Osteoporosis and metabolic syndrome according to socio-economic status, contribution of PTH, vitamin D and body weight: The Canarian Osteoporosis Poverty Study (COPS)

Background Poverty is associated with a great number of diseases, but the prevalence of vitamin D deficiency, secondary hyperparathyroidism and the potential association of osteoporosis, osteoporotic fractures and metabolic syndrome in this situation are less well known. Objective To evaluate the associations between poverty, bone density, fragility fractures and metabolic syndrome in a population of southern European postmenopausal women. Also, to assess the potential role of vitamin D and parathyroid hormone (PTH) levels in these associations. Method Cross-sectional study was carried out in 1250 postmenopausal Caucasian Spanish women. The socio-economic status of the participants was determined after a personal interview, according to the criteria of the Spanish Institute of Statistics. Participants were divided into two socio-economic levels: low (poverty) and medium or high socioeconomic level. The study protocol included a health questionnaire, a complete physical examination, lateral radiograph of the dorsal and lumbar spine and measurement of bone mineral density (BMD) at the lumbar spine (L2-L4) and proximal femur. Fasting blood was obtained to measure 25-hydroxy-vitamin D (25-OHD), intact PTH and selected biochemical variables. Results Low socio-economic status was associated with 25-OHD insufficiency, higher values of PTH, higher body weight and body mass index (BMI), lower values of BMD at the lumbar spine and a higher prevalence of fragility fractures, both vertebral and nonvertebral. Poverty was also associated with higher prevalence of metabolic syndrome, but this association was driven mainly by the higher BMI and not by poverty itself. Both vitamin D insufficiency and elevated PTH were consistently related to poverty and osteoporotic fractures. Conclusions Poor postmenopausal women in southern Europe have a high prevalence of metabolic syndrome and osteoporotic fractures. Poverty was associated with higher BMI and metabolic syndrome on the one hand and, on the other, with 25OHD insufficiency, higher PTH levels and osteoporosis. 25OHD insufficiency and/or secondary hyperparathyroidism do not have a significant influence on the presence of metabolic syndrome in this population.