Objectives: Although cigarette smoking has been known as a risk factor for degenerative arthritis, recent studies showed a negative correlation between smoking and degenerative arthritis. This study aimed to investigate the correlation of knee radiographic osteoarthritis (ROA) according to smoking amount in general population.
Materials and Methods: This cross-sectional study used public data from the Fifth and Sixth Korean National Health and Nutrition Examination Survey (2010 to 2013). Subjects included 11,638 community-dwelling adults aged ≥50 years. Knee ROA were defined as a Kellgren/Lawrence grade ≥2 on the plain radiographic study. The lifetime cigarette smoking amount was calculated as quartiles in terms of pack-year. Independent correlation of smoking on knee ROA was determined using odds ratios (OR) adjusted for age group, sex, obesity, physical activity, and household income on multivariate logistic regression analysis.
Results: Prevalence of knee ROA was 37.3% and lifetime cigarette smokers was 24.0% of the target population. Subjects with knee ROA had higher mean age, female sex ratio, and body mass index in contrast with lower physical activity (Table 1). The adjusted logistic regression model revealed that female sex (OR 2.110, 95% CI 1.895-2.349) was significantly associated knee ROA. Older age, obesity and lower household income showed positive correlations with knee ROA. Second and fourth quartile of smoker had the lower prevalence of ROA compared to never-smoker (OR 0.800, 95% CI 0.643-0.994 and OR 0.812, 95% CI 0.684-0.965) (Table 2).
Conclusion: Negative correlation with knee ROA was confirmed only in moderate to high smokers. Prospective studies will be needed to reveal the effect of smoking on knee ROA.
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