) 4 (0.1) < Ch. VII diseases of the eye and adnexa, H00 H (3.8) 74 (0.9) < H25 senile cataract 154 (1.9) 8 (0.1) < H40 glaucoma 33 (0.4) 24 (0.3) H54 visual impairment including blindness 64 (0.8) 2 (0.0) < Ch. VIII diseases of the ear and mastoid 116 (1.5) 57 (0.7) < process, H60 H95 H81 disorders of vestibular function 16 (0.2) 36 (0.5) H90 conductive and sensorineural hearing loss 16 (0.2) 2 (0.0) H91 other hearing loss 54 (0.7) 9 (0.1) < Ch. IX diseases of the circulatory system, I00 I (19.5) 1696 (21.4) I10 essential (primary) hypertension 748 (9.4) 1173 (14.8) < I48 atrial fibrillation and flutter 235 (3.0) 329 (4.1) < I50 heart failure 326 (4.1) 198 (2.5) < Ch. X diseases of the respiratory system, J00 J (15.7) 608 (7.7) < J15 bacterial pneumonia, not elsewhere classified 332 (4.2) 83 (1.0) < J18 pneumonia, organism unspecified 603 (7.6) 150 (1.9) < J45 asthma 136 (1.7) 119 (1.5)

6 162 Journal of Applied Research in Intellectual Disabilities Table 1 (continued) ICD-10 chapter Intellectual disabilities, n (%) Control group, n (%) P-value OR 95% CI Ch. XI diseases of the digestive system, K00 K (16.6) 862 (10.9) < K59 other functional intestinal disorders 364 (4.6) 70 (0.9) < K80 cholelithiasis 193 (2.4) 167 (2.1) K92 other diseases of digestive system 191 (2.4) 68 (0.9) < Ch. XII diseases of the skin and 197 (2.5) 102 (1.3) < subcutaneous tissue, L00 L99 L02 cutaneous abscess, furuncle and carbuncle 26 (0.3) 16 (0.2) L08 other local infections of skin and subcutaneous 29 (0.4) 11 (0.1) tissue L40 psoriasis 26 (0.3) 29 (0.4) L89 decubitus ulcer and pressure area 33 (0.4) 7 (0.1) < Ch. XIII diseases of the musculoskeletal system and 611 (7.7) 779 (9.8) < connective tissue, M00 M99 M16 coxarthrosis 116 (1.5) 190 (2.4) < M17 gonarthrosis 73 (0.9) 189 (2.4) < M79 other soft tissue disorders, not elsewhere 65 (0.8) 89 (1.1) classified Ch. XIV diseases of the genitourinary system, 981 (12.4) 435 (5.5) < N00 N99 N10 acute tubulo-interstitial nephritis 111 (1.4) 29 (0.4) < N30 cystitis 96 (1.2) 19 (0.2) < N39 other disorders of urinary system 627 (7.9) 212 (2.7) < Ch. XVII congenital malformations, deformations and 443 (5.6) 14 (0.2) < chromosomal abnormalities, Q00 Q99 Q21 congenital malformations of cardiac septa 19 (0.2) 2 (0.0) Q87 other specified congenital malformation 15 (0.2) 1 (0.0) syndromes affecting multiple systems Q90 down syndrome 339 (4.3) Ch. XVIII symptoms, signs and abnormal clinical 1494 (18.8) 983 (12.4) < and laboratory findings, not elsewhere classified, R00 R99 R07 pain in throat and chest 254 (3.2) 426 (5.4) < R10 abdominal and pelvic pain 356 (4.5) 197 (2.5) < R33 retention of urine 197 (2.5) 59 (0.7) < Ch. XIX injury, poisoning and certain other 1578 (19.9) 776 (9.8) < consequences of external causes, S00 T98 S06 intracranial injury 151 (1.9) 75 (0.9) < S72 fracture of femur 550 (6.9) 106 (1.3) < S82 fracture of lower leg, including ankle 326 (4.1) 110 (1.4) < Ch. XX external causes of morbidity 1615 (20.4) 804 (10.1) < and mortality, V01 Y98 W01 fall on same level from slipping, tripping and 788 (9.9) 250 (3.2) < stumbling W19 unspecified fall 389 (4.9) 132 (1.7) < Y83 surgical and other medical procedures as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure 148 (1.9) 121 (1.5) ICD-10, International Classification of Diseases and Related Health Problems, 10th Revision; Intellectual disabilities = case group; significant differences in bold.

