Table 2. Baseline characteristics of the iPSYCH2012 case–cohort.
|
Initial sample, N=86 189 |
Passed sample QC, N=77 639 |
|||
|---|---|---|---|---|
| Casesa, N=57 377 | Cohorta, N=30 000 | Casesa, N=51 101 | Cohorta, N=27 605 | |
| Sex | ||||
| Male | 32 243 (56.19%) | 15 308 (51.03%) | 29 048 (56.84%) | 14 090 (51.04%) |
| Female | 25 134 (43.81%) | 14 692 (48.97%) | 22 053 (43.16%) | 13 515 (48.96%) |
| Year of birth | ||||
| 1981–1985 | 11 909 (20.76%) | 4858 (16.19%) | 9409 (18.41%) | 4175 (15.12%) |
| 1986–1990 | 14 506 (25.28%) | 5838 (19.46%) | 12 766 (24.98%) | 5361 (19.42%) |
| 1991–1995 | 14 521 (25.29%) | 6597 (21.99%) | 13 508 (26.43%) | 6190 (22.42%) |
| 1996–2000 | 10 306 (17.96%) | 6461 (21.54%) | 9796 (19.17%) | 6182 (22.39%) |
| 2001–2005 | 6144 (10.71%) | 6246 (20.82%) | 5622 (11.00%) | 5697 (20.64%) |
| Diagnosisb | ||||
| Schizophrenia | 3540 (6.17%) | 90 (0.30%) | 2738 (5.36%) | 65 (0.24%) |
| Bipolar affective disorder | 1928 (3.36%) | 42 (0.14%) | 1452 (2.84%) | 31 (0.11%) |
| Affective disorder | 26 380 (45.98%) | 543 (1.81%) | 22 809 (44.64%) | 467 (1.69%) |
| Autism | 16 146 (28.14%) | 324 (1.08%) | 14 812 (28.99%) | 309 (1.12%) |
| ADHD | 18 726 (32.64%) | 387 (1.29%) | 17 249 (33.75%) | 360 (1.30%) |
| None of the above | 0 (0.00%) | 28812 (96.04%) | 0 (0.00%) | 26 538 (96.13%) |
| Parental originc | ||||
| Denmark | 49 737 (86.68%) | 25 159 (83.86%) | 44 284 (86.66%) | 23 213 (84.09%) |
| Africa | 619 (1.08%) | 446 (1.49%) | 566 (1.11%) | 400 (1.45%) |
| America | 472 (0.82%) | 228 (0.76%) | 419 (0.82%) | 204 (0.74%) |
| Asia | 731 (1.27%) | 672 (2.24%) | 648 (1.27%) | 616 (2.23%) |
| Australia | 51 (0.09%) | 29 (0.10%) | 47 (0.09%) | 29 (0.11%) |
| Europe excl Scandinavia | 2508 (4.37%) | 1557 (5.19%) | 2228 (4.36%) | 1406 (5.09%) |
| Greenland | 341 (0.59%) | 162 (0.54%) | 306 (0.60%) | 148 (0.54%) |
| Middle East | 666 (1.16%) | 625 (2.08%) | 604 (1.18%) | 568 (2.06%) |
| Scandinavia excl Denmark | 1168 (2.04%) | 600 (2.00%) | 1047 (2.05%) | 549 (1.99%) |
| Mixed parentage | 221 (0.39%) | 166 (0.55%) | 190 (0.37%) | 146 (0.53%) |
| Unknown | 863 (1.50%) | 356 (1.19%) | 762 (1.49%) | 326 (1.18%) |
| Birth weight | ||||
| <1500 g | 475 (0.83%) | 145 (0.48%) | 381 (0.75%) | 125 (0.45%) |
| 1500–2499 g | 2613 (4.55%) | 924 (3.08%) | 2197 (4.30%) | 808 (2.93%) |
| 2500–3499 g | 26 735 (46.60%) | 13 302 (44.34%) | 23 758 (46.49%) | 12 245 (44.36%) |
| 3500–4499 g | 25 500 (44.44%) | 14 491 (48.30%) | 22 918 (44.85%) | 13 425 (48.63%) |
| ⩾4500 g | 1739 (3.03%) | 954 (3.18%) | 1600 (3.13%) | 883 (3.20%) |
| Missing information | 315 (0.55%) | 184 (0.61%) | 247 (0.48%) | 119 (0.43%) |
| Gestational age | ||||
| <35 weeks | 1342 (2.34%) | 458 (1.53%) | 1105 (2.16%) | 397 (1.44%) |
| 35–36 weeks | 1907 (3.32%) | 857 (2.86%) | 1648 (3.22%) | 776 (2.81%) |
| 37–38 weeks | 8650 (15.08%) | 4305 (14.35%) | 7754 (15.17%) | 3998 (14.48%) |
| 39–40 weeks | 29 768 (51.88%) | 15 835 (52.78%) | 26 642 (52.14%) | 14 640 (53.03%) |
| ⩾41 weeks | 14 995 (26.13%) | 8239 (27.46%) | 13 440 (26.30%) | 7594 (27.51%) |
| Missing information | 715 (1.25%) | 306 (1.02%) | 512 (1.00%) | 200 (0.72%) |
| Apgar score (5 min) | ||||
| 1–5 | 238 (0.41%) | 113 (0.38%) | 204 (0.40%) | 107 (0.39%) |
| 6–7 | 617 (1.08%) | 224 (0.75%) | 523 (1.02%) | 199 (0.72%) |
| 8–9 | 3460 (6.03%) | 1712 (5.71%) | 3083 (6.03%) | 1573 (5.70%) |
| 10 | 52 284 (91.12%) | 27 590 (91.97%) | 46 666 (91.32%) | 25 445 (92.18%) |
| Missing information | 778 (1.36%) | 361 (1.20%) | 625 (1.22%) | 281 (1.02%) |
Abbreviations: ADHD, attention-deficit/hyperactivity disorder; iPSYCH, Integrative Psychiatric Research; QC, quality control.
Persons who were both selected as cases and cohortees constitute 1188 persons in the initial sample and 1067 persons in the QC’ed sample. These individuals were counted both in the case and cohort group.
Psychiatric diagnosis at time of selection as described in the method section. Some persons may both be selected in the case and cohort group, have more than one diagnoses and may later have additional diagnoses.
Persons with both parents born in Denmark were classified as having Danish parental origin. Persons having a Danish-born parent and a foreign born parent were classified as the foreign-born parents region of birth. Persons having two foreign-born parents born in the same region were classified with that region. Persons having two foreign-born parents born in different regions were classified as mixed.