For individuals who were present in both samples (n = 60) we retained the diagnostic criteria from Study 2. Missing items were replaced by the item sample mean and individuals with missing values on more than 25% of the items were removed from the dataset. The combined sample from the two studies comprised 298 cases and 4518 controls; the mean age of the cases was 33.3 years (SD = 8.9; range 18–74 years), while the mean age of the controls was 34.6 years (SD = 9.1; range 18–77 years).
