Patients With Ulcerative Colitis Miss More Days of Work Than the General Population, Even Following Colectomy

GASTROENTEROLOGY 2013;144:536 543 Patients With Ulcerative Colitis Miss More Days of Work Than the General Population, Even Following Colectomy MARTIN NEOVIUS, ELIZABETH V. ARKEMA, PAUL BLOMQVIST, ANDERS EKBOM, and KARIN E. SMEDBY Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden BACKGROUND & AIMS: It is unclear whether colectomy restores the ability of patients with ulcerative colitis (UC) to work to precolectomy levels. We estimated the burden of sick leave and disability pension in a population-based cohort of patients with UC and the effects of colectomy. METHODS: We performed a register-based cohort study using the Swedish National Patient Register and identified working-age patients with UC in 2005 (n 19,714) and patients who underwent colectomies between 1998 and 2002 (n 807). Sick leave and disability pension data were retrieved from Statistics Sweden (1995 2005). Data from each patient in the study were compared with those from 5 age-, sex-, education-, and countymatched individuals from the general population. RE- SULTS: In 2005, 15% of patients with prevalent UC received a disability pension, compared with 11% of the general population, and 21% vs 13% had 1 sick leave episode (P.001 for each comparison). The annual median work days lost was 0 in both groups, but patients with UC had higher mean (65 vs 45 days; difference, 20; 95% confidence interval [CI], 18 22 days) and 75th percentile work days lost (37 vs 0 days; difference, 37; 95% CI, 36 38 days). Among patients who underwent colectomies, annual days lost increased from a mean of 40 (median, 0) days 3 years before surgery to 141 (median, 99) days during the year of surgery (P.001). The number then decreased to a mean of 85 days 3 years after surgery (median, 0). The corresponding 75th percentile days were 17, 207, and 130, respectively. Three years after colectomy, 12% did not work at all compared with 7.2% of the general population (risk difference, 5.2%; 95% CI, 2.7% 7.7%) and compared with 5.9% 3 years before colectomy (P.001). CONCLUSIONS: Patients with UC miss more work days than the general population in Sweden. Although most patients had no registered work loss 3 years after colectomy, work loss was not restored to presurgery or general population levels in the group that underwent colectomy during several years of follow-up. Keywords: Inflammatory Bowel Disease; Productivity; Sweden; Complications. American studies ranged from $1800 to $8000, whereas European estimates ranged from 500 to 14,000. 1 This variation may be explained by a number of factors, including study population characteristics and small sample sizes. Few studies have been large enough to permit robust analyses of subgroups of patients with UC by age, sex, or education, and only a few have made comparisons with the general population. 4,5,7,8 Also, most studies have been based on self-reported work loss and could thereby be affected by both nonresponse and recall bias. 3 5,9 11 Several studies have reported indirect costs associated with inflammatory bowel disease (IBD) as a group without distinguishing between UC and Crohn s disease, making comparisons with disease-specific estimates difficult. 2,4,10 It is also unclear whether colectomy restores work ability to precolectomy levels or even general population levels. It has been reported that up to 40% of patients with UC eventually require surgical intervention, 12 but there are few longitudinal studies comparing sick leave and disability pension before and after colectomy. 10,13 We investigated sick leave and disability pension in a nationwide Swedish cohort of patients with prevalent UC and in the general population overall as well as by age, sex, and educational level. We also examined sick leave and disability pension before and after colectomy. Patients and Methods Setting In 2006, Sweden had a population of 9.1 million (Statistics Sweden; www.scb.se). The Swedish health care system was tax funded and offered universal access, with prescription drugs provided free of charge above an annual threshold of SEK 1800 (approximately $250). The Swedish social insurance system provided compensation for sick leave and disability pension, both of which may be complete or partial. Data were recorded by the Swedish Social Insurance Agency. The retirement age was 65 years, but employees had the right to retire at 61 years of age or continue to work until 67 years of age. Ulcerative colitis (UC) develops in many patients at an early age. The ensuing morbidity is therefore associated with high societal costs due to work disability. 1 Estimates of indirect costs due to work loss among patients with UC have varied greatly in previous studies. 2 6 In a review, annual indirect costs per patient with UC in Abbreviations used in this paper: CI, confidence interval; COPD, chronic obstructive pulmonary disease; ICD, International Classification of Diseases; LISA, longitudinal integrated database for health insurance and labor market studies. 2013 by the AGA Institute 0016-5085/$36.00 http://dx.doi.org/10.1053/j.gastro.2012.12.004

