Table 1: Quality assessment according to the Newcastle-Ottawa Scale (NOS): one star indicates one point.

Study Selection of Subjects Comparability of Subjects Exposure Total Scores
Definition of Cases Representativeness of the Cases Selection of Controls Definition of Controls Comparability of First Factor Ascertainment
of Exposure
Same Method of Ascertainment for Cases and Controls Non-response Score
Albert 2010 * * * * No * No * 6
Support
for judgement and quote
“A systematic face-to-face interview that consisted of structured and semistructured components was used to collect data from patients. Diagnostic evaluation and Axis I comorbidities were recorded by means of the Structured Clinical Interview for the DSM-IV Axis I Disorders. Personality disorders were ascertained with the Structured Clinical Interview for DSM-IV Axis II Disorders […] The interview and all the ratings were completed by psychiatrists with at least 4 year experience in anxiety and mood disorders”.
“[…] We enrolled all consecutive patients with a principal diagnosis of OCD and with a YBOCS total score of 16 or greater who were referred to the Mood and Anxiety Disorders Unit of the University of Turin, Italy. This is a tertiary referral center located within the university hospital and specialized in the treatment of patients with OCD”.
“The normative sample included 2031 Italian individuals drawn from the general population and who participated in the validation study of the Italian translation of the SF-36. The sample consisted of 999 (49.2%) males and 1031 (50.8%) females; their mean age was 47.73 (range, 18-96); 22.5% were single, 67.6% married, 8.0% widowed, and 2.0% separated”. Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “A systematic face-to-face interview that consisted of structured and semistructured components was used to collect data from patients. Diagnostic evaluation and Axis I comorbidities were recorded by means of the Structured Clinical Interview for the DSM-IV Axis I Disorders. Personality disorders were ascertained with the Structured Clinical Interview for DSM-IV Axis II Disorders […] The interview and all the ratings were completed by psychiatrists with at least 4 year experience in anxiety and mood disorders”.
“We enrolled all consecutive patients with a principal diagnosis of OCD and with a YBOCS total score of 16 or greater who were referred to the Mood and Anxiety Disorders Unit of the University of Turin, Italy”.
The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study provided sufficient information about non-response rate
All patients gave their informed consent before enrolment in the study”.
Eisen 2006 * * * * No * No No 5
Support for judgement and quote “Participants were 197 consecutive adult individuals recruited to be part of a 5-year prospective naturalistic study of course of illness in OCD. Inclusion criteria were 18 years or older, primary OCD (defined as the disorder participants considered their biggest problem overall), and treatment seeking. Recruitment was from a large OCD clinic, group psychiatric practices, psychologists’ offices, and mental health clinics in Rhode Island and Massachusetts”.
“Interviewers went through a rigorous training process consisting of a training period, followed by a series of observed and taped interviews. Each case was presented at a weekly conference to review diagnoses and psychosocial impairment to ensure ongoing consistency in ratings”.
“The community norms of the US general population (n = 2474) obtained from the validation study of the SF-36 (Ware, 1993)”. Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “Interviewers went through a rigorous training process consisting of a training period, followed by a series of observed and taped interviews. Each case was presented at a weekly conference to review diagnoses and psychosocial impairment to ensure ongoing consistency in ratings”. The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide sufficient information about non-response rate.
Fontenelle 2010 * * * * No * No No 5
Support for judgement and quote “Volunteers for this study were consecutively recruited among patients undergoing treatment in the (1) Anxiety and Depression Research Program at the Institute of Psychiatry of the Universidade Federal do Rio de Janeiro (IPUB/UFRJ), the (2) Division of Applied Psychology at the Institute of Psychology of the same university (DPA/UFRJ) and (3) the first author’s private practice. The inclusion criteria were (1) the diagnosis of OCD, with or without psychiatric comorbidity confirmed by means of the Structured”. “The control group consisted of community members recruited through local advertisements and included medical and administrative staff of the Universidade Federal do Rio de Janeiro. Inclusion criteria for the control group were (1) age between 18 and 80 years, and (2) the absence of any other neurological, endocrinological, or systemic disorder that could interfere with the interpretation of our results. Controls were not screened beforehand for the presence of psychiatric disorders, since we intended to avoid the selection of a ‘supernormal’ sample, which would be not representative of the general population”. Although comparisons between cases and control were performed on demographic and clinical variables to test for the comparability of the two groups, cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “The diagnosis of OCD, with or without psychiatric comorbidity without psychiatric comorbidity confirmed by means of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth Edition, (DSM-IV) Axis I disorders”. The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide sufficient information about non-response rate.
