Patient adherence to cognitive behavioural therapy for obsessive-compulsive disorder: a systematic review and meta-analysis

Journal article

Leeuwerik, T., Cavanagh, K. and Strauss, C. 2019. Patient adherence to cognitive behavioural therapy for obsessive-compulsive disorder: a systematic review and meta-analysis. Journal of Anxiety Disorders. 68, pp. 102-135.
AuthorsLeeuwerik, T., Cavanagh, K. and Strauss, C.

Whilst cognitive behavioural therapy (CBT) is the treatment of choice for obsessive-compulsive disorder (OCD), around half of the participants do not experience remission following treatment. As yet, there is no comprehensive systematic review of the extent to which patient non-adherence presents a challenge to the overall benefit of CBT for OCD. The aim of this systematic review and meta-analysis was to identify the magnitude, moderators and reasons for poor patient adherence to CBT for OCD in terms of: (1) treatment refusal, (2) treatment dropout, (3) session at- tendance/module completion, and (4) between-session CBT task adherence. Sociodemographic and clinical variables, treatment and study design characteristics were examined as moderators of adherence. The systematic search identified 123 studies including 5627 participants taking part in CBT or control conditions. A pooled rate of 15.6% of eligible patients refused CBT and a further 15.9% of treatment starters dropped out from treatment. Group CBT had significantly lower dropout rates than individually-delivered CBT. No other significant moderators were found. Most studies reported moderate to good adherence to between-session CBT tasks, which had a significant medium to large association with post-treatment OCD symptom reduction. Recommendations for enhanced measurement and re- porting of patient adherence to CBT for OCD are made along with clinical implications of findings.

KeywordsObsessive compulsive disorder ; Adherence Refusal Attrition; CBT; Meta-analysis
JournalJournal of Anxiety Disorders
Journal citation68, pp. 102-135
Digital Object Identifier (DOI)doi:10.1016/j.janxdis.2019.102135
Official URL
FunderEconomic and Social Research Council
Publication dates
Online28 Aug 2019
Publication process dates
Accepted23 Aug 2019
Deposited13 Jan 2020
Accepted author manuscript
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Abramowitz, J. S., Franklin, M. E., Zoellner, L. A., & DiBernardo, C. L. (2002). Treatment compliance and outcome in obsessive-compulsive disorder. Behavior Modification, 26(4), 447–463.
Abramowitz, J. S., Taylor, S., & McKay, D. (2005). Potentials and limitations of cognitive treatments for obsessive-compulsive disorder. Cognitive Behaviour Therapy, 34(3), 140–147.
Aderka, I. M., Anholt, G. E., van Balkom, A. J. L. M., Smit, J. H., Hermesh, H., Hofmann, S.
G., & van Oppen, P. (2011). Differences between early and late drop-outs from treatment for obsessive–compulsive disorder. Journal of Anxiety Disorders, 25(7), 918–923.
Aloe, A. M., & Thompson, C. G. (2013). The synthesis of partial effect sizes. Journal of the
Society for Social Work and Research, 4(4), 390–405. 2013.24.
American Psychiatric Association (APA) (2007). Practice guideline for the treatment of
patients with obsessive-compulsive disorder. Arlington, VA.
American Psychiatric Association (2013). Diagnostic and statistical manual of mental dis- orders (fifth edition). Washington DC: Author.
Andersen, R. M. (2017). Revisiting the Behavioral Model and Access to Medical Care: Does it Matter? Journal of Health and Social Behavior, 36(1), 1–10.
Bachofen, M., Nakagawa, A., Marks, I. M., Park, J. M., Greist, J. H., Baer, L., & Dottl, S. L. (1999). Home self-assessment and self-treatment of obsessive-compulsive disorder using a manual and a computer-conducted telephone interview: Replication of a UK- US study. The Journal of Clinical Psychiatry, 60(8), 545–549.
Barrett, M. S., Chua, W.-J., Crits-Christoph, P., Gibbons, M. B., & Thompson, D. (2008).
