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Predictors of treatment outcome after cognitive behavior therapy and antispasmodic treatment for patients with irritable bowel syndrome in primary care
Journal of Psychosomatic Research 68 (2010) 385 – 388
Predictors of treatment outcome after cognitive behavior therapy and antispasmodic treatment for patients with irritable bowel syndrome in primary care Silje Endresen Reme⁎, Tom Kennedy, Roger Jones, Simon Darnley, Trudie Chalder Department of Psychological Medicine, King's College London, UK Received 12 October 2009; received in revised form 17 December 2009; accepted 5 January 2010
Abstract Objective: To examine predictors of treatment outcome in IBSpatients who participated in a randomized controlled trial in primary care, where 149 irritable bowel syndrome (IBS) patients were randomized to mebeverine hydrochloride (n=77) or mebeverine+cognitive behavior therapy (CBT) (n=72). CBT offered additional benefit over mebeverine alone. Methods: Regression analyses were used to identify predictors of work and social adjustment 12 months after treatment ended. The intervention groups were analyzed separately in order to look at the separate effects in each group. Results: Lower levels of psychological distress (anxiety and depression) at baseline predicted a good
outcome in the mebeverine group [β=0.388 (95% CI: 0.065– 0.936), P=.025] but not in the mebeverine+CBT group. In the adjusted model for the mebeverine+CBT group less adaptive IBS related behavioral coping predicted a good outcome [β=0.285 (95% CI: 0.002–0.210), P=.045]. Conclusion: Different factors are associated with outcome depending on the treatment received. At assessment clinicians should assess patients coping styles and may want to consider recommending CBT to those patients with IBS in primary care who are engaging in unhelpful coping behavior. © 2010 Elsevier Inc. All rights reserved.
Keywords: Cognitive behavior therapy; Irritable bowel syndrome; Primary care; Predictors of treatment outcome; Clinical implications
Introduction Few studies have looked specifically at predictors of treatment outcome after cognitive-behavioral treatments (CBT) for irritable bowel syndrome (IBS). Those who have find psychological disturbance to be an important predictor of a poor outcome. Less baseline anxiety predicted a better outcome in one study [1], whereas others have found a lower likelihood of success with the presence of one or more psychiatric disorders [2,3] and baseline depression [4]. Although psychological distress overall seems to predict a poor outcome in CBT treatments, studies from other
⁎ Corresponding author. Research Centre for Health Promotion, Faculty of Psychology, University of Bergen, Christies gt 13, 5015 Bergen, Norway. Tel.: +47 55583991; fax: +47 55 58 98 78. E-mail address: [email protected] (S.E. Reme). 0022-3999/10/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2010.01.003
psychological treatments reveal results that point in the opposite direction [5,6]. Symptom characteristics also show some inconsistencies in the literature, in that severity of gastrointestinal symptoms predicted a poor outcome in one study [1] and a good outcome in another [7]. Conflicting results may reflect the different measures of outcome or criterion used, the intervention received, or lack of statistical power due to few participants in the studies. In a recent randomized controlled trial (RCT) from primary care where CBT was added to antispasmodic treatment (mebeverine), we found that CBT offered additional effects over mebeverine alone [8]. CBT might therefore be useful to certain IBS patients in primary care. In order to find out who may benefit from which treatment, predictors of treatment outcome need to be identified. This article reports on predictors of treatment outcome through a secondary analysis of the aforementioned RCT in primary care. We
386
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388
chose predictors which represented the multidimensional nature of the disorder and included measures of distress, unhelpful perceptions/cognitions, and behavioral coping. Based on previous findings, we hypothesized that psychological distress (anxiety and depression) would predict a poor treatment outcome at 12 months of follow-up for both groups. Method Patients diagnosed with IBS aged 16–50 years were recruited from 10 general practices in London. Three hundred thirty-four patients were referred to the study; 235 consented to participate, and those still symptomatic (moderate to severe IBS symptoms) after 2 weeks of general practitioner care and 4 weeks of mebeverine hydrochloride (275 mg 3 times a day) were included in the trial (n=149). Of those consenting to participate, 52 were no longer symptomatic at the time of inclusion, while 34 dropped out [8]. Participants were randomized to receive six sessions of CBT in addition to mebeverine (72 patients) or continue with mebeverine alone (77 patients). Four general practice nurses delivered the CBT. All participants were asked to complete a series of questionnaires. Of these, the following were hypothesized to predict treatment