March 2013 ULCERATIVE COLITIS, COLECTOMY, AND WORK LOSS 537 Identification of Patients With UC A cohort of patients with at least 2 records of a main or contributory UC diagnosis (International Classification of Diseases [ICD]-10 K51, ICD-9 556) was identified through the National Patient Register kept by the Swedish National Board of Health and Welfare using data from between 1987 and 2005. This register holds individual-level information on inpatient care by county since 1964 (nationwide since 1987) and on nonprimary outpatient care since 2001. 14 The proportion of nonregistrations for somatic short-term care including surgery has been estimated to be less than 2%. 14 Patients with registered Crohn s disease diagnoses were excluded due to the resulting diagnostic ambiguity. Information on colectomy was collected through surgical procedure coding for the period from 1980 to 2005 (JFH, JFG60, JGB50, JGB60; 4650, 4654). The validity of surgical procedure coding in the National Patient Register has been reported to be high, with an estimated 0.1% of procedures miscoded. 15 In an exploratory analysis of potential differences in work loss by type of surgical procedure, we grouped patients into those receiving a pouch (directly or within 2 years after an ileostomy; JFH30/33), an ileorectal anastomosis (directly or within 2 years after an ileostomy; JFH00/01), or an ileostomy (JFH10/11/20). In a complementary analysis, we also considered rehospitalizations within 30 days for any reason or an index admission with a length of stay greater than the 90th percentile. Identification of General Population Comparators General population comparators were sampled from the Register of the Total Population kept by Statistics Sweden. The register covers the entire Swedish population and includes information on age, sex, and county of residence as well as dates of birth, death, immigration, and emigration. For each patient with UC, we randomly sampled 5 comparators from this register using age ( 1 year), sex, education, and county of residence as matching factors. Outcome Assessment The longitudinal integrated database for health insurance and labor market studies (LISA), which includes data on sick leave and disability pension, integrates administrative information from the labor market and educational and social sectors from 1990 onward on all individuals 16 years or older registered as residents in Sweden, and it is updated annually. 16 LISA includes personal data on work-related and socioeconomic variables, including education level, marital status, unemployment status, and net days per year of sick leave and disability pension (annual data retrieved for 1995 2005). Data from LISA were linked to patients with UC and their general population comparators using each Swedish resident s unique personal identification number. The outcome was net annual days of sick leave and disability pension (maximum of 365). All-cause mortality data were retrieved from the Causes of Death Register to assess vital status during follow-up in the longitudinal analysis and to determine vital status on January 1, 2006, for the analysis of patients with prevalent UC. Sick leave. During the study period, the first day of a sick leave episode was not compensated ( waiting period ). After the 7th day of the sick leave, a doctor s note confirming the medical diagnosis was required. Compensation from the 2nd to the 14th day of each sick leave episode was paid by the employer from 1998 onward ( sick pay period ; between January 1997 and March 1998, this period was from the 2nd to the 28th day). After the 14th day, compensation was paid by the Social Insurance Agency. Therefore, only sick leave episodes 14 days were recorded in the LISA database. However, a patient with an episode occurring within 5 days of a previous one did not require a new waiting period or sick pay period, and patients with multiple short-term episodes could waive these periods. Because patients with UC and comparators with 0 days registered may in fact have had one or a few sick leave episodes 14 days, the group was denoted 0 days to acknowledge this uncertainty. Disability