Coping strategies, illness perception, anxiety and depression of patients with idiopathic constipation: a population-based study

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1 Aliment Pharmacol Ther 2003; 18: doi: /j x Coping strategies, illness perception, anxiety and depression of patients with idiopathic constipation: a population-based study C. CHENG*, A. O. O. CHAN, W. M. HUI & S. K. LAM *Division of Social Science, the Hong Kong University of Science and Technology, Hong Kong; and Department of Medicine, the University of Hong Kong, Hong Kong Accepted for publication 26 May 2003 SUMMARY Background: Functional constipation has important psychological elements. Aim: To investigate the prevalence of functional constipation in an Asian population, and the interplay among functional constipation, anxiety/depression, perception and coping strategies. Methods: An interview of 3282 patients was made by telephone survey. Constipation was diagnosed by Rome II criteria. Coping ability and anxiety/depression were assessed by validated questionnaires. Results: Fourteen percent of the interviewees had constipation. Anxiety and depression scores were higher in constipated than in healthy subjects (P < and < ), and in female than male patients (P ¼ 0.02 and < ). Patients who were aware of their symptoms perceived greater impact on their lives (P < 0.001). Frequent use of coping strategies associated with lower anxiety scores (P < ). Female were more frequently aware of the symptoms (P ¼ 0.004), less frequently used coping strategies (P ¼ 0.008). Regression analysis showed that female and high anxiety level were the independent factors for predicting the perception of constipation, whereas anxiety was the only independent factor for predicting the use of coping strategies. Conclusion: Constipation associated with anxiety and depression is prevalent in the general Asian population. Female sex and anxiety are important aetiological factors in constipation, affecting perception and the use of coping strategies. INTRODUCTION Constipation is a common problem in clinical practice. In the Western population, the prevalence was reported as high as 24% in elderly subjects and more commonly among women. 1 In the Asian population, the reported prevalence in the elderly was around 12%. 2 The prevalence in different age strata in Asian populations has not been reported. Demographic factors, lifestyle factors and health care utilisation have been reported on the population level. 1, 2 There is growing interest in exploring the role Correspondence to: Dr A. O. O. Chan, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong. aoochan@hkusua.hku.hk of psychological factors on the pathogenesis of idiopathic constipation. Patients with idiopathic constipation who seek medical attention in tertiary centres generally have a higher prevalence of anxiety, depression and social dysfunction than do normal controls. 3, 4 Slow colonic transit, an important pathogenetic factor in idiopathic constipation, is associated with psychological symptoms of anxiety, depression and obsessive compulsion in the elderly. 5, 6 A recent study demonstrated that general psychosocial function, somatisation, anxiety, depression and feelings about the female role are impaired in women with constipation and are associated with altered rectal mucosal blood flow, which was a measure of extrinsic gut innervation. 7 These findings suggest a link between psychological symptoms and gut dysfunction. Ó 2003 Blackwell Publishing Ltd 319

2 320 C. CHENG et al. It is noteworthy that the psychological factors included in previous studies on constipation are confined to psychological symptoms. The more fundamental psychological factors, such as subjective perception of constipation symptoms, responses to cope with constipation symptoms and the effectiveness of such responses, remained unexplored. For the same physical problem, individuals differ considerably in their appraisals of it. 8, 9 Their perception in turn influences their subsequent responses to handling the problem. Coping ability plays an important role in amelioration of stressful events and behaviour. 