Relatively low and moderate pre-fracture serum 25-hydroxyvitamin D levels associated with the highest survival in elderly hip fracture patients in Finland: a minimum 3-year follow-up

SUMMARY: The association between serum 25-hydroxyvitamin D level and post-fracture mortality indicates beneficial relatively high serum 25-hydroxyvitamin D concentrations. A 1-year cohort study on 245 hip fracture patients in Finland indicated the lowest 3-year mortality and highest survival among patients with serum 25-hydroxyvitamin D level of 50–74 nmol/L. PURPOSE: To explore pre-fracture serum 25-hydroxyvitamin D level as a factor associated with post-fracture survival among a cohort of hip fracture patients in Finland. METHODS: A prospectively collected cohort of hip fracture patients (n = 245, 70% women) from two hospitals was followed for 3.2 post-hip fracture years. Serum 25-hydroxyvitamin D was measured in admission to the hospital and classified: < 50, 50–74, 75–99, and ≥ 100 nmol/L. Survival was analyzed with a Bayesian multivariate model. Relative survival was explored with the life table method according to serum 25-hydroxyvitamin D. Mortality according to serum 25-hydroxyvitamin D level and to the hospital was calculated. RESULTS: Mortality in the patients with serum 25-hydroxyvitamin D level of 50–74 nmol/L was significantly lower than in all other patients together at every post-fracture year. The most important factors for survival were age under 85 years; living in an actual/private home; serum 25-hydroxyvitamin D level of 50–74 nmol/L, followed by 75–99 nmol/L; ASA classes 1–2 and 3; and female sex. The mean age of patients with serum 25-hydroxyvitamin D level of 50–99 nmol/L was significantly higher than in other levels. Relative survival was highest in men, women, and patients in hospital B with serum 25-hydroxyvitamin D level of 50–74 nmol. CONCLUSION: The highest 3-year survival and the lowest mortality in this cohort appeared in patients with pre-fracture serum 25-hydroxyvitamin D level of 50–74 nmol/L. This result differs from similar studies and is lower than the recommended level of 25-hydroxyvitamin D among hip fracture patients. The results should be examined in future research with larger data. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00198-021-06094-z.