Long-term remission rates and trajectory predictors in obsessive-compulsive disorder: Findings from a six-year naturalistic longitudinal cohort study.

BACKGROUND: This naturalistic study, utilizing data from the Netherlands Obsessive-Compulsive Disorder Association (NOCDA) cohort, investigated the long-term remission rates and predictors of different trajectories of obsessive-compulsive disorder (OCD) within a clinical population. METHODS: A sample of 213 participants was classified into three illness trajectories: "Chronic," "Episodic, "and "Remitted-OCD." Long-term remission rates were calculated based on three follow-up measurements over a 6-year period. A multinomial logistic regression model, incorporating five selected predictors with high explanatory power and one covariate, was employed to analyze OCD trajectory outcomes. RESULTS: The long-term full remission rates, calculated from all the measurements combined (14%), were significantly lower than what was observed in earlier studies and when compared to assessments at each individual follow-up (∼30%). Moreover, high baseline symptom severity and early age of onset were identified as significant risk factors for a chronic course of OCD, while male sex and younger age predicted a more favorable trajectory. Notably, the likelihood of an episodic course remained high even without identified risk factors. LIMITATIONS: The bi-annual data collection process is unable to capture participants' clinical conditions between assessments. Additionally, no data was collected regarding the specific type and duration of psychological treatment received. Regarding the type of treatment participants received. CONCLUSIONS: Results suggest that long-term remission rates may be lower than previously reported. Consequently, employing multiple assessment points in longitudinal studies is necessary for valid estimation of long-term full remission rates. The results emphasize the importance of personalized clinical care and ongoing monitoring and maintenance for most OCD cases.

Changes in insight throughout the natural four-year course of obsessive-compulsive disorder and its association with OCD severity and quality of life.

Objective: Patients with obsessive-compulsive disorder (OCD) and poor insight show higher symptom severity, lower quality of life (QoL), and a reduced treatment response compared to patients with good insight. Little is known about changes in insight. This study explored the course of insight and its association with OCD severity and QoL among 253 patients with OCD participating in the prospective naturalistic Netherlands Obsessive Compulsive Disorder Association (NOCDA) Study. Results: In 70% of the participants with available insight data, the level of insight changed during the four-year course. Insight was most variable in participants with poor insight. Improvement of insight scores was statistically significantly associated with improvement of Y-BOCS scores (r = 0.19), but not with changes in QoL scores. Change in insight in the first 2 years was not statistically significantly predictive of OCD severity or QoL at four-year follow-up. Conclusion: These findings suggest that patients' levels of insight may change during the natural four-year course of OCD and that improvement in the level of insight have a positive association with improvement in OCD severity.

Predictors of the 6-year outcome of obsessive-compulsive disorder: Findings from the Netherlands Obsessive-Compulsive Disorder Association study.

OBJECTIVE: Obsessive-compulsive disorder is characterized by a chronic course that can vary between patients. The knowledge on the naturalistic long-term outcome of obsessive-compulsive disorder and its predictors is surprisingly limited. The present research was designed to identify clinical and psychosocial predictors of the long-term outcome of obsessive-compulsive disorder. METHODS: We included 377 individuals with a current diagnosis of obsessive-compulsive disorder, who participated in the Netherlands Obsessive Compulsive Disorder Association study, a multicenter naturalistic cohort study. Predictors were measured at baseline using self-report questionnaires and clinical interviews. Outcome was assessed using the Yale-Brown Obsessive Compulsive Scale at 2-, 4- and 6-year follow-up. RESULTS: The overall course of obsessive-compulsive disorder was characterized by two prominent trends: the first reflected an improvement in symptom severity, which was mitigated by the second, worsening trend in the long term. Several determinants affected the course variations of obsessive-compulsive disorder, namely, increased baseline symptom severity, late age of onset, history of childhood trauma and autism traits. CONCLUSION: The long-term outcome of obsessive-compulsive disorder in naturalistic settings was characterized by an overall improvement in symptom severity, which was gradually halted to the point of increased worsening. However, after 6 years, the severity of symptoms remained below the baseline level. While certain determinants predicted a more favorable course, their effect diminished over time in correspondence to the general worsening trend. The results highlight the importance of a regular and continuous monitoring for symptom exacerbations as part of the management of the obsessive-compulsive disorder, regardless of the presence of putative predictors.

Poor Insight in Obsessive-Compulsive Disorder as a Multifaceted Phenomenon: Evidence From Brain Activation During Symptom Provocation.

