Table IIc. Summary of the sample, interventions, and outcome measures used in included studies that measured symptoms using PROMs.

Reference	Study sample (N, number of sites, country)	Study methodology	PROM(s) used	Major findings
Aardema et al161	85 OCD patients; Canada	Cross-sectional	OBQ, PI-R	The relationship between obsessive beliefs and OC symptoms decreased significantly when inferential confusion was controlled. Conversely, the relationship between inferential confusion and OC symptoms was not substantially affected when obsessive belief was controlled.
Abramowitz et al171	77 OCD patients; 2 sites; Minnesota & Connecticut, USA	Cross-sequential	OCI-R	Analyses suggest that OCI-R is sensitive to treatment effects and that pre- to post-test change on this instrument reflects improvement in OCD and other symptoms following CBT.
Alonso et al127	50 OCD patients, 30 healthy controls; Spain	Cross-sectional	OBQ	A correlation between OBQ-44 domains and regional grey matter was not observed in OCD patients. Study also suggests a significant correlation between OC-related dysfunctional beliefs and morphometric variability in the anterior temporal lobe.
Alonso et al169	141 OCD patients; Spain	Cross-sectional	OBQ	Change in dysfunctional beliefs was not affected by the COMT and BDNF genotype in isolation. Their interaction, however, had an effect on the responsibility/overestimation of threat and over importance/need to control thoughts scores.
Aksaray et al157	23 OCD female & 26 GAD female patients; Turkey	Cross-sectional	MOCI	Women with OCD were more sexually nonsensual avoidant and anorgasmic than the women with GAD. The patients with fear of contamination obsessions on MOCI were more sexually nonsensual, and avoidant than obsessive compulsives with other types of fears.
Altemus et al185	8 OCD patients; USA	Longitudinal	MOCI	Subjects reported no significant improvements in OC symptoms on MOCI or Y-BOCS following 8 weeks open trial of flutamide. However, feelings of aggressiveness did fall.
Andersson et al82	23 OCD patients; Sweden	Longitudinal	Y-BOCS-SR, OCI-R	Participants reported statistically significant improvements in self-rated OCD symptoms (Y-BOCS & OCI-R) following a 15-weeks of internet-based CBT.
Anholt et al139	66 OCD, 20 panic & or agoraphobia, 20 PG patients, 30 controls; Netherlands	Cross-sectional	OBQ, PI-R	OCD patients reported higher OBQ-87 scores than both panic patients and normal controls, but did not differ from the pathological gambling patients. Pathological gamblers however, reported no increase in OCD symptoms. The OC spectrum theory for pathological gambling is questionable.
Anholt et al126	50 tic-free OCD, 19 OCD +tic, 18 TS w/o OCD patients, 30 controls; Netherlands	Cross-sectional	OBQ, PI	Tic-free OCD patients scored higher OBQ-87 than TS patients while no differences were found between OCD with or without tic patients. Thus, dysfunctional beliefs have no discriminative power with respect to OCD with or without tic patients.
Anholt et al190	120 OCD patients; Netherlands	Cross-sectional	PI-R	Differences in neither the measurement between self- and clinician-administered measures nor the way severity is being calculated can account for the differences between the PI-R and the Y-BOCS Severity scale. Findings suggest that the two scales measure unrelated features of OCD.
Anholt et al174	104 OCD patients; Netherlands	Cross-sequential	OBQ, PI-R	OBQ-44 and OBQ-87 were compared for sensitivity to treatment change and other OCD measures. Results revealed identical medium effect size, the limitation of OBQ as a primary measure of treatment change and a lack of symptom dimension association to OBQ pre-post- treatment changes.
Arntz et al104	27 OCD, 37 non-OCD anxiety patients, 28 non patients; Netherlands	Cross-sectional	PI	Subjective OCD-like experience and checking behaviors were higher in OCD patients being exposed to a high responsibility classification task than in all other groups. Although the PI checking subscale correlated with their subjective ratings, it was not correlated with their checking behaviors, suggesting the causal role of responsibility in OCD.
Baptista et al141	24 OCD and 24 Medical Clinic(MC) patients for chronic diseases; 2 sites; Brazil	Cross-sectional	OBQ	MC group scored higher than the OCD group in domains of OBQ-Tolerance for Uncertainty, Threat estimation, Responsibility and Perfectionism. The same findings occurred with DAS, which was significantly correlated with the OBQ.