9 Although individuals may attempt to cope, some coping strategies may be beneficial in mitigating 10, 11 the problem whereas others may not be useful. Ineffective coping should be related to maladaptive 12, 13 outcomes, such as anxiety and depression. In the present study, we aim at identifying the prevalence of idiopathic constipation in the Chinese population. In addition, we aim at examining the hypothesis that a positive link exists between psychological factors and idiopathic constipation, which in turn affects illness perception and hence coping strategies. METHODOLOGY Patients The present study adopted a population-based design with a telephone survey. A computer-assisted telephone interviewing (CATI) system was used for selecting sample from the population and for entry of data. Random samples of the telephone directory of the population for the survey were generated from the computer program. In Hong Kong, the population is around The selected subjects were contacted by the interviewers and asked to participate in the survey. Three thousand patients were randomly generated from a computer program and subdivided into two phases. Phase I of the study aimed at identifying the coping strategies used by the constipated subjects using opened-end questions. The strategies were collected, identified and used in the Phase II of the study. Those whose age is between 18 and 80 were recruited. The study was approved by the ethics committee of Queen Mary Hospital. Instruments The questionnaire consists of three parts: the diagnosis of constipation; anxiety and depressive scores; as well as the use of coping ability. The diagnosis of constipation was based on the Rome II criteria 14 on functional constipation. This is based on patients with changes in the nature of the stool and difficulty in the passage of stool for a period of at least 3 months (which need not be consecutive) in the past 12 months. The survey was translated from the English version, and was then back-translated into the English version by two translators. The two versions were compared and differences from the original version were modified accordingly. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale (HAD). 15 This has been developed and found suitable for assessing medical out-patients. The scale has been validated in 16, 17 the Chinese version. The perception of constipation was assessed using four questions: (1) Are you aware that you have constipation? (2) Do you think you can control the severity of the constipation symptoms? (3) Do the constipation symptoms affect your life? (4) Are the coping methods effective in relieving your symptoms? The coping ability was assessed by a set of coping categories specifically designed for this study by the authors. Because of the potential social and cultural differences, the first phase of the study used openended questions to explore the array of coping strategies actually used by people in general. As a result, a total of 16 coping categories have been identified. Validation of the questionnaire The validity of the diagnosis of idiopathic constipation was tested. The questions were made into a colloquial form and were easily understood. In the first and second phases, the questions for the diagnosis of constipation were administered to 1080 patients and 2022 patients, respectively. Correlation and concordance in the prevalence of constipation between the two phases were made by a chi-square (v 2 ) test. Furthermore, the test retest reliability of the questionnaire was examined. Specifically, the questionnaire was administrated twice at the beginning and at the end of a period of 7 days. Results showed that the questions were easily understood and relevant to gastrointestinal diseases. The test retest reliability was indicated by weighted kappa and then by Spearman correlations.

3 COPING STRATEGIES AND CONSTIPATION 321 PROCEDURE The questionnaires were administrated by a panel of students who went through a period of intensive training for one week. In the telephone survey, the household member with the birthday falling closest to the date of interview was chosen. If the target subject was unavailable, the one with the next closest birthday was invited to participate. If that target subject was still unavailable but she or he agreed to participate at the later date or time, a follow-up call was scheduled. The interviewed subjects were assured of the confidentially of the survey. agreement, while values between 0.4 and 0.75 indicate good agreement; values above 0.75 indicate excellent agreement. 