BACKGROUND: Poor insight in obsessive-compulsive disorder (OCD) is associated with higher symptom severity, more comorbidities, and worse response to treatment. This study aimed to elucidate underlying mechanisms of poor insight in OCD by exploring its neurobiological correlates. METHODS: Using a symptom provocation task during functional magnetic resonance imaging, we compared brain activation of patients with poor insight (n = 19; 14 female, 5 male), good/fair insight (n = 63; 31 female, 32 male), and healthy control participants (n = 42; 22 female, 20 male) using a Bayesian region-of-interest and a general linear model whole-brain approach. Insight was assessed using the Overvalued Ideas Scale. RESULTS: Compared with patients with good/fair insight and healthy control participants, patients with OCD and poor insight showed widespread lower task-related activation in frontal areas (subgenual anterior cingulate cortex, ventromedial prefrontal cortex, dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, supplementary motor area, precentral gyrus), parietal areas (posterior parietal cortex, precuneus), and the middle temporal gyrus and insula. Results were not driven by interindividual differences in OCD symptom severity, medication usage, age of disorder onset, or state distress levels. CONCLUSIONS: During symptom provocation, patients with OCD and poor insight show altered activation in brain circuits that are involved in emotional processing, sensory processing, and cognitive control. Future research should focus on longitudinal correlates of insight and/or use tasks that probe emotional and sensory processing and cognitive control.

Therapeutic Alliance and Treatment Outcome in Cognitive Behavior Therapy for Obsessive-Compulsive Disorder.

Objective: Therapeutic alliance has consistently been found to predict treatment outcomes across various psychotherapies and patient diagnosis. However, the relationship between therapeutic alliance and outcome in Cognitive Behavioral Therapy (CBT) has shown mixed results. This study investigated the impact of different aspects of therapeutic alliance in CBT for Obsessive-Compulsive Disorder (OCD). Method: Data from two previously completed randomized controlled trials of 208 patients with OCD and their therapists were analyzed. Therapeutic alliance was assessed at week 4 of treatment with the patient-rated and therapist-rated Working Alliance Inventory (WAI), which includes three subscales to measure alliance domains (Goal, Task and Bond). Higher WAI score reflects a better therapeutic relationship. OCD severity was rated by independent assessors at baseline and post-treatment using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Linear regression analyses were used to examine the effects of the different aspects of therapeutic alliance on treatment outcome, adjusted for baseline symptom severity. Results: A higher total WAI score as rated by therapists significantly predicted a lower post-treatment Y-BOCS. Further, higher scores on the Goal and Task subscales of the WAI were associated with lower post-treatment severity. However, these significant outcomes reflected only small effect sizes. Conclusions: In the treatment of OCD, the strength of the therapeutic alliance contributes to outcomes, though to a limited extent. Effective OCD treatment involves the delivery of specific therapy interventions, in the context of a strong therapeutic alliance.

Responsiveness and other psychometric properties of the Yale-Brown Obsessive-Compulsive Scale Severity Scale-Second Edition in a Dutch clinical sample.

The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) is a widely used clinician-rated interview to assess the presence and severity of obsessive-compulsive disorder (OCD). The scale is revised (Y-BOCS-II) to overcome several psychometric limitations, for example by extending the scoring for better discrimination within higher severity levels. The aim of the present study was to examine the responsiveness and other psychometric properties of the Y-BOCS-II Severity Scale in a Dutch clinical sample. The Y-BOCS-II is translated into Dutch and administered to 110 patients seeking therapy for OCD. This was done twice, before and after treatment. The original Y-BOCS was simultaneously rated. Self-report measures regarding depression, symptom severity and OCD symptoms were assessed. The Y-BOCS-II has a good internal consistency (Cronbach's α = 0.84), test-retest (intraclass correlation coefficient [ICC] = 0.89) and interrater reliability (ICC = 0.98). The construct validity proved to be modest to good. The responsiveness over time was in favour of the Y-BOCS-II, compared with the Y-BOCS-I, particularly in the moderate-severely affected OCD patients. The Y-BOCS-II Severity Scale is a reliable and valid instrument for accurately assessing the severity of OCD symptoms and for measuring treatment-induced change. This second version also has clinical and psychometric advantages over the Y-BOCS-I. When these findings are sufficiently replicated, use of the Y-BOCS-II as the new common standard seems recommendable.

