Smoking is associated with impaired bone mass development in young adult men: A five year longitudinal study.

It has previously been shown that smoking is associated with reduced bone mass and increased fracture risk but no longitudinal studies have been published investigating altered smoking behavior at the time of bone mass acquisition. The aim of this study was to investigate the development of bone density and geometry according to alterations in smoking behavior in a five-year longitudinal, population-based study of 833 young men, 18-20 yrs (baseline). Furthermore, we aimed to examine the cross-sectional, associations between current smoking and parameters of trabecular microarchitecture of the radius and tibia, using High-Resolution peripheral Quantitative Computed Tomography(HR-pQCT), in young men at the age of 23-25 years (five-year follow-up). Men who had started to smoke since baseline had considerably smaller increases in areal bone mineral density(aBMD) at the total body (0.020 ± 0.047 mg/cm(2) (mean ± SD) vs. 0.043 ± 0.040mg/cm(2) , p < 0.01) and lumbar spine (0.027 ± 0.062 mg/cm(2) vs. 0.052 ± 0.065mg/cm(2) , p = 0.04), and substantially greater decreases in aBMD at the total hip (-0.055 ± 0.058mg/cm(2) vs. -0.021 ± 0.062mg/cm(2) , p < 0.01) and femoral neck (-0.077 ± 0.059 mg/cm(2) vs. -0.042 ± 0.070mg/cm(2) , p < 0.01) than men who were non-smokers at both the baseline and follow-up visits. At the tibia, subjects who had started to smoke had a smaller increment of the cortical CSA than non-smokers (8.1 ± 4.3mm(2) vs. 11.5 ± 8.9mm(2) , p = 0.03), and a larger decrement of trabecular vBMD than non-smokers (-13.9 ± 20.5mg/mm(3) vs. -4.1 ± 13.9 mg/mm(3) , p < 0.001). In the cross-sectional analysis at follow-up (23-25 yrs), smokers had significantly lower trabecular vBMD at the tibia (7.0%, p < 0.01) due to reduced trabecular thickness (8.9%, p < 0.001), as assessed using HR-pQCT, than non-smokers. In conclusion, this study is the first to report that men who start to smoke in young adulthood have poorer development of their aBMD at clinically important sites such as the spine and hip than non-smokers, possibly due to augmented loss of trabecular density and impaired growth of cortical cross-sectional area. © 2012 American Society for Bone and Mineral Research