Table 1.
Baseline characteristics of IgAN diagnosed in Sweden in 1974–2011
| Characteristics | IgAN | General Population Controls | IgAN | Siblings | IgAN | Spouses |
|---|---|---|---|---|---|---|
| n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |
| Total | 3622 | 18,041 | 2773 | 6210 | 2234 | 2234 |
| Matched variables | ||||||
| Sex | ||||||
| Women | 1084 (29.9%) | 5408 (30.0%) | 802 (28.9%) | 3036 (48.9%) | 664 (29.7%) | 1591 (71.2%) |
| Men | 2538 (70.1%) | 12,633 (70.0%) | 1971 (71.1%) | 3174 (51.1%) | 1570 (70.3%) | 643 (28.8%) |
| Age | ||||||
| Age, mean (SD) | 39.6 (17.1) | 39.6 (17.1) | 35.8 (15.2) | 35.5 (16.9) | 44.1 (14.9) | 43.5 (15.2) |
| Age, median (IQR) | 38.8 (26.0–52.0) | 38.7 (26.0–52.0) | 34.9 (23.3–47.0) | 35.8 (22.9–48.4) | 43.7 (32.6–54.8) | 43.3 (32.3–54.3) |
| ≤17 yr | 370 (10.2%) | 1843 (10.2%) | 351 (12.7%) | 1025 (16.5%) | 62 (2.8%) | 90 (4.0%) |
| 18–39 yr | 1548 (42.7%) | 7754 (43.0%) | 1346 (48.5%) | 2601 (41.9%) | 864 (38.7%) | 864 (38.7%) |
| 40–59 yr | 1214 (33.5%) | 6010 (33.3%) | 887 (32.0%) | 2115 (34.1%) | 949 (42.5%) | 949 (42.5%) |
| ≥60 yr | 490 (13.5%) | 2434 (13.5%) | 189 (6.8%) | 469 (7.6%) | 359 (16.1%) | 326 (14.6%) |
| Unknown | 0 (0.0%) | 5 (0.2%) | ||||
| Calendar year | ||||||
| Entry year, median (IQR) | 2001 (1994–2007) | 2001 (1994–2007) | 2001 (1994–2008) | 2001 (1994–2007) | 2000 (1992–2006) | 2000 (1992–2006) |
| 1974–1988 | 428 (11.8%) | 2135 (11.8%) | 311 (11.2%) | 712 (11.5%) | 317 (14.2%) | 317 (14.2%) |
| 1989–2001 | 1448 (40.0%) | 7214 (40.0%) | 1086 (39.2%) | 2447 (39.4%) | 974 (43.6%) | 974 (43.6%) |
| 2002–2015 | 1746 (48.2%) | 8692 (48.2%) | 1376 (49.6%) | 3051 (49.1%) | 943 (42.2%) | 943 (42.2%) |
| Unmatched variables | ||||||
| Follow-up | ||||||
| Mean (SD) | 14.9 (8.61) | 15.4 (8.66) | 15.5 (8.58) | 16 (8.62) | 16 (8.83) | 16.8 (8.79) |
| Median (IQR) | 13.6 (7.99–20.8) | 14.1 (8.32–21.5) | 14.3 (8.46–21.4) | 14.8 (9.01–22.2) | 15.3 (8.93–22.4) | 16 (9.57–23.3) |
| <1 yr | 49 (1.4%) | 152 (0.8%) | 15 (0.5%) | 30 (0.5%) | 29 (1.3%) | 15 (0.7%) |
| 1–4 yr | 366 (10.1%) | 1690 (9.4%) | 238 (8.6%) | 469 (7.6%) | 197 (8.8%) | 147 (6.6%) |
| ≥5 yr | 3207 (88.5%) | 16,199 (89.8%) | 2520 (90.9%) | 5711 (92.0%) | 2008 (89.9%) | 2072 (92.7%) |
| Reason for ending the follow-up | ||||||
| Death | 577 (15.9%) | 2066 (11.5%) | 257 (9.3%) | 362 (5.8%) | 400 (17.9%) | 245 (11.0%) |
| Emigration | 101 (2.8%) | 664 (3.7%) | 76 (2.7%) | 152 (2.4%) | 47 (2.1%) | 39 (1.7%) |
| May 31, 2017 | 2944 (81.3%) | 15,311 (84.9%) | 2440 (88.0%) | 5696 (91.7%) | 1787 (80.0%) | 1950 (87.3%) |
| Person-years | 54,058 | 277,463 | 43,106 | 99,467 | 35,774 | 37,566 |
| Country of origin | ||||||
| Nordic | 3317 (91.6%) | 16,277 (90.2%) | 2715 (97.9%) | 6069 (97.7%) | 2008 (89.9%) | 1963 (87.9%) |
| Non-Nordic | 304 (8.4%) | 1762 (9.8%) | 58 (2.1%) | 141 (2.3%) | 226 (10.1%) | 211 (9.4%) |
| Unknown | 1 (<1%) | 2 (<1%) | 0 (0.0%) | 60 (2.7%) | ||
| Educational level | ||||||
| Compulsory school, ≤9 yr | 770 (21.3%) | 3823 (21.2%) | 468 (16.9%) | 1140 (18.4%) | 518 (23.2%) | 435 (19.5%) |
| Upper secondary school, 1–3 yr | 1611 (44.5%) | 8016 (44.4%) | 1300 (46.9%) | 2941 (47.4%) | 955 (42.7%) | 984 (44.0%) |
| University level | 1148 (31.7%) | 5745 (31.8%) | 958 (34.5%) | 1908 (30.7%) | 734 (32.9%) | 732 (32.8%) |
| Unknown | 93 (2.6%) | 457 (2.5%) | 47 (1.7%) | 221 (3.6%) | 27 (1.2%) | 83 (3.7%) |
| Henoch–Schönlein purpuraa | ||||||
| Yes | 227 (6.3%) | 26 (0.1%) | 191 (6.9%) | 18 (0.3%) | 93 (4.2%) | 4 (0.2%) |
| Medical historyb | ||||||
| Cardiovascular disease | 1283 (35.4%) | 1595 (8.8%) | 867 (31.3%) | 455 (7.3%) | 863 (38.6%) | 252 (11.3%) |
| Cancer | 226 (6.2%) | 973 (5.4%) | 150 (5.4%) | 339 (5.5%) | 148 (6.6%) | 141 (6.3%) |
| Diabetes, type 1 or 2 | 157 (4.3%) | 344 (1.9%) | 87 (3.1%) | 108 (1.7%) | 100 (4.5%) | 59 (2.6%) |
| Other systemic inflammatory disease | 292 (8.1%) | 434 (2.4%) | 205 (7.4%) | 198 (3.2%) | 189 (8.5%) | 74 (3.3%) |
| First-degree relative with renal disease | ||||||
| IgA nephropathyc | 35 (1.0%) | 31 (0.2%) | ||||
| ESRDd | 74 (2.0%) | 118 (0.7%) | ||||
a
Within 1 year of first renal biopsy indicating IgAN.
b
Before study entry (date of biopsy and corresponding date in controls). For definitions, see Supplemental Table 1.
c
Same definition as in the IgAN cohort (biopsy report of IgAN 1974–2011).
d
For relevant ICD and procedure codes, see Supplemental Table 2.