Black et al194	38 non-depressed OCD patients; USA	RCT	MOCI, SCL-90-R	Respondents were less symptomatic on their MOCI doubting/conscientious and checking scores and marginally better on the SCL-90-R positive symptom distress index, given 12 weeks of treatment with paroxetine, placebo or CBT.
Bortoncello et al177	104 OCD patients; Brazil	Longitudinal	OBQ	OBQ-44's sensitivity to treatment change following CBGT was good and all 3 belief domains declined significantly, hence proving the quality of this measure.
Brakoulias et al33	154 OCD patients; Australia	Cross-sectional	OBQ	The relationship between 5 Y-BOCS-derived OC symptom dimensions and the 3 OC cognitive Domains (OBQ) was examined. The symmetry/ordering dimension was associated with increased perfectionism/intolerance of uncertainty, the unacceptable/taboo thoughts dimension was associated with increased importance/control of thoughts and the doubt/checking dimension was associated with increased responsibility/threat estimation.
Brakoulias et al148	154 OCD patients; Australia	Cross-sectional	VOCI, SDS	VOCI obsessions were found to be correlated with higher usage rates of both psychotropic agent and antipsychotic agent.
Calamari et al151	367 OCD patients; USA & Canada	Cross-sectional	OBQ, Y-BOCS-SR	Relations between belief and symptom -based subgroups were examined. Symmetry symptom subgroup membership was modestly associated with membership in the Perfectionism/Certainty beliefs subgroup.
Careau et al160	83 OCD patients, 213 student controls; Canada	Cross-sectional	OBQ	The relationship between 5 different childhood experiences to 5 conceptually matched OBQ belief domains was examined. Beliefs related to responsibility, threat perception, and perfectionism showed association to their theoretically related early experiences. Threat perception and sociotropy experiences were closely related to most OBQ belief domains.
Chik et al99	88 OCD, 44 OAD patients, 48 student controls; USA	Cross-sectional	OBQ, OCI-R	OCD patients with high, OCD-H or low, OCD-L dysfunctional beliefs differed in their 1) metacognitive beliefs which correlated with the OC symptom measures in the OCD-H and 2) monitoring tendencies which correlated with the OC symptom measures in the OCD-L.
Choi et al166	22 OCD patients and 22 matched healthy controls; South Korea	Cross-sectional	MOCI	Regional brain gray matter volumes were not correlated with the MOCI scores in patients with OCD despite significant volume reduction in bilateral planum polare.
Clark et al88	56 OCD patients, 38 non-obsessional psychiatric outpatients, 35 community adults and 403 undergraduate students; Canada, Australia, USA	Cross-sectional	CBOCI, PI-WSUR	A validation study of CBOCI. The OCD group scored significantly higher on the CBOCI total score than all other groups.
Dastgiri & Nateghian102	25 OCD, 25 GAD patients and 25 normal subjects; Iran	Cross-sectional	PI	Results revealed a significant correlation between PI scores and worry. While is PI is able to differentiate OCD and GAD from normal subjects, PI is unable to differentiate OCD from GAD subjects unless worry score is being controlled.
de Berardis et al146	112 OCD patients; Italy	Cross-sectional	MOCI	TAS-20 (measure for Alexithymia) total score and sub factors positively correlated with score for item #11 on the Y-BOCS, severity of OCD (as measured by MOCI) and MADRS scores (depression measure).
Dehlin et al85	5 scrupulosity-based OCD patients; USA	Longitudinal	OCI-R	Treatment outcomes in 5 scrupulosity-based OCD patients following 8 sessions of ACT were assessed. Average daily compulsions and avoided valued activities decreased significantly.
Doyle et al135	62 patients with schizophrenia treated with clozapine, 35 OCD patients; Ireland	Cross-sectional	OCI	The OCD group reported significantly more symptoms for all OCI subscales compared to the clozapine group. In terms of profile, the clozapine group scored highest on the Doubting scale, a cognitive symptom whereas the OCD group scored highest on Washing, a behavioral symptom. Both groups reported greater distress with cognitive rather than behavioral symptoms.