outcome: psychological distress (anxiety and depression combined score) [9,10], illness perceptions (IPQs) [11], IBS symptoms [12], cognitions about IBS [13], and IBS-related coping behavior. The latter is a new questionnaire designed and validated by the researchers. It allows assessment of changes in specific coping behaviors used by patients with IBS and includes items related to avoidance behavior and toileting behavior. It was found to be both valid and reliable (Cronbach's α=.89) [14]. The primary outcome for the prediction analyses was the work and social adjustment (WASA) scale at 12 months of follow-up which measures ability to work, manage the home, and participate in social and private leisure activities and relationships. The scale ranges from 0 to 40, with higher scores indicating more disability [15]. Ethical approval was received from St. Thomas' Hospital Research Ethics Committee; Guy's Hospital Research Ethics Committee; and Barnet, Enfield, and Haringey LREC. Statistical analyses All analyses were performed using SPSS version 15. The participants filled out questionnaires 3, 6, 9, and 12 months
after treatment ended. IBS tends to be a chronic condition and the 12-month follow-up was therefore chosen as the outcome in this study. WASA was a secondary outcome in the trial but was chosen as the main outcome of this study since health status and functionality can be argued to be more important than symptom severity and because the difference between the treatment groups were still detectable on WASA at 12 months. Both outcome and predictor variables were continuous, and the association between them was assumed to be linear. Multiple linear regression analyses were therefore chosen. Unadjusted and adjusted analyses were used to assess the strength of relationships between hypothesized predictors and outcome. All models were stratified by intervention group and examined separately in order to assess determinants of outcome for each treatment. Statistically significant predictors (Pb.01) from the unadjusted analyses were included in an adjusted regression model. Results In the previous study, the addition of CBT to mebeverine produced a significant benefit compared with the mebeverine-only group on symptom severity and WASA. The difference on the WASA scale represented therapeutic gains of approximately 20% and 40%, respectively. The improvements began to wane over time, and by 12 months of follow-up, significant therapeutic benefit of the addition of CBT could only be detected on the WASA scale. Full details of main findings and response rates are reported elsewhere [8]. Most patients were women (85%), mean age was 33.8 years (S.D. 9.1), and the majority were Caucasian British (69%); 50% had experienced IBS for more than 5 years, and 52% reported psychological problems during the last 5 years. Follow-up data on the WASA scale at 12 months were available from 73% of the participants, 71% in the mebeverine+CBT group (n=51) and 75% in the mebeverine group (n=58). The results from the unadjusted analyses showed that baseline WASA scores, psychological distress (anxiety and depression), IBS-coping behavior, and a belief that the IBS would have serious consequences for the patient's life, health and well-being (IPQ consequences), all predicted degree of disability (WASA) at 12 months for both intervention groups (Table 1). In the fully adjusted model, a lower level of
Table 1 Unadjusted models for each treatment group separately; only significant (Pb.01) predictors included Outcome: work and social adjustment 12 months
Mebeverine
Predictor variables
B (95% CI)
P
Mebeverine+CBT B (95% CI)
P
Work and social adjustment (higher score=more disability) Psychological distress (anxiety and depression) (higher score=more distress) Behavioral Scale (higher score=more adaptive behavior) IPQ consequences (higher score=worse consequences)
0.598 (0.414-0.782) 0.658 (0.445-0.870) 0.202 (0.135-0.270) 6.354 (4.253-8.456)
b.001 b.001 b.001 b.001
0.443 (0.248-0.638) 0.482 (0.237-0.727) 0.160 (0.093-0.227) 5.492 (3.226-7.757)
b.001 b.001 b.001 b.001
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388
387
Table 2 Adjusted models for each treatment group separately Outcome: work and social adjustment 12 months
Mebeverine
Predictor variables
B (95% CI)
P
B (95% CI)
P
Work and social adjustment (higher score=more disability) Psychological distress (anxiety and depression) (higher score=more distress) Behavioral scale (higher score=more adaptive behavior) IPQ consequences (higher score=worse consequences)
0.071 (−0.306 to 0.468) 0.388 (0.065 to 0.936) 0.051 (−0.20 to 0.187) 1.984 (−2.938 to 5.023)
.68 .025 .11 .60
0.274 (−0.021 to 0.520) −0.001 (−0.338 to 0.335) 0.285 (0.002 to 0.210) 0.199 (−1.201 to 6.208)
.07 .99 .045 .18
psychological distress (anxiety and depression combined) was the only significant predictor in the mebeverine group (Table 2). In the fully adjusted model for the mebeverine +CBT group less adaptive IBS-behavior at baseline predicted better WASA outcome at 12 months. The fully adjusted model explained a total variance of 40% for the mebeverine group and 38% for the mebeverine+CBT group.
