OBJECTIVES: To characterize the effectiveness measures of cost-effectiveness studies of ophthalmic drugs.

METHODS: Cost-effectiveness studies evaluating ophthalmic drugs were identified through a systematic search conducted in Pubmed and Embase from its inception until November 2018. Therapeutic area, type of economic study (trial- or model-based), effectiveness measures and sources of effectiveness were extracted. Study design and study outcomes were extracted from the sources of effectiveness measures. The adequacy of the sample size of the clinical studies used as effectiveness sources was assessed. If cost-effectiveness studies have retrieved effectiveness data from multiple sources, the appropriateness of the method to combine the results was analyzed.

RESULTS: Forty-five cost-effectiveness studies were included. Thirty-one (68.9%) retrieved their effectiveness measures from experimental studies, five (11.1%) from observational studies and nine (20%) from other type of data sources. Eight (17.8%) cost-effectiveness studies used data from a primary outcome of a study as an effectiveness measure, eight (17.8%) used data from secondary outcomes, seven (15.6%) used data from both primary and secondary outcomes and for 22 (48.9%) it was not possible to identify the outcomes used. From the 23 (51.1%) cost-effectiveness studies based on a single clinical study, three (6.7%) included data from clinical studies which had an adequate sample size to detect significant differences in the clinical outcomes used as effectiveness measures. From the 17 (37.8%) cost-effectiveness studies based on multiple clinical studies, only one (2.2%) used and/or reported an adequate method of quantitative synthesis (meta-analysis).

CONCLUSIONS: A considerable number of cost-effectiveness studies in ophthalmology report results using effectiveness measures which were not assessed as primary outcomes nor based on adequate sample sizes in clinical studies.