Observational Study of Treatment Compliance in Women Initiating Antiresorptive Therapy with or Without Calcium and Vitamin D Supplements in Spain

Objective: The aims of this study were to evaluate the compliance with antiresorptive therapy (ART) and supplements in Spain and to analyze the validity of the different treatment compliance assessment methods.

Methods: A cross-sectional study with retrospective data collection was carried out in women starting ART, evaluating indirect objective compliance, self-reported compliance, and the Morisky-Green questionnaire.

Results: A total of 480 women with a mean (SD) age of 65.8 (9.2) years were studied. Of these women, 62.9% received calcium and/or vitamin D supplements in addition to ART. According to the objective compliance method, 76.9% of the women were compliers (≥80%) with bisphosphonates; 69.4%, with selective estrogen receptor modulators; and 61.8%, with supplements (P < 0.01). Using the self-reported compliance, we identified 91% compliers with antiresorptive drugs and 75% with supplements. Using the Morisky-Green test, we classified 60.8% of the women as compliers with antiresorptive drugs and 48.4% with supplements. Combining the objective and self-reported compliance, 29.5% of the women did not adequately comply with ART and 56% with the drug supplements.

Conclusions: With all three compliance measures, supplements were the treatment yielding the lowest percentage of compliers. Bisphosphonates constituted the treatment offering the best objective compliance: 38.2% of the women with drug supplements and between 23.1% and 30.6% of the women with ART failed to exceed the theoretical value of 80% regarded as representing good compliance.