pension. In 2003, disability pension was replaced by 2 types of compensation depending on age. Sickness compensation was introduced among individuals 30 to 64 years old, whereas individuals 19 to 29 years old were eligible for activity compensation. Both sickness and activity compensation could be time limited or permanent and required at least 25% reduction in work capacity expected to remain for at least 1 year. In this study, disability pension was used to denote either disability pension (1995 2002) or sickness/activity compensation (2003 2005). Follow-up of Patients Who Underwent Colectomy In analyses of work loss before and after colectomy performed between 1998 and 2002, patients were followed up from 3 years before to 3 years after the year of colectomy. These analyses included patients aged 19 to 59 years at colectomy to reduce the likelihood of patients retiring due to old age during follow-up. In a calendar period analysis, patients with UC who underwent colectomy in 1998 and in 2002, and their general population comparators, were followed up from 1995 to 2005, permitting assessment of work loss for up to 7 years before surgery (patients who underwent colectomy in 2002) and 7 years after surgery (patients who underwent colectomy in 1998). Comorbidity To investigate the impact of comorbidity on work loss, we assessed history of malignancies (ICD-9 and ICD-10 chapter 2) and specifically colorectal cancer (ICD-10 C18 C20, ICD-9 153 154), depression (ICD-10 F32 F33, ICD-9 300E/311), chronic obstructive pulmonary disease (COPD; ICD-10 J41 J44, ICD-9 491 492, 496), and cardiovascular disease (ICD-10 chapter 9, ICD-9 chapter 7) using records of hospital admissions and nonprimary outpatient care visits in the National Patient Register (1987 2005). 14 Statistics Due to the non-normal distribution of days on sick leave and disability pension, we described the distribution by categories ( 0, 1 49, 50 199, 200 364, and 365 days) with the arithmetic mean, the median (50th percentile), and the 75th percentile. The reason for presenting the arithmetic mean despite the non-normal distribution is that this metric multiplied by the number of patients represents the overall burden to society and has been described as the metric of greatest policy interest, 17 whereas the full distribution and percentile days more clearly reflect the proportion of patients affected. For analysis of patients with prevalent UC, the mean, median, and 75th percentile were calculated overall and by age, sex, education level, and colectomy status. The differences in mean, median, and 75th percentile net annual days between patients with UC and matched general population comparators were computed with 95% confidence intervals (CIs) estimated by non-

538 NEOVIUS ET AL GASTROENTEROLOGY Vol. 144, No. 3 parametric bootstrapping to avoid distributional assumptions. In multivariable regression models using nonparametric bootstrapping, we additionally explored the difference in work days lost between patients with UC and general population comparators, adjusting for history of COPD, cardiovascular disease, malignancies, and depression. For the longitudinal analysis of patients who underwent colectomy, mean, median, and 75th percentile days of work loss per year were estimated, as well as the categorical distribution from 3 years before to 3 years after the year of colectomy. In a multivariable regression model, we explored whether the type of initial surgical procedure was associated with work days lost during the year of colectomy and 3 years after, adjusting for age, sex, educational level, and work days lost during the year before colectomy. Statistical analyses were performed using SAS statistical software (version 9.2; Cary, NC) and Stata (version 11.2; College Station, TX). Ethics The study was approved by the Regional Ethics Committee at Karolinska Institutet (Stockholm, Sweden). Table 1. Characteristics of Register-Identified a Patients With Prevalent UC Aged 19 to 64 Years on January 1, 2006, in Sweden Overall Underwent colectomy Total, n (%) 19,714 (100) 3070 (100) Women 9044 (46) 1231 (40) Men 10,670 (54) 1839 (60) Age (y) in 2006, mean (SD) 44 (12) 46 (11) At identification 36 (13) 32 (11) At colectomy 35 (11) Age (y),n(%) 19 29 2891 (15) 279 (9) 30 39 4351 (22) 626 (20) 40 49 4956 (25) 860 (28) 50 59 5227 (27) 901 (29) 60 64 2289 (12) 404 (13) Education (y),n(%) 9 3211 (16) 549 (18) 10 12 11,150 (57) 1738 (57) 12 5353 (27) 783 (26) Comorbidity history (%) b Colorectal cancer 153 (0.8) 101 (3.3) Colon cancer 124 (0.6) 82 (2.7) Rectal cancer 38 (0.2) 26 (0.8) Depression 670 (3.4) 118 (3.8) Malignancy 2717 (13.8) 452 (14.7) COPD 504 (2.6) 