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Table 2 Association between antibiotic prescriptions and RA

From: Antibiotic use and the risk of rheumatoid arthritis: a population-based case-control study

Variables Controls Cases Crude OR (95% CI) Adjusted ORa (95% CI)
N % N %
Any antibiotic use
 No prescriptions 16,242 18.0 2369 10.4 Reference Reference
 ≥ 1 prescription 73,771 82.0 20,308 89.6 2.02 (1.92–2.12) 1.60 (1.51–1.68)
No. of prescriptions (quartile) (median (IQR))
 1 (1 (1, 2)) 20,321 22.6 4128 18.2 1.49 (1.41–1.57) 1.40 (1.32–1.48)
 2 (4 (3, 5)) 18,923 21.0 4592 20.2 1.85 (1.75–1.96) 1.66 (1.57–1.77)
 3 (8 (7, 9)) 17,524 19.5 5231 23.1 2.36 (2.23–2.50) 2.04 (1.92–2.17)
 4 (19 (14, 29)) 17,003 18.9 6357 28.0 3.10 (2.93–3.28) 2.56 (2.39–2.74)
Recency of therapy (therapy termination)b
 1–2 years before diagnosis 30,041 35.2 9557 43.9 2.34 (2.23–2.46) 1.80 (1.70–1.90)
 2–5 years before diagnosis 26,898 31.5 7016 32.2 1.91 (1.81–2.01) 1.57 (1.49–1.66)
 5–10 years before diagnosis 12,183 14.3 2846 13.1 1.70 (1.59–1.80) 1.48 (1.39–1.58)
Antibiotic type
 Bacteriostatic
  Unexposedc 43,580 48.4 8778 38.7 Reference Reference
  Exposed 46,433 51.6 13,899 61.3 1.55 (1.50–1.60) 1.31 (1.27–1.36)
 Bactericidal
  Unexposedd 21,892 24.3 3595 15.9 Reference Reference
  Exposed 68,121 75.7 19,082 84.2 1.80 (1.72–1.87) 1.45 (1.39–1.51)
  1. aAdjusted for age, BMI, smoking status, Charlson comorbidity index, alcohol, and infections
  2. bMost recent course of therapy
  3. cIncluding those people exposed only to bactericidal antibiotics
  4. dIncluding those people exposed only to bacteriostatic antibiotics