Underweight a risk factor for vertebral fractures in older men

Underweight increases susceptibility to fractures, especially those at the hip, in the elderly, a study reports. However, the effect of underweight on vertebral fracture risk is observed in older men only.

The retrospective study included 24,691 older adults who underwent health examinations in 2010 and were living in the Fukuoka Prefecture, Japan. The mean age of the population was 79.4 years, 56 percent were women, and the mean duration of observation was 6.9 years.

Men and women were grouped according to the following body mass index categories: underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), and overweight/obese (≥25.0 kg/m²).

The rates of incident vertebral fractures and hip fractures were 16.8 percent and 6.5 percent, respectively. On the Kaplan-Meier curve, the cumulative incidence rates of vertebral fractures at the last observation (8 years) in the underweight, normal weight, and overweight/obese groups were 14.7 percent, 10.4 percent, and 9.0 percent, respectively, in men and 14.1 percent, 9.0 percent, and 8.1 percent, respectively, in women. The corresponding rates for hip fractures were 24.9 percent, 23.0 percent, and 21.9 percent in women and 6.3 percent, 2.9 percent, and 2.4 percent in men.

Both vertebral and hip fractures were significantly higher in underweight groups regardless of sex. Multivariable Cox proportional hazards models confirmed that underweight was a significant risk factor for vertebral fractures only in men and for hip fractures in both men and women.

The findings underscore the importance of evaluating older people with underweight at health examinations and providing therapeutic interventions to prevent subsequent fractures and improve healthy life expectancy.