Gros 2013 * * * * No * * * 7
Support for judgement and quote “Veterans were randomly selected from a master list of patients who had attended a primary care appointment at one of four target VAMCs “Diagnostic criteria were based on the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition.2”.
[…]”Interviewers were master’s level clinicians trained and supervised by a licensed psychologist. Interview reliability was investigated through a random sample of interviews conducted via speakerphone by two interviewers (approximately 8%).”
“Eligible patients were those who had been primary care attenders at any of the four target hospitals in fiscal year 1999. Stratifying on hospital, each patient was assigned a random number and the patient list ordered. According to this ordered list, blocks of 200 patients were sent to each hospital (new blocks were sent when these lists were exhausted)”.
“Patients with known dementia, octogenarians and nonagenarians were excluded due to concern over ability to recall information critical to the study”.
The control group consisted of veterans extracted from the sample reference population of cases Although comparisons between cases and control were performed on demographic and clinical variables to test for the comparability of the two groups, cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “Participants with OCD were significantly younger than participants without OCD (F=5.7; P=.02). No additional group differences were observed (χ2b1.8; PsN.17)”. “Diagnostic criteria were based on the Diagnostic and Statistical Manual
for Mental Disorders, Fourth Edition [13]. Interviewers were master’s level
clinicians trained and supervised by a licensed psychologist.
Interview reliability was investigated through a random sample of interviews conducted via speakerphone by two interviewers (approximately 8%)”.
The study used the same method to ascertain exposure in cases and controls (DSM-IV criteria and MINI) The study provided sufficient information about non-response rate
“Afterwards, 854 participants (79.4%) completed follow-up phone interviews involving the Mini International Neuropsychiatric Interview (MINI) to assess current psychiatric disorders”
Hou 2010 * * * * No * * * 7
Support for judgement and quote “From February to November 2008, 65 patients with OCD were consecutively recruited from the outpatient psychiatric clinics at a medical center and a regional teaching hospital in Southern Taiwan”
“A psychiatrist systematically assessed all patients to confirm the diagnosis of OCD using the structured Mini-International Neuropsychiatric Interview [26] based on the diagnostic schemes of the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders”
“To recruit subjects for the control group, we posted an advertisement in the hospital and in newspapers to invite participation. A total of 157 persons responded to the advertisement. A psychiatrist assessed all responders systematically to determine whether they had any mood or psychotic disorders using the Mini-International Neuropsychiatric Interview. Those who had OCD, mood disorders, psychotic disorders, drank alcohol more than once per month, used any illicit drugs or had low mentality were excluded. A
total of 106 subjects conformed to the criteria and were recruited as the control group“.
Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis “A psychiatrist systematically
assessed all patients to confirm the diagnosis of OCD
using the structured Mini-International Neuropsychiatric
Interview [26] based on the diagnostic schemes of the 4th edition of the Diagnostic and Statistical Manual
of Mental Disorders [27]”.
The study used the same method to ascertain exposure in cases and controls (DSM-IV criteria and MINI) The study provided sufficient information about non-response rate
“From February to November 2008, 65 patients with OCD were consecutively recruited from the outpatient psychiatric clinics at a medical center and a regional teaching hospital in Southern Taiwan. Of these, five patients (3 men and 2 women) refused to participate in this study”.
Jahangard 2018 * * * * No * * * 7
Support for judgement and quote “Outpatients diagnosed with OCD from the Farshchian Psychiatric Hospital in Hamadan (Iran) […] were approached to participate in the present cross-sectional and questionnaire-based study”
“A total of 258 patients with OCD were approached and assessed against inclusion and exclusion criteria (see inclusion and exclusion criteria below). Inclusion criteria were as follows: (1) diagnosis by a psychiatrist of current OCD according to the DSM 5 (American Psychiatric Association, 2013); (2) Yale-Brown Obsessive Compulsive Scale (Y-BOCS; Goodman et al., 1989) score of 15 points or higher (see below); (3) no comorbid psychiatric disorders, except for diagnosis of a mild to moderate major depressive disorder, and no substance use disorder (SUD) of tobacco or cannabis or benzodiazepines; (4) no neurological, or other somatic disorders, as ascertained from patients’ reports and their medical records; (5) age between 18 and 65 years; (5) willing and able to participating in the study, and (6) written informed consent (see also Table 1). Exclusion criteria were: (1) acute psychosis and (2) acute suicidality
(3) severe MDD and severe SUD of opioids, amphetamines/methamphetamines. The nature of the current treatment regimen (psychopharmacological treatment, psychotherapy, neuromodulation; combinations of such treatments) was not an exclusion criterion”.
