Methodological quality of the review: Low confidence

Author: Holmstrom S, Buchholz P, Walt J, Wickstrøm, Aagren M

Geographical coverage: Not specified

Sector: Glaucoma

Sub-sector: Treatment of primary open angle glaucoma

Equity focus: Adults more than 18 years old

Review type: Effectiveness review

Quantitative synthesis method: Narrative/thematic synthesis

Qualitative synthesis method: Not applicable

Background: The most commonly used treatments for glaucoma patients are prostaglandin analogues for controlling intra-ocular pressure (IOP). Therefore, it is important to assess the efficacy of these drugs.

Objectives: To evaluate different measures of efficacy of the IOP-lowering lipid class agents (bimatoprost, latanoprost and travoprost) in the treatment of primary open angle glaucoma (POAG).

Main findings: In total, authors included 42 studies in this review, in which 9295 patients participated in the included trials. The analysis showed that timolol, on average, had a weighted mean IOP reduction of 22.2%, while latanoprost, travoprost and bimatoprost had a weighted mean IOP reduction of 26.7%, 28.7% and 30.3% respectively.

Analysis of target achievement to various IOP levels showed that bimatoprost was more effective than latanoprost. The direct comparisons also showed that bimatoprost is the most efficacious treatment, however authors stated that it is not conclusive whether latanoprost or travoprost is better in reducing IOP. The authors concluded that head-to-head studies confirm that bimatoprost is likely to be the most efficacious treatment in lowering IOP.

Authors noted that lipid class drugs are superior to timolol in IOP reduction and reducing IOP to a target level. Therefore, it was suggested they are the first-line therapy alongside beta-blockers. In addition, authors emphasised the importance of taking into account the time of IOP measurement when combining and evaluating the data.

Methodology: MEDLINE and EMBASE were searched for English-language literature from January 1992 to October 2004. The following search terms were used: glaucoma, ophthalmic, clinical trial and either travoprost, latanoprost or bimatoprost. Also, references from relevant articles were searched for additional studies.

The following criteria were considered for selection of articles: English language from 1992 to October 2004, randomised controlled trials (RCTs) double masked or investigator masked, adults more than 18 years old, diagnosis including primary open angle glaucoma. Two reviewers assessed the articles independently of each other and had to agree on inclusion. Also, two reviewers extracted data and made the estimations independently before agreeing on results.

Results were combined based on the mean estimates of efficacy of the included studies weighted by number of patients.

Applicability/external validity: No methods were used either to assess the applicability/external validity of the results or to discuss how generalizable the results are.

Geographic focus: This review focuses on all countries, however it is not clear if the authors found any results from low/middle-income settings or not.

Summary of quality assessment: Authors conducted a narrative synthesis of the findings. Authors appropriately reported inclusion/exclusion criteria used for study selection. However, this review had some important limitations. The authors did not avoid publication and language bias in the search as only articles written in English were included in the review. Authors used appropriate methods to screen studies for inclusion and extract data of included studies.

However, authors did not appraise the methodological quality of studies, and as such it is not clear if studies are subject to high or low risk of bias. This also has an impact on the overall reliability of findings of this review. Therefore, there is low confidence in the conclusions about the effects of this study.