104 (3.4) Cardiovascular disease 2867 (14.5) 538 (17.5) a Requiring at least 2 registered visits listing UC in inpatient and/or nonprimary outpatient care. b Assessed via diagnoses in inpatient care (1987 2005) and nonprimary outpatient care (2001 2005) in the Swedish National Patient Register. Results We identified 19,714 patients with prevalent UC aged 19 to 64 years alive on January 1, 2006, with at least 2 listings of UC in inpatient and/or nonprimary outpatient care (Table 1). More men than women had undergone colectomy (P.001), and a history of colorectal cancer was more common among patients who underwent colectomy than in the prevalent UC population overall (P.001). Prevalence of Sick Leave and Disability Pension Fifteen percent of patients with prevalent UC compared with 11% in the matched general population received disability pension benefits in 2005, and 21% compared with 13% had at least one registered sick leave episode (both P.001; Figure 1). In total, 33% of patients with UC and 22% in the general population had a registered sick leave episode or disability pension in 2005 (P.001), compared with 43% of patients who had undergone colectomy. The prevalence of having a disability pension was higher among women, older individuals, and those with a lower educational level in both patients with UC and the general population (Figure 1). The prevalence of sick leave was also higher among women but varied less by age and educational level. In all subgroups, patients with UC had a higher prevalence of sick leave and disability pension than the general population. Days of Sick Leave and Disability Pension The distribution of work days lost in 2005 was non-normal, with a median of 0 days in both patients with UC and the general population (Figure 2). There was a statistically significant association between UC status and categories of work days lost, with greater work loss in the UC group than in the general population (P.001; Figure 2). Sixty-seven percent of patients with UC compared with 78% in the general population did not have any registered work days lost in 2005, and 11% of patients with UC (15% of patients with UC who underwent colectomy) were absent all days of the year compared with 8% in the general population (P.001). Among patients with prevalent UC as well as general population comparators, both the mean and the 75th percentile annual work days lost were generally higher among women than men, among older than younger individuals, and among those with a lower compared with higher level of education (Table 2). The median differences were 0 in all groups except for 60 to 64 year olds, reflecting that at least 50% of patients with UC and the general population had no registered work days lost in every subgroup except the oldest. Mean work days lost were consistently higher in patients with UC compared with the general population, with a difference ranging from 11 in 19 to 29 year olds to 44 additional days annually in patients who underwent colectomy (Table 2). For all subgroups defined by age and educational level, the variation in mean differences in lost work days was larger in the UC patient group than between patients with UC and general population comparators. In a multivariable regression model adjusted for age, sex, and educational level, patients with UC had on average 20 more work days lost than the general population

March 2013 ULCERATIVE COLITIS, COLECTOMY, AND WORK LOSS 539 Figure 1. Proportion of patients on any disability pension or sick leave in 2005 in the Swedish register identified UC population (n 19,557) and in matched general population comparators (n 97,785) matched 5:1 by age, sex, education, and county. The colectomy subgroup refers to patients with UC who have undergone a colectomy. Their general population comparators are matched by age, sex, education, and county but not colectomy status. The bars represent a mix of full-time and part-time sick leave and disability pension. Some sick leave episodes 14 days were not captured due to the 1-day waiting period and the 13-day sick pay period, which could be waived only under certain circumstances. Figure 2. Distribution of days on sick leave and disability pension in 2005 in the Swedish register identified UC population and in matched general population comparators matched 5:1 by age, sex, education, and county. For 157 patients, we were unable to identify matched comparators. These 157 patients were dropped. 