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Table 1 Demographic characteristics of the patients used and non-used N-acetylcysteine in Taiwan

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

Variable N-acetylcysteine useda Standardized mean differenceb
No Yes
n = 51,715 n = 12,928
N (%) N (%)
Sex
 Female 23,379 (45.2) 5838 (45.2) 0.001
 Male 28,336 (54.8) 7090 (54.8) 0.001
Age at baseline, years
 25–39 years 1718 (3.3) 485 (3.8) 0.023
 40–64 years 34,088 (65.9) 8578 (66.4) 0.009
 Older than 65 years 15,909 (30.8) 3865 (29.9) 0.019
 Mean (SMD)    
Comorbidities
 Myocardial infarction 776 (1.5) 239 (1.9) 0.027
 Congestive heart failure 2109 (4.1) 665 (5.1) 0.051
 Cerebral vascular disease 6447 (12.5) 1739 (13.5) 0.029
 Rheumatoid arthritis 790 (1.5) 201 (1.6) 0.002
 Systemic lupus erythematosus 267 (0.5) 73 (0.6) 0.007
 Diabetes mellitus 10,997 (21.3) 2805 (21.7) 0.011
 Hypertension 23,911 (46.2) 5850 (45.3) 0.020
 Gout 7109 (13.8) 1832 (14.2) 0.012
 Septic arthritis 156 (0.3) 50 (0.4) 0.015
 Aseptic necrosis 234 (0.5) 57 (0.4) 0.002
 COPD 13,814 (26.7) 3647 (28.2) 0.034
 Obesity 463 (0.9) 116 (0.9) < 0.001
 Osteoarthritis of hand 36 (0.1) 9 (0.1) < 0.001
 Previous knee, leg, ankle, and foot injury 113 (0.2) 21 (0.2) 0.013
  1. a The means (median) of follow-up period were 5.3 (4.8) years and 6.5 (6.01) years for N-acetylcysteine cohort group and compared cohort group
  2. b An SMD (standardized mean difference) of ≤0.1 indicates a negligible difference between the two cohorts