Proof of Principle: Is a Pre-treatment Behavior Approach Test a Potential Predictor for Response to Intensive Residential Treatment in Patients With Treatment Refractory Obsessive Compulsive Disorder?

Patients with severe and treatment refractory obsessive compulsive disorder (OCD) are usually referred to a specialized center for intensive residential treatment (IRT), consisting of exposure and response prevention (EX/RP), pharmacotherapy and additional therapies. About 50% of the patients does not respond to IRT. Currently we are not able to predict treatment response. If we were to have predictive tools, we could personify treatment at an earlier stage. Recent studies show that early adherence and willingness to EX/RP and low avoidance during EX/RP measured during treatment were associated with treatment response. In this observational study willingness and ability of patients with severe and treatment refractory OCD (N = 58) is conceptualized by a behavioral measurement, measured before the start of 12 weeks of IRT, using a Behavior Approach Test (BAT), as opposed to relying on self-report measurements. A medium or strong association between pre-treatment performance on the BAT and treatment response would justify next steps to test the BAT as a predictive tool for IRT. Results of regression analyses showed that there is a significant association between the performance on the BAT and change in OCD symptom severity after IRT. However, the effect-size is too small to use the BAT in its current form as predictor in clinical practice. The principle of the association between pre-treatment behaviorally measured willingness and ability to fully engage in EX/RP, and treatment response has now been proven. To ultimately design a predictive tool, future research is needed to refine a behavioral measurement of pre-treatment willingness and ability.

Development and psychometric evaluation of the Decision Tool Anxiety Disorders, OCD and PTSD (DTAOP): Facilitating the early detection of patients in need of highly specialized care.

BACKGROUND: Early identification of patients with an anxiety disorder, obsessive-compulsive disorder (OCD), or post-traumatic stress disorder (PTSD) in need of highly specialized care could facilitate the selection of the optimal initial treatment in these patients. This paper describes the development and psychometric evaluation of the Decision Tool Anxiety Disorders, OCD and PTSD (DTAOP), which aims to aid clinicians in the early identification of patients with an anxiety disorder, OCD, or PTSD in need of highly specialized mental healthcare. METHODS: A systematic literature review and a concept mapping procedure were carried out to inform the development of the DTAOP. To evaluate the psychometric properties of the DTAOP, a cross-sectional study in 454 patients with a DSM-IV-TR anxiety disorder was carried out. Feasibility was evaluated by the completion time and the content clarity of the DTAOP. Inter-rater reliability was assessed in a subsample of 87 patients. Spearman's rank correlation coefficients between the DTAOP and EuroQol five-dimensional questionnaire (EQ-5D-5L) scores were computed to examine the convergent validity. Criterion validity was assessed against independent clinical judgments made by clinicians. RESULTS: The average time required to complete the eight-item DTAOP was 4.6 min and the total DTAOP was evaluated as clear in the majority (93%) of the evaluations. Krippendorff's alpha estimates ranged from 0.427 to 0.839. Based on the qualitative feedback, item wording and instructions were improved. As hypothesized, the DTAOP correlated negatively with EQ-5D-5L scores. The area under the curve was 0.826 and the cut-off score of ≥4 optimized sensitivity (70%) and specificity (71%). CONCLUSIONS: The DTAOP demonstrated excellent feasibility and good validity, but weak inter-rater reliability. Based on the qualitative feedback and reliability estimates, revisions and refinements of the wording and instructions were made, resulting in the final version of the DTAOP.

The correlates of social phobia in OCD: Findings from a large clinical sample.

OBJECTIVES: Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder, often complicated with comorbidities. Social phobia (SP) is the most frequent co-occurring anxiety disorder in OCD, associated with increased clinical severity. However, no study had examined the relevance of interpersonal processes in this comorbidity, which are at the core of SP. This study characterized the clinical (i.e., symptom profile, age of onset, chronicity, and comorbidity), vulnerability (i.e., childhood trauma, negative life events), and interpersonal (attachment style, expressed emotion, and social support) correlates of comorbid SP in a large sample of OCD patients. METHODS: We analysed the data of 382 OCD patients participating in the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study. We examined the correlates of SP in OCD using self-report questionnaires and structured clinical interviews. In addition, data of 312 non-OCD SP patients were drawn from the Netherlands Study of Depression and Anxiety (NESDA), to compare the age of onset of SP between groups. Descriptive univariate analyses were followed by backward stepwise logistic regression analyses. RESULTS: Social phobia was present among approximately 20% of OCD patients. Social phobia in OCD was associated with increased depression severity and decreased ratings of secure attachment style. Among OCD patients, SP had a significantly earlier age onset as compared to SP in non-OCD patients. CONCLUSION: Social phobia in OCD might render a vulnerable clinical picture, characterized with early onset of SP symptoms, insecure attachment style, and increased depressive symptoms. Future studies should use prospective designs to better understand the nature of comorbid SP in OCD. PRACTITIONER POINTS: Approximately one fifth of OCD patients were diagnosed with comorbid social phobia in a large representative clinical sample. OCD patients with comorbid social phobia presented with a vulnerable clinical picture, characterized with increased depression severity and decreased ratings of secure attachment style. Social phobia in OCD was associated with an earlier AOO as compared to the AOO of social phobia without OCD. The findings are limited by a cross-sectional design; thus, causality could not be assessed. Research is needed to further examine the mechanisms of comorbid social phobia in OCD.

