Table 1 Basic characteristics of cases and controls
From: Antibiotic use and the risk of rheumatoid arthritis: a population-based case-control study
Variable | Controls (n = 90,013) | RA cases (n = 22,677) | ||
|---|---|---|---|---|
N | % | N | % | |
Year of RA diagnosis | ||||
 1995–1999 | 8086 | 9 | 2033 | 9 |
 2000–2004 | 15,253 | 16.9 | 3849 | 17 |
 2005–2009 | 24,713 | 27.5 | 6232 | 27.5 |
 2010–2014 | 31,699 | 35.2 | 7980 | 35.2 |
 2015–2017 | 10,262 | 11.4 | 2583 | 11.4 |
Age at index (years) | ||||
 < 40 | 19,064 | 21.2 | 4857 | 21.4 |
 40–59 | 20,416 | 22.7 | 5095 | 22.5 |
 60–69 | 22,257 | 24.7 | 5588 | 24.6 |
 70–79 | 19,238 | 21.4 | 4843 | 21.4 |
 80–89 | 8366 | 9.3 | 2093 | 9.2 |
 ≥ 90 | 672 | 0.7 | 201 | 0.9 |
Mean age (SD) | 61.4 | (14.1) | 61.4 | (14.3) |
Gender, female | 60,620 | 67.3 | 15,276 | 67.4 |
Median follow-up before RA diagnosis (IQR) | 10 | (7–14) | 10 | (7–14) |
Body mass index | ||||
 Underweight | 22,337 | 24.8 | 5102 | 22.5 |
 Normal | 2402 | 2.7 | 694 | 3.1 |
 Overweight | 28,948 | 32.2 | 7456 | 32.9 |
 Obese | 24,610 | 27.3 | 7308 | 32.2 |
 Missing | 11,716 | 13 | 2117 | 9.3 |
Smoking status | ||||
 Never/ex-smokers | 74,043 | 82.3 | 17,840 | 78.7 |
 Current | 15,970 | 17.7 | 4837 | 21.3 |
Alcohol | ||||
 Never/ex-drinker | 29,159 | 32.4 | 7341 | 32.4 |
 1–10 units/weeks | 46,692 | 51.9 | 11,976 | 52.8 |
 > 10 units/week | 14,162 | 15.7 | 3360 | 14.8 |
Charlson comorbidity index | ||||
 0 | 56,683 | 63 | 12,813 | 56.5 |
 1–2 | 24,356 | 27.1 | 7219 | 31.8 |
 3–5 | 7937 | 8.8 | 2355 | 10.4 |
 > 5 | 1037 | 1.2 | 290 | 1.3 |