factors were significant predictors of treatment outcome in the adjusted and/or unadjusted analyses, indicating that all these factors are important in the treatment of IBS patients. The relatively small sample size is a limitation in the current study. However, compared to most comparative studies (e.g., Refs. [1–3]), our study has a reasonably high number of patients included in the analyses and, therefore, does not violate the recommendations for sample size in linear regression [17]. However, similar studies should be conducted in order to replicate these findings, particularly in the primary care setting. In conclusion, the results showed that lower levels of psychological distress (anxiety and depression) predicted less disability at 12 months for the mebeverine group but not for the mebeverine+CBT group. The results further showed that maladaptive IBS behavior predicted less disability at 12 months for the mebeverine+CBT group. Clinical implications could involve recommending CBT to those patients with IBS in primary care who are engaging in unhelpful coping behavior.
Discussion This is the first study to examine predictors of treatment outcome in IBS patients receiving CBT and mebeverine in the context of a RCT in primary care. The results showed that more psychological distress (anxiety and depression) at baseline predicted more disability (WASA) at 1-year follow up in the mebeverine group, while less adaptive IBS behavior at baseline predicted less disability (WASA) at 1-year follow up in the mebeverine+CBT group. The results partly confirmed our hypothesis that psychological distress would predict a poor outcome. However, we only found this for the mebeverine only group, not for the mebeverine+CBT group. This result therefore deviates from previous findings [1–4] indicating that psychological distress does not interfere with a successful treatment course of CBT and, therefore, could be recommended to IBS patients with comorbid psychological symptoms. The results also showed that those IBS patients who presented more maladaptive behavior (e.g., avoidance behavior) and received mebeverine+CBT treatment, experienced less disability after 12 months. This could imply that the CBT treatment was especially effective in changing maladaptive IBS-coping behavior (e.g., avoidance behavior), leading to less disability in terms of better work and social adjustment. The clinical implications of this finding could be to recommend CBT treatment to IBS patients presenting in primary care with maladaptive IBS-coping behavior. The IBS-coping behavior was investigated through a new questionnaire designed for measuring coping behaviors in IBS and has therefore never been reported before as far as we know. Since IBS-coping behavior was found to predict treatment outcome, future studies should consider including this questionnaire for research as well as clinical purposes. The results strengthen the validity of the CBT model for IBS patients [16] in that both emotional (anxiety and depression), cognitive (IPQs), and behavioral (IBS behavior)
Mebeverine+CBT
Acknowledgments We would like to thank the Health Technology Assessment program for funding this study. We would also like to thank the study nurses—Rebecca Holt, Tricia Lewis, Sheila Morton, and Lindsey Shephard—for their contribution, as well as the patients, doctors, and staff at the participating general practices. Trudie Chalder acknowledges financial support from the Department of Health via the National Institute for Health Research Specialist Biomedical Research Centre for Mental Health award to South London and Maudsley NHS Foundation Trust and the Institute of Psychiatry at King's College London. Finally, we would like to thank Stein Atle Lie who provided valuable statistical advice in the revision process of the article. References [1] Blanchard EB, Schwarz SP, Neff DF, Gerardi MA. Prediction of outcome from the self-regulatory treatment of irritable bowel syndrome. Behav Res Ther 1988;26:187–90. [2] Blanchard EB, Scharff L, Payne A, Schwarz SP, Suls JM, Malamood H. Prediction of outcome from cognitive-behavioral treatment of irritable bowel syndrome. Behav Res Ther 1992;30:647–50. [3] Blanchard EB, Lackner JM, Gusmano R, Gudleski GD, Sanders K, Keefer L, et al. Prediction of treatment outcome among patients with
