Use of glaucoma medications: state of the science and directions for observational research

Methodological quality of the review: Low confidence

Author: Lu VH, Goldberg I, Lu CY

Geographical coverage: United States of America (USA), United Kingdom (UK), Australia, Canada, Israel, Finland and others

Sector: Glaucoma

Sub-sector: Medication adherence and persistence

Equity focus: Not specified

Review type: Other review

Quantitative synthesis method: Narrative/thematic synthesis

Qualitative synthesis method: Not applicable

Background: Pharmacoepidemiology applies epidemiologic methods to assess the use of pharmaceutical products and patient outcomes under non-experimental situations, for which various data sources – such as patient questionnaires, medical and administrative records – can be used. The quality of data collected from patient questionnaires is low due to recall bias and participation rates. Therefore, researchers/investigators frequently use large healthcare databases, such as pharmacy claims databases and general practitioners’ records.

These databases are often representative and complete for very large number of patients and comprehensively cover different drug groups, patient populations and geographical regions, from which patterns of medication use (e.g. selection of drug therapies, adherence) in clinical practice over time can be described. It can also reflect real-world settings with respect to patient behaviour and prescriber and other healthcare provider choices.

Objectives: To summarise observational studies that focus on the use of glaucoma medications and to identify gaps in knowledge to guide future investigation.

Main findings: In this review, 55 observational studies were identified. They were classified according to the predominant area of focus into trends in prescription choices (n=13); adherence, persistence or both (n=31); rational use of medications (n=9); and policy-related issues (n=2). Studies by countries were USA (n=31), UK (n=8), Australia (n=3), Canada (n=1), Israel (n=3), Finland (n=1) and others (n=8). Authors noted that most studies have focused on adherence to glaucoma medications and changes in treatment choices. Authors also noted that the use of newer glaucoma medications such as prostaglandin analogues has increased substantially over the last decade across countries.

There are major gaps in knowledge regarding prescribing patterns by prescriber specialty (ophthalmologists, primary care physicians and optometrists), medication related problems and subsequent adverse health outcomes. These gaps should be addressed in future studies according to the authors, particularly analysis of prescribing patterns and medication-related problems by prescriber specialty.

Methodology: Authors conducted a search on the following databases: Medline (from 1950), EMBASE (from 1980) and PUBMED (from 1949) through to December 2009. Search terms include: drug utilisation, physician’s practice patterns, drug prescriptions, pharmaceutical services, medication adherence, ocular, ophthalmic and glaucoma. Non-original articles and clinical studies investigating the efficacy, safety, or both, of a drug or drug group were included in this study.

Studies using questionnaires or medical chart review and studies written in English were excluded. Only articles in which medication use was a main outcome measure were included. Reference lists of included studies were also reviewed as part of the search strategy. Two authors examined these titles and abstracts for inclusion. Key features (study population, data sources, outcome measures, main findings) of the selected studies were extracted and summarised. Authors conducted a narrative synthesis of included studies.

Applicability/external validity: The authors did not discuss the applicability/external validity of the results.

Geographic focus: The review focused on all countries, however almost all studies included in the review were from high-income countries, mainly the USA.

Summary of quality assessment: Overall, there is low confidence in the conclusions about the effects of this study as major limitations were identified. Authors did not conduct thorough searches of the literature, indicating the presence of publication bias within the review. In addition, language bias was not avoided as articles written in English only were included in the review. It is not clear from the review if appropriate methods were used to screen studies for inclusion and to extract data of included studies. As such it is not clear if selection bias was avoided and if results of included studies were reliably reported within the review. In addition, authors did not asses the methodological quality of included studies.