Given the reported variations in comorbidity frequency across OCD samples, and the clinical and research implications of these differences, a critical evaluation of the extant literature is required. As a result, we report here a systematic review and meta-analysis of OCD comorbidities with the aim to estimate lifetime prevalence and age-related patterns of comorbidity (psychiatric, personality, and medical/neurological disorders) in OCD. A secondary aim was to examine the association between comorbidities and demographic (age at assessment, gender distribution) and clinical variables (age of onset, illness severity).
