Economic evaluations of vision screening to detect amblyopia and refractive errors in children: a systematic review

Authors: Asare AO, Wong AM, Maurer D, Kulandaivelu Y, Saunders N, Ungar WJ.

Geographical coverage: Worldwide

Sector: Impact/economic evaluation

Sub-sector: Cost

Equity focus: Children

Study population: Children under 6 years of age  

Review type: Other review

Quantitative synthesis method: Systematic review

Qualitative synthesis method: Not applicable

Background:

Amblyopia and refractive errors are the most common vision impairments affecting children worldwide, with a prevalence of 3-5% for amblyopia and 10% for refractive errors. These conditions may affect quality of life and add financial burden. Policymakers are increasingly required to provide information on the costs and benefits of interventions such as testing of vision.

Objectives: To synthesise and appraise economic evaluations of vision screening to detect vision impairment in children.

Main findings:

A total of 13 studies conducted in five countries: China (n = 1), United States (n = 4), United Kingdom (n = 1), Canada (n = 1), and Germany (n = 6). Analytical techniques included cost-utility/cost-effectiveness combination (n = 2), cost-effectiveness analysis (n = 7), cost-utility analysis (n = 1), cost-benefit analysis (n = 1), cost-consequence analysis (n = 1) and cost analysis (n = 1). Six studies were determined to be of high quality.

The authors found that the incremental cost-effectiveness ratios varied widely, from C$1,056 to C$151,274 per additional case detected/prevented and from C$9,429 to C$30,254,703 per additional quality-adjusted life year (QALY) gained, depending on the type of screening service and comparator.

In Germany, three alternative strategies for children up to 4 years old were compared, with costs ranging from C$4,502 to C$9,774 per additional case detected. In the US, three strategies were compared to no screening, with costs ranging from C$28,322 to C$40,654 per additional QALY gained. In the UK, seven strategies were evaluated, with costs ranging from C$10,392 to C$151,274 per additional case prevented. Two studies from Germany reported costs per additional case detected, with costs ranging from C$1,056 to C$1,348 depending on the screening strategy and visual acuity thresholds for referrals.

Based on these findings of the literature identified and included in the review, authors concluded that strategies in children demonstrate significant variability in types of screening services and the type and quality of methods used, yielding highly variable results. Authors note the need of more strategies for enhancing the quality of economic evaluations of visions screening strategies and guidelines on conducting effective vision screening programmes. Furthermore, authors emphasise the need for prospective studies on the impact of amblyopia and/or refractive errors on the health-related quality of life of young children to generate reliable utilities for use in cost-utility analysis.

Methodology:

Authors included a study if it: (1) was a full, comparative economic evaluation; (2) used any one of the analytic methods (cost-utility analysis, cost-benefit analysis, cost-effectiveness analysis, cost-minimisation analysis, cost-consequence analysis, and cost-analysis); and (3) evaluated screening services for children under the age of 6 years to detect amblyopia, strabismus (as a risk factor for amblyopia), and/or uncorrected refractive errors. A study was excluded if: (1) the full text was unavailable; (2) it was a review, commentary, case series, case report, editorial, letter or conference abstract; or (3) it was published before 1995. No country or language restrictions were applied.

The authors conducted a search on seven electronic databases: Medline, EMBASE, the Cochrane Library, the Cost-effectiveness Analysis Registry (CEA), Global Health CEA Registry, Paediatric Economic Database Evaluation, and EBSCO. Authors also searched a range of grey literature sources and reviewed references of key articles and searched websites of agencies that routinely conduct health technology assessments.

Key aspects of studies were extracted for included studies. Currencies reported were converted into Canadian dollars for the year of pricing. Two reviewers assessed the identified studies independently. Furthermore, authors used Bank of Canada annual average exchange rates. To assess the quality of included studies, authors used the Paediatric Quality Appraisal Questionnaire, a comprehensive instrument demonstrating face and content validity, and strong interrater and test-retest reliability in the appraisal of paediatric economic evaluations. Two authors independently screened the studies for inclusion and assessed the quality of inclusion studies.

Separate synthesis was undertaken for findings of high quality studies, of which there were six in total.

Applicability/external validity:

Authors note that results of included studies may not be generalisable to populations at high-risk of developing vision disorders due to the differences in the prevalence of target conditions, availability, and costs of follow-up care in high-risk vs general populations.

Geographic focus:

Only one of the 13 included studies (for China) was conducted in a low- and middle-income country. However, all of the studies included in the synthesis of high-quality studies were produced in high income settings (UK, US and Germany).

Summary of quality assessment:

This review transparently outlines the criteria for inclusion and exclusion and employs suitable methods for screening studies for inclusion and evaluating the quality of the included studies. The review adopts a narrative approach and bases its assessments on the quality of the studies. However, certain limitations were noted. The review authors did not specify the methods used to extract data from the included studies and did not reach out to authors/experts or check references as part of their search strategy. As a result, this review’s conclusions are regarded with medium confidence.