Early withdrawal from mental health treatment: Implications for psychotherapy practice. Psychotherapy Theory Research Practice Training, 45(2), 247–267. https://
Beck, A. T., Steer, R. A., & Garbin, M. G. (1988). Psychometric properties of the Beck
Depression Inventory: Twenty-five years of evaluation. Clinical Psychology Review, 8(1), 77–100.
Borenstein, M., Hedges, L. V., Higgings, J. P. O., & Rothstein, H. R. (2009). Introduction to
meta-analysis. West Sussex: Wiley.
Comprehensive Meta-Analysis (2014). (Version 3) [Computer software]. Available fromEnglewood, NJ: Biostat.
Cottraux, J., Note, I., Yao, S. N., Lafont, S., Note, B., Mollard, E., & Dartigues, J. F. (2001).
A randomized controlled trial of cognitive therapy versus intensive behavior therapy in obsessive compulsive disorder. Psychotherapy and Psychosomatics, 70(6), 288–297.
Cougle, J. R., Timpano, K. R., Fitch, K. E., & Hawkins, K. A. (2011). Distress tolerance and obsessions: An integrative analysis. Depression and Anxiety, 28(10), 906–914.
Craske, M. G., Treanor, M., Conway, C. C., Zbozinek, T., & Vervliet, B. (2014). Maximizing exposure therapy: An inhibitory learning approach. Behaviour Research and Therapy, 58, 10–23.
De Araujo, L. A., Ito, L. M., & Marks, I. M. (1996). Early compliance and other factors predicting outcome of exposure for obsessive–compulsive disorder. The British Journal of Psychiatry, 169(6), 747–752.
Di Bona, L., Saxon, D., Barkham, M., Dent-Brown, K., & Parry, G. (2014). Predictors of
patient non-attendance at Improving Access to Psychological Therapy services de- monstration sites. Journal of Affective Disorders, 169, 157–164. 1016/j.jad.2014.08.005.
Diefenbach, G. J., Wootton, B. M., Bragdon, L. B., Moshier, S. J., & Tolin, D. F. (2015). Treatment outcome and predictors of internet guided self-help for obsessive-com- pulsive disorder. Behavior Therapy, 46(6), 764–774. 2015.06.001.
Duval, S., & Tweedie, R. (2000). Trim and fill: A simple funnel-plot–Based method of
testing and adjusting for publication Bias in meta-analysis. Biometrics, 56(2), 455–463.
Egger, M., Davey Smith, G., Schneider, M., & Minder, C. (1997). In BMJ Clinical research

(Vol. Ed.), Bias in meta-analysis detected by a simple, graphical test: vol. 315, (pp. 629– 634). . BMJ 315.
Fals-Stewart, W., & Lucente, S. (1993). An MCMI cluster typology of obsessive-compul- sives: A measure of personality characteristics and its relationship to treatment participation, compliance and outcome in behavior therapy. Journal of Psychiatric Research, 27(2), 139–154.
Fernandez, E., Salem, D., Swift, J. K., & Ramtahal, N. (2015). Meta-analysis of dropout
from cognitive behavioral therapy. Journal of Consulting and Clinical Psychology, 83(6), 1108–1122.
Foa, E. B., & Kozak, M. J. (1986). Emotional processing of fear. Exposure to corrective information. Psychological Bulletin, 99(1), 20–35.
Fisher, P. L., & Wells, A. (2005). How effective are cognitive and behavioral treatments for obsessive-compulsive disorder? A clinical significance analysis. Behaviour Research and Therapy, 43(12), 1543–1558.
Fu, R., Gartlehner, G., Grant, M., Shamliyan, T., Sedrakyan, A., Wilt, T. J., ... Trikalinos, T.
A. (2011). Conducting quantitative synthesis when comparing medical interventions: AHRQ and the Effective Health Care Program. Journal of Clinical Epidemiology, 64(11), 1187–1197.
Goetter, E. M., Herbert, J. D., Forman, E. M., Yuen, E. K., & Thomas, J. G. (2014). An open
trial of videoconference-mediated exposure and ritual prevention for obsessive- compulsive disorder. Journal of Anxiety Disorders, 28(5), 460–462. 10.1016/j.janxdis.2014.05.004.
