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Table 2 Cox model with hazard ratios and 95% confidence intervals of osteoarthritis of knees associated with N-acetylcysteine used

From: Increased risk of knee osteoarthritis in patients using oral N-acetylcysteine: a nationwide cohort study

Variable Osteoarthritis of knees Crudea Adjustedb
no. (n = 8240) HR (95%CI) p-value HR (95%CI) p-value
N-acetylcysteine used
 No 6406 reference   reference  
 Yes 1834 1.39 (1.32–1.46) < 0.001 1.42 (1.35–1.49) < 0.001
Sex
 Female 4858 reference   reference  
 Male 3382 0.58 (0.55–0.61) < 0.001 0.56 (0.53–0.58) < 0.001
Age at baseline, years
 25–39 years 36 0.06 (0.05–0.09) < 0.001 0.09 (0.07–0.13) < 0.001
 40–64 years 4663 0.47 (0.45–0.49) < 0.001 0.54 (0.52–0.57) < 0.001
 Older than 65 years 8113 reference   reference  
Comorbidities
 Myocardial infarction 127 1.19 (1.00–1.42) 0.049 0.94 (0.79–1.13) 0.52
 Congestive heart failure 429 1.62 (1.47–1.78) < 0.001 1.06 (0.96–1.17) 0.261
 Cerebral vascular disease 1299 1.61 (1.52–1.71) < 0.001 1.11 (1.04–1.18) 0.001
 Rheumatoid arthritis 216 1.95 (1.70–2.23) < 0.001 1.57 (1.37–1.80) < 0.001
 Systemic lupus erythematosus 35 0.81 (0.58–1.14) 0.226 0.78 (0.56–1.09) 0.151
 Diabetes mellitus 2142 1.49 (1.42–1.57) < 0.001 1.12 (1.06–1.17) < 0.001
 Hypertension 4909 2.04 (1.95–2.13) < 0.001 1.52 (1.45–1.60) < 0.001
 Gout 1489 1.53 (1.44–1.62) < 0.001 1.39 (1.31–1.47) < 0.001
 Septic arthritis 35 1.63 (1.17–2.27) 0.004 1.31 (0.94–1.83) 0.108
 Aseptic necrosis 38 1.19 (0.87–1.64) 0.278 1.37 (0.99–1.88) 0.055
 COPD 2587 1.32 (1.26–1.38) < 0.001 1.31 (1.25–1.37) < 0.001
 Obesity 79 1.16 (0.93–1.45) 0.186 1.03 (0.82–1.29) 0.796
 Osteoarthritis of hand 4 0.80 (0.30–2.14) 0.663 0.72 (0.27–1.92) 0.514
 Previous knee, leg, ankle, and foot injury 20 1.37 (0.88–2.13) 0.157 1.42 (0.91–2.20) 0.118
  1. Crude HRa represented relative hazard ratio, Adjusted HRb represented adjusted hazard ratio: mutually adjusted for N-acetylcysteine used, age, gender and baseline comorbidities (as like tables) in Cox proportional hazard regression