Factors affecting changes in the serum levels of 25-hydroxyvitamin D: a 3-year follow-up of the ROAD study

Vitamin D deficiency is a risk factor for new fractures in Japanese postmenopausal women with rheumatoid arthritis: results from the IORRA cohort study

In this study, we assess the association between the occurrence of new fractures and vitamin D deficiency in Japanese patients with rheumatoid arthritis using our large IORRA cohort. The results suggest that vitamin D deficiency is a significant risk factor for new fractures in Japanese female patients over the age of 50 years with rheumatoid arthritis.

PURPOSE

Both rheumatoid arthritis (RA) and menopause are known risk factors for the onset of osteoporosis. The occurrence of new clinical fractures in patients with RA can significantly lower quality of life. The purpose of this study was to investigate whether vitamin D deficiency in Japanese women with RA could be a risk factor for new fractures.

METHODS

Between 2011 and 2017, a total of 2567 female patients with RA over the age of 50 years (mean age, 65.9 years) were enrolled in a prospective observational study. Self-reported occurrences of new fractures were verified using patient medical records. Vitamin D deficiency was defined as serum 25(OH)D levels < 20 ng/mL. Cox proportional hazards models were used to analyze the independent contributions of various risk factors to the occurrence of a new fracture.

RESULTS

New clinical fractures were sustained by 205 patients in the included cases. Among them, new osteoporotic fractures were sustained by 139 patients (63 vertebral fractures and 76 non-vertebral fractures). Among all patients, the mean (SD) serum 25(OH)D level was 16.9 (5.89) ng/mL and the prevalence of vitamin D deficiency was 72.6%. A Cox proportional hazards model revealed that vitamin D deficiency was significantly associated with all new clinical fractures (hazard ratio, 1.44 [95% confidence interval 1.02‒2.05]; p = 0.0365) and all new osteoporotic fractures (hazard ratio, 1.75 [95% confidence interval 1.14‒2.69]; p = 0.0109).

CONCLUSION

Vitamin D deficiency is a risk factor for new fractures in Japanese female patients over the age of 50 years with RA. Screening these patients for serum 25(OH)D could potentially be seminal to reducing their risk of fractures.

Predictors of decline in vitamin D status in middle-aged and elderly individuals: a 5-year follow-up study

Little is known about predictors of decline in vitamin D status (vitamin D decline) over time. We aimed to determine demographic and lifestyle variables associated with vitamin D decline by sufficiently controlling for seasonal effects of vitamin D uptake in a middle-aged to elderly population. Using a longitudinal study design within the larger framework of the Murakami Cohort Study, we examined 1044 individuals aged between 40 and 74 years, who provided blood samples at baseline and at 5-year follow-up, the latter of which were taken on a date near the baseline examination (±14 d). Blood 25-hydroxyvitamin D (25(OH)D) concentrations were determined with the Liaison® 25OH Vitamin D Total Assay. A self-administered questionnaire collected demographic, body size and lifestyle information. Vitamin D decline was defined as the lowest tertile of 5-year changes in blood 25(OH)D (Δ25(OH)D) concentration (<6·7 nmol/l). Proportions of those with vitamin D decline were 182/438 (41·6 %) in men and 166/606 (27·4 %) in women (P < 0·0001). In men, risk of vitamin D decline was significantly lower in those with an outdoor occupation (P = 0·0099) and those with the highest quartile of metabolic equivalent score (OR 0·34; 95 % CI 0·14, 0·83), and higher in those with 'university or higher' levels of education (OR 2·92; 95 % CI 1·04, 8·19). In women, risk of vitamin D decline tended to be lower with higher levels of vitamin D intake (Pfor trend = 0·0651) and green tea consumption (Pfor trend = 0·0025). Predictors of vitamin D decline differ by sex, suggesting that a sex-dependent intervention may help to maintain long-term vitamin D levels.