Einstein & Menzies149	60 OCD patients; Australia	Cross-sectional	PI, OCI-SV	Magical ideation (Ml) was found to correlate highly with impaired control over mental activities, and urges and worries about losing control over motor behaviors in PI. It also attained positive correlations with the checking subscales on the PI and on the neutralising, obsessing, and hoarding scales of the OCI-SV. Neither the PI nor the OCI-SV contamination/washing scales were significantly correlated with MI.
Einstein & Menzies119	11 cleaning & 20 checking OCD patients, 19 PD patients, 21 controls; Australia	Cross-sectional	MOCI, OCI-SV	OCD group reported magical ideation scores higher than both the PD group and normal subjects. OCD washers obtained higher MI scores than OCD checkers but they did not differ on scores on MOCI and OCI-SV.
Einstein & Menzies170	34 OCD outpatients; Australia	Cross-sequential	MOCI, OCI-SV, PI	OC symptoms decreased significantly following CBT. MI improvement was significantly correlated with improvement on both the PI and the OCI-SV.
Emmelkamp et al108	89 OCD, 45 neurotic patients & 79 normal subjects; Netherlands	Longitudinal	MOCI; LOI	The MOCI may be used to evaluate effects of treatment, but it less sensitive than target ratings of obsessional problems. It reliably discriminates between obsessional patients and normal, patients with anorexia nervosa and anxiety disorders; however, it failed to discriminate the obsessionals from depressives.
Enander et al195	48 OCD patients; Sweden	RCT	DOCS, OCI-R	DOCS found to show fair sensitivity treatment effects following Internet-delivered CBT with intervention being exposure with response prevention.
Enright et al164	32 OCD patients and 32 with OAD; UK	Cross-sectional	MOCI	A distinction between checkers and non-checkers in the OCD group was made using MOCI. Non-checkers displayed greater negative priming across all presentation speeds compared to checkers.
Ettelt et al149	70 CCD patients & their 139 relatives, 70 control & their 134 relatives, 4 sites; Germany	Cross-sectional	PI	Significant correlations of cognitive impulsiveness (BIS-11 subscale) were found with PI subscales of aggressive thoughts concerning self/others, aggressive impulses concerning self/ others, checking and symmetry separately. No other subscale of impulsiveness was significantly associated with OCD symptoms.
Exner et al10	19 OCD patients, 19 matched controls; Germany	Cross-sectional	PI-R	Study revealed that episodic and semantic memory performance, but not working memory, reduced significantly in OCD subjects compared to controls. Episodic memory performance in both samples was significantly related to the Padua Rumination and Checking, even after controlled for depression and OC symptom severity. Linear regression revealed that Rumination was most closely related to episodic memory performance in both samples above Checking.
Filomensky et al131	35 OCD, 21 BP patients, 24 compulsive buyers; Brazil	Cross-sectional	PI-WSUR	OCD patients scored higher on OC symptoms than those with CB and BD; particularly higher on the PI contamination/washing and checking dimensions; however, they did not score higher on any hoarding dimension.
Fontenelle et al133	23 OCD patients and 40 obese individuals; Brazil	Cross-sectional	SCL-90	Patients with OCD had significantly higher obsessive-compulsive scores than obese non-binge and obese binge eaters.
Fontenelle et al137	34 OCD, 30 SAD patients; Brazil	Cross-sectional	OCI	Patients with OCD reported significantly lower rates of exposure to traumatic events. Statistical analyses revealed that the OCI scores better predicted the variance on Dissociative Experience Scale scores in the OCD sample, while the Liebowitz Social Anxiety Scale did so better in the social anxiety group.
Fontenelle et al156	53 OCD patients, 53 matched individuals; 3 sites; Brazil	Cross-sectional	OCI-R	Patients with OCD displayed greater levels of affective sympathy and personal discomfort than controls. Analyses revealed that severity of hoarding symptoms in OCD correlated with empathic concern, fantasy, and personal discomfort.
Fontenelle et al51	53 OCD patients, 53 matched controls; 2 sites; Brazil	Cross-sectional	OCI-R	Washing symptoms explained 31% of the variance of limitation due to physical health problems. Other analyses howeve concluded that depressive, but not obsessive-compulsive symptoms, explained the remaining SF-36 dimensions.
