Prostaglandin analogues for the treatment of glaucoma and ocular hypertension: a systematic review of economic evidence.

We conducted a systematic review of economic studies of prostaglandin analogues for the treatment of glaucoma to assess the scope of current cost-effectiveness evidence and its relevance to decision-makers. The literature search retrieved 102 studies published before July 2005; after additional hand searching of conference proceedings, 13 full-text articles and 13 abstracts met the inclusion criteria. The reviewers extracted the key characteristics of each of the economic evaluations, and all studies received a grade in five categories to summarise the quality of the study: methodology, transparency, sensitivity, relevance and overall score. The current economic literature is predominantly focused on identifying the short-term direct cost of glaucoma treatment, particularly the precise quantification of glaucoma drug costs. Using the European and US treatment guidelines as a benchmark, it is evident that the current body of literature does not satisfy the needs of decision-makers, although certain studies provide some valuable information, which is a step towards reaching this goal. The main methodological issue in the economic models is an absence of a clinically relevant long-term effectiveness measure, or where this measure is produced, there is a lack of transparency and validation of the methods used. More attention needs to be given to modelling the consequences of treatment, and those consequences should include patient compliance, control of intraocular pressure and progression of visual field deficit, since these drive both the costs and the overall outcomes. We recognise that constructing the 'ideal' clinical outcome measure represents a major challenge to researchers. As such, we have outlined a modelling framework that could be used to produce the required level of economic evidence, and ongoing clinical research (such as the Early Manifest Glaucoma Trial) could provide the validated link between intraocular pressure and disease progression, which forms an essential part of such models.