Association between cigarette smoking and mortality in patients with hip fracture: A systematic review and meta-analysis.

Introduction: Hip fracture is associated with substantial morbidity and mortality, especially among the elderly. Current evidence on the association between cigarette smoking and mortality in hip-fracture patients is controversial. We performed a systematic review and meta-analysis of studies on this association.

Methods: The databases Medline/PubMed, Embase, Web of Science, and Cochrane Library were searched for studies that estimated the effect of smoking on the risk of mortality in hip-fracture patients. Pooled analyses were conducted of the associations, expressed in relative risk (RR) and 95% confidence intervals (CIs). Heterogeneity was assessed using the I statistic. Study quality was assessed by the modified Newcastle-Ottawa Scale (NOS) and publication bias was evaluated by a funnel plot, Begg's and Egger's tests. Subgroup analyses were performed by study design, race/ethnicity, age ≥60 years, smoking status, and follow-up period.

Results: A total of six articles involving 3739 hip-fracture patients were included in the meta-analysis. Our results indicate that ever-active smoking was significantly associated with an increased risk of death in hip-fracture patients (pooled RR=1.26; 95% CI: 1.08-1.46). In further subgroup analysis, the risk of death was significantly higher in ever-active smokers than in never smokers in White participants (pooled RR=1.23; 95% CI: 1.05-1.44) and elderly aged ≥60 years (pooled RR=1.19; 95% CI: 1.01-1.40), with no significant association in Asian participants (pooled RR=1.42; 95% CI: 0.95-2.11). Current smokers had more risk of death than never smokers (pooled RR=1.26; 95% CI: 1.08-1.46). The association was significant in follow-up periods of ≤1 year (pooled hazard ratio, HR=1.34; 95% CI: 1.05-1.71), 3 years (pooled HR=1.22; 95% CI: 1.05-1.43), and 5 years (pooled HR=1.26; 95% CI: 1.08-1.46).

Conclusions: Cigarette smoking is associated with an increased risk of mortality in hip-fracture patients, especially in elderly patients aged ≥60 years, current smokers, and White participants. With the extension of follow-up period, the effect on mortality of smoking is profound and lasting.