Smoking and Alcohol Intake but Not Muscle Strength in Young Men Increase Fracture Risk at Middle Age: A Cohort Study Linked to the Swedish National Patient Registry

We aimed to determine the relationship between handgrip strength, smoking, and alcohol consumption in young men and fracture risk at middle age. Thus, we carried out a cohort study including young men undergoing conscription examination in Sweden from September 1969 to May 1970 at a typical age of 18 years. Data on muscle strength, height, weight, and lifestyle factors were linked to the National Patient Register 1987-2010. Handgrip strength was considered the main exposure and smoking and alcohol consumption as secondary exposures. Outcomes were all fractures (except face, skull, digits), major osteoporotic fractures (thoracic/lumbar spine, proximal humerus, distal forearm or hip), and major traumatic fractures (shaft of humerus, forearm, femur, or lower leg) based on ICD-9 and -10 codes. We used Cox regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) according to handgrip strength as a continuous variable (per 1 SD), after adjustment for weight, height, parental education, smoking, and alcohol consumption. A total of 40,112 men were included, contributing 892,572 person-years. Overall, 3974 men fractured in middle age with the incidence rate (95% CI) of 44.5 (43.2-45.9) per 1000 person-years. The corresponding rates were12.2 and 5.6 per 1000 person-years for major osteoporotic and traumatic fractures, respectively. Handgrip strength-adjusted HR (95% CI) was 1.01 (0.98-1.05), 0.94 (0.88-1.00), and 0.98 (0.88-1.08) per SD for all, major osteoporotic, and major traumatic fractures, respectively. Adjusted HR (95% CI) for smokers (>21 cigarettes/d) was 1.44 (1.21, 1.71) for all fractures, while the association between alcohol consumption and hazards of fracture was J-shaped. Therefore, young adult handgrip strength was not associated with fracture risk in middle-age men, although smoking and high alcohol consumption did confer an increased risk. (c) 2019 American Society for Bone and Mineral Research. (c) 2019 American Society for Bone and Mineral Research.