0 days may include sick leave episodes 14 days. (95% CI, 18 22; Supplementary Table 1). Further adjustment for history of COPD, cardiovascular disease, depression, and malignancy decreased the estimate to 12 days (95% CI, 11 14). Older age, lower level of education, female sex, and each comorbidity were all independently and significantly associated with greater number of work days lost (P.001). Longitudinal Work Loss in Relation to Colectomy Among all patients with prevalent UC identified through 2005, 16% underwent colectomy (Table 1). Of these, 807 patients underwent colectomy between 1998 and 2002 and qualified for follow-up of work loss for a minimum of 3 years before and after surgery. Twenty-eight percent of these patients had work days lost registered 3 years before colectomy, which increased to 42% the year before colectomy and to 90% the year of colectomy (Figure 3). The median remained at 0 days up to the year of colectomy. From 1 year before to 1 year after the year of colectomy, mean annual work days lost increased from 58 to 112, the median from 0 to 44, and the 75th percentile from 67 to 204 days. More than half (55%) of the patients worsened in terms of lost work days, 15% improved, 25% had 0 days, and 5% had 365 annual days both 1 year before and 1 year after the year of colectomy. Although median work days lost returned to presurgery levels ( 0 days) 3 years after surgery, both mean and 75th percentile work days lost remained considerably higher

540 NEOVIUS ET AL GASTROENTEROLOGY Vol. 144, No. 3 Table 2. Annual Days of Sick Leave and Disability Pension in 2005 in Patients With Register-Identified a UC and Matched General Population Comparators Matched 5:1 by Age, Sex, County of Residence, and Education Level Annual days of sick leave and disability pension n Mean Median 75th Percentile Difference (95% CI) Patients with UC General population Patients with UC General population Patients with UC General population Patients with UC General population Mean Median 75th percentile Overall 19,557 b 97,785 65 45 0 0 37 0 20 (18 22) 0 (0 0) 37 (36 38) Women 8982 44,910 79 56 0 0 92 10 23 (20 26) 0 (0 0) 82 (79 85) Men 10,575 52,875 52 35 0 0 11 0 17 (15 19) 0 (0 0) 11 (10 12) Age (y) 19 29 2813 14,065 20 9 0 0 0 0 11 (9 13) 0 (0 0) 0 ( 1 to1) 30 39 4311 21,555 36 21 0 0 4 0 15 (12 17) 0 (0 0) 4 (3 5) 40 49 4932 24,660 59 41 0 0 29 0 18 (15 21) 0 (0 0) 29 (28 30) 50 59 5222 26,110 85 63 0 0 136 20 22 (18 26) 0 (0 0) 115 (105 126) 60 64 2279 11,395 139 101 8 0 365 198 39 (32 46) 8 ( 2 to 18) 168 (166 170) Education (y) 9 3116 15,580 112 89 0 0 274 183 22 (17 28) 0 (0 0) 91 (57 126) 10 12 11,142 55,710 63 43 0 0 35 0 21 (18 23) 0 (0 0) 35 (34 36) 12 5299 26,495 40 23 0 0 1 0 17 (14 19) 0 (0 0) 1 (0.2 2) Colectomy c No 16,514 82,570 60 44 0 0 23 0 15 (14 17) 0 (0 0) 23 (22 24) Yes 3043 15,215 92 48 0 0 182 0 44 (39 48) 0 ( 1 to 1) 182 (181 183) NOTE. Some sick leave episodes 14 days were not captured due to the 1-day waiting period and the 13-day sick pay period (waived only under certain circumstances). 95% CI was estimated using nonparametric bootstrapping. a Requiring at least 2 registered visits listing UC in inpatient (1987 2005) and/or nonprimary outpatient care (2001 2005). b For 157 patients, we were unable to identify matched comparators. These 157 patients were dropped from analyses. c The colectomy subgroup refers to patients with UC who had undergone a colectomy. Their comparators were matched on age, sex, education, and county but not colectomy status. among patients who underwent colectomy compared with general population comparators (mean: 85 vs 44 days; difference, 41; 95% CI, 30 52; 75th percentile: 130 vs 0 days; difference, 130; 95% CI, 72 188; Figure 3). After 3 years, 12.4% were fully work disabled compared with 5.9% 3 years before colectomy (P.001), a level almost twice as high as in the general population (12.4% vs 7.2%; risk difference, 5.2%; 95% CI, 2.7% 7.7%). Type of colectomy. During 3 years of follow-up after surgery, we did not observe any large differences in mean, median, or 75th percentile days lost by type of surgery (Figure 4). Age. Similar to the findings in the cross-sectional analysis (Table 2), age was strongly associated with levels of sick leave and disability pension before and after colectomy, but the trend in means and medians over time was similar among patients younger than 40 years versus 40 years of age and older (Supplementary Figure 1). Calendar period. We did not observe any obvious calendar period differences in patients who underwent colectomy in 1998 compared with patients who underwent colectomy in 2002 (Supplementary Figure 2). Extending follow-up to 7 years after colectomy showed that the mean, median, and 75th percentile number of days remained stable from 2 to 3 years after colectomy at least up to 7 years. Complications. In an exploratory analysis grouping