Screening young people for obsessive compulsive disorder

Obsessive–compulsive disorder (OCD) in young people is underrecognised and undertreated. Simple screening tools suitablefor general practice and community services are needed. Wecreated a seven-item self-report Short OCD Screener (SOCS)and administered itto young people aged 11–15 years,including 116 patients with OCD, 181 healthy community controlsand 33 young people with other psychiatric diagnoses. The SOCShas excellent sensitivity of 0.97 (95% CI 0.91–0.98)to detect OCD cases. Its specificity is good in children withoutpsychiatric diagnoses, but low in a psychiatric sample. TheSOCS is a screening tool suitable for community but not specialistsettings.

INTRODUCTION

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INTRODUCTION

Obsessive–compulsive disorder (OCD) commonly arises inchildhood and adolescence (Heyman et al, 2001). Young peoplewith the disorder perceive their symptoms as embarrassing anddo not disclose them unless specifically asked. Therefore, OCDin this age group often remains unrecognised and untreated.The associated distress and developmental handicap are avoidableas effective treatments are available, namely cognitive–behaviouraltherapy with or without serotonin reuptake inhibiting medication (Heyman et al, 2006). There is evidence that early detectionand intervention improve outcome (Stewart et al, 2004). TheNational Institute for Health and Clinical Excellence (NICE)guidance on the assessment and treatment of OCD recommends routine screening of young people at risk in general practice or othersettings where they may present for help (National Collaborating Centre for Mental Health, 2005).Such screening requires short, easy-to-use and widely availablemeasures. We report on the development, validation and disseminationof such a self-report tool, the Short OCD Screener (SOCS).

METHOD

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METHOD

The questionnaire was developed from the five most discriminantitems of the 44-item child version of the Leyton ObsessionalInventory (Berg et al, 1986). These items enquire about commonsymptoms including checking, touching, cleanliness/washing,repeating and exactness. Two further questions were designedto gauge the associated impairment and resistance. A three-option response format (‘no’, ‘a bit’, or‘a lot’) was used throughout. A SOCS score is calculatedby summing the scores for all seven items (‘no’,0, ‘a bit’, 1; ‘a lot’, 2).

We administered the SOCS to 127 individuals aged 11–15years consecutively referred to the Clinic for Obsessive–Compulsiveand Related Disorders at the Michael Rutter Centre, MaudsleyHospital, London. Of the 127 referred individuals, 114 metICD–10 diagnostic criteria for OCD (World Health Organization, 1992),established by a comprehensive psychiatric assessment and thestructured Child Yale–Brown Obsessive–CompulsiveScale (CY–BOCS; Scahill et al, 1997). The remaining13 individuals received other ICD–10 diagnoses, includinganxiety disorder (n=7), conduct disorder (n=4), hyperactivity(n=3) and depression (n=3). All participants completed theSOCS prior to clinical assessment.

We further administered the SOCS to a community sample of 203children aged 11–15 years as a part of the British nationwidepilot survey of child and adolescent mental health (Goodman, 1999).Diagnoses of ICD–10 psychiatric disorders in the communitysample were established using the Development and Well-Being Assessment (Goodman et al, 2000). Two of the individuals inthis sample met diagnostic criteria for OCD and 20 had otherICD–10 diagnoses including conduct disorder (n=12), anxietydisorders (n=6), hyperkinetic disorder (n=3) and depression(n=2). The clinic and community samples were combined to obtaina group of 116 cases of OCD, including 72 boys and 44 girlswith mean age 13.3 years (s.d.=1.3, range 11–15), meanduration of illness 3.3 years (s.d.=2.2, range 0.5–10)and mean total CY–BOCS impairment score 23.1 (s.d.= 5.0, range 15–40).