Goodman, W., Price, L., Rasmussen, S., Mazure, C., R, F., & Charney, D. (1989). The yale- brown obsessive compulsive scale. I. development, use, and reliability. Archives of General Psychiatry, 46(11), 1006–1111.
Goodwin, R., Koenen, K. C., Hellman, F., Guardino, M., & Struening, E. (2002).
Helpseeking and access to mental health treatment for obsessive-compulsive dis- order. Acta Psychiatrica Scandinavica, 106(2), 143–149. 1600-0447.2002.01221.x.
Greist, J. H., Marks, I. M., Baer, L., Kobak, K. A., Wenzel, K. W., Hirsch, M. J., & Clary, C.
M. (2002). Behavior therapy for obsessive-compulsive disorder guided by a computer or by a clinician compared with relaxation as a control. The Journal of Clinical Psychiatry, 63(2), 138–145.
Greist, J. H., Marks, I. M., Baer, L., Parkin, J. R., Manzo, P. A., Mantle, J. M., ... Forman, L.
(1998). Self-treatment for obsessive compulsive disorder using a manual and a computerized telephone interview: A US-UK study. M D Computing, 15(3), 149–157.
Hans, E., & Hiller, W. (2013). A meta-analysis of nonrandomized effectiveness studies on outpatient cognitive behavioral therapy for adult anxiety disorders. Clinical Psychology Review, 33(8), 954–964.
Hedges, L., & Olkin, I. (1985). Statistical methods in meta-analysis. Orlando, FL: Academic Press.
Higgins, J. P. T., Thompson, S. G., Deeks, J. J., & Altman, D. G. (2003). Measuring in- consistency in meta-analyses. BMJ : British Medical Journal, 327(7414), 557–560.
Hsieh, H.-F., & Shannon, S. E. (2005). Three appproaches to qualitative content analysis.
Qualitative Health Research, 15(9), 1277–1288.
Jacobson, N. S., Roberts, L. J., Berns, S. B., & McGlinchey, J. B. (1999). Methods for defining and determining the clinical significance of treatment effects: Description, application, and alternatives. Journal of Consulting and Clinical Psychology, 67(3), 300–307.
Jacobson, N. S., & Truax, P. (1991). Clinical significance: A statistical approach to de-
fining meaningful change in psychotherapy research. Journal of Consulting and Clinical Psychology, 59(1), 12–19
Jacoby, R. J., & Abramowitz, J. S. (2016). Inhibitory learning approaches to exposure therapy: A critical review and translation to obsessive-compulsive disorder. Clinical Psychology Review, 49, 28–40.
Jadad, A. R., Moore, R. A., Carroll, D., Jenkinson, C., Reynolds, D. J. M., Gavaghan, D. J., & McQuay, H. J. (1996). Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Controlled Clinical Trials, 17(1), 1–12.

Kazantzis, N., Whittington, C., Zelencich, L., Kyrios, M., Norton, P. J., & Hofmann, S. G. (2016). Quantity and quality of homework compliance: A meta-analysis of relations with outcome in cognitive behavior therapy. Behavior Therapy, 47(5), 755–772.
Kelley, G. A., & Kelley, J. S. (2012). Statistical models for meta-analysis: A brief tutorial.
World Journal of Methodology, 2(4), 27.
Kenwright, M., Marks, I., Graham, C., Franses, A., & Mataix-Cols, D. (2005). Brief scheduled phone support from a clinician to enhance computer-aided self-help for obsessive-compulsive disorder: Randomized controlled trial. Journal of Clinical Psychology, 61(12), 1499–1508.
Kobak, K. A., Greist, R., Jacobi, D. M., Levy-Mack, H., & Greist, J. H. (2015). Computer-
assisted cognitive behavior therapy for obsessive-compulsive disorder: A randomized trial on the impact of lay vs. Professional coaching. Annals of General Psychiatry, 14.
Kozak, M., & Foa, E. (1997). Mastery of obsessive-compulsive disorder: A cognitive-behavioral
approach. Therapist guide. San Antonio TX: Graywind.
