Table 2.
Familial risk of incident UC and CD with affected FDR of the same subtype according to type of family relationship
| With affected father* | With affected mother* | With affected sibling* | With affected twin* | With more than one affected FDR* | With positive family history* | No family history of IBD | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||||
| N | (%) | N | (%) | N | (%) | N | (%) | N | (%) | N | (%) | N | (%) | |
|
| ||||||||||||||
| UC | ||||||||||||||
| Individuals at risk | 32,800 | 23,093 | 15,949 | 138 | 572 | 72,552 | 21,839,800 | |||||||
| Male | 18,045 | (55) | 12,811 | (55) | 8,212 | (52) | 83 | (60) | 289 | (51) | 39,440 | (54) | 12,067,365 | (55) |
| Female | 14,755 | (45) | 10,282 | (45) | 7,737 | (48) | 55 | (38) | 283 | (49) | 33,112 | (46) | 9,772,435 | (45) |
| Patients | 165 | 147 | 206 | 20 | 38 | 576 | 14,988 | |||||||
| Person-year | 465,748 | 327,633 | 250,507 | 2,062 | 8,583 | 1,056,686 | 307,000,000 | |||||||
| Incidence rate per 10 5 person-years (95% CI) | 35.4 (30.4–41.3) | 44.9 (38.2–52.7) | 82.2 (71.7–94.3) | 969.8 (620–1500) | 442.8 (322.2–608.5) | 54.5(50.2–59.1) | 4.9(4.8–5.0) | |||||||
| Crude IRR (95% CI) | 7.26 (6.19–8.46) | 9.19 (7.76–10.81) | 16.84 (14.61–19.33) | 198.64 (121–306) | 90.68(64.15–124.54) | 11.17 (10.26–12.14) | 1.00 | |||||||
| Adjusted ** IRR (95%CI) | 7.11 (6.10–8.29) | 8.77 (7.46–10.32) | 13.09 (11.41–15.02) | 163.73 (105–253) | 72.36 (52.63–99.49) | 10.20(9.39–11.09) | 1.00 | |||||||
| CD | ||||||||||||||
| Individuals at risk | 8,460 | 5,267 | 14,312 | 130 | 133 | 28,302 | 21,839,800 | |||||||
| Male | 4,490 | (55) | 2,837 | (55) | 7,109 | (52) | 91 | (70) | 58 | (51) | 14,585 | (54) | 12,067,365 | (55) |
| Female | 3,970 | (45) | 2,430 | (45) | 7,203 | (48) | 39 | (30) | 75 | (49) | 13,717 | (46) | 9,772,435 | (45) |
| Patients | 37 | 19 | 304 | 30 | 10 | 400 | 12,983 | |||||||
| Person-year | 105,367 | 71,279 | 222,649 | 1,788 | 1,971 | 403,054 | 307,000,000 | |||||||
| Incidence rate per 10 5 person-years (95% CI) | 35.1(25.4–48.5) | 26.7(17.0–41.8) | 136.5(122.0–152.8) | 1678.3(1170–2400) | 507.4(273.0–942.9) | 99.2(90.0–109.5) | 4.2(4.2–4.3) | |||||||
| Crude IRR (95% CI) | 8.30(5.84–11.45) | 6.30(3.79–9.85) | 32.29(28.72–36.18) | 396.86(267–566) | 119.97(57.52–220.7) | 23.47(21.19–25.92) | 1.00 | |||||||
| Adjusted ** IRR (95%CI) | 9.40(6.81–12.98) | 6.54(4.17–10.25) | 27.56(24.59–30.88) | 336.21(234–481) | 107.52(57.84–199.8) | 22.15(20.05–24.47) | 1.00 | |||||||
*
Familial risk of incident IBD with same subtype of affected FDR (e.g. risk of UC with UC affected FDR)
**
adjusted for age, sex, calendar periods, maternal and paternal age at birth
N – number of individuals, CD - Crohn’s disease, CI – confidence interval, FDR – first degree relatives, IRR – incidence risk ratio, IBD – inflammatory bowel disease, UC - ulcerative colitis.