Methodological quality of the review: High confidence
Author: Wormald R, Wilkins M, Bunce C.
Geographical coverage: Not specifed
Sub-sector: Post operative intervension
Equity focus: None specified.
Review type: effectiveness review
Quantitative synthesis method: narrative/thematic synthesis; meta-analysis etc?
Qualitative synthesis method: Not applicable
Background: Trabeculectomy is performed as a treatment for many types of glaucoma in an attempt to lower the intraocular pressure. The surgery involves creating a channel through the sclera, through which intraocular fluid can leave the eye. If scar tissue blocks the exit of the surgically created channel intraocular pressure rises and the operation fails. Antimetabolites such as 5-Fluorouracil (5-FU) are used to inhibit wound healing to prevent the conjunctiva scarring down on to the sclera.
Objectives: To assess the effects of postoperative injections of 5-FU in eyes of patients undergoing surgery for glaucoma.
Main findings: The initial search identified 70 studies, after application of inclusion/exclusion criteria, searching reference lists and quality assessment, 9 studies were included in this review. In which 614 participants were randomized. Authors noted that based on the information provided on trial reports the methodological quality of the trials was not high. Postoperative injection of 5-FU both in eyes at high risk of failure and those undergoing surgery for the first time appears to be effective in reducing the likelihood of surgical failure of trabeculectomy. The results suggest that injection of low doses of 5-FU may not be effective. Whilst no evidence was found of an increased risk of serious sight threatening complications, other complications are more common after 5-FU injections. None of the trials reported on the participants’ perspective of care. The authors concluded that, “postoperative injections of 5-FU are now rarely used as a planned series but are increasingly used on an ad hoc basis. This presumably reflects an aspect of the treatment that is unacceptable to both patients and doctors. None of the trials reported on the participants’ perspective of care which constitutes a serious omission for an invasive treatment such as this”.
Methodology: The following electronic database were searched, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 1966 to October 2008) and EMBASE (January 1980 to October 2008). There were no language or date restrictions in the search for trials and resources were available for translation where necessary. The electronic databases were last searched on 29 October 2008. The reference lists of identified trials were searched to find additional trials. The Science Citation Index was used to find studies which had cited in the identified trials. The investigators of the identified trials and practitioners who were active in the field were contacted to identify additional published and unpublished studies. Authors included randomized controlled trials of postoperative 5-FU injections compared to placebo injections or no injections in trabeculectomy for glaucoma.
Two authors independently screened the titles and abstracts resulting from the searches. All full copies were assessed according to the definitions in the ’Criteria for considering studies for this review’. Only trials meeting these criteria were assessed for methodological quality. The quality of the papers and data extraction was also done independently by 2 reviewers. Data were summarised using risk ratio, Peto odds ratio and mean difference as appropriate.
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: The review does not focus specifically on low/ middle income countries.
Summary of quality assessment: Authors conducted a thorough literature search in order to ensure all available studies were included in the review, avoiding publication and language bias. They used appropriate criteria to assess the quality and risk of bias in analysing them. Limitations of the included studies for meta-analysis were acknowledged. Overall, high confidence was attributed in the in conclusion regarding the effects of this study.