“[…] Healthy controls drawn from the hospital and university staff were approached to participate in the present cross-sectional and questionnaire-based study”
“Healthy controls were recruited by advertisements on the homepage of the hospital and the University of Hamadan, and by word-of-mouth; during weekly staff meetings, staff members from different wards and departments of the university were encouraged to participate in the study and to ask and encourage other staff members to take part. Inclusion criteria were as follows: (1) age between 18 and 65 years; (2) no psychiatric disorders, as ascertained by a thorough neuropsychiatric”
interview (Sheehan et al., 1998) conducted by trained psychiatrists and
clinical psychologists; (3) no somatic illnesses, as ascertained by a
thorough medical interview; (4) written informed consent”.
Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis “[…] diagnosis by a
psychiatrist of current OCD according to the DSM 5 (American
Psychiatric Association, 2013); (2) Yale-Brown Obsessive Compulsive
Scale (Y-BOCS; Goodman et al., 1989) score of 15 points or higher (see
below)”.
The study used the same method to ascertain exposure in cases and controls (DSM-5 criteria and MINI) The study provided sufficient information about non-response rate
As mentioned above (see inclusion and exclusion criteria in the Method section), a total of 258 patients with OCD were approached and after thorough assessment 117 (45,3%) were enrolled in the study. Of these, 17 patients (12.32%) declined participation; thus, the final sample consisted of 100 patients with OCD (72.46%)”.
Kivircik Akdede 2005 * * * * No * * No 6
Support for judgement and quote “[…] subjects who were in follow up at out-patient clinic with the diagnosis of “Obsessive Compulsive Disorder” according to DSM-IV diagnostic criteria”.
“Inclusion criteria were determined as absence of known physical or neurological disorder, Hamilton
Depression Rating Scale less than 16 points and negative history of electro-convulsive therapy within last 6 months”.
“All subjects were assessed by a psychiatrist initially. The patients who were diagnosed as obsessive-compulsive disorder and found to be eligible for the study in the first interview were directed towards a second investigator who was not unblinded to the diagnosis”.
“Healthy individuals without self or family history of psychiatric diseases constituted the control group”.
“All subjects were assessed by a psychiatrist
initially. The patients who were diagnosed as
obsessive-compulsive disorder and found to be eligible for the study in the first interview were directed towards a second investigator who was not unblinded to the diagnosis”.
Although comparisons between cases and control were performed on demographic and clinical variables to test for the comparability of the two groups, cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis.
“There were no
statistically significant differences between two
groups in age, gender, hand preferences and
educational level”.
The study provides sufficient information about ascertainment of exposure.
“[…] subjects who were in follow up at out-patient clinic with the diagnosis of “Obsessive Compulsive Disorder” according to DSM-IV diagnostic criteria”.
“All subjects were assessed by a psychiatrist initially. The patients who were diagnosed as obsessive-compulsive disorder and found to be eligible for the study in the first interview were directed towards a second investigator who was not unblinded to the diagnosis”.
The study used the same method to ascertain exposure in cases and controls (DSM-IV criteria).
“All subjects were assessed by a psychiatrist initially. The patients who were diagnosed as obsessive-compulsive disorder and found to be eligible for the study in the first interview were directed towards a second investigator who was not unblinded to the diagnosis”.
The study does not provide sufficient information about non-response rate.
Koran 1996 * * * * No * No No 5
Support for judgement and quote ”At baseline an experienced clinical interviewer administered the Structured Clinical Interview for DSM-III-R (SCID) to establish psychiatric diagnoses”
“We used the Yale-Brown Obsessive Compulsive Scale […] to quantify the severity of the patients’ obsessive compulsive symptoms”.
To compare the quality of life or our obsessive compulsive patients to the of the U.S. general population, we used U.S. population norms reflecting a representative sample of the non-institutionalized population.” Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. ”At baseline an experienced clinical interviewer administered the Structured Clinical Interview for DSM-III-R (SCID) to establish psychiatric diagnoses”
“We used the Yale-Brown Obsessive Compulsive Scale […] to quantify the severity of the patients’ obsessive compulsive symptoms”.