388
[4]
[5]
[6]
[7]
[8]
[9]
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388 irritable bowel syndrome treated with group cognitive therapy. Behav Res Ther 2006;44:317–37. Drossman DA, Toner BB, Whitehead WE, Diamant NE, Dalton CB, Duncan S, et al. Cognitive-behavioral therapy versus education and desipramine versus placebo for moderate to severe functional bowel disorders. Gastroenterology 2003;125:19–31. Creed F, Guthrie E, Ratcliffe J, Fernandes L, Rigby C, Tomenson B, et al. Does psychological treatment help only those patients with severe irritable bowel syndrome who also have a concurrent psychiatric disorder? Aust N Z J Psychiatry 2005;39:807–15. Guthrie E, Creed F, Dawson D, Tomenson B. A controlled trial of psychological treatment for the irritable bowel syndrome. Gastroenterology 1991;100:450–7. Lackner JM, Jaccard J, Krasner SS, Katz LA, Gudleski GD, Blanchard EB. How does cognitive behavior therapy for irritable bowel syndrome work? A mediational analysis of a randomized clinical trial. Gastroenterology 2007;133:433–44. Kennedy T, Jones R, Darnley S, Seed P, Wessely S, Chalder T. Cognitive behaviour therapy in addition to antispasmodic treatment for irritable bowel syndrome in primary care: randomised controlled trial. BMJ (Clinical research ed 2005;331:435. Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand 1983;67:361–70.
[10] Dowell AC, Biran LA. Problems in using the hospital anxiety and depression scale for screening patients in general practice. Br J Gen Pract 1990;40:27–8. [11] Weinman J, Petrie KJ, Moss-Morris R, Horne R. The illness perception questionnaire: a new method for assessing the cognitive representation of illness. Psychology and Health 1996:11. [12] Francis CY, Morris J, Whorwell PJ. The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress. Aliment Pharmacol Ther 1997;11:395–402. [13] Toner BB, Segal ZV, Emmott S, Myran D, Ali A, DiGasbarro I, et al. Cognitive-behavioral group therapy for patients with irritable bowel syndrome. Int J Group Psychother 1998;48:215–43. [14] Reme SE, Darnley S, Kennedy T, Chalder T. The Development of the Irritable Bowel Syndrome-Behavioural Responses Questionnaire (IBSBRQ). J Psychosom Res, in press. [15] Mundt JC, Marks IM, Shear MK, Greist JH. The Work and Social Adjustment Scale: a simple measure of impairment in functioning. Br J Psychiatry 2002;180:461–4. [16] Deary V, Chalder T, Sharpe M. The cognitive behavioural model of medically unexplained symptoms: a theoretical and empirical review. Clin Psychol Rev 2007;27:781–97. [17] Tabachnick BG, Fidell LS. Using multivariate statistics. Boston (Mass): Allyn and Bacon, 2001.
Predictors of treatment outcome after cognitive behavior therapy and antispasmodic treatment for patients with irritable bowel syndrome in primary care Silje Endresen Reme⁎, Tom Kennedy, Roger Jones, Simon Darnley, Trudie Chalder Department of Psychological Medicine, King's College London, UK Received 12 October 2009; received in revised form 17 December 2009; accepted 5 January 2010
Abstract Objective: To examine predictors of treatment outcome in IBSpatients who participated in a randomized controlled trial in primary care, where 149 irritable bowel syndrome (IBS) patients were randomized to mebeverine hydrochloride (n=77) or mebeverine+cognitive behavior therapy (CBT) (n=72). CBT offered additional benefit over mebeverine alone. Methods: Regression analyses were used to identify predictors of work and social adjustment 12 months after treatment ended. The intervention groups were analyzed separately in order to look at the separate effects in each group. Results: Lower levels of psychological distress (anxiety and depression) at baseline predicted a good
outcome in the mebeverine group [β=0.388 (95% CI: 0.065– 0.936), P=.025] but not in the mebeverine+CBT group. In the adjusted model for the mebeverine+CBT group less adaptive IBS related behavioral coping predicted a good outcome [β=0.285 (95% CI: 0.002–0.210), P=.045]. Conclusion: Different factors are associated with outcome depending on the treatment received. At assessment clinicians should assess patients coping styles and may want to consider recommending CBT to those patients with IBS in primary care who are engaging in unhelpful coping behavior. © 2010 Elsevier Inc. All rights reserved.
