Methodological quality of the review: High confidence
Author: Leay L, Lindsley K, Tielsch J, Katz J, Schein O.
Region: United States of America (USA), Canada, Italy and Brazil
Sector: Cataract surgery
Sub-sector: Preoperative medical testing
Equity focus: None specified
Review type: Effectiveness review
Quantitative synthesis method: Meta-analysis
Qualitative synthesis methods: Not applicable
Cataract surgery is practised widely and substantial resources are committed to an increasing cataract surgical rate in developing countries. With the current volume of cataract surgery and the increase in the future, it is critical to optimize the safety and cost-effectiveness of this procedure. Most cataracts are performed on older individuals with correspondingly high systemic and ocular comorbidities. It is likely that routine preoperative medical testing will detect medical conditions, but it is questionable whether these conditions should preclude individuals from cataract surgery or change their perioperative management.
To investigate the evidence for reductions in adverse events through preoperative medical testing, and to estimate the average cost of performing routine medical testing.
Authors included three randomized clinical trials from USA, Canada, Italy and Brazil, in which routine preoperative, medical testing was compared to no routine preoperative or selective preoperative testing prior to cataract surgery.
The three randomized clinical trials included in this review reported results for 21,531 total cataract surgeries, with 707 surgery-associated adverse medical events, including 61 hospitalizations and three deaths. Of the 707 adverse medical events reported, 353 occurred in the pre-testing group and 354 occurred in the no-testing group. Most events were cardiovascular and occurred during the intraoperative period. Routine preoperative medical testing did not reduce the risk of intraoperative (OR 1.02, 95% CI 0.85 to 1.22) or postoperative medical adverse events (OR 0.96, 95% CI 0.74 to 1.24) when compared to selective or no testing. Cost savings were evaluated in one study which estimated the costs to be 2.55 times higher in those with preoperative medical testing compared to those without preoperative medical testing. There was no difference in cancellation of surgery between those with preoperative medical testing and those with no or limited preoperative testing, reported by two studies. As such, authors concluded that pre-operative testing did not increase the safety of cataract surgery.
Alternatives to routine preoperative medical testing had been proposed, including self-administered health questionnaires, which could substitute for health provider histories and physical examinations. Such avenues may lead to cost-effective means of identifying those at increased risk of medical adverse events due to cataract surgery. However, despite the rare occurrence, adverse medical events precipitated by cataract surgery remained a concern because of the large number of elderly patients with multiple medical comorbidities who have cataract surgery. Another direction for research was to be able to control the level of risk through variation in anaesthetic management.
The studies summarized in this review should assist recommendations for the standard of care of cataract surgery, at least in developed settings. Unfortunately, in developing country settings, medical history questionnaires would be useless to screen for risk since few people have ever been to a physician, let alone been diagnosed with any chronic disease.
Authors included randomized controlled trials which examined the impact of preoperative medical testing on the risk of adverse medical events. Participants included all individuals who required cataract surgery due to age-related cataract. The primary outcome of the review was the rate of adverse medical events which occurred within seven days of surgery and had a ‘plausible causal relationship to the surgery’.
Authors conducted a systematic search of the literature on various databases including MEDLINE, EMBASE and LILACS. Reference lists and the Science Citation Index were also used to search for additional studies. No date and language restrictions were applied. Two review authors independently assessed abstracts to identify possible trials for inclusion. For each included study, two review authors independently documented study characteristics, extracted data, and assessed methodological quality.
Authors conducted a pooled analysis of the studies included using a fixed-effect model.
The review authors noted that a cost-effective alternative to routine preoperative medical testing cited in the review, the self-administered health questionnaire, would really only apply to developed settings. In developing countries, medical history questionnaires would not be feasible since a lot of the population would not have routine physician diagnosis of diseases or knowledge of their medical history.
The review includes a study from Brazil, an upper middle-income country. See above for applicability of results in different country contexts.
This systematic review was based on comprehensive literature searches and appropriate methods to reduce risk of bias in terms of study selection, data extraction and analysis. The likelihood of bias within each study was addressed and studies included each had a relatively low risk of bias.
Methods used to analyse the findings of the included studies was clear and all three studies were in agreement that ‘preoperative medical testing in cataract surgery is not protective against adverse medical events’. Little was discussed around the generalizability of the results, although it was noted that cost effective alternatives to preoperative medical testing such as the self-administered health questionnaire really only applied to develop countries. High confidence was attributed in the conclusions about the effects of this study.