[en] OBJECTIVES: This study aims to estimate the clinical and economic burden of non-adherence with oral bisphosphonates in osteoporotic patients and the potential cost-effectiveness of adherence-enhancing interventions. METHODS: A validated Markov microsimulation model estimated costs and outcomes (i.e. the number of fractures and the quality-adjusted life-year (QALY)) for three adherence scenarios: no treatment, real-world adherence and full adherence over 3 years. The real-world adherence scenario employed data from a published observational study. The incremental cost per QALY gained was estimated and compared across the three adherence scenarios. RESULTS: The number of fractures prevented and the QALY gain obtained at real-world adherence levels represented only 38.2% and 40.7% of those expected with full adherence, respectively. The cost per QALY gained of real-world adherence compared with no treatment was estimated at euro10279, and full adherence was found to be cost-saving compared with real-world adherence. CONCLUSIONS: This study suggests that more than half of the potential clinical benefits from oral bisphosphonates in patients with osteoporosis are lost due to poor adherence with treatment. Depending on their cost, interventions with improved adherence to therapy have the potential to be an attractive use of resources.