Lewin, A. B., De Nadai, A. S., Park, J., Goodman, W. K., Murphy, T. K., & Storch, E. A. (2011). Refining clinical judgment of treatment outcome in obsessive-compulsive disorder. Psychiatry Research, 185(3), 394–401.
Leung, A. W., & Heimberg, R. G. (1996). Homework compliance, perceptions of control, and outcome of cognitive-behavioral treatment of social phobia. Behaviour Research and Therapy, 34(5–6), 423–432.
Lipsey, M. W., & Wilson, D. B. (2001). Practical meta-analysis. Thousand Oaks, Calif: Sage Publications.
Macy, A. S., Theo, J. N., Kaufmann, S. C., Ghazzaoui, R. B., Pawlowski, P., Fakhry, H. I., & IsHak, W. W. (2013). Quality of life in obsessive compulsive disorder. CNS Spectrums, 18(1), 21–33.
Mancebo, M. C., Pinto, A., Rasmussen, S. A., & Eisen, J. L. (2008). Development of the
treatment adherence survey-patient version (TAS-P) for OCD. Journal of Anxiety Disorders, 22(1), 32–43. Retrieved from 70159124?accountid=14182.
Mancebo, M. C., Eisen, J. L., Sibrava, N. J., Dyck, I. R., & Rasmussen, S. A. (2011). Patient utilization of cognitive-behavioral therapy for OCD. Behavior Therapy, 42(3), 399. Retrieved from
Mataix-Cols, D., & Marks, I. M. (2006). Self-help with minimal therapist contact for ob- sessive-compulsive disorder: A review. European Psychiatry, 21(2), 75–80.
Mataix-Cols, D., Fernandez de La Cruz, L., Nordsletten, A. E., Lenhard, F., Isomura, K., & Simpson, H. B. (2016). Towards an international expert consensus for defining
treatment response, remission, recovery and relapse in obsessive-compulsive dis- order. World Psychiatry : Official Journal of the World Psychiatric Association (WPA), 15(1), 80–81.
McKay, D., Sookman, D., Neziroglu, F., Wilhelm, S., Stein, D. J., Kyrios, M., ... Veale, D.
(2015). Efficacy of cognitive-behavioral therapy for obsessive–compulsive disorder.
Psychiatry Research, 225(3), 236–246.
National Institute of Health and Care Excellence [NICE] (2005). Obsessive-compulsive disorder: Core interventions in the treatment of obsessive-compulsive disorder and body dysmorphic disorder. London: Author.
Obsessive Compulsive Cognitions Working Group (1997). Cognitive assessment of ob- sessive-compulsive disorder. Behaviour Research and Therapy, 35(7), 667–681.
Obsessive Compulsive Cognitions Working Group (2005). Psychometric validation of the obsessive belief questionnaire and interpretation of intrusions inventory – Part 2: Factor analyses and testing of a brief version. Behaviour Research and Therapy, 43(11), 1527–1542.
Olatunji, B. O., Davis, M. L., Powers, M. B., & Smits, J. A. J. (2013). Cognitive-behavioral therapy for obsessive-compulsive disorder: A meta-analysis of treatment outcome and moderators. Journal of Psychiatric Research, 47(1), 33–41.
Olatunji, B. O., Deacon, B. J., & Abramowitz, J. S. (2009). The cruelest cure? Ethical issues in the implementation of exposure-based treatments. Cognitive and Behavioral Practice, 16(2), 172–180.
Ong, C. W., Clyde, J. W., Bluett, E. J., Levin, M. E., & Twohig, M. P. (2016). Dropout rates
in exposure with response prevention for obsessive-compulsive disorder: What do the data really say? Journal of Anxiety Disorders, 40, 8–17. janxdis.2016.03.006.
Öst, L. G. (2008). Cognitive behavior therapy for anxiety disorders: 40 years of progress.
Nordic Journal of Psychiatry, 62(Suppl 47), 5–10. 08039480802315590.
Öst, L. G., Havnen, A., Hansen, B., & Kvale, G. (2015). Cognitive behavioral treatments of
obsessive-compulsive disorder. A systematic review and meta-analysis of studies published 1993–2014. Clinical Psychology Review, 40, 156–169. 1016/j.cpr.2015.06.003.
