Differential impact of cigarette smoking on fracture risks in subjective cognitive decline and dementia: A nationwide longitudinal study

Objective We aimed to explore the differential impact of cigarette smoking on fracture risks in SCD and dementia. Methods A nationwide population-based cohort study design was used. Out of all the people aged 66 (n=1,555,103) who went through the National Screening Program from 2009–2014, 968,240 participants with eligible data were included in the study. Time-to-event was calculated as the duration between the NSPTA and fracture incidence. Cox proportional-hazard regression analyses were conducted to evaluate the risk of fractures. Results Increased risk of all [adjusted hazard ratio (aHR)=1.184; 95% confidence interval (CI)=1.184, 1.093–1.283], hip (aHR=1.518; 95% CI=1.168–4.972), vertebral (aHR=1.235; 95% CI=1.101–1.386) fractures were increased in current smokers with more than 20 or more pack years (≥20 py) of SCD group, after adjusting for all relevant confounding factors. In dementia group, however, current smokers ≥20 py were at reduced risk of hip fractures (aHR=0.249; 95% CI=0.089–0.97). Conclusion There was a disparate influence of cigarette smoking on the fracture risks in SCD and dementia group. Further studies are warranted to explicate this phenomenon, and personalized preventive measures according to one’s cognitive status are imperative, since risk factors of fractures can exert disparate influence on patients at different stage of cognitive trajectory.