Assessing generalisability in model-based economic evaluation studies: a structured review in osteoporosis

To support decision making, many countries have now introduced some formal assessment process to evaluate whether health technologies represent good 'value for money'. These often take the form of decision models that can be used to explore elements of importance to generalisability of study results across clinical settings and jurisdictions. The objective of this review was to assess whether articles reporting decision-analytic models in the area of osteoporosis provided enough information to enable decision makers in different countries/jurisdictions to fully appreciate the variability of results according to location and be able to apply the evaluation to their own setting. Of the 18 articles included in the review, only three explicitly stated the decision-making audience. It was not possible to infer a decision-making audience in eight studies. The target population was well reported, as were resource and cost data, and clinical data used for estimates of relative risk reduction. However, baseline risk was rarely adapted to the relevant jurisdiction, and when no decision maker was explicit it was difficult to assess whether the reported cost and resource use data were in fact relevant. A few studies used sensitivity analysis to explore elements of generalisability, such as compliance rates and baseline fracture risk rates, although such analyses were generally restricted to evaluating parameter uncertainty. This review found that variability in cost effectiveness across locations is addressed to a varying extent in modelling studies in the field of osteoporosis, limiting their use for decision makers across different locations. Transparency of reporting is expected to increase as methodology develops and decision makers publish 'reference case' type guidance.