18 Demographic characteristics of subjects The demographic characteristics of the interviewed population were comparable to the general population as reported in the Hong Kong census in The mean age of the interviewed subjects was with a range of The female : male sex ratio was 1.3 : 1. The percentage of patients with secondary education and above was 68%. Statistical analysis Because previous studies showed that the prevalence rate of functional constipation ranges from 11 to 15% 1, 2 a sample size of 1000 subjects was estimated to provide a 95% confidence interval (CI) ± 2.0%. From the population survey, the prevalence rates of constipation by age, gender and social economic status were calculated. The overall prevalence of constipation was adjusted for age and sex according to the statistics of the population of Hong Kong in 2000 (using the Hong Kong Year Book 2000). Results were shown by prevalence rates. The relationship between the constipation and its subtypes, coping strategy and constipation were studied using both univariate and multivariate analyses. The independent-sample t-tests were conducted to examine differences of the means. The chi-square test was used to examine differences between categorical variables. The relationships among the variables were examined by logistic regression analyses. RESULTS Indices of reliability and validity There were 16 interviewers who conducted the telephone survey. The inter-interview reliability was high, r ¼ 0.85, P < The average acceptance rate is 73% (SD ¼ 3.2), which is also high. Validation of the questionnaire by the test and retest method indicated that the reliability of the questionnaire was high (P < 0.05, kappa values ranged from 0.4 to 0.9; and P < 0.05 by the Spearman correlation method). A kappa value less than 0.4 indicates significant but poor Prevalence of constipation and its subtypes In the first survey, among the 1080 subjects interviewed, there were 156 (14.4%) subjects with constipation. In the second survey a total of 2202 patients were interviewed, and there were 302 subjects (13.7%) with constipation. There was good concordance between Phase I and Phase II of the survey, v 2 ¼ , P > As there was no significant difference in the prevalence of idiopathic constipation between the two phases of this study, the data on constipation of both phases were combined for analysis of constipation. The percentages of patients with respective symptoms of constipation were as shown in Table 1. The prevalence of constipation when adjusted for age and sex are shown in Table 2. The prevalence of constipation did not differ between the younger and the older age group. However, the prevalence of constipation showed a steady increase in the male subjects ( %) but remained steady in the female subjects ( %). Females had a higher prevalence of constipation. Anxiety and depression in constipated patients The anxiety and depression scores for subjects with functional constipation were 6.68 ± 5.35 and 6.25 ± 4.93, respectively, compared to 2.89 ± 3.09 and 3.72 ± 2.45, respectively, in normal subjects, implying that patients with functional constipation were more anxious (P < ) and depressed (P < ). In addition, female patients with constipation also had higher anxiety (7.6 ± 5.2 vs. 5.3 ± 5.2, P ¼ 0.02) and depression scores (7.5 ± 5.4 vs. 4.4 ± 3.4, P < ) than male patients.

4 322 C. CHENG et al. Phase I (n ¼ 1080) Phase II (n ¼ 2202) Male (total 469) Percentage Female (total 611) Percentage Male (total 950) Percentage Female (total 1252) Percentage Table 1. Percentages of patients with symptoms of constipation Straining Hard stool Incomplete evacuation Sense of obstruction < 3 bowel motions/week Manual manoeuvres Constipation by Rome II Phase I (n ¼ 1080) Number (%) Phase II (n ¼ 2202) Number (%) Pooled (n ¼ 3282) Number (%) Gender Male 64 (13.9) 137 (13.9) 201 (13.9) Female 92 (14.8) 165 (14.3) 257 (14.5) Age group < (14.6) 80 (14.5) 117 (14.5) (14.3) 46 (13.2) 74 (13.6) (12.6) 40 (11.4) 62 (11.8) (14.6) 39 (13.1) 65 (13.7) > (15.4) 97 (14.8) 140 (14.9) Education No education 15 (14.7) 32 (14.4) 47 (14.5) Primary school 26 (12.1) 54 (12.3) 80 (12.2) Junior high school 26 (13.9) 49 (15.3) 75 (14.8) High school 32 (12.8) 69 (12.6) 101 (12.6) Matriculation 13 (14.3) 18 (13.7) 31 (14.0) University/above 26 (13.2) 60 (14.5) 86 (14.1) Occupation Manager 4 (13.8) 9 (11.8) 13 (12.4) Professional 10 (11.4) 24 (14.8) 34 (13.6) Clerk 26 (13.5) 50 (13.5) 76 (13.5) Service 12 (14.5) 34 (15.7) 46 (15.4) Mechanic 14 (13.0) 28 (13.3) 42 (13.2) Nonskilled labour 10 (14.9) 19 (13.0) 29 (13.6) Unemployed 11 (14.3) 25 (13.4) 36 (13.7) Retired 21 (15.6) 34 (14.2) 55 (14.7) Student 18 (11.8) 27 (12.5) 45 (12.2) Homemaker 9 (13.9) 22 (14.6) 31 (14.4) Other 3 (6.8) 9 (11.5) 12 (9.8) 30 (14.6) 66 (14.9) 96 (14.8) Income (HK$) < (14.6) 66 (14.9) 96 (14.8) (12.3) 50 (12.6) 78 (12.5) (12.4) 26 (12.7) 42 (12.6) (13.8) 30 (12.2) 41 (12.5) (14.8) 5 (11.1) 9 (12.5) > (13.3) 14 (13.0) 22 (13.1) No income 18 (12.4) 32 (14.4) 50 (13.6) Table 2. The prevalence of constipation by sex and by age in the first and second survey