Owens, P. L., Hoagwood, K., Horwitz, S. M., Leaf, P. J., Poduska, J. M., Kellam, S. G., & Ialongo, N. S. (2000). Barriers to children’s mental health services. Journal of the
American Academy of Child and Adolescent Psy, 41(6), 731–738. 1097/00004583-200206000-00013.
Pallanti, S., International Treatment Refractory OCD Consortium, Hollander, E., Bienstock, C., Koran, L., Leckman, J., & Zohar, J. (2002). Treatment non-response in OCD: Methodological issues and operational definitions. The International Journal of Neuropsychopharmacology, 5, 181–191.
Pallanti, S., & Quercioli, L. (2006). Treatment-refractory obsessive-compulsive disorder:
Methodological issues, operational definitions and therapeutic lines. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 30(3), 400–412.

Ponniah, K., Magiati, I., & Hollon, S. D. (2013). An update on the efficacy of psychological therapies in the treatment of obsessive-compulsive disorder in adults. Journal of Obsessive-compulsive and Related Disorders, 2(2), 207–218. jocrd.2013.02.005.
Primakoff, L., Epstein, N., & Covi, L. (1986). Homework compliance: An uncontrolled variable in cognitive therapy outcome research. Behavior Therapy, 17(4), 433–446.
Richards, D. A., & Borglin, G. (2011). Implementation of psychological therapies for anxiety and depression in routine practice: Two-year prospective cohort study. Journal of Affective Disorders, 133(1–2), 51–60.
Rosa-Alcazar, A. I., Sanchez-Meca, J., Gomez-Conesa, A., & Marin-Martinez, F. (2008). Psychological treatment of obsessive-compulsive disorder: A meta-analysis. Clinical
Psychology Review, 28(8), 1310–1325. Rowa, K., Antony, M. M., Summerfeldt, L. J., Purdon, C., Young, L., & Swinson, R. P.
(2007). Office-based vs. Home-based behavioral treatment for obsessive-compulsive disorder: A preliminary study. Behaviour Research and Therapy, 45(8), 1883–1892.
Sabate, E. (2003). Adherence to long term therapies: Evidence for action. Geneva: World Health Organization.
Santana, L., & Fontenelle, L. F. (2011). A review of studies concerning treatment ad- herence of patients with anxiety disorders. Patient Preference and Adherence, 5, 427–439.
Schulz, K. F., Altman, D. G., & Moher, D. (2010). CONSORT 2010 statement: Updated
guidelines for reporting parallel group randomised trials. Journal of Pharmacology & Pharmacotherapeutics, 1(2), 100–107.
Seol, S. H., Kwon, J. S., Kim, Y. Y., Kim, S. N., & Shin, M. S. (2016). Internet-based cognitive behavioral therapy for obsessive-compulsive disorder in Korea. Psychiatry Investigation, 13(4), 373–382.
Simpson, H. B., Maher, M., Page, J. R., Gibbons, C. J., Franklin, M. E., & Foa, E. B. (2010).
Development of a patient adherence scale for exposure and response prevention therapy. Behavior Therapy, 41(1), 30–37.
Simpson, H. B., Zuckoff, A. M., Maher, M. J., Page, J. R., Franklin, M. E., Foa, E. B., ... Wang, Y. (2010). Challenges using motivational interviewing as an adjunct to ex-
posure therapy for obsessive-compulsive disorder. Behaviour Research and Therapy, 48(10), 941–948.
Simpson, H. B., Maher, M. I. J., Wang, Y., Bao, Y., Foa, E. B., & Franklin, M. (2011).
Patient adherence predicts outcome from cognitive behavioral therapy in obsessive- compulsive disorder. Journal of Consulting and Clinical Psychology, 79(2), 247–252.
Simpson, H. B., Foa, E. B., Liebowitz, M. R., Huppert, J. D., Cahill, S., Maher, M. J., &
Campeas, R. (2013). Cognitive-behavioral therapy vs risperidone for augmenting serotonin reuptake inhibitors in obsessive-compulsive disorder a randomized clinical trial. JAMA Psychiatry, 70(11), 1190–1198.