patients based on the presence or absence of complications (defined as 30-day rehospitalization for any cause after colectomy or an index colectomy admission length of stay greater than the 90th percentile), patients with complications had greater mean and 75th percentile, but not median, work days lost 3 years after colectomy (Supplementary Figure 3). Discussion In this large nationwide study of patients with prevalent UC in 2005, we found that 33% of patients with UC versus 22% in the general population experienced sick leave or received a disability pension. Patients with UC lost an average of 20 more work days annually compared with the general population, and the 75th percentile differed by 37 days. There was no difference in the median days lost, reflecting that at least 50% of the individuals in both groups had no registered work loss. In 807 patients with UC who underwent colectomy monitored for up to 7 years after surgery, a rapid increase in mean and 75th percentile, but not median, days on sick leave and disability pension occurred before colectomy. Lower levels were observed postoperatively, and the majority of the patients (57%) had returned to full-time work 3 years after colectomy. However, neither the mean nor the 75th percentile days lost returned to the level of the general population or to precolectomy levels during follow-up, indicating that the net impairment affected at least 25% of the patients. There were no obvious differences by type of initial surgery in the development of work days lost after colectomy. We are unaware of any earlier studies investigating sick leave and disability pension development in relation to colectomy in patients with UC. There are some data on work capacity from a Danish study of 49 patients with UC who underwent an ileal pouch-anal anastomosis, in which 6% reported reduced work capacity postoperatively com-

March 2013 ULCERATIVE COLITIS, COLECTOMY, AND WORK LOSS 541 Figure 3. Patients with register-identified UC who underwent colectomy between 1998 and 2002 (n 807) and matched general population comparators in a longitudinal analysis of annual days of sick leave and disability pension from 3 years before to 3 years after colectomy matched 5:1 by age, sex, education, and county. Some sick leave episodes 14 days were not captured due to the 1-day waiting period and the 13-day sick pay period, which could be waived only under certain circumstances. The figures show the full distribution of days in categories including median and 75th percentile days (upper and middle panels) and mean days (lower panel). Figure 4. Mean, median, and 75th percentile days of sick leave and disability pension by type of initial surgery in register-identified patients with UC who underwent colectomy between 1998 and 2002. Some sick leave episodes 14 days were not captured due to the 1-day waiting period and the 13-day sick pay period, which could be waived only under certain circumstances. Pouch includes patients who first had a colectomy and ileostomy followed by a pouch operation within 2 years. pared with 88% preoperatively. 13 Sixty-seven percent of the patients were employed full-time postoperatively. Several studies have reported work loss in patients with UC or undifferentiated IBD but were limited by low response rates, misclassification, and small sample sizes. Longobardi et al 5 found a 1.2 times greater risk of labor force nonparticipation the year preceding diagnosis in Canadian patients with IBD (n 187) compared with non-ibd respondents. The investigators noted that they may have included up to 50% non-ibd patients due to reliance on self-report of IBD, resulting in an underestimate of the influence of IBD on work loss. In a similar study from the United States, patients with IBD had 1.5 times the odds of labor force nonparticipation than non-ibd patients; there was no increased odds for asymptomatic patients (n 82) but twice the odds for symptomatic patients with IBD (n 105). 4 The investigators did not find any differences in maintaining em-