Fontenelle et al32	40 OCD patients, 40 healthy controls; Brazil	Cross-sectional	OCI-R	Patients with OCD displayed higher plasma levels of CCL3. CXCL8, sTNFR1, and sTNFR2 than controls. The levels of sTNFR1 correlated positively with washing symptoms while CCL24 levels correlated negatively with hoarding.
Fontenelle et al168	40 OCD patients, 40 healthy controls; Brazil	Cross-sectional	OCI-R	Patients with OCD displayed lower levels of BDNF and significantly increased levels of NGF as compared to healthy controls. A positive correlation between both NGF and GDNF and severity of washing symptoms was also found.
Fritzler et al179	9 OCD patients; USA	Cross-sectional	MOCI, Y-BOCS-SR	Subjects in the Delayed treatment condition following self-directed ERP showed no significant improvements. However, as a combined group with those in the Immediate treatment condition, improvements were observed in outcome measures of Y-BOCS and MOCI.
Fullana et al103	56 OCD patients, 40 healthy controls; Spain	Cross-sectional	PI	OCD patients scored higher in all PI subscales and were also more anxious and depressed than controls. Results showed that patients scored higher on Neuroticism, Sensitivity to Punishment and Psychoticism than normal controls; scored lower on Extraversion. No differences in Sensitivity to Reward found.
Grabe et al155	70 OCD patients; Germany	Cross-sectional	HZI/HOCI	The dimensions 'Checking' and 'Symmetry and Ordering' were significantly related to dissciative symptomatology. A clear-cut lack of association was found in 'Washing and Cleaning', 'Counting and Touching' and 'Aggessive impulses and Fantasies'. HZI dimensions significantly discriminated patients with high from patients with low dissociative symptomatology.
Grabe et al158	61 OCD patients; Germany	Cross-sectional	HZI-/HOCI	In female patients, controlling behavior and obsessions and compulsions associated with counting, touching and talking were associated with bulimia whereas obsessions associated with words, pictures o thought-chains were related to drive for thinness, thus pointing to a differential gender and symptoms-specific relationship between OCD and ED.
Greist et al180	325 non-depressive OCD patients; USA	RCT	MOCI	Analysis of the MOCI administered at baseline and endpoint revealed significant improvement in pooled sertraline group compared to placebo group.
Hashimoto et al162	63 OCD patients, 50 healthy controls; Japan	Cross-sectional	PI	For the logical memory tasks, a positive association was observed with PI's washing scale but a negative association was observed with PI's precision scale. Positive correlation between interference scores and PI'S precision scale was also observed. Results support the hypothesis that different symptoms may represent distinct and partially overlapping neurocognitive networks in OCD.
Hermans et al120	17 OCD patients, 17 non-anxious control; Belgium	Cross-sectional	MOCI, PI	General reality monitoring ability, and selective reality monitoring ability for anxiety relevant actions in was examined. There was no difference observed for patients that reported low or high frequencies of checking behavior.
Hunter et al193	198 OCD patients, 1457 adult psychiatric outpatients in all; USA	Cross-sectional	SCL-90	SCL diagnostic scales were shown to differentiate patients positive for each of the eight psychiatric disorders from other psychiatric patients who did not have that disorder.
Huppert et al125	128 OCD, 109 PTSD, 63 OAD patients, 40 students; USA	Cross-sectional	OCI	Study revealed presence of relationship between symptoms of OCD and PTSD in all samples, largely accounted for by a combination of symptom overlap and depression.
Jiménez-Murcia et al132	90 female patients (30 OCD, 30 anorexia nervosa, 30 bulimia nervosa); Spain	Cross-sectional	MOCI	Higher MOCI scores and Eating Disorder Inventory (EDI)-Perfectionism scores predicted higher EDI score Thus, severity of ED symptomatology increases as OC symptomatology increases.
Jones & Menzies.110	21 OCD patients, 10 controls; Australia	RCT	MOCI, LOI	11 patients who received the Danger Ideation Reduction Therapy (DIRT) observed significantly greater improvements from pre-treatment to after-treatment on all measures including MOCI and LOI.
