A hierarchy of preferred rating scales for the primary outcome measure was established a priori to limit possible investigator reporting bias. In order of preference, these OCD ratings scales for treatment efficacy included the CY-BOCS,[59] and the National Institute of Mental Health Global OCD Scale (NIMH-GOCS).[60] For classification of treatment response, preference was placed on the Clinical Global Impression of Improvement (CGI-Improvement),[61] with treatment response considered a rating of “much improved” or “very much improved” consistent with extant RCTs. When the CGI-Improvement was unavailable, a reduction of 25% or greater on the CY-BOCS was used as it corresponds with a treatment response on the CGI-Improvement.[55] For classification of symptom/diagnostic remission, preference was placed on CY-BOCS 14 as it corresponds with a Clinical Global Impression-Severity (CGI-Severity) rating of “no illness” or “mild illness”.[55] If CY-BOCS remission cut-off scores were not reported and/or unavailable, diagnostic remission on the ADIS-P was preferred.[62] Finally, a CY-BOCS reduction of 40–50% was considered to be permissible in the absence of the other two measures, as it corresponds well to CGI-Severity ratings of “no illness” or “mild illness”.[55]