542 NEOVIUS ET AL GASTROENTEROLOGY Vol. 144, No. 3 ployment during 12 months among patients with IBD compared with non-ibd respondents in the Canadian study or the US study. 4,5 Another Canadian study estimated the odds of labor force nonparticipation to be twice that of the general population among 80 patients with administrative claims for IBD. 7 We found a prevalence ratio of 1.4 for disability pension compared with matched general population comparators (15% vs 11%), which is in the range of these previous US and Canadian studies. In a study of 359 Dutch patients with UC, Boonen et al 3 reported that 28% of men and 20% of women with UC had chronic work disability compared with 12% and 9% among age- and sex-matched comparators. The estimates for disability pension among the patients with UC were lower in our study, but the proportions for the general population were similar. Boonen et al reported no difference by sex, but a higher proportion of disability was found among younger and more educated patients. In contrast, we found that Swedish women, patients as well as the general population, had more work loss than men. Furthermore, we observed increasing absolute differences with age and lower educational level for patients with UC versus the general population. Our results also differ from those of a study of 334 Norwegian patients with UC, 9 which found similar or lower proportions (depending on age) of self-reported disability pension in patients with UC compared with the general population. Given the chronic relapsing course of UC with a need for hospitalizations and surgery in some patients, 6,10,12 the increased levels of both sick leave and disability pension compared with the general population are not surprising although not universally found. 9 For many patients with UC, keeping a job may depend on close access to a toilet, and patients with stomas or pouches might face additional practical obstacles. 10,13 Furthermore, major surgery such as colectomy may have social as well as psychological consequences, both of which may increase work loss. Our results indicate that comorbidity, such as COPD, cardiovascular disease, malignancies, and depression, explains some of the mean work loss difference compared with the general population. However, it is unclear whether these characteristics are confounders or mediators. For example, psychiatric disorders may be caused by UC or colectomy, and chronic inflammation may also increase the risk of cardiovascular disease and malignancies. Therefore, the results of our exploratory analyses including comorbidities should be interpreted with caution. However, some support for a role of postsurgical complications was rendered by the findings of greater work loss 3 years after colectomy among patients with a long postoperative stay or rehospitalization within 30 days of colectomy. Labor market inertia may also contribute to continued work loss despite health improvements after a long sick leave episode, especially in patients who underwent colectomy who may also need repeated surgery and postsurgical convalescence periods. To our knowledge, this is the largest study on productivity losses in patients with UC to date and the first longitudinal study on sick leave and disability pension in relation to colectomy. Also, the investigation is population based and relies on comprehensive register-retrieved data instead of self-reported information more prone to bias. Another strength is the use of general population comparators individually matched to each patient with UC on productivity-related factors. Using a register-based design, attrition was avoided, and the large sample size allowed for assessment of both subgroup variations and calendar period effects. There are also limitations to consider. The identification of patients with UC was based on diagnoses from inpatient and nonprimary outpatient care, an identification method with a specificity of approximately 90% for inpatient care. 18 It is likely that most patients with prevalent UC visited a gastroenterologist or surgeon, or required hospitalization, at least twice during the study period and were thereby included, but we opted to exclude patients with records of both UC and Crohn s disease, possibly excluding some true cases of UC. The Social Insurance Agency data used do not include sick leave episodes 14 days because these are covered by the employer, resulting in some underestimation of lost work days, but this also applies to our comparator population. Another limitation is that Sweden has a generous welfare system, potentially making our results less generalizable to other countries. Although we addressed potential confounding by age, sex, geography, and education by matching, as well as comorbidity in multivariable analyses, we did not have data on smoking and obesity, 2 important predictors of work loss. 19,20 However, for these to be confounders in our study, they must also be associated with UC. Also, we could not account for physical labor types and long working hours, which may also influence work loss. For these variables to modify our findings, they would have to be differently distributed in patients with UC and the general population after accounting for age, sex, county, and education. Finally, this study did not include