Predictors of Intensive Treatment in Patients With Obsessive-Compulsive Disorder.

Background: Few studies have investigated which patients with obsessive-compulsive disorder (OCD) do not recover through regular cognitive behavior therapy or pharmacotherapy and subsequently end up in intensive treatment like day treatment or inpatient treatment. Knowing the predictors of intensive treatment in these patients is significant because it could prevent intensive treatment. This study has identified predictors of intensive treatment in patients with OCD. Methods: Using 6-year longitudinal data of the Netherlands Obsessive Compulsive Disorder Association (NOCDA), potential predictors of intensive treatment were assessed in patients with OCD (n = 419). Intensive treatment was assessed using the Treatment Inventory Costs in Patients with Psychiatric Disorders (TIC-P). Examined potential predictors were: sociodemographics, and clinical and psychosocial characteristics. Logistic Generalized Estimating Equations was used to estimate to what extent the various characteristics (at baseline, 2- and 4-year assessment) predicted intensive treatment in the following 2 years, averaged over the three assessment periods. Results: Being single, more severe comorbid depression, use of psychotropic medication, and a low quality of life predicted intensive treatment in the following 2 years. Conclusions: Therapists should be aware that patients with OCD who are single, who have more severe comorbid depression, who use psychotropic medication, and who have a low quality of life or a drop in quality of life are at risk for intensive treatment. Intensive treatment might be prevented by focusing regular treatment not only on OCD symptoms but also on comorbid depression and on quality of life. Intensive treatment might be improved by providing extra support in treatment or by adjusting treatment to impairments due to comorbid depressive symptoms or a low quality of life.

Use of videotaped personal compulsions to enhance motivation in obsessive-compulsive disorder.

BACKGROUND: Watching videotaped personal compulsions together with a therapist might enhance the effect of cognitive-behavioural therapy in obsessive-compulsive disorder (OCD) but little is known about how patients experience this.AimsTo performed a qualitative study that describes how watching these videos influences motivation for treatment and whether patients report any adverse events. METHOD: In this qualitative study, data were gathered in semi-structured interviews with 24 patients with OCD. The transcripts were coded by two researchers. They used a combination of open and thematic coding and discrepancies in coding were discussed. RESULTS: The experience of watching videos with personal compulsions helped patients to realise that these compulsions are aberrant and irrational. Patients report increased motivation to resist their OCD and to adhere to therapy. No adverse events were reported. CONCLUSIONS: Videos with personal compulsions create more awareness in patients with OCD that compulsions are irrational, leading to enhanced motivation for treatment.Declaration of interestNone.

Obsessive compulsive disorder with and without hoarding symptoms: Characterizing differences.

OBJECTIVE: In recent years there has been some ambiguity about the way hoarding and OCD are related to each other. The present study examines the differences between persons with OCD/hoarding and OCD/non-hoarding and examines which characteristics are associated with the OCD/hoarding group. Information is established about prevalences, socio-demographical characteristics, OCD and related characteristics, OCD subtypes, comorbidity (depression, anxiety disorders and PTSD) and personality traits. METHODS: Data from baseline assessment of The Netherlands Obsessive Compulsive Disorder Association (NOCDA) study are used. The NOCDA sample consists of 419 participants between 18 and 79 years of age, including participants with current or remitted full DSM-IV-TR criteria for OCD. RESULTS: Results show that 58 persons (14.3%) are classified as persons with OCD/hoarding and 349 persons (85,7%) are classified as persons with OCD/non-hoarding. OCD/hoarding is independently associated with severity of autism symptoms (p<.001), living without a partner (p<.05) and being less conscientious (p<.05). Persons with OCD/hoarding are not associated with childhood trauma (p=.31), PTSD (p=.91) and AD(H)D, inattentive type (p=.22) and hyperactive type (p=.57). LIMITATIONS: Causal interferences about associations between the risk indicators and hoarding symptoms were precluded since results were based on cross-sectional data. CONCLUSION: This study confirmed differences between persons with OCD/hoarding and persons with OCD/non-hoarding. The most relevant outcome of this study was the association between persons with OCD/hoarding and the increased severity of autism symptoms. These results provide a better understanding of persons with OCD/hoarding and have the potential to improve treatment.

