Cut-off points for associations between vitamin D and musculoskeletal outcomes vary in women aged 36–57 years

摘要

Background/Aims: To describe associations between serum 25-hydroxyvitaminD [25(OH)D] and musculoskeletal outcomes in middle-agedwomen.Methods: This cross-sectional analysis from a cohort of 348 women (meanage 50 year) used nonlinear least-squares estimation to determine flexionpoints for associations of 25(OH)D with lumbar spine (LS) bone mineraldensity (BMD), femoral neck (FN) BMD, lower limb muscle strength (LMS),timed up and go test (TUG), functional reach test (FRT), lateral reach test(LRT) and step test (ST) and piecewise regression to determine how associationsdiffered by 25(OH)D level.Results: Mean (95%CI) flexion points were 25 (16, 33), 42 (16, 68), 26 (20,32), 41 (23, 60), 18 (12, 24), 48 (-158, 254) and 24 (12, 35) nmol/L for FNBMD, LS BMD, TUG, ST, FRT, LRT and LMS, respectively. Significant associationsbetween 25(OH)D and musculoskeletal outcomes occurred only inparticipants with low 25(OH)D. Differences in slope between 25(OH)Dgroups became statistically significant at 35 nmol/L for FN BMD, blow (inlow group) ? 0.0044 (95%CI: 0.0009, 0.0078), between-group difference inb (Db) ? 0.0044, p ? 0.020; and TUG, blow?-0.027 (-0.052, -0.002); Db ?-0.030, p ? 0.028; 30 nmol/L for LS BMD, blow ? 0.0059 (0.0002, 0.0117); Db ? 0.0066, p ? 0.034, 25 nmol/L for FRT, blow ? 0.684 (0.075, 1.292); Db ?0.697, p ? 0.027 and LMS, blow ? 1.703 (0.241, 3.165); Db ? 1.802, p ? 0.020,and 60 nmol/L for ST, blow ? 0.030 (-0.001, 0.061); Db ? 0.051, p ? 0.038.Conclusions: In middle-aged women, the point at which relationships between25(OH)D and musculoskeletal outcomes change varies for differentoutcomes. The current cut-off of 50 nmol/L appears too high for some outcomesbut reasonable overall to optimise bone and balance inthispopulation.