Keywords: Cognitive behavior therapy; Irritable bowel syndrome; Primary care; Predictors of treatment outcome; Clinical implications
Introduction Few studies have looked specifically at predictors of treatment outcome after cognitive-behavioral treatments (CBT) for irritable bowel syndrome (IBS). Those who have find psychological disturbance to be an important predictor of a poor outcome. Less baseline anxiety predicted a better outcome in one study [1], whereas others have found a lower likelihood of success with the presence of one or more psychiatric disorders [2,3] and baseline depression [4]. Although psychological distress overall seems to predict a poor outcome in CBT treatments, studies from other
⁎ Corresponding author. Research Centre for Health Promotion, Faculty of Psychology, University of Bergen, Christies gt 13, 5015 Bergen, Norway. Tel.: +47 55583991; fax: +47 55 58 98 78. E-mail address: [email protected] (S.E. Reme). 0022-3999/10/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2010.01.003
psychological treatments reveal results that point in the opposite direction [5,6]. Symptom characteristics also show some inconsistencies in the literature, in that severity of gastrointestinal symptoms predicted a poor outcome in one study [1] and a good outcome in another [7]. Conflicting results may reflect the different measures of outcome or criterion used, the intervention received, or lack of statistical power due to few participants in the studies. In a recent randomized controlled trial (RCT) from primary care where CBT was added to antispasmodic treatment (mebeverine), we found that CBT offered additional effects over mebeverine alone [8]. CBT might therefore be useful to certain IBS patients in primary care. In order to find out who may benefit from which treatment, predictors of treatment outcome need to be identified. This article reports on predictors of treatment outcome through a secondary analysis of the aforementioned RCT in primary care. We
386
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388
chose predictors which represented the multidimensional nature of the disorder and included measures of distress, unhelpful perceptions/cognitions, and behavioral coping. Based on previous findings, we hypothesized that psychological distress (anxiety and depression) would predict a poor treatment outcome at 12 months of follow-up for both groups. Method Patients diagnosed with IBS aged 16–50 years were recruited from 10 general practices in London. Three hundred thirty-four patients were referred to the study; 235 consented to participate, and those still symptomatic (moderate to severe IBS symptoms) after 2 weeks of general practitioner care and 4 weeks of mebeverine hydrochloride (275 mg 3 times a day) were included in the trial (n=149). Of those consenting to participate, 52 were no longer symptomatic at the time of inclusion, while 34 dropped out [8]. Participants were randomized to receive six sessions of CBT in addition to mebeverine (72 patients) or continue with mebeverine alone (77 patients). Four general practice nurses delivered the CBT. All participants were asked to complete a series of questionnaires. Of these, the following were hypothesized to predict treatment outcome: psychological distress (anxiety and depression combined score) [9,10], illness perceptions (IPQs) [11], IBS symptoms [12], cognitions about IBS [13], and IBS-related coping behavior. The latter is a new questionnaire designed and validated by the researchers. It allows assessment of changes in specific coping behaviors used by patients with IBS and includes items related to avoidance behavior and toileting behavior. It was found to be both valid and reliable (Cronbach's α=.89) [14]. The primary outcome for the prediction analyses was the work and social adjustment (WASA) scale at 12 months of follow-up which measures ability to work, manage the home, and participate in social and private leisure activities and relationships. The scale ranges from 0 to 40, with higher scores indicating more disability [15]. Ethical approval was received from St. Thomas' Hospital Research Ethics Committee; Guy's Hospital Research Ethics Committee; and Barnet, Enfield, and Haringey LREC. Statistical analyses All analyses were performed using SPSS version 15. The participants filled out questionnaires 3, 6, 9, and 12 months