Julien et al153	126 OCD patients; Canada	Cross-sectional	OBQ, PI-R	Specificity of belief domains in OCD symptom subtype was investigated. Analyses revealed that participants in the rumination subtype scored higher on Importance/ Control of Thoughts than those in the washing subtype when anxiety was controlled. Responsibility/Threat Estimation predicted rumination scores, Perfectionism/Certainty predicted checking and precision scores, and Importance/Control of Thoughts predicted impulse phobia scores when negative mood states were controlled.
Karadag et al163	32 OCD patients and 31 healthy controls; Turkey	Cross-sectional	MOCQ	MOCQ was used to define checkers from non-checkers using cut-off score of 5 and above. The OCD patients with checking compulsions were no different from the non-checking group for memory of OC relevant material and confidence.
Kearns et al176	24 OCD patients; Ireland	Longitudinal	MOCI	Significant reduction in clinical symptom ratings on completion of group based CBT for OCD patients was observed in measures including MOCI.
Keijsers et al183	40 OCD patients; Netherlands	Cross-sectional	MOCI	No differential treatment effects between exposure in vivo alone and response prevention alone could be found, although ritualistic behavior was less strongly affected by exposure in vivo following response prevention.
Kennedy et al192	280 patients with 6 diagnoses: 33 with OCD, others with major depression, panic disorder, GAD, social phobia and mixed anxiety and depression 31 graduate students as comparison group	Cross-sectional	SCL-90	Each diagnostic group had a significantly high score on its corresponding subscale. The OCD group had only 2 high subscale scores — obsessive-compulsive and phobic anxiety subscale scores. OCD subjects had the lowest general anxiety and depression scores among the 6 diagnostic groups. Those with GAD endorsed many OCD symptoms.
Kirkby et al189	13 OCD patients; Australia	Longitudinal	PI-R	Across three computer treatment sessions that provided vicarious exposure and response prevention for OCD, all subjects increased their vicarious exposure behaviors that predicted symptom reduction on PI.
Krochmalik et al178	5 OCD patients; Australia	Longitudinal	MOCI, PI	On the MOCI, 4 of the 5 subjects (unchanged by ERP) met recovery criteria following DIRT. Changes were maintained at follow-up.
Kyrios & lob.100	15 OCD patients, 15 normal controls; Australia	Cross-sectional	PI	Significant associations were found between interference scores of OCD-threat words (masked only) with both the depression and anxiety symptom measures, but not with OC symptom severity (measured on PI).
Li et al184	16 OCD patients; USA	Double-blind, placebo-controlled, crossover study	SCL-90	Significant reduction in the SCL-90R obsession and anxiety scale was observed with both risperidone and haloperidol compared to placebo augmentation of serotonin reuptake inhibitors in the treatment of OCD patients. On the depression scale, scores of those on risperidone but not haloperidol treatment separated out from placebo.
López-Solà et al107	110 OCD patients, 237 non-clinical sample; Spain	Cross-sectional	DOCS, OBQ	The association between OC symptom dimensions in DOCS and obsessive beliefs was examined. In OCD patients, Contamination, Responsibility for Harm, and Unacceptable Thoughts were predicted by OBQ-Responsibility. For the Symmetry dimension the OBQ-Perfectionism domain emerged as the only significant predictor.
Mantovani et al187	18 OCD subjects through stringent recruitment; USA	RCT (Sham)	Y-BOCS-SR	Correlation between changes in Y-BOCS-SR and cortical excitability measures was examined and results suggested that low-frequency repetitive transcranial magnetic stimulation are supportive of the role of SMA in the modulation of OCD symptoms.
Mass et al136	15 OCD, 50 schizophrenia (25 with severe negative symptoms) and 25 alcohol dependence patients; Germany	Cross-sectional	HZI-K/HOCI	OCD subjects had the highest compulsion scores but the obsessions scores on HZI-K did not differ among the groups.
Muller et al109	31 OCD, 18 with TS, 13 with Parkinson's Disease & 46 controls; Germany	Cross-sectional	MOCI, HZI-K	On most subscales -Checking, Ordering, and Counting/touching, TS patients scored higher than controls but reported fewer symptoms than OCD patients, particularly on the MOCI subscales 'Checking' and 'Slowness/Repetition' as well as on the MOCI total score and on the HZI subscales 'Cleaning' and 'Obsessive Thoughts'.
