Cigarette smoking and risk of total knee replacement for severe osteoarthritis among Chinese in Singapore – the Singapore Chinese health study

SummaryPurposeData on the effects of cigarette smoking with osteoarthritis (OA) are inconsistent and no study has examined the effect of smoking cessation. We examined smoking status, duration, dosage and cessation in association with risk of total knee replacement (TKR) for severe knee OA among elderly Chinese in Singapore.MethodsWe used data from the Singapore Chinese Health Study, a population-based prospective cohort of 63,257 Chinese men and women aged 45–74 years during enrollment between 1993 and 1998. Detailed information on smoking, current diet and lifestyle factors were obtained through in person interviews. As of 31 December 2011, 1,973 incident TKR cases for severe knee OA had been identified via linkage with nationwide hospital discharge database. We used Cox regression methods to examine smoking in relation to TKR risk with adjustment for age, gender, education, body mass index (BMI), comorbidities and physical activity level.ResultsCompared to never smokers, current smokers had a 51% decrease in risk of TKR [Hazards ratio (HR) = 0.49; 95% confidence interval (CI) = 0.40–0.60]. Among current smokers, there was a very strong dose-dependent association between increasing duration and dosage of smoking with decreasing risk of TKR (P for trend