5 COPING STRATEGIES AND CONSTIPATION 323 Perception of constipation Amongst the constipated patients, only 57.4% were aware of having constipation. For the perceived dimension of controllability, 26.6% of the patients considered that they can control all or most of their symptoms; 58.7% thought that they could control a few of their symptoms. For the perceived dimensions of impact, only 5.6% of the patients felt the symptoms affected their life significantly. Patients who knew that they suffered from constipation tended to perceive that this problem had a greater impact on their daily life, P < , and were more likely to believe that they could not control the symptoms (20% vs. 8%, P ¼ 0.04). Perception was different in the two sexes: more female patients were aware that they had constipation symptoms (82/125, 66%) than were males (42/91, 46%) (P ¼ 0.004). However, no difference between males and females was observed in the perception of controlling the severity of the constipation symptoms (P ¼ 0.3) and in the perception of impact of constipation symptoms on their daily life (P ¼ 0.4). Patients who were aware of the constipation symptoms had higher anxiety scores (8.5 ± 5.7 vs. 4.8 ± 4.4, P < ) but not depression scores (6.9 ± 5.2 vs. 5.9 ± 4.7, P ¼ 0.2). The anxiety and depression scores did not differ significantly in patients who perceived they could control the constipation symptoms and that constipation symptoms had no impact on their lives. Coping strategies used by constipated subjects Table 3 summarises the frequency of patients using the 16 types of coping. The strategies most frequently deployed by patients included taking prescribed medicine, changing eating habits, taking alternative therapy like acupuncture, taking western medicine and doing nothing. 38.2% of the patients used one type of coping strategy only, 37.2% used two kinds of coping strategies, 16.3% used three, 5.6% used four, 1.7% used five and 0.4% used six. Male patients tended to use more coping strategies to relieve constipation symptoms than their female counterparts (2.2 vs. 1.8 types of coping strategies used, P ¼ 0.008). Interestingly, the number of coping strategies used correlated negatively with anxiety scores (r ¼ ) 0.3, P < ). On the other hand, no such correlation was observed between the number of coping strategies used and depression scores. Table 3. Frequencies of subjects using strategies to cope with functional constipation Coping strategies Percentage (%) Taking prescribed Western medicine 18.9 Taking prescribed Chinese medicine 8.2 Taking prescribed medicine 26.2 Taking alternative therapy 19.7 Doing exercise 15.5 Change in lifestyle 5.2 Change in eating habits (e.g. fibre, fruits) 24.0 Drinking more water 9.4 Massaging the abdomen 5.2 Taking leisure activities 4.7 Changinge one s thinking style 7.3 Spiritual support (e.g. religion, yoga, meditation) 4.3 Seeking support from others 6.9 Seeking information from media 4.3 (e.g. books, websites) Doing nothing 16.3 Other 20.6 Among the constipated patients, 90.8% of subjects considered that these coping strategies are effective in improving their symptoms: only the remaining 9.2% considered these coping strategies not effective. Health-seeking behaviour of constipated subjects Amongst the constipated subjects, only 25.3% reported a physician visit, and 2.6% visited Chinese doctors for constipation. The constipated subjects seeking medical help were most likely to be those who were aware of their symptoms (56/121 vs. 7/90, P < ), female (45/133 vs. 19/96, P ¼ 0.019), those who perceived that their symptoms were not controllable (13/26 vs. 43/153, P ¼ 0.026), and those who perceived the symptoms had impact on their daily life (7/11 vs. 56/199, P ¼ 0.018). In addition, the subjects who sought medical advice were more likely to be elderly (mean age 52 ± 17 years vs. 45 ± 19 years, P ¼ 0.018), and had higher anxiety scores (8 ± 6 vs. 6 ± 5, P ¼ 0.039). Logistic regression analysis among demographic data, anxiety and depression, perception of constipation and coping strategies used in constipated subjects The demographic data, the levels of anxiety and depression are the potential factors that may affect the perception of constipation, and hence these variables