Murayama et al112	22 OCD, 19 controls; Japan	Cross-sectional	MOCI	Both checkers and washers were compared with the controls on a symptom provocation task on fMRI. The checkers showed slightly higher activation in the left caudate and left AC which saw a positive correlation between activation and symptom severity. The washers showed higher activation in several bilateral cortico-cerebellar regions which saw a position correlation between symptom severity and the bilateral fronto-temporal gyrus.
Nakamae et al167	23 non-medicated OCD patients, 23 healthy controls; Japan	Cross-sectional	OBQ	The relationship between gray matter volume and each dimension of OBQ was explored. Only a significant negative correlation was found between gray matter volume and OBQ-(over-importance and over-control of thoughts) scores in the left amygdala.
Niemeyer et al129	34 OCD, 34 healthy controls; Germany	Cross-sectional	OBQ, Y-BOCS-SR, OCI-R	Metacognition (measured on OBQ) contributed significantly but modestly to OC symptoms (measured on the OC scales) after responsibility was controlled for, and conversely responsibility made a significant contribution after controlling for metacognition.
O'Connor et al171	44 OCD patients; Canada	Cross-sequential	PI, OBQ	After 20 weeks of treatment s (cognitive appraisal model, exposure and response prevention or inference-based approach), all groups showed a significant reduction in scores including PI. Participants with high levels of obsessional conviction showed greater benefit from IBA than CAM.
Okada et al113	12 OCD subjects and 12 matched controls; Japan	Cross-sectional	MOCI	The study found that oxy-Hb changes in the OCD group during the Stroop color-word task (SCWC) were significantly smaller than those in the control group, especially in the frontopolar cortex. No significant correlations between the SCWC score and age, FIQ, and MOCI score.
Olantunji et al106	30 OCD and 30 non-clinical controls; USA	Cross-sectional	DOCS	DOCS score was found to correlate inversely with the disengagement efficiency score when erotic images served as the distractor, indicating that OCD subjects showed a weakened ability to disengage their attention.
Overbeek et al182	120 OCD patients for baseline ratings and 12 for post-treatment ratings; Netherlands	Longitudinal	MOCI	Severity of OCD symptoms on the 120 patients following a combined psychopharmacologic and behavioral therapy differed for depressed and nondepressed on the anxiety and depression measures, but not OCD measures. Post-treatment scores on YBOCS and MOCI were also found to be worse for depressed OCD patients despite the lack of difference at baseline.
Peng et al122	100 OCD, 38 OCD + other psychosis patients, 101 controls, 47 healthy OCD's relatives; China	Cross-sectional	OCI-R	OCD patients with or without comorbid psychosis scored higher in motor coordination and total neurological soft signs (NSS) than controls, with no significant difference between them in general
Radomsky et al128	33 OCD patients, 143 students; Canada	Cross-sectional	OBQ, VOCI	The compulsive checking group reported greater trait anger, but not greater anger expression, than the control group. Beliefs concerning perfectionism and intolerance of uncertainty were positively correlated with anger expression and trait anger among compulsive checkers but not among the control group.
Rector et al142	14 OCD probands, their 14 lst degree relatives, 87 normal controls;	Cross-sectional	OBQ	1st degree relatives scored significantly higher than controls on the OBQ domains- inflated responsibility and overestimation of threat. In addition, relatives of early onset OCD probands scored significantly higher than controls on both the inflated responsibility and overestimation of threat domain and the domain tapping perfectionism and intolerance of uncertainty.
Rubenstein et al115	50 OCD, 69 normal weight bulimia nervosa patients & 28 controls (all females); USA	Cross-sectional	MOCI, SCL-90-R (OC)	Study confirmed that OCD patients scored higher than both normal volunteers and bulimics, and bulimics scored higher than normal volunteers on the OC subsection of the SCL-90-R and on the MOCI.
Rufer et al154	50 OCD patients; Germany	Cross-sectional study	HZI/HOCI	The checking dimension was most strongly related to dissociation, followed by the symmetry/ordering and obsessive thoughts dimensions. Multiple regression analyses revealed that: (1) only the checking dimension showed an independent positive correlation with dissociation, and (2) only higher scores on the DES subscale “amnestic dissociation” were associated with higher scores for checking compulsions.
