Table 1.
Characteristics of the study population
| Characteristics | Cases (n = 40 545) | Controls (n = 202 720) | P a |
|---|---|---|---|
| Sex, No. (%)b | |||
| Men | 21 458 (52.9) | 107 285 (52.9) | |
| Women | 19 087 (47.1) | 95 435 (47.1) | 1.00 |
| County, No. (%)b | |||
| Region Stockholm | 6 995 (17.3) | 34 974 (17.3) | |
| Region Skåne | 5 481 (13.5) | 27 403 (13.5) | |
| Region Västra Götaland | 7 060 (17.4) | 35 300 (17.4) | |
| Other regionsc | 21 009 (51.8) | 105 043 (51.8) | 1.00 |
| Country of birth, No. (%) | |||
| Sweden | 35 391 (87.3) | 175 288 (86.5) | |
| Rest of Europe | 4 090 (10.1) | 20 662 (10.2) | |
| Non-European country | 936 (2.3) | 6 757 (3.3) | <.001 |
| Unknown | 128 (0.3) | 13 (<0.01) | |
| Education, No. (%) | |||
| Primary school up to 9 years | 15 031 (37.1) | 74 912 (37.0) | |
| Secondary school | 16 028 (39.5) | 78 030 (38.5) | |
| Postsecondary school | 8 672 (21.4) | 44 618 (22.0) | <.001 |
| Unknown | 814 (2.0) | 5 160 (2.5) | |
| Marital status, No. (%) | |||
| Married/Living with partner | 21 382 (52.7) | 105 802 (52.2) | |
| Widower/Widow | 7 653 (18.9) | 38 702 (19.1) | |
| Unmarried | 5 018 (12.4) | 25 740 (12.7) | |
| Divorced | 6 492 (16.0) | 32 475 (16.0) | .14 |
| Unknown | 0 (<0.01) | 1 (<0.01) | |
| Specialist visits, mean (SD) | |||
| All specialist visits within the study period | 28.6 (29.5) | 15.6 (25.5) | <.001 |
| Specialist visits up to 2 years before case diagnosisd | 4.2 (7.9) | 3.0 (7.1) | <.001 |
| Specialist visits more than 2 years before case diagnosisd | 8.2 (15.6) | 7.2 (13.5) | <.001 |
| Hospitalizations, mean (SD) | |||
| All hospitalizations within the study period | 5.6 (5.1) | 2.7 (4.4) | <.001 |
| Hospitalizations up to 2 years before case diagnosisd | 1.1 (1.7) | 0.5 (1.4) | <.001 |
| Hospitalizations more than 2 years before case diagnosisd | 1.2 (2.5) | 1.1 (2.4) | <.001 |
| Antibiotics exposure, No. (%) | |||
| No use | 7 568 (18.7) | 45 427 (22.4) | |
| Low (1-10 days) | 5 847 (14.4) | 28 106 (13.9) | |
| Moderate (11-60 days) | 18 695 (46.1) | 90 005 (44.4) | |
| High (61-180 days) | 6 685 (16.5) | 31 269 (15.4) | |
| Very high (>180 days) | 1 750 (4.3) | 7 913 (3.9) | <.001 |
P value for Pearson χ2 test (categorical variables) in which missing categories were excluded or 2-sample t test (continuous variables). All tests were 2-sided.
Matching variables.
All other counties in Sweden.
For the matched controls, the diagnosis date of the index case was used.