7 Journal of Applied Research in Intellectual Disabilities 163 the intellectual disability group than in the control group, especially for the latter years (Table 2a). There were significant differences in those aged <60 for , in those aged for 2006 and , and those aged for 2009 and 2010 (Table 2a). No significant differences between case and control groups were found in those 70. There was a significant increase over time in all age groups in both the intellectual disability and control groups (Table 3). Chapter IV: endocrine, nutritional and metabolic diseases, E00 E90 Higher numbers of diagnoses were found for those aged <60, and in the intellectual disability group than in the control group (Table 2a). The differences were significant for 4 of the years in those aged <60, 8 of the years in those aged and for 3 years in those aged (Table 2a). However, no significant differences were found between the case and control groups for those aged 70 (Table 2a). The linear relationship over time reached significance (P < 0.001), with an increase in all age groups in both the intellectual disability and control groups (Table 3). Chapter VII: diseases of the eye and adnexa, H00 H59 Few individuals had diagnoses of the eye and adnexa. In some years, the control group did not have any individuals with such a diagnosis in some of the age groups (Table 2a). There was a significant linear increase for all age groups in the case group. For the control group, non-significant linear trends were found in all age groups, except for those aged 70 (Table 3). Chapter VIII: diseases of the ear and mastoid process, H60 H95 For diagnoses of diseases of the ear and mastoid process, 0.2% of those aged <60, and in both the case and control groups had been registered with such a diagnoses in any years from 2002 to 2009 (data not shown). The highest number (0.6%) of these diagnoses was in those aged in the case group in 2011 (data not shown). Where comparisons could be made, no significant differences were found (data not shown). In the case group, there was a significant linear increase for all age groups, except for those aged <60 (Table 3). Non-significant linear trends were found for all age groups in the control group except for those aged (Table 3). Chapter V: mental and behavioural disorders, F00 F99 The intellectual disability groups had higher numbers of mental and behavioural disorders than the control groups with significant differences in all age groups for all years. Values in the case group ranged from 1.0% (those aged <60 in 2003) to 9.2% (those aged 70 in 2012). Values in the control group ranged from 0.2% (in those aged <60 in 2006; those aged in 2003; those aged in ; and in those 70 in , 2005, and 2007) to 2.0% (in those aged 70 in 2012), with ORs ranging from 2.80 (<60 years in 2003) to ( 70 years in 2004) (data not shown). There was a significant linear increase over time in all age groups (Table 3). Chapter VI: diseases of the nervous system, G00 G99 The same patterns were seen here as seen in Chapter V, with significantly higher values in the case group for all age groups and for all years compared with the control group (Table 2a). There was also a significant linear increase over time in all age groups in both intellectual disability and control groups (Table 3). Chapter IX: diseases of the circulatory system, I00 I99 With two exceptions, non-significant differences in diagnoses of the circulatory system between the case and control groups were found for all study years for those aged <60, and (Table 2a). There was a significant difference in those aged 70 years for all years ( ), with higher values in the control group and with ORs ranging from 0.42 to 0.72 (Table 2a). There was a significant (P 0.001) increase over time in all age groups in both the intellectual disability and control groups (Table 3). Chapter X: diseases of the respiratory system, J00 J99 Analyses of diagnoses of the respiratory system revealed a significantly higher number of diagnoses in the intellectual disability group than the control group for nine of the study years in those aged <60 and 10 of the study years in those aged (Table 2b). In the case group, those aged had a significantly higher number of diagnoses in six of the years (2002, 2005 and ), and those aged 70 had a higher number of diagnoses in three of the years (2005, 2009

8 164 Journal of Applied Research in Intellectual Disabilities Table 2 Proportion of case and control group individuals in all age groups with a diagnosis in each chapter; P-values, odds ratio (OR) and 95% confidence intervals (CI) for group differences (a)

9 Journal of Applied Research in Intellectual Disabilities 165 Table 2 (continued) (b) Significant differences in bold; intellectual disabilities (ID) = case group; C = control group.

