Tobacco smoking and risk of hip fracture in men and women

Background Previous findings suggest that tobacco smoking increases the risk of hip fracture in women. A similar adverse effect of smoking is suspected to be present in men, but bone mineral density studies have raised the concern that men may be more sensitive to the deleterious effect of smoking on bone than women. In this study we prospectively determined the influence of current, previous, and cumulative smoking history on risk of hip fracture in men and women and addressed the issue of possible gender difference in the susceptibility to tobacco smoking. Methods Pooled data from three population studies conducted in Copenhagen with detailed information on smoking habit. A total of 13 393 women and 17 379 men, initially examined between 1964 and 1992, were followed until 1997 for first admission due to hip fracture. The relative risks (RR) of hip fracture associated with smoking were estimated by means of multiplicative Poisson regression models. Results During follow-up, 722 hip fractures were identified in women, and 447 in men. After adjustment for potential confounders, including body mass index, female current smokers had an RR of hip fracture of 1.36 (95% CI : 1.12-1.65) and male smokers 1.59 (95% CI:1.04-2.43) relative to never smokers. In both sexes, the RR of hip fracture gradually increased by current and accumulated tobacco consumption. The RR were consistently higher in men than in women, but the test for interaction between sex and tobacco smoking was insignificant. After 5 years, male ex-smokers had an adjusted RR of 0.73 (95% CI:0.55-0.98) relative to current smokers, while no significant decrease in risk was observed in female ex-smokers (RR = 0.91; 95% CI : 0.72-1.17). Approximately 19% of all hip fractures in the present study population were attributable to tobacco smoking. Conclusions Tobacco smoking is an independent risk factor for hip fracture in men and women, and there appears to be no gender differences in smoking related risk. Smoking cessation reduces the risk of hip fracture in men after 5 years, while the deleterious effect of smoking seems to be more long-lasting in female ex-smokers.