Serum 25-hydroxyvitamin D level as an independent determinant of quality of life in osteoporosis with a high risk for fracture

Background Deteriorated quality of life (QOL) is a major problem in osteoporotic women. However, little is known regarding the determinants of QOL in patients with osteoporosis. Objective Our aim was to explore the role of vitamin D status on QOL score in osteoporosis with high fracture risk. Methods Patients were osteoporotic women aged ≥70 years and with ≥1 risk factor for incident fracture, namely prevalent osteoporotic fracture, bone mineral density (BMD) >-3.0 SD of young adult mean, or high bone turnover marker. Health-related QOL was assessed using the Japanese Osteoporosis Quality of Life Questionnaire (JOQOL). When patients were classified into quartiles by total QOL score). Serum 25-hydroxyvitamin D (25[OH]D) level was measured by immunoassay. Results A total of 1585 osteoporotic women were included in the study (age range, 70-95 years). Age, body mass index, serum 25(OH)D status (low, normal, or high), bone mineral density, number of prevalent vertebral fractures, presence of hypertension, presence of osteoarthritis, and history of falls were significantly correlated with QOL quartile. Multivariate liner regression analysis indicated that low serum 25(OH)D level (<20 ng/mL) was an independent determinant of total QOL score quartile (P = 0.0055). The conventional determinants of QOL - age (P < 0.0001), body mass index (P = 0.0060), number of prevalent vertebral fractures (P < 0.0001), presence of osteoarthritis (P = 0.0074), and history of fall (P = 0.0098) - were also independent determinants of total QOL score. Conclusions These results strongly suggest that low serum 25(OH)D level was a significant determinant of QOL in these osteoporotic women, independently of the conventional factors that reduce QOL. Maintenance of serum 25(OH)D levels >20 ng/mL may be required to maintain patients' QOL in osteoporosis.