Determinant Factors of Osteoporosis Patients' Reported Therapeutic Adherence to Calcium and/or Vitamin D Supplements A Cross-Sectional, Observational Study of Postmenopausal Women

Background: Among the various treatments for osteoporosis, calcium and/or vitamin D supplements are frequently included. Objective: The objective of the study was to analyse adherence to calcium and/or vitamin D treatment and to identify related predictors of non-adherence in a sample of postmenopausal women treated for osteoporosis in primary care. Methods: A cross-sectional, observational study was conducted in a sample of postmenopausal women receiving pharmaceutical treatment for osteoporosis with vitamin D and/or calcium. Sociodemographic, general and osteoporosis-related data were collected. Patient's perceptions of the adverse effects of treatment, their knowledge of osteoporosis (Batalla test), their attitude towards treatment (Morisky-Green test) and their self-reported therapeutic adherence (Haynes-Sackett test) were assessed. Results: Of 630 women (mean age +/- SD 64.1 +/- 8.7 years) evaluated, 36.2% (95% CI 32.4, 39.9) had problems with treatment tolerability, 63.5% (95% CI 59.7, 67.3) had good knowledge of osteoporosis, 20.5% (95% CI 17.3, 23.6) had a good attitude to treatment and 50.0% (95% CI 46.1, 53.9) had good self-reported adherence to treatment. Patients in the poor adherence group had higher mean body mass index (p=0.014), more concurrent pathologies (p=0.003), more tolerability problems (p<0.001) and worse attitude to treatment (p < 0.001). The multivariate model showed a positive relationship between therapeutic adherence and good attitude to treatment (odds ratio [OR] = 11.7; p<0.001), not having tolerability problems (OR=3.3; p<0.001) and no polymedication (OR = 0.80; p = 0.017). Conclusions: Only one in two postmenopausal women with osteoporosis who take calcium and/or vitamin D have good self-reported therapeutic adherence to this treatment. Determinant factors of adherence to calcium and/or vitamin D treatment were patient's. attitude to the treatment, tolerability problems with the treatment and number of concurrent treatments.