10 166 Journal of Applied Research in Intellectual Disabilities and 2011) than the control group. There was a significant linear increase (P < 0.001) over time in all age groups in both the intellectual disability and control groups (Table 3). Chapter XI: diseases of the digestive system, K00 K93 The number of people with diagnoses in this chapter was, in general, higher in the intellectual disability group than the control group (Table 2b). The differences reached significance for those aged < and ; in those aged in and ; in those aged for 2002, and 2010; and in those aged 70 in , 2006, 2009 and 2011 (Table 2b). In the control group, those aged showed a non-significant linear trend (P = 0.051). For all other age groups, there was a significant increasing linear trend over time (Table 3). Chapter XII: diseases of the skin and subcutaneous tissue, L00 L99 The number of people with skin diagnoses was generally low, with proportions ranging from 0.0 to 0.5% for all age groups in the years In some years and age groups, no individuals with such diagnoses in either the case or control group were found (data not shown). There were some significant differences between the intellectual disability and control groups, with higher numbers of diagnoses in the intellectual disability group for those aged in 2008 (0.4 versus 0.0, P = 0.050; OR 8.03, 95% CI ) and 2012 (0.9 versus 0.2, P = 0.011; OR 3.62, 95% CI ), and in those aged in 2012 (1.0 versus 0.4, P = 0.047; OR 2.44, 95% CI ) (data not shown). There was a significant increasing linear trend for all age groups in both the case and control groups (Table 3). Chapter XIII: diseases of the musculoskeletal system and connective tissue, M00 M99 No significant differences were found in the number of diagnoses in this chapter for those aged <60, and (Table 2b). In those aged 70 years, the number of diagnoses were significantly lower for the case group for 7 of the study years ( , 2007 and ), with ORs ranging from 0.32 to 0.53 (Table 2b). There was a significant (P < 0.001) increasing linear trend over time in all age groups in both the case and control groups (Table 3). Chapter XIV: diseases of the genitourinary system, N00 N99 There were more diagnoses in this chapter in all age groups in the intellectual disability group than in the control group (Table 2b). There were significant differences between groups for all years in those aged <60 and 60 64; in 8 years for those aged 65 69; and 6 years for those aged 70 years. ORs ranged from 2.22 to 4.52 for those aged <60, 2.85 to for those aged 60 64, for those aged and for those aged 70 years or older (Table 2b). There was a significant linear increase over time in all age groups in both the intellectual disability and control groups (Table 3). Chapter XVII: congenital malformations, deformations and chromosomal abnormalities, Q00 Q99 The number of diagnoses in chapter XVII was low in the control group, with no individuals with these diagnoses in many of the age groups in several years. Of the 14 comparisons that could be made, 11 revealed significantly higher numbers in the case group, with ORs ranging from 5.53 to (data not shown). There was a significant (P < 0.001) increase over time in all ages in the intellectual disability group and for those aged <60 in the control group (Table 3). In the control group, those aged 60 64, and 70 showed nonsignificant linear associations (Table 3). Chapter XVIII: symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified, R00 R99 For diagnoses in this chapter, those aged <60, and showed different patterns than those aged 70 years. Those in the case group aged <60 and had significantly higher numbers of diagnoses in 8 of the study years, and those aged had higher numbers of diagnoses in 6 years, compared with the control group (Table 2b). For those aged 70, no significant differences between the case and control groups were found (Table 2b). The linear trend over time reached significance with an increase in all age groups in both the intellectual disability and control groups (Table 3). Chapter XIX: injury, poisoning and certain other consequences of external causes, S00 T98 The numbers of primary or secondary diagnoses in chapter XIX were significantly higher for the case group

11 Journal of Applied Research in Intellectual Disabilities 167 than the control group, with few exceptions. Significant differences were found in eight or more of the years in all age groups (Table 2b). There was a significant linear trend over time with an increase in all age groups in both the intellectual disability and control groups (Table 3). Chapter XX: external causes of morbidity and mortality, V01 Y98 Significantly higher numbers of diagnoses in this chapter were found in the case group than the control group in seven or more of the years in all age groups (Table 2b). In addition, there was a significant linear trend over time with an increase in all age groups in both the case and control groups (Table 3). Discussion The results showed that the population of older people with intellectual disabilities had a higher number of several diagnoses than controls. While diseases such as congenital malformations, deformations and chromosomal abnormalities, and mental and behavioural disorders are to be expected in the case group, infections, diseases of the nervous system, genitourinary and respiratory diseases, injuries and unspecified symptoms, and external causes of morbidity were also more common in the case group over the