Examining the factor structure of the self-report Yale-Brown Obsessive Compulsive Scale Symptom Checklist.

Obsessive-compulsive symptom dimensions are important in studies about the pathogenesis and treatment of obsessive-compulsive disorder. More than 30 factor analytic studies using the Yale-Brown Obsessive Compulsive Scale Symptom Checklist (Y-BOCS-SC) interview version have been published. However, a drawback of the Y-BOCS-SC interview is that it is time-consuming for the clinician. Baer's self-report version of the Y-BOCS-SC could be a less time-consuming alternative. The purpose of this study was to examine the factor structure of Baer's self-report Y-BOCS-SC. In a sample of 286 patients, we performed two factor analyses, one using categories and one using items of the Y-BOCS-SC. Using category-level data, we identified four factors; when using items we identified six factors. Symptom dimensions for contamination/cleaning, symmetry/repeating/counting/ordering and hoarding were found in both analyses. The impulsive aggression, pathological doubt, sexual, religious somatic and checking categories formed one factor in the analysis using category-level data and divided into three factors using item-level data. These factors correspond with studies using the interview version and support our hypothesis that the self-report version of the Y-BOCS-SC could be an alternative for the interview version.

Chronic obsessive-compulsive disorder: prognostic factors.

BACKGROUND: The course of illness in obsessive-compulsive disorder (OCD) varies significantly between patients. Little is known about factors predicting a chronic course of illness. The aim of this study is to identify factors involved in inducing and in maintaining chronicity in OCD. METHODS: The present study is embedded within the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study, an ongoing multicenter naturalistic cohort study designed to identify predictors of long-term course and outcome in OCD. For this study, 270 subjects with a current diagnosis of OCD were included. Chronicity status at 2-year follow-up was regressed on a selection of baseline predictors related to OCD, to comorbidity and to stress and support. RESULTS: Psychotrauma [odds ratio (OR) 1.98, confidence interval (CI) 1.22-3.22, p = 0.006], recent negative life events (OR 1.42, CI 1.01-2.01, p = 0.043), and presence of a partner (OR 0.28, CI 0.09-0.85, p = 0.025) influenced the risk of becoming chronic. Longer illness duration (OR 1.46, CI 1.08-1.96, p = 0.013) and higher illness severity (OR 1.09, CI 1.03-1.16, p = 0.003) increased the risk of remaining chronic. CONCLUSIONS: External influences increase the risk of becoming chronic, whereas the factors involved in maintaining chronicity are illness-related. As the latter are potentially difficult to modify, treatment should be devoted to prevent chronicity from occurring in the first place. Therapeutic strategies aimed at alleviating stress and at boosting social support might aid in achieving this goal.

New treatment models for compulsive disorders.

Obsessive compulsive disorder (OCD) as well as related disorders such as body dysmorphic disorder, tic disorder, and trichotillomania are all common and often debilitating. Although treatments are available, more effective approaches to these problems are needed. Thus this review article presents what is currently known about OCD and related disorders and suggests that understanding OCD more broadly as a compulsive disorder may allow for more effective treatment options. Toward that goal, the review presents new models of psychopharmacology and psychotherapy, as well as new brain stimulation strategies. Treatment advances, grounded in the neuroscience, have promise in advancing treatment response for OCD as well as other disorders of compulsivity.

Inference-Based Approach versus Cognitive Behavioral Therapy in the Treatment of Obsessive-Compulsive Disorder with Poor Insight: A 24-Session Randomized Controlled Trial.