Sookman, D. (2016). Specialized cognitive behavior therapy for obsessive compulsive disorder.
An exert clinician guidebook. New York, NY: Guilford Press.
Sookman, D., & Steketee, G. (2010). Specialized cognitive behavior therapy for treatment resistant obsessive compulsive disorder. In D. Sookman, & R. L. Leahy (Eds.).
Treatment resistant anxiety disorders. Resolving impasses to symptom remission (pp. 31– 74). New York, NY: Routledge.
Sterne, J. A. C., Egger, M., & Moher, D. (2011). Chapter 10: Addressing reporting biases.
In J. P. T. Higgins, & S. Green (Eds.). Cochrane handbook for systematic reviews of intervention. Version 5.1.0 (updated March 2011)The Cochrane Collaboration.
Available from
Swift, J. K., & Greenberg, R. P. (2014). A Treatment by disorder meta-analysis of dropout from Psychotherapy. Journal of Psychotherapy Integration, 24(3), 193–207. https://
Swift, J. K., Greenberg, R. P., Whipple, J. L., & Kominiak, N. (2012). Practice re- commendations for reducing premature termination in therapy. Professional
Psychology, Research and Practice, 43(4), 379–387. a0028291.
Taylor, S., Abramowitz, J. S., & McKay, D. (2012). Non-adherence and non-response in the treatment of anxiety disorders. Journal of Anxiety Disorders, 26(5), 583–589.
Tetley, A., Jinks, M., Huband, N., & Howells, K. (2011). A systematic review of measures of therapeutic engagement in psychosocial and psychological treatment. Journal of Clinical Psychology, 67(9), 927–941.
Tolin, D. F., Diefenbach, G. J., & Gilliam, C. M. (2011). Stepped care versus standard
cognitive-behavioral therapy for obsessive-compulsive disorder: A preliminary study of efficacy and costs. Depression and Anxiety, 28(4), 314–323.
Tolin, D. F., Hannan, S., Maltby, N., Diefenbach, G. J., Worhunsky, P., & Brady, R. E. (2007). A randomized controlled trial of self-directed versus therapist-directed cog- nitive-behavioral therapy for obsessive-compulsive disorder patients with prior medication trials. Behavior Therapy, 38(2), 179–191. 2006.07.001.
Tolin, D. F., Maltby, N., Diefenbach, G. J., Hannan, S. E., & Worhunsky, P. (2004).
Cognitive-behavioral therapy for medication nonresponders with obsessive-compul- sive disorder: A wait-list-controlled open trial. The Journal of Clinical Psychiatry, 65(7), 922–931.
Vogel, P. A., Stiles, T. C., & Gotestam, K. G. (2004). Adding cognitive therapy elements to exposure therapy for obsessive compulsive disorder: A controlled study. Behavioural and Cognitive Psychotherapy, 32(3), 275–290.
Wheaton, M. G., Galfalvy, H., Steinman, S. A., Wall, M. M., Foa, E. B., & Simpson, H. B.

(2016). Patient adherence and treatment outcome with exposure and response pre- vention for OCD: Which components of adherence matter and who becomes well? Behaviour Research and Therapy, 85, 6–12. 010.
Wheaton, M. G., Huppert, J. D., Foa, E. B., & Simpson, H. B. (2016). How important is the therapeutic alliance in treating obsessive-compulsive disorder with exposure and response prevention? An empirical report. Clinical Neuropsychiatry: Journal of
Treatment Evaluation, 13(6), 88–93.
Whittal, M. L., Thordarson, D. S., & McLean, P. D. (2005). Treatment of obsessive-compulsive disorder: Cognitive behavior therapy vs. Exposure and response pre- vention. Behaviour Research and Therapy, 43(12), 1559–1576. 1016/j.brat.2004.11.012.
Whittal, M. L., Woody, S. R., McLean, P. D., Rachman, S. J., & Robichaud, M. (2010).
Treatment of obsessions: A randomized controlled trial. Behaviour Research and Therapy, 48(4), 295–303.
Wierzbicki, M., & Pekarik, G. (1993). A meta-analysis of psychotherapy dropout.
EBSCOhost, 24(2), 190–195.

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