years investigated (Table 1, Table 2a,b). It is recognized that people with intellectual disabilities have more health problems (McCarron et al. 2013) and have differences in overall health compared with the general population, including a decreased life expectancy, an increase in both morbidity and negative health determinants, and a higher risk of poor access to healthcare services (Scheepers et al. 2005). The results of our national population-based study are consistent with previous research showing that older people with intellectual disabilities are more prone to various diseases and health problems, although to our knowledge, no published studies have covered such a wide diagnostic spectrum. Research into patterns of disease, health problems and morbidity in people with intellectual disabilities is sparse, and this is especially true for older adults (Coppus 2013). It has been suggested that the ageing process starts earlier in people with intellectual disabilities, which carries an increased risk of morbidity and an earlier onset of age-related diagnoses, and could also be related to the syndromes associated with intellectual disabilities. The presence of infectious diseases, diseases in the blood and blood-forming organs, urogenital diseases, endocrinological diseases, nutritional and metabolic diseases, and symptoms and signs not classified elsewhere did not differ significantly between cases and controls in those aged 70 years (Table 2a,b), which may reflect that these diagnoses are not related to the ageing process alone. Evenhuis et al. (2001) have noted that healthy ageing in adults with intellectual disabilities is complex and affected by several specific factors. Conditions related to old age have to be considered in relation to syndrome-specific conditions, associated intellectual disabilities and conditions that are related to lifestyle, environment, health promotion and preventive practices. The results of our study do not provide the tools to pinpoint diagnoses that are caused by an earlier ageing process alone, rather than a combination of ageing and other factors. More research on morbidity during the ageing process in people with intellectual disabilities is therefore needed. One striking result was that older adults with intellectual disabilities aged 70 had significantly lower rates of tumours, CVD and musculoskeletal diseases compared with those in the same age group in the general population (Table 2a,b). Coppus (2013) reported that the overall cancer risk for people with intellectual disabilities is equal to that in the general population, but that there is a special distribution of cancer types, with an underrepresentation of solid tumours. This requires more attention. Haveman et al. (2010) conducted a literature review, and their results did not show that older people with intellectual disabilities had a lower number of individuals with musculoskeletal conditions. Other studies have indicated that even though cardiovascular conditions are one of the most common causes of death, the number of these conditions may be lower in people with intellectual disabilities than in the general population (Patja et al. 2001; Haveman et al. 2010). Conversely, there are studies that have reported a higher number of individuals with CVD among people with intellectual disabilities compared with the general population (Draheim 2006). A lower number of CVD diagnoses could be a result of differences in lifestyles, with, for example, lower rates of smoking and alcohol intake among people with intellectual disabilities (Heller & Sorensen 2013). The results from our study may also be a reflection of how healthcare and social services are distributed to older people with intellectual disabilities. It is known that the need for routine health screening, such as blood

12 168 Journal of Applied Research in Intellectual Disabilities Table 3 Chi-square test for linear trends over time in each diagnosis chapter for each age group in the case and control groups Age < 60 Age Age Age 70 ICD-10 chapter Intellectual disabilities Control group Intellectual disabilities Control group Intellectual disabilities Control group Intellectual disabilities Control group Ch. I certain infectious and parasitic <0.001 <0.001 < <0.001 <0.001 <0.001 <0.001 diseases, A00 B99 Ch. II neoplasms, C00 D48 < <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Ch. III diseases of the blood and <0.001 <0.001 < < <0.001 <0.001 blood-forming organs and certain disorders involving the immune mechanism, D50 D89 Ch. IV endocrine, nutritional and <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 metabolic diseases, E00 E90 Ch. V mental and behavioural < < <0.001 <0.001 <0.001 <0.001 disorders, F00 F99 Ch. VI diseases of the nervous <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 system, G00 G99 Ch. VII diseases of the eye and < < <0.001 adnexa, H00 H59 Ch. VIII diseases of the ear and < mastoid process, H60 H95 Ch. IX diseases of the circulatory <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 system, I00 I99 Ch. X diseases of the respiratory <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 system, J00 J99 Ch. XI diseases of the digestive < < <0.001 <0.001 <0.001 <0.001 system, K00 K93 Ch. XII diseases of the skin and <0.001 < <0.001 < <0.001 subcutaneous tissue, L00 L99 Ch. XIII diseases of the musculoskeletal <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 system and connective tissue, M00 M99 Ch. XIV diseases of the genitourinary <0.001 <0.001 < <0.001 <0.001 <0.001 <0.001 system, N00 N99 Ch. XVII congenital malformations, < < < deformations and chromosomal abnormalities, Q00 Q99 Ch. XVIII symptoms, signs and abnormal <0.001 <0.001 < <0.001 <0.001 <0.001 <0.001 clinical and laboratory findings, not elsewhere classified, R00 R99 Ch. XIX injury, poisoning and certain other < < <0.001 <0.001 <0.001 consequences of external causes, S00 T98 Ch. XX external causes of morbidity and mortality, V01 Y98 < < <0.001 <0.001 <0.001 Significant differences in bold; Intellectual disabilities = case group. pressure and cholesterol checks, increases with age, and it has been noted that older people with intellectual disabilities may have less access to screening and diagnostic services compared with the general population (Heller & Sorensen 2013). Fisher (2004) reported in her review that people with intellectual disabilities may have been caught between two systems, as general practitioners may believe that screening initiatives and health promotion for people with intellectual disabilities were the domains of specialists, thus creating a gap in the required care. This means that there is a risk that older people with intellectual

13 Journal of Applied Research in Intellectual Disabilities 169 disabilities are underdiagnosed and suggests our findings could also be a result of other causes. Therefore, more research on the reasons underlying our findings is necessary. Another important result was that the number of all diagnoses, except for chapters VII, VIII and XVII, increased during the study period in both cases and controls (Table 3). Statistics from the Swedish National Board of Health and Welfare (2014) showed that inpatient care registrations increased during the last decade. This could be an actual increased utilization or it could reflect more thorough registrations by healthcare agencies. The National Board of Health and Welfare (2014) proposed that it was due to the latter. However, the pattern was similar in both intellectual disability and control groups, and regardless of the reason, the results indicate that it is common for older people with intellectual disabilities to be admitted to hospital with a variety of diseases and health problems. This requires organizational resources and also staff knowledge so that the health system can provide holistic care for this population. Methodological Considerations Our study has strengths and weaknesses, and the results should be interpreted with these in mind. The case control design increased the internal validity and the possibility of drawing valid conclusions. The study was based on a unique amalgamation of data from two public national registers and included data for a large group of people aged 55 and older who were registered with intellectual disabilities during 2012, along with a matched control group, who were followed retrospectively for 11 years. The validity of inpatient care in the Swedish NPR has been investigated in a review of 132 papers by Ludvigsson et al. (2011). They concluded that the validity was high for most diagnoses, with a positive predictive value of 85 95% in general (Ludvigsson et al. 2011). The present authors have not been able to find another study with a similar design and sample size. It is probable that the sample is representative of the Swedish population, which, together with the high validity of the public compulsory NPR, means that these results could be generalized to similar contexts. However, our sample was not divided into levels of intellectual disabilities. Such an approach could have provided interesting and more in-depth knowledge about the occurrence of diagnoses in people with mild, moderate and severe intellectual disabilities. It was not possible to perform these divisions based on the NPR data. In addition, the diagnosis was registered by inpatient care and the numbers may therefore be underestimated. It is possible that people had the diagnosis registered in outpatient clinics, and primary care. To register a diagnosis as present regardless the number of registrations during 1 year could also lead to an underestimation of recurrent diagnoses. However, making the opposite assumption would have yielded an overestimation of chronic diseases with several registrations for the same condition. However, this would be the case in both groups and would not affect the ratio between the groups. The control group was matched only on birth year and sex, which could have an implied risk for selection bias and therefore impact on internal validity. It would have been desirable to match on other demographic variables such as place of residence, socio-economic status and educational level; however, no such data were available in the registers. It is also important to acknowledge that the registers did not give specific information on when an illness first occurred, making it more difficult to relate the diagnoses to the ageing process. To some extent, differences may also be related to cohort effects, meaning that people with intellectual disabilities that survived and turned 55 years or older might be healthier than their younger non-surviving peers. Nonetheless, this provides valuable information about earlier onset of diagnoses among people with intellectual disabilities compared with the general population. However, the use of both primary and secondary diagnoses meant that the present authors obtained the most comprehensive view possible. Another limitation is that the ICD-10 is not only a classification of diseases. The present authors decided to include all diagnoses, including health problems, as they relate to the health status of the individual, and may reflect the difficulties people with intellectual disabilities may have when they describe their disease. The risk of type II error (Altman 1991), that is, mass significance, may have been a threat to the statistical validity. However, with such a large study population, the risk was judged to be small. Conclusions Infections, diseases of the nervous system, genitourinary and respiratory diseases, injuries, as well as unspecified symptoms and external causes of morbidity are more common in people ageing with intellectual disabilities