Salkovskis et al121	83 OCD, 48 anxiety & 218 non-clinical participants; UK	Cross-sectional	MOCI, OCI	Responsibility Attitude Scale (SAS) & Responsibility Interpretations Questionnaire (RIQ) were significantly correlated to both MOCI & OCI, indicating that the two responsibility scales are strong predictors of obsessions.
Scarrabelotti et al101	20 OCD patients and 151 controls; Australia	Cross-sectional	PI	After controlling for depression, neuroticism and responsibility were significant predictors of discomfort from obsessions and compulsions (Pl) in both the OCD and normal sample, while extraversion and psychoticism were not important.
Selvi et al181	57 OCD patients; Turkey	Longitudinal	OBQ	Patients had reduced scores on OBQ-44 following 12 weeks of SSRI treatment. Mean changes in OBQ-44 Importance & Control of Intrusive Thoughts subscale of responders were significantly higher than those of SSRI-resistant patients.
Shin et al111	30 OCD patients and 30 healthy controls; Korea	Cross-sectional	MOCI	The MOCI score was found to be negatively correlated with Immediate Presence and Accuracy, Delayed Presence and Accuracy, Immediate Retention, and Organization scores on the ROCF. This study indicates that people with OCD have poor memory function and organizational deficits.
Simpson et al196	56 OCD + eating disorder patients; USA	Longitudinal	Y-BOCS-SR	Significant decrease in OCD severity, measured by Y-BOCS was observed in patients following a residential treatment program.
Solem et al173	83 OCD patients; Norway	Longitudinal	OBQ	Y-BOCS & OBQ were administered at pre-, post-treatment and follow ups to OCD patients undergoing ERP and results showed significant improvements in symptoms, metacognition score, responsibility and perfectionism.
Souza et al123	64 OCD, 33 social phobia, 33 panic disorder, 130 controls; Brazil	Longitudinal	OCI-R	OCI's sensitivity to change was evaluated by comparing changes in its total score administered before and after CBGT and by comparing these to changes in Y-BOCS scores. Analyses revealed that OCI-R showed a good ability to assess the effects of treatment in OCD patients.
Starcevic et al22	148 OCD participants, of which 70 had OCPD and 78 without; Australia	Cross-sectional	VOCI, SCL-90-R	Results on VOCI showed that all OCD symptom dimensions except for contamination and checking were significantly more prominent in participants with OCPD. OCPD participants also scored significantly higher on all dimensions of psychopathology based on SCL-90-R.
Stein et al134	17 OCD, 12 trichotillomania and 14 borderline personality disorder patients	Cross-sectional	LOI	Trichotillomania and borderline personality disorder parents had significantly lower scores of obsessive-compulsive symptoms than OCD patients.
Storch et al14	87 OCD patients; 2 sites; Minnesota & Florida; USA	Cross-sectional	OCI-R	Factors associated with OCD related functional disability were examined. Depressive symptoms and the extent to which a patient attempts to resist and is able to control OCD symptoms predict functional disability strongly.
Taylor et al145	248 OCD patients; 12; USA, Canada & Australia	Cross-sectional	PI, OBQ	Given PI subscales and OBQ (inflated responsibility, perfectionism and controlling one's thought), analyses revealed significant main effects. There was no evidence that beliefs interact in their effects on OC symptoms.
Thiel et al188	75 female inpatients with anorexia or bulimia nervosa; 29 met criteria for concomitant OCD; Germany	Longitudinal	HZI/HOCI	Clinically significant change, as reflected by improvement in scores on the Eating Disorder Inventory, was seen more often in patients without concomitant OCD, but this trend was not statistically significant. The patients whose eating disorders were most improved at follow-up also showed the highest reduction of obsessions and compulsions.
Tumkaya et al114	42 OCD patients and 42 healthy controls; Turkey	Cross-sectional	MOCI	There were significant correlations between situational awareness scores and slowness and doubt scores of MOCI in OCD patients. Results indicated that (l) OCD patients have problems of perception, integration, and comprehension of complex visual perceptions; (II) situation awareness deficits associated with severity and prevalence of obsessions and compulsions.
Tynes & Winstead.144	41 OCD patients; USA	Retrospective	MOCI	Total BDI score was found to be significantly correlated with total MOCI score in the 41 participants. Checking was correlated with Retarded depression while doubting correlated with both Guilty depression and Retarded depression.