after treatment ended. IBS tends to be a chronic condition and the 12-month follow-up was therefore chosen as the outcome in this study. WASA was a secondary outcome in the trial but was chosen as the main outcome of this study since health status and functionality can be argued to be more important than symptom severity and because the difference between the treatment groups were still detectable on WASA at 12 months. Both outcome and predictor variables were continuous, and the association between them was assumed to be linear. Multiple linear regression analyses were therefore chosen. Unadjusted and adjusted analyses were used to assess the strength of relationships between hypothesized predictors and outcome. All models were stratified by intervention group and examined separately in order to assess determinants of outcome for each treatment. Statistically significant predictors (Pb.01) from the unadjusted analyses were included in an adjusted regression model. Results In the previous study, the addition of CBT to mebeverine produced a significant benefit compared with the mebeverine-only group on symptom severity and WASA. The difference on the WASA scale represented therapeutic gains of approximately 20% and 40%, respectively. The improvements began to wane over time, and by 12 months of follow-up, significant therapeutic benefit of the addition of CBT could only be detected on the WASA scale. Full details of main findings and response rates are reported elsewhere [8]. Most patients were women (85%), mean age was 33.8 years (S.D. 9.1), and the majority were Caucasian British (69%); 50% had experienced IBS for more than 5 years, and 52% reported psychological problems during the last 5 years. Follow-up data on the WASA scale at 12 months were available from 73% of the participants, 71% in the mebeverine+CBT group (n=51) and 75% in the mebeverine group (n=58). The results from the unadjusted analyses showed that baseline WASA scores, psychological distress (anxiety and depression), IBS-coping behavior, and a belief that the IBS would have serious consequences for the patient's life, health and well-being (IPQ consequences), all predicted degree of disability (WASA) at 12 months for both intervention groups (Table 1). In the fully adjusted model, a lower level of
Table 1 Unadjusted models for each treatment group separately; only significant (Pb.01) predictors included Outcome: work and social adjustment 12 months
Mebeverine
Predictor variables
B (95% CI)
P
Mebeverine+CBT B (95% CI)
P
Work and social adjustment (higher score=more disability) Psychological distress (anxiety and depression) (higher score=more distress) Behavioral Scale (higher score=more adaptive behavior) IPQ consequences (higher score=worse consequences)
0.598 (0.414-0.782) 0.658 (0.445-0.870) 0.202 (0.135-0.270) 6.354 (4.253-8.456)
b.001 b.001 b.001 b.001
0.443 (0.248-0.638) 0.482 (0.237-0.727) 0.160 (0.093-0.227) 5.492 (3.226-7.757)
b.001 b.001 b.001 b.001
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388
387
Table 2 Adjusted models for each treatment group separately Outcome: work and social adjustment 12 months
Mebeverine
Predictor variables
B (95% CI)
P
B (95% CI)
P
Work and social adjustment (higher score=more disability) Psychological distress (anxiety and depression) (higher score=more distress) Behavioral scale (higher score=more adaptive behavior) IPQ consequences (higher score=worse consequences)
0.071 (−0.306 to 0.468) 0.388 (0.065 to 0.936) 0.051 (−0.20 to 0.187) 1.984 (−2.938 to 5.023)
.68 .025 .11 .60
0.274 (−0.021 to 0.520) −0.001 (−0.338 to 0.335) 0.285 (0.002 to 0.210) 0.199 (−1.201 to 6.208)
.07 .99 .045 .18
psychological distress (anxiety and depression combined) was the only significant predictor in the mebeverine group (Table 2). In the fully adjusted model for the mebeverine +CBT group less adaptive IBS-behavior at baseline predicted better WASA outcome at 12 months. The fully adjusted model explained a total variance of 40% for the mebeverine group and 38% for the mebeverine+CBT group.
factors were significant predictors of treatment outcome in the adjusted and/or unadjusted analyses, indicating that all these factors are important in the treatment of IBS patients. The relatively small sample size is a limitation in the current study. However, compared to most comparative studies (e.g., Refs. [1–3]), our study has a reasonably high number of patients included in the analyses and, therefore, does not violate the recommendations for sample size in linear regression [17]. However, similar studies should be conducted in order to replicate these findings, particularly in the primary care setting. In conclusion, the results showed that lower levels of psychological distress (anxiety and depression) predicted less disability at 12 months for the mebeverine group but not for the mebeverine+CBT group. The results further showed that maladaptive IBS behavior predicted less disability at 12 months for the mebeverine+CBT group. Clinical implications could involve recommending CBT to those patients with IBS in primary care who are engaging in unhelpful coping behavior.