14 170 Journal of Applied Research in Intellectual Disabilities compared with the general population. The higher numbers do not seem to be a result of the ageing process alone. The lower number of individuals with cancer, CVD and musculoskeletal diseases in those with intellectual disabilities aged 70 years requires further attention, and more research is needed on the reasons behind these findings. Implications This study shows that older people with intellectual disabilities have a higher number of individuals with some diseases and health problems compared with the general population, while other diagnoses occur at lower rates. This requires specific staff knowledge and organizational resources if the health system is to provide high-quality care for this population. It is also important that people with intellectual disabilities have access to screening procedures and the regular health checks that are needed during the ageing process to detect symptoms and signs of diseases (Robertson et al. 2014). Acknowledgments We should like to acknowledge Forte; the Swedish Research Council for Health, Working Life and Welfare (Grant No ), the Faculty of Medicine, Lund University, Sweden, and the Greta and Johan Kock s Foundation, for financing this study. We would also like to acknowledge the cooperation of the FUB, The Swedish National Association for Persons with Intellectual Disability. Registers have been delivered by the Swedish National Board of Health and Welfare (Stockholm, Sweden) and Statistics Sweden ( Orebro, Sweden). Conflict of Interest There are no conflict of interests. Correspondence Any correspondence should be directed to Magnus Sandberg, Department of Health Sciences, Lund University, P.O. Box 157, SE Lund, Sweden ( Magnus.Sandberg@med.lu.se). References Altman D. G. (1991) Practical Statistics for Medical Research. Chapman & Hall, London. Anell A., Glenngard A. H. & Merkur S. M. (2012) Sweden: health system review. Health Systems in Transition 14, Bigby C. (2007) Aging with an Intellectual Disability. In: Comprehensive Guide to Intellectual & Developmental Disabilities (eds I. Brown & M. Percy) pp Brookes Publishing Co, Baltimore, MA. Blackman N. (2007) People with learning disabilities an ageing population. The Journal of Adult Protection 9, 3 8. Center J., Beange H. & McElduff A. (1998) People with mental retardation have an increased prevalence of osteoporosis: a population study. American Journal of Mental Retardation 103, Coppus A. M. (2013) People with intellectual disability: what do we know about adulthood and life expectancy? Developmental Disabilities Research Reviews 18, Danielsson M. & Talb ack M. (2012) Public health: an overview: Health in Sweden: The National Public Health Report Chapter 1. Scandinavian Journal of Public Health, 40, Draheim C. C. (2006) Cardiovascular disease prevalence and risk factors of persons with mental retardation. Mental Retardation and Developmental Disabilities Research Reviews 12, Evenhuis H., Henderson C. M., Beange H., Lennox N. & Chicoine B. (2001) Healthy ageing adults with intellectual disabilities: physical health issues. Journal of Applied Research in Intellectual Disabilities 14, 175. Evenhuis H. M., Hermans H., Hilgenkamp T. I., Bastiaanse L. P. & Echteld M. A. (2012) Frailty and disability in older adults with intellectual disabilities: results from the healthy ageing and intellectual disability study. Journal of the American Geriatrics Society 60, Fisher K. (2004) Health disparities and mental retardation. Journal of Nursing Scholarship 36, Haveman M., Heller T., Lee L., Maaskant M., Shooshtari S. & Strydom A. (2010) Major health risks in aging persons with intellectual disabilities: an overview of recent studies. Journal of Policy and Practice in Intellectual Disabilities 7, Haveman M., Perry J., Salvador-Carulla L., Walsh P. N., Kerr M., Van Schrojenstein Lantman-de Valk H., Van Hove G., Berger D. M., Azema B., Buono S., Cara A. C., Germanavicius A., Linehan C., M a att a T., Tossebro J. & Weber G. (2011) Ageing and health status in adults with intellectual disabilities: results of the European POMONA II study. Journal of Intellectual & Developmental Disability, 36, Heller T. & Sorensen A. (2013) Promoting healthy aging in adults with developmental disabilities. Developmental Disabilities Research Reviews 18, Janicki M. P., Davidson P. W., Henderson C. M., McCallion P., Taets J. D., Force L. T., Sulkes S. B., Frangenberg E. & Ladrigan P. M. (2002) Health characteristics and health services utilization in older adults with intellectual disability living in community residences. Journal of Intellectual Disability Research 46, Kapell D., Nightingale B., Rodriguez A., Lee J. H., Zigman W. B. & Schupf N. (1998) Prevalence of chronic medical conditions