Table 1. Distribution of Study Variables Among Study Cohort Members Born in Sweden Between 1976 and 1998, Stratified by Obsessive-Compulsive Disorder.
| Characteristic, No. (%) | Individuals With Obsessive-Compulsive Disorder (n = 15 120) |
Unaffected Individuals (n = 2 100 434 ) |
|---|---|---|
| Female | 8996 (59.5) | 1 021 113 (48.6) |
| Age of mothers at birth of study participant, mean (SD), ya | 28.4 (5.3) | 28.0 (5.0) |
| Age of fathers at birth of study participant, mean (SD), ya | 31.2 (6.2) | 30.7 (5.8) |
| Missing | 101 (0.7) | 13 950 (0.7) |
| Paritya | ||
| 1 | 6444 (42.6) | 853 017 (40.6) |
| 2 | 5227 (34.6) | 766 216 (36.5) |
| 3 | 2253 (14.9) | 326 417 (15.5) |
| ≥4 | 1000 (6.6) | 125 379 (6.0) |
| Missing | 196 (1.3) | 29 403 (1.4) |
| Comorbidity | ||
| Attention-deficit/hyperactivity disordera | 2644 (17.5) | 53 215 (2.5) |
| Other neuropsychiatric disordersa,b | 2718 (18.0) | 27 020 (1.3) |
| Schizophrenia, schizotypal, or delusional disordersa | 982 (6.5) | 9133 (0.4) |
| Phobic, anxiety, stress reaction, and adjustment disordersa | 8643 (57.2) | 129 872 (6.2) |
| Affective disordersa | 7132 (47.2) | 109 494 (5.2) |
| Substance use disordersa | 2343 (15.5) | 88 730 (4.2) |
| Other disordersa,c | 2517 (16.7) | 33 358 (1.6) |
a
Statistically significant between-group difference determined with a χ2 test or 2-tailed t test; all marked comparisons yielded P < .001.
b
Includes pervasive developmental disorders, Tourette syndrome and chronic tic disorders, and learning disabilities.
c
Includes dissociative, somatoform, other neurotic, and eating disorders.