The Effect of Smoking Cessation versus Current Smoking on Fracture Risk: The Manitoba BMD Registry

Current tobacco smoking is included in FRAX^TM calculator for fracture risk assessment. It is unknown whether previous smoking increases the risk of fracture. The current analysis was performed to compare incident fracture risk associated with current smoking, smoking cessation and non-smoking. The study population comprised 18,115 individuals aged 40 years and older (mean age 68.8 years, 95.1% female) from a large clinical registry of DXA tests for the Province of Manitoba, Canada, with two consecutive visits (mean interval 4.4 years) where current smoking was recorded. Smokers (N=1620) were defined as those reporting current smoking at visit 2 (index date), non-smokers (N=15,942) as answering no to current smoking at both visits, and ex-smokers (N=553) as answering yes to current smoking at visit 1 but no at visit 2. Incident fractures were identified through healthcare data linkage. Compared with non-smokers, risk for any incident fracture (primary outcome) was significantly greater in current smokers (hazard ratio [HR] 1.41, 95% CI 1.19-1.67 adjusted for age/sex; HR 1.22, 95% CI 1.03-1.44 full adjusted) and ex-smokers (HRs 1.56, 95% CI 1.19-2.024 and 1.42, 95% CI 1.09-1.86, respectively). Similar directions and magnitudes of effect were seen for incident major osteoporotic fractures and hip fractures (secondary outcomes), with point estimates for ex-smokers that were close to current smokers. In summary, recent smoking cessation was associated with ongoing increased short-term fracture risk similar to current smoking. Larger studies are needed to better define the time course of fracture risk after smoking cessation.