6 324 C. CHENG et al. were put into the logistic regression model. Female sex (P ¼ 0.04) and high anxiety scores (P ¼ 0.002) were the independent factors in predicting the awareness of constipation in these subjects by using logistic regression analysis. As the use of coping strategies may be affected by the demographic data, the levels of anxiety and depression, as well as the perception of constipation, these variables were put into the ordinal regression model. Anxiety was the only independent factor in predicting the use of number of coping strategies (P ¼ 0.015). The significant factors for predicting health-seeking behaviour from univariate analysis were put into the logistic regression analysis. The perception of constipation (awareness) was the only independent factor (P ¼ 0.001) for predicting health-care seeking. Multiple regression analyses were used to examine the relationship between coping strategies and subjects selfrated coping effectiveness. The coping strategies were entered into the regression equations as predictor variables, whereas subjects self-rated coping effectiveness was the dependent variable. Results showed that taking prescribed medicine, changing eating habits, drinking more water and massaging the abdomen were significant predictors positively related to self-rated coping effectiveness. However, results also showed that taking alternative therapy and taking leisure activities were significant predictors inversely related to self-rated coping effectiveness. Multiple regression analyses were also used to examine the relationship between these coping strategies and measures of psychological well-being (i.e. anxiety and depression). Results showed that taking prescribed medicine, doing exercise, a change in thinking style and seeking support from others were significant predictors inversely related to anxiety. These strategies were related to a reduction in anxiety for subjects with functional constipation. Results also showed that taking Chinese medicine, doing exercise, changing eating habits and seeking information from the Web were significant predictors inversely related to depression. These strategies were found to mitigate depression for subjects with functional constipation. DISCUSSION Studies on the prevalence of idiopathic constipation amongst the Asian are rare. The reported prevalence among the elderly was 11.6%. 2 The present study reported the prevalence in all age strata, as well as the coping strategies used by the patients. Although the data were based on a telephone survey and should not be considered as evidence-based guidelines for treatment of constipation, the current study provides important preliminary data. The overall prevalence is estimated to be 14.3% for the Hong Kong population. The prevalence in different age strata is similar and the female : male ratio is 1.3 : 1. The present study adopted a population-based design to yield a representative sample, using the Rome II criteria for the diagnosis of constipation. The use of a two-phase population survey on constipation, each with an adequate sample, allows the testing of reliability and validity. The percentage of patients is comparable with western populations 19, 20 and is similar to that reported in elderly Asian subjects. 2 Furthermore, about 25% of the patients consulted doctors for constipation, which is comparable with those reported by western studies. 19 It is interesting to note that only 57.4% of our patients were aware of their constipation symptoms. In the current study, constipation was diagnosed according to the Rome II criteria. The reason for the discrepancy between the presence of symptoms and the actual perception of symptoms is unknown. One possible explanation is that the Rome II criteria may not be a good diagnostic tool. Furthermore, the discrepancy could be due to the fact that the perception of illness in Chinese patients is different from that in patients from western countries. Hence it would be necessary to identify from the population itself which symptoms the patients felt to be the most troubling or predominant. Awareness of the constipation symptoms is important because according to the transactional theory of coping 9 the component of cognitive appraisals is a major factor influencing the use of coping strategies. In this study, cognitive appraisals were operationalised by illness perception. We have demonstrated that constipated subjects are more anxious and depressed than their counterparts without constipation. It has been reported that patients who were severely constipated but with normal transit time were characterised by increased psychological distress. 21 Slow colonic transit in the constipated elderly has also been reported to be associated with increased psychological symptoms. 5 The present study provided support for these findings and extended the findings to the whole spectrum of severity of constipation. However, the association between the two conditions does

