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