Methodological quality of the review: Low confidence
Author: Lewallen S, Mousa A, Bassett K, Courtright P.
Region: Africa, Asia, Middle East, South America
Sector: Cataract surgical coverage
Type of cataract: Age-related cataract
Equity focus: Gender: focus on cataract surgical coverage for women
Review type: Effectiveness review
Quantitative synthesis method: Meta-analysis
Qualitative synthesis methods: Not applicable
Research has indicated that women constitute two thirds of the world’s blind and that the incidence of cataract is the main form of blindness in low income settings. Research has previously found that women do not receive cataract surgery at the same rates as men; a factor that needs to be addressed when initiatives (for example, VISION 2020) aims to increase the numbers of people receiving cataract surgery, particularly in low- and middle-income countries.
‘We searched the published literature for reports of CSC [cataract surgical coverage] published since 2000 with the goal of comparing rates in men and women.’
Authors included 23 population-based surveys from developing country settings (Argentina, Bangladesh, China, East Timor, Guatemala, China, India, Kenya, Malawi, Nepal, Nigeria, Oman, Pakistan, Papua New Guinea, Philippines, Rwanda, Tanzania, Turkmenistan and Zanzibar) in the systematic review, each looking at cataract surgical coverage.
21 of the 23 studies reviewed showed higher CSC among men: ‘The Peto odds ratio revealed that men were 1.71 times (95% CI 1.48 to 1.97) more likely to have cataract surgery than women’. Gender inequity in cataract surgical coverage rates and cataract services persist in low- and middle-income countries. Authors noted, from their review findings, that blindness and severe visual impairment could be reduced by 11% in low- and middle-income settings if women were to receive cataract surgery at the same rate as men. They also note that more effort globally needs to go on ensuring that women have the same access to cataract surgery, at the same rate as men.
The review authors searched three databases – MEDLINE, EMBASE and Cochrane (2000- 2008) – using terms related to cataract surgery in developing countries and cataract surgical coverage. Additionally, authors conducted a general search through Google, searched their personal libraries for additional articles, and contacted authors of included studies for additional information. Authors excluded studies that did not present cataract surgical coverage by sex or did not provide the data to make this possible.
Authors extracted data on sex-specific cataract surgical coverage rates and estimated the overall CSC difference using meta-analysis. Authors note that not all studies included data needed to conduct a Peto odds ratio with confidence intervals. Therefore, authors used three methods to combine the data: (1) Calculation of the weighted mean of the odds ratio; (2) Calculation of a Peto OR with 95% confidence intervals and relative risk; and (3) Calculation of the risk differences (RD) for men and women.
It was also noted that many of included studies used methodologies of the Rapid Assessment of Avoidable Blindness (RAAB) or Rapid Assessment of Cataract Surgical Services (RACSS), which are deemed to be epidemiologically sound, although tend not to be large enough to ‘demonstrate statistically significant differences in CSC’.
Authors note that, the surveys included ‘may or may not represent all of the low- and middle-income countries, although to our knowledge, there is no rationale for study-site selection based upon perceived gender inequity’.
The review specifically focusses on low- and middle-income countries and this was defined as a search parameter from the initial selection of studies by the reviewers.
This study was awarded low confidence in the conclusions about the effects of this review. Although authors searched relevant databases including one source of grey literature and contacted authors/ experts for additional information, it was not clear whether the search is reasonably comprehensive. Authors reported excluding two studies as these were written in Chinese and therefore language bias could not be avoided; it was not clear if reference lists of the included articles were reviewed, although authors did note that they searched their private libraries and professional networks for additional articles. A date restriction was applied to search back as far as 2000, which seemed justified in light of the review’s aim of establishing current trends in cataract surgical coverage between men and women.
It was not clear if independent screening of the full texts and data extraction was conducted by the two reviewers cited. Therefore, it was not possible to be certain whether the results of the included studies were reported reliably.