Seasonality of hip fracture and vitamin D deficiency persists in a sub-tropical climate.

Both hip fractures and vitamin D (25-hydroxyvitamin D (25-OHD)) deficiency are more common in winter in regions with temperate climates, but few data exist for a sub-tropical climate. In a South East Queensland tertiary hospital over a 7-year period, there were significantly more hip fractures in winter than the other three seasons (analysis of variance P = 0.003), with associated higher frequency of 25-OHD deficiency - 42.5% in winter compared to 28.5% in summer, odds ratio 1.86 (95% confidence interval 1.35-2.56), P = 0.0001. Seasonality of hip fracture and 25-OHD deficiency occurs even in a sub-tropical climate.