The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide sufficient information about non-response rate.
Kumar 2012 * * * * No * No No 5
Support for judgement and quote “Consecutive patients (n=31) who satisfied study criteria were recruited between July 2008 and February 2009 from the Behavioral Medicine Unit of the NIMHANS”
“Inclusion criteria for patients were age between 18 and 55 years, ability to read and write in English language, a primary diagnosis of OCD according to DSM-IV, and a score of 16 on the Y-BOCS. Patients who had severe comorbid psychiatric, physical and neurological disorders (i.e., psychosis, bipolar affective disorder, current psychoactive substance abuse or dependence, mental retardation, cancer, chronic pain, arthritis, asthma, head injury, and/or epilepsy), and those who had received exposure/response prevention or cognitive behaviour therapy (CBT)in the preceding year were excluded”.
“The principal author performed all the evaluations using the following instruments: the mini International Neuropsychiatry Interview […]”.
“Normal controls (n=30) comparable to patients with respect to age and gender were recruited by word of mouth from the local community. Only those who scored less than 2 on the General Health Questionnaire-12 were considered as normal controls”. Although comparisons between cases and control were performed on demographic and clinical variables (e.g., depression and anxiety), and no difference emerged, except for education years, cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “[…] a primary diagnosis of OCD according to DSM-IV, and a score of 16 on the Y-BOCS […]”
“The principal author performed all the evaluations using the following instruments: the mini International Neuropsychiatry Interview […]”
The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide sufficient information about non-response rate.
Rodriguez-Salgado 2006 * * * * No * No * 6
Support for judgement and quote Between November 2002 and November 2004, we recruited 64 adult patients (older than 18) with OCD
diagnosis (according to DSM-IV criteria) at the psychiatric outpatient clinic at Ramon y Cajal General Hospital”.
All patients were interviewed by a clinical psychiatrist and assessed with the 5.0.0 Spanish version of the Mini International Psychiatric Interview (MINI) […]”.
Spanish general population Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. All patients were interviewed by a clinical psychiatrist and assessed with the 5.0.0 Spanish version of the Mini International Psychiatric Interview (MINI) […]” The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study provided sufficient information about non-response rate
“All of them agreed to participate in the study and signed a consent form”.
Souza Vivan 2013 * * * * No * * * 7
Support for judgement and quote “All participants were recruited from a population-based, epidemiological study conducted with high school students from the city of Porto Alegre, southern Brazil, designed to assess the prevalence of OCD and obsessive-compulsive symptoms in adolescents”.
“Subjects with OCD should meet the diagnostic criteria for the disorder according to DSM-IV 1 and score o 16 on the Yale-Brown Obsessive-Compulsive Scale (YBOCS)”.
“Data were collected between May 2009 and August 2011. Adolescents were interviewed individually by
previously trained psychologists at a university hospital (Hospital de Clınicas de Porto Alegre) or at their homes”.
“The Brazilian version of the K-SADS-PL was used to confirm the diagnosis of OCD”.
“Controls were randomly selected among participants; they had to score, 21 on the scale used to screen for obsessive-compulsive symptoms (Obsessive Compulsive Inventory - Revised, OCI-R) and should not have a diagnosis of OCD”. Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis.
“The two groups were significantly different in relation to sex (p = 0.008)”.
“Subjects with OCD should meet the diagnostic criteria for the disorder according to DSM-IV 1 and score of 16 on the Yale-Brown Obsessive-Compulsive Scale (YBOCS)”.
“Data were collected between May 2009 and August 2011. Adolescents were interviewed individually by
previously trained psychologists at a university hospital (Hospital de Clınicas de Porto Alegre) or at their homes”.
“The Brazilian version of the K-SADS-PL was used to confirm the diagnosis of OCD”
The study used the same method to ascertain exposure in cases and controls (DSM-IV criteria and K-SADS) The study provided sufficient information about non-response rate
“Seventy six adolescents with OCD were identified, but one refused to participate in the present experiment”.
Srivastava 2011 * * * * ** * * * 9
Support for judgement and quote “Forty five consecutive subjects with the diagnosis of OCD, according to the DSM-IV-TR criteria, from the psychiatry outpatients’ services of the University College of Medical Sciences and G. T. B. Hospital, a tertiary care hospital in Delhi were recruited for the study.”