Discussion This is the first study to examine predictors of treatment outcome in IBS patients receiving CBT and mebeverine in the context of a RCT in primary care. The results showed that more psychological distress (anxiety and depression) at baseline predicted more disability (WASA) at 1-year follow up in the mebeverine group, while less adaptive IBS behavior at baseline predicted less disability (WASA) at 1-year follow up in the mebeverine+CBT group. The results partly confirmed our hypothesis that psychological distress would predict a poor outcome. However, we only found this for the mebeverine only group, not for the mebeverine+CBT group. This result therefore deviates from previous findings [1–4] indicating that psychological distress does not interfere with a successful treatment course of CBT and, therefore, could be recommended to IBS patients with comorbid psychological symptoms. The results also showed that those IBS patients who presented more maladaptive behavior (e.g., avoidance behavior) and received mebeverine+CBT treatment, experienced less disability after 12 months. This could imply that the CBT treatment was especially effective in changing maladaptive IBS-coping behavior (e.g., avoidance behavior), leading to less disability in terms of better work and social adjustment. The clinical implications of this finding could be to recommend CBT treatment to IBS patients presenting in primary care with maladaptive IBS-coping behavior. The IBS-coping behavior was investigated through a new questionnaire designed for measuring coping behaviors in IBS and has therefore never been reported before as far as we know. Since IBS-coping behavior was found to predict treatment outcome, future studies should consider including this questionnaire for research as well as clinical purposes. The results strengthen the validity of the CBT model for IBS patients [16] in that both emotional (anxiety and depression), cognitive (IPQs), and behavioral (IBS behavior)
Mebeverine+CBT
Acknowledgments We would like to thank the Health Technology Assessment program for funding this study. We would also like to thank the study nurses—Rebecca Holt, Tricia Lewis, Sheila Morton, and Lindsey Shephard—for their contribution, as well as the patients, doctors, and staff at the participating general practices. Trudie Chalder acknowledges financial support from the Department of Health via the National Institute for Health Research Specialist Biomedical Research Centre for Mental Health award to South London and Maudsley NHS Foundation Trust and the Institute of Psychiatry at King's College London. Finally, we would like to thank Stein Atle Lie who provided valuable statistical advice in the revision process of the article. References [1] Blanchard EB, Schwarz SP, Neff DF, Gerardi MA. Prediction of outcome from the self-regulatory treatment of irritable bowel syndrome. Behav Res Ther 1988;26:187–90. [2] Blanchard EB, Scharff L, Payne A, Schwarz SP, Suls JM, Malamood H. Prediction of outcome from cognitive-behavioral treatment of irritable bowel syndrome. Behav Res Ther 1992;30:647–50. [3] Blanchard EB, Lackner JM, Gusmano R, Gudleski GD, Sanders K, Keefer L, et al. Prediction of treatment outcome among patients with
388
[4]
[5]
[6]
[7]
[8]
[9]
S.E. Reme et al. / Journal of Psychosomatic Research 68 (2010) 385–388 irritable bowel syndrome treated with group cognitive therapy. Behav Res Ther 2006;44:317–37. Drossman DA, Toner BB, Whitehead WE, Diamant NE, Dalton CB, Duncan S, et al. Cognitive-behavioral therapy versus education and desipramine versus placebo for moderate to severe functional bowel disorders. Gastroenterology 2003;125:19–31. Creed F, Guthrie E, Ratcliffe J, Fernandes L, Rigby C, Tomenson B, et al. Does psychological treatment help only those patients with severe irritable bowel syndrome who also have a concurrent psychiatric disorder? Aust N Z J Psychiatry 2005;39:807–15. Guthrie E, Creed F, Dawson D, Tomenson B. A controlled trial of psychological treatment for the irritable bowel syndrome. Gastroenterology 1991;100:450–7. Lackner JM, Jaccard J, Krasner SS, Katz LA, Gudleski GD, Blanchard EB. How does cognitive behavior therapy for irritable bowel syndrome work? A mediational analysis of a randomized clinical trial. Gastroenterology 2007;133:433–44. Kennedy T, Jones R, Darnley S, Seed P, Wessely S, Chalder T. Cognitive behaviour therapy in addition to antispasmodic treatment for irritable bowel syndrome in primary care: randomised controlled trial. BMJ (Clinical research ed 2005;331:435. Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand 1983;67:361–70.
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