Three overlapping control groups were used. The first comparisongroup comprised the 181 individuals without any psychiatricdiagnosis from the community sample, constituting the ‘purehealthy control’ group (mean age 13.0 years, s.d.= 1.4;98 boys). This group was used to obtain estimates of how wellthe SOCS can discriminate OCD cases from healthy individuals.The second control group was also drawn from the community sample and consisted of healthy individuals and those with non-OCDpsychiatric diagnoses, forming a ‘mixed community control’group of 201 with a proportion of individuals with other psychiatricdiagnoses representative of the general population (mean age13.0 years, s.d.=1.4; 111 boys). This group was used to providemore realistic estimates of discrimination in a community setting.The third control group is a ‘psychiatric control’group, included 33 individuals with a psychiatric diagnosisother than OCD from both the community and the clinic samples(mean age 13.1 years, s.d.=1.3; 20 boys); this group was usedto explore whether the SOCS could discriminate OCD from otherpsychiatric disorders in clinical samples.

We used receiver operating characteristics analysis to establishoptimal cut-offs for screening (Fombonne, 1991). The 95% confidenceintervals for proportions were calculated using the efficientscore method (Newcombe, 1998).

RESULTS

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RESULTS

The mean total SOCS scores were 9.7 (s.d.=2.2) for the OCD group,3.0 (s.d.=2.3) for the healthy control group, 3.3 (s.d.=2.5)for the mixed community control group and 5.8 (s.d.=2.8) forthe psychiatric control group. Thus an average OCD case scored3 standard deviations above the healthy population mean and1.5 standard deviations above the mean of psychiatric controls.

Internal consistency of the SOCS was good, with Cronbach’s ${alpha}$ =0.85. Item-total correlations were all above 0.4. A principalaxis factor analysis clearly indicated unidimensionality dimensionalitywith a single latent factor explaining 53% of variance andall item loadings >0.4.

A SOCS score of 6 or more differentiated OCD cases with a sensitivityof 0.97 (95% CI 0.91–0.99). The specificity was 0.88(95% CI 0.82–0.92) for differentiation from the healthycontrol group, 0.84 (95% CI 0.78–0.89) for the mixedcommunity control group, and 0.52 (95% CI 0.34–0.69)for the psychiatric control group. Thus the screener identifiesalmost all true cases of OCD, approximately one in ten healthy adolescents and one in two of those with other psychiatricdisorders (Table 1). In the composite sample of OCD casesand mixed community controls, the positive predictive valuewas 0.78 (95% CI 0.70–0.84) and the negative predictivevalue was 0.98 (95% CI 0.94–0.99).

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Table 1 Numbers of true and false positives/negatives using the cut-off score of 6 or more on the Short OCD Screener

DISCUSSION

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DISCUSSION

The SOCS is shorter than other self-report tools (Bamber et al, 2002; Hudziak et al, 2006) and has comparable or better discriminantcharacteristics. The high sensitivity and negative predictivevalue make the SOCS an adequate screening tool for settingssuch as general practice, educational psychology, paediatric services or dermatology clinics. Because of its moderate specificitythe SOCS cannot be recommended for making diagnoses in psychiatricsamples.

The use of a composite sample from the general population andfrom referred patients allowed collection of a large sampleof young people with OCD. However, this enriched sample differedfrom the population encountered in community practice. Obsessive–compulsivedisorder was more prevalent in the study sample and more severeforms of the disorder might be over-represented. A study ofyoung people attending primary care will be needed to establishmore accurate estimates of discriminatory characteristics forthis setting.

The questionnaire is available online at http://ocdyouth.iop.kcl.ac.uk/downloads/socs.pdf. We hope that this simple tool will help to implement the NICEguideline recommendation to increase the awareness and detectionof OCD in young people (National Collaborating Centre for Mental Health, 2005).It is potentially suitable for use in primary care, communitychild health services, educational psychology or specialistmedical settings where OCD is common, such as dermatology clinics (Fineberg et al, 2003). A negative result (SOCS score 5 orlower) means that OCD is unlikely. A positive result does notmean that the young person has OCD but should serve as a basisfor discussion with the young person and parents, and diagnosticassessment. In our experience, young people find that completing this measure helps them with the initial stages of treatment,as it provides them with a vocabulary to use with their therapist.

REFERENCES

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