“The inclusion criteria of the OCD group were a) Subjects of either gender, aged ≥18 years with diagnosis according to the DSM-IV-TR criteria; b) Subjects included only newly diagnosed cases.
The study excluded a) Subjects with past history or current evidence of schizophrenia, bipolar affective disorder, major depressive disorder, organic mental disorders and seizure disorders; b) Subjects having clinically significant and unstable renal, hepatic, cardio-vascular, respiratory or cerebrovascular disease or any other serious and progressive physical disease”.
“Patients’ diagnoses of obsessive compulsive disorder and major depressive disorder were established by senior psychiatrist on the basis of history and clinical interview in accordance with DSM-IV criteria”
“The diagnosis was reconfirmed by the principal author using the Mini-International Neuropsychiatry Interview (MINI)”.
“A group of 150 healthy volunteers were included after excluding evidence of any psychiatric or medical/surgical illness after thorough history, physical examination and routine investigations (complete blood count, urinalysis, chest radiograph and electrocardiogram).
The exclusion criteria were
a) Subjects with past history or current evidence of schizophrenia, obsessive compulsive disorder, bipolar affective disorder, organic mental disorders and seizure disorders; b) Subjects having clinically significant and unstable renal, hepatic, cardiovascular, respiratory or cerebro-vascular disease or any other serious and progressive physical disease”.
“The healthy control group was carefully matched with the OCD group with respect to potentially confounding variables like age and gender”. “Patients’ diagnoses of obsessive compulsive disorder and major depressive disorder were established by senior psychiatrist on the basis of history and clinical interview in accordance with DSM-IV criteria”
“The diagnosis was reconfirmed by the principal author using the Mini-International Neuropsychiatry Interview (MINI)”.
The study used the same method to ascertain exposure in cases and controls (DSM-IV criteria and MINI) The study provided sufficient information about non-response rate
“Four patients declined participation in the study”.
Stengler-Wenzke 2006 * * * * No * No No 5
Support for judgement and quote “Seventy-five patients (ICD-10 F42.0-F42.2; WHO 1993) treated in the outpatient clinic for patients with OCD and anxiety disorders at the Department of Psychiatry of the University of Leipzig were consecutively recruited”. “In 2004 a representative survey was conducted in Germany among persons of German nationality who were aged 18 years and older and were not living in institutional settings. The sample was drawn using a random three-stage sampling: (1) electoral wards, (2) households, and (3) individuals within the target households. Target households within the sample points were determined according to the random route procedure; target persons were selected according to random digits. For our study only those respondents residing in Saxony, the state in which the city of Leipzig is located, were selected (n = 315)”. Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “[…] patients (ICD-10 F42.0-F42.2; WHO 1993)”.
“Severity of OCD symptoms was assessed
by the Yale-Brown Obsessive-Compulsive Scale […]”.
The study did not use the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide information about non-response rate
Trettim 2017 * * * * No * * * 7
Support for judgement and quote “The sample selection was performed by clusters, considering a population of 39.667 in the age range of interest according to the current census of 448 sectors in the city. To ensure the necessary sample size, 89 census-based sectors were randomly selected. Household selection in the sectors was performed according to a systematic sampling process, the first house being the one at the corner designated by IBGE (IBGE, 2008; http://ibge.gov.br) as starting the sector; every third house was selected”.
“The study included seven interviewers, all of whom were undergraduate psychology or physical therapy students of Universidade Católica de Pelotas (UCPel). The interviewers were trained to administer the instrument by psychologists with extensive experience and weekly meetings were conducted throughout the data collection period. The interviews were conducted at home and lasted for about 40 minutes. After identifying the subjects, the interviewers were previously trained about the details of the application of instruments. The data were collected between August 2007 and December 2009. Young people that were unable to answer the diagnostic interview due to physical or cognitive problems were excluded”.
Cases and controls were not matched in the design and potential confounders were not adjusted for in the analysis. “Brazilian Portuguese validated version of the Mini
Neuropsychiatric Interview (MINI) by Amorim (2000), a
structured interview with proven validity and reliability, was used in the study”.
The study used the same method to ascertain exposure in cases and controls, since controls were unscreened participants The study does not provide information about non-response rate
Of the initial 1762 subjects identified for study inclusion, 11.5% refused to participate. Thus the final sample was composed of 1569 participants”.

Note. OCD = Obsessive-Compulsive Disorder, SF-36 = Medical Outcomes Survey 36-Item Short-Form Health Survey.

Back to Article