An analysis of the effectiveness outcomes of economic studies evaluating ophthalmic drugs: a systematic review

To characterize the effectiveness measures of cost-effectiveness studies (CES) of ophthalmic drugs.

A systematic review was conducted in PubMed/Embase until October 2019. Cost-effectiveness studies (CES) evaluating ophthalmic drugs were included. Sources of effectiveness measures were extracted. Data on study design and study outcomes were extracted from sources of effectiveness measures. The adequacy of the sample size of the clinical studies used as sources of effectiveness measures was assessed. If CES have retrieved effectiveness data from multiple sources, the appropriateness of the method to combine the results was analysed.

Forty-five CES 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%) CES 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 the both primary and secondary outcomes and for 22 (48.9%) it was not possible to identify the outcomes used. From the 23 (51.1%) CES 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%) CES based on multiple clinical studies, only one (2.2%) used and/or reported an adequate method of quantitative synthesis (meta-analysis).

A considerable number of CES in ophthalmology were not based on clinical studies with adequate sample sizes and report results from effectiveness measures not assessed as primary outcomes.