Tolin et al138	77 OCD patients, 35 anxious control; USA	Cross-sectional	OBQ, OCI-R	Thought Control Questionnaire- Punishment scale correlated significantly with the OBQ-44 importance/Control of Thoughts scale. Regression revealed that beliefs about the Importance/Control of Thoughts accounted for the relations between OCD and the use of Punishment as a thought control strategy.
Tolin et al150	99 OCD patients; USA	Cross-sectional	OCI	Relationship between OCD symptoms and obsessional beliefs was explored. Washing was predicted by responsibility/threat estimation beliefs. Checking/ doubting was not predicted by any obsessional beliefs. Hoarding was predicted by perfectionism/certainty beliefs. Neutralizing was predicted by responsibility/threat estimation beliefs. Obsessing was predicted by importance/control of thoughts and perfectionism/certainty beliefs. Ordering was predicted by perfectionism/certainty beliefs.
van Balkom et al186	117 OCD patients; Netherlands	RCT	PI-R, SCL-90	Study aimed to investigate the differential efficacy of cognitive therapy or exposure in vivo with response prevention for OCD versus the sequential combination with fluvoxamine. Results revealed decreases in OC symptom scales (including PI-R and SCL-90) across all 4 treatments, but they did not differ among each other.
van Noppen et al175	90 OCD patients; USA	Longitudinal	Y-BOCS-SR	A significant decrease was observed in the 90 OCD subjects on the Y-BOCS-SR scores; (mean ± SD) 21.8±5.6 at baseline and 16.6 ± 6.4 after the 10-week treatment of behavioral group therapy.
van Oppen et al191	63 OCD patients; Netherlands	Longitudinal	PI-R	PI-R demonstrated not only significant treatment effects, but also large effect sizes, thereby providing evidence of its sensitivity to change. The PI-R and the Y-BOCS were comparable in terms of reliable change and clinical significance.
Victoria et al165	48 OCD patients, 24 controls; Brazil	Cross-sectional	OCI-R	Positive correlations between reaction time to content-specific stimuli and OC symptom severity was found, suggesting that OCD patients experience difficulty in disengaging attention from personally salient stimuli.
Vulink et al143	101 female OCD outpatients; Netherlands	Cross-sectional	Y-BOCS-SR	59 patients reported an exacerbation of OCD symptoms during premenstrual period, 9 during menopause and 17 patients during pregnancy, whereas 11 patients mentioned improvement of OCD symptoms during pregnancy.
Wahl et al130	34 OCD, 34 MDD; Brazil	Cross-sectional	OCI-R	OCI-R scores were significantly higher in OCD patients as compared to patients with major depressive disorder.
Wellen et al140	92 OCD and 376 non-OCD subjects; USA	Cross-sectional	LOI	The relationship between the factors, OCD and OCPD was evaluated using logistic regression. Five factors underlying the LOI were identified. Obsessional ruminations and compulsions, organizing activities, and contamination fears may indicate OCD, and ordering and arranging symptoms indicate OCPD.
Wheaton et al152	135 OCD patients; 3 sites; USA	Cross-sectional	DOCS, OBQ	Using DOCS and OBQ, contamination symptoms were predicted by responsibility/threat estimation beliefs, symmetry symptoms were predicted by perfectionism/certainty beliefs, unacceptable thoughts were predicted by Importance/control of thoughts beliefs and symptoms related to being responsible for harm were predicted by responsibility/threat estimation beliefs.
Woo et al124	91 OCD patients, 702 students; Korea	Cross-sectional	OCI-R, PI-WSUR	The receiver operating characteristic analyses showed that the OCI-R is an effective screening tool for OCD.
Wootton et al38	22 OCD patients; Australia	Longitudinal	OCI-R	Following an 8-week online CBT course, OCD participants improved significantly on outcome measures including OCI-R, hence providing support for the efficacy of Internet administered treatment program.
Yap et al159	56 OCD, 46 OCD + depression patients; Australia	Cross-sectional	OBQ, Y-BOCS-SR, PI-R	The study examined differences between depressed and non-depressed OCD cohorts on OCD-related and non-specific factors. The two tested groups did not differ on these variables although depression severity was correlated with obsessional impulses to harm self/others.