For family studies, the analysis unit was the FDR(s) of the OCD patients or controls, and the outcomes of interest were: (a) the familial recurrence rates of definite and probable/subthreshold OCD in FDRs of OCD compared with FDRs of control probands; and (b) the familial recurrence rates of definite and probable/subthreshold OCD in FDR of early-onset (before 18 years old) OCD probands compared with FDRs of late-onset (after 18 years old) OCD probands. We conducted these analyses three times: once for all studies, once for studies involving children/adolescents, and once for adults.