premature death or presenteeism as sources of productivity losses. In conclusion, the mean and 75th percentile level of sick leave and disability pension among patients with UC in Sweden varied markedly between subgroups but was consistently higher among patients with UC than in the general population. Colectomy did not fully restore the mean or 75th percentile level of work ability, with work loss reaching neither presurgery nor general population levels during 3 to 7 years of follow-up. However, it is equally important to note that more than 50% of patients ( 50%) did not experience any work loss before or 3 years after colectomy. Supplementary Material Note: To access the supplementary material accompanying this article, visit the online version of

March 2013 ULCERATIVE COLITIS, COLECTOMY, AND WORK LOSS 543 Gastroenterology at www.gastrojournal.org, and at http:// dx.doi.org/10.1053/j.gastro.2012.12.004. References 1. Cohen RD, Yu AP, Wu EQ, et al. Systematic review: the costs of ulcerative colitis in Western countries. Aliment Pharmacol Ther 2010;31:693 707. 2. Blomqvist P, Ekbom A. Inflammatory bowel diseases: health care and costs in Sweden in 1994. Scand J Gastroenterol 1997;32: 1134 1139. 3. Boonen A, Dagnelie PC, Feleus A, et al. The impact of inflammatory bowel disease on labor force participation: results of a population sampled case-control study. Inflamm Bowel Dis 2002;8: 382 389. 4. Longobardi T, Jacobs P, Bernstein CN. Work losses related to inflammatory bowel disease in the United States: results from the National Health Interview Survey. Am J Gastroenterol 2003;98: 1064 1072. 5. Longobardi T, Jacobs P, Wu L, et al. Work losses related to inflammatory bowel disease in Canada: results from a National Population Health Survey. Am J Gastroenterol 2003;98:844 849. 6. Stark R, Konig HH, Leidl R. Costs of inflammatory bowel disease in Germany. Pharmacoeconomics 2006;24:797 814. 7. Bernstein CN, Kraut A, Blanchard JF, et al. The relationship between inflammatory bowel disease and socioeconomic variables. Am J Gastroenterol 2001;96:2117 2125. 8. Marri SR, Buchman AL. The education and employment status of patients with inflammatory bowel diseases. Inflamm Bowel Dis 2005;11:171 177. 9. Bernklev T, Jahnsen J, Henriksen M, et al. Relationship between sick leave, unemployment, disability, and health-related quality of life in patients with inflammatory bowel disease. Inflamm Bowel Dis 2006;12:402 412. 10. Wyke RJ, Edwards FC, Allan RN. Employment problems and prospects for patients with inflammatory bowel disease. Gut 1988; 29:1229 1235. 11. Severens JL, Mulder J, Laheij RJ, et al. Precision and accuracy in measuring absence from work as a basis for calculating productivity costs in The Netherlands. Soc Sci Med 2000;51:243 249. 12. Farmer RG, Easley KA, Rankin GB. Clinical patterns, natural history, and progression of ulcerative colitis. A long-term follow-up of 1116 patients. Dig Dis Sci 1993;38:1137 1146. 13. Damgaard B, Wettergren A, Kirkegaard P. Social and sexual function following ileal pouch-anal anastomosis. Dis Colon Rectum 1995;38:286 289. 14. Socialstyrelsen. In English - the National Patient Register. 2011. Available at: http://www.socialstyrelsen.se/register/halsodataregister/patientregistret/inenglish. 15. Spetz CL, Carlsson CL, Engqvist M, et al. [Reintroduction of social security numbers gives better basis for evaluation. The patient registry is open for research]. Lakartidningen 1996;93:1844 1847. 16. StatisticsSweden. Background Facts, Labor and Education Statistics, integrated database for labor market research. 2009. 17. Thompson SG, Barber JA. How should cost data in pragmatic randomised trials be analysed? BMJ 2000;320:1197 1200. 18. Ekbom A, Helmick C, Zack M, et al. The epidemiology of inflammatory bowel disease: a large, population-based study in Sweden. Gastroenterology 1991;100:350 358. 19. Neovius K, Neovius M, Rasmussen F. The combined effects of overweight and smoking in late adolescence on subsequent disability pension: a nationwide cohort study. Int J Obes (Lond) 2010;34:75 82. 20. Neovius K, Johansson K, Kark M, et al. Obesity status and sick leave: a systematic review. Obes Rev 2009;10:17 27. Received September 2, 2011. Accepted December 3, 2012. Reprint requests Address requests for reprints to: Martin Neovius, PhD, Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet, SE-171 76 Stockholm, Sweden. e-mail: martin.neovius@ki.se; fax: (46) 8 517 793 04. Conflicts of interest The authors disclose no conflicts. Funding Supported by Stockholm County Council (ALF) and Schering- Plough. Representatives from Schering-Plough did not read or comment on any version of the manuscript.