To assess the validity of the TS/CT Narrow and Intermediate disease definitions, gender ratios and rates of OCD and ADHD were compared across different TS/CT disease groups and tested formally for heterogeneity (Table 3). As expected, male-to-female gender ratios were significantly higher in both TS case definitions (TS Narrow, 3.6:1; TS Intermediate, 2.3:1) compared with controls (0.9:1; p = .006 and p = .002, respectively). A low-to-moderate degree of heterogeneity26 was present between the two TS definitions (I2 = 32.8%, p = .22). Similarly, CT Narrow and CT Intermediate groups had a higher proportion of males than controls (CT Narrow, 1.9:1; CT Intermediate, 2.4:1; p = .047 and p < .001, respectively) with no heterogeneity between the two CT definitions (I2 = 0%, p = .64). The gender ratios for the CMT and CVT case definitions were similar to those for overall CT with no heterogeneity between the Narrow and Intermediate groups (Table S3, available online).