7 COPING STRATEGIES AND CONSTIPATION 325 not necessarily imply causality. It can be argued that anxiety and depression predispose the subjects to constipation, but it is equally possible that constipated subjects may themselves be high in anxiety and depression. Previous studies showed no definite relationships between psychological distress and colonic motility. 21, 22 Future studies should adopt a multiwave longitudinal design to test the causality of these relationships. Female predominance has been reported in functional constipation. It was observed from our study that female patients are characterised by high levels of anxiety and depression, and were more likely to be aware of their constipation symptoms, which resulted in an increase in impact on their daily life and an increase in uncontrollable symptoms. In addition, female patients were more likely to use fewer coping strategies, especially the psychological type of coping strategy. More importantly, our study showed that female sex and high level of anxiety were two independent factors in predicting the perception of constipation, suggesting that sex and anxiety level were important aetiological factors in the perception of constipation. The predominance of female gender in idiopathic constipation could possibly be explained by the fact that this is associated with higher anxiety level, which leads to more frequent perception of constipation symptoms and less frequent use of coping strategies, and hence more frequent healthseeking behaviour. The present study identified coping strategies that were perceived as effective measures for alleviating constipation symptoms. Effective coping strategies include taking prescribed medicine, changing eating habits, drinking more water and massaging the abdomen. However, the pitfall is that the effectiveness was selfrated and hence subjective; no physiological data were available in the current study. Despite this, these results provide some support for previous clinical studies, which revealed that taking laxatives and increasing fluid and fibre intake can improve symptoms of constipation. 23, 24 The prescribed medicine included proprietary drugs, some of which probably contain laxatives. Although there were findings revealing the beneficial value of acupuncture, 25 the data should be regarded as preliminary. Also, previous studies have reported that physical exercise has no major effect on constipation, despite the fact that these studies were on healthy subjects rather than on constipated patients; this is in agreement with our current finding. The role of massaging the abdomen is unknown, but it is interesting to note that clinical biofeedback, which is an effective therapy for treating constipation, involves relaxation and the correct use of abdominal muscle. 29 Further studies should be conducted to replicate the present results for a more reliable conclusion of the beneficial role of these coping strategies. This study also identified coping strategies that were perceived as effective measures for alleviating anxiety and depression symptoms. Our findings showed that coping strategies could mitigate constipation and psychological symptoms. Coping strategies perceived to be effective in relieving constipation symptoms may not be the same as those perceived to be effective in relieving psychological symptoms. As shown in this study, only taking prescribed medicine and changing eating habits are perceived to be effective in relieving both constipation and psychological symptoms. Drinking more water and massaging the abdomen are perceived to be effective in mitigating constipation symptoms only, whereas doing exercise, changing thinking style, seeking support, taking prescribed medicine and seeking information from the Web are perceived to be effective in mitigating psychological symptoms. Such results imply that different coping strategies may have different effectiveness toward these two types of symptoms. Hence, though the findings are preliminary, clinicians may consider advising patients with constipation to broaden their coping repertoire by including a greater repertoire of coping strategies in order to relieve both types of symptoms. Our study demonstrated that sex and anxiety level were important factors in predicting the perception of constipation, which may subsequently affect the use of coping strategies and health-care seeking behaviour. The use of different coping strategies could alleviate constipation symptoms as well as psychological symptoms. This reinforces an important link between psychological factors and idiopathic constipation. ACKNOWLEDGEMENTS The project was supported by the Janssen Pharmaceutical Company and the Peptic Ulcer Research Fund. REFERENCES 1 Talley NJ, O Keefe EA, Zinsmeister AR, Melton LJ, 3rd. Prevalence of gastrointestinal symptoms in the elderly: a population-based study. Gastroenterology 1992; 102:

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