OBJECTIVE: Obsessive-compulsive disorder (OCD) with poor insight has severe consequences for patients; nonetheless, no randomized controlled trial has ever been performed to evaluate the effectiveness of any treatment specifically for poor-insight OCD. A new psychotherapy for OCD, the inference-based approach (IBA), targets insight in OCD by strengthening normal sensory-driven reality testing. The goal of the present study is to compare the effectiveness of this new treatment to the effectiveness of cognitive behavior therapy (CBT) for patients with OCD with poor insight. METHOD: A randomized controlled trial was conducted, in which 90 patients with OCD with poor insight received either 24 CBT sessions or 24 IBA sessions. The primary outcome measure was the Yale-Brown Obsessive Compulsive Scale (YBOCS). Secondary outcome measures were level of insight, anxiety and depressive symptoms, and quality of life. Mixed-effects models were used to determine the treatment effect. RESULTS: In both conditions, a significant OCD symptom reduction was reached, but no condition effects were established. Post hoc, in a small subgroup of patients with the worst insight (n = 23), it was found that the patients treated with the IBA reached a significantly higher OCD symptom reduction than the patients treated with CBT [estimated marginal mean = -7.77, t(219.45) = -2.4, p = 0.017]. CONCLUSION: Patients with OCD with poor insight improve significantly after psychological treatment. The results of this study suggest that both CBT and the IBA are effective treatments for OCD with poor insight. The IBA might be more promising than CBT for patients with more extreme poor insight.

The relationship between adverse childhood experiences and symptom severity, chronicity, and comorbidity in patients with obsessive-compulsive disorder.

BACKGROUND: Studies on the relationship between adverse childhood experiences (ACEs) and obsessive-compulsive disorder (OCD) symptom severity are scarce. Available studies leave a considerable degree of uncertainty. The present study examines the relationship between ACEs and symptom severity, chronicity, and comorbidity in a sample of patients with OCD. METHOD: Baseline data of the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study, in which 382 referred patients with DSM-IV-diagnosed OCD participated, were analyzed. ACEs (physical abuse, sexual abuse, witnessing interparental violence, maternal dysfunction, paternal dysfunction, and early separation from a parent) were measured using a structured interview. Data were collected between September 2005 and November 2009. RESULTS: None of the ACEs were related to OCD symptom severity or chronicity, nor was there a dose-response relationship between ACEs and OCD severity or chronicity, but results of linear regression analysis revealed that ACEs were related to comorbidity in patients with OCD (P < .001), in particular to comorbid affective disorders (P < .01), substance use disorders (P < .01), and eating disorders (P < .01), but not to comorbid anxiety disorders. CONCLUSIONS: Results of the study suggest that unlike in other psychiatric disorders, ACEs play no significant role in symptom severity and chronicity of OCD. This study was the first to reveal evidence for a relationship between ACEs and comorbidity in patients with OCD. Conclusions about trauma-relatedness of OCD based on studies finding higher trauma rates or severity among patients with OCD than among healthy controls, should be critically reconsidered, since presence of comorbidity might account for these differences.

Obsessive-compulsive disorder; chronic versus non-chronic symptoms.

OBJECTIVE: Understanding chronicity in OCD is hampered by contradictory findings arising from dissimilar definitions of chronic OCD. The purpose of this study was to investigate the magnitude of chronicity in OCD and to examine if chronic OCD is critically different from non-chronic OCD, using a chronicity definition that reflects empirical findings. METHOD: Baseline data of the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study, in which 379 OCD patients participated, were analyzed. Chronic OCD was defined as "continuous presence of at least moderately severe OCD symptoms during at least two years", and was assessed retrospectively using a Life-Chart Interview. RESULTS: Application of the chronicity criterion resulted in two groups with highly distinguishable course patterns. The majority of the sample (61.7%) reported a chronic course. Patients with a chronic course reported significantly more severe OCD symptoms, more illness burden, more comorbidity, an earlier OCD onset and more contamination and washing - and symmetry and ordering symptoms. Multivariable logistic regression analysis revealed that chronic OCD was independently associated with more OCD-subtypes (p<0.001), contamination and washing symptoms (p<0.001), earlier OCD onset (p=0.05) and higher severity of compulsions (p<.01). LIMITATIONS: The findings are based on a cross-sectional survey. Furthermore course was assessed retrospectively, implying the possibility of overestimation of persistence and severity of symptoms. CONCLUSION: Chronicity is the rule rather than the exception in OCD in clinical samples. Chronic OCD is critically different from non-chronic OCD. Further attempts to break down the heterogeneity of OCD in homogeneous course subtypes should be made to allow for a more precise determination of the pathogenesis of OCD and better treatment.