Risk factors for acute endophthalmitis following cataract surgery: A systematic review and meta-analysis

Methodological quality of the review: High confidence

Author: Cao H, Zhang L, Li L, Lo S.

Region: Europe, United States of America (USA), Canada, Asia and Australia

Sector: Age-related cataract

Sub-sector: Surgery, clinical outcome

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis methods: Not applicable

Background

Acute endophthalmitis is one of the most serious complications of cataract surgery and often results in severe visual impairment. Several risk factors for acute postoperative endophthalmitis (POE) following cataract surgery have been reported with varied levels of strength of association. This study critically appraised published reports and summarized clinical risk factors associated with acute POE which could be easily assessed by ophthalmologists for the introduction and implementation of preventive measures.

Research objectives

To identify the risk factors associated with acute endophthalmitis following cataract surgery in order to facilitate detection of the disease before the onset of irreversible visual loss enabling earlier intervention.

Main findings

Authors included 42 studies from across the world in the meta-analysis, with a total of 6,686,169 participants and 8,963 cases of endophthalmitis.  This included ten prospective studies, two cross-sectional studies and thirty retrospective studies.

Nine risk factors were identified for analysis. Seven were strongly associated with postoperative endophthalmitis (Pooled Odds Ratio reported):

1. Without intracameral cefazolin [10.76(6.45 – 17.95)];
2. Posterior capsular rupture [6.34(4.23- 9.52)];
3. Without intracameral cefuroxime[5.48(3.79-7.92) ];
4. Intraoperative complications [5.29(2.73-10.18) ];
5. Clear corneal incision [3.60(2.05-6.31)];
6. Silicone based IOL [3.02(2.03-4.49)];
7. ECCE/ICCE [2.19(1.40- 3.24)].

The remaining two risk factors were less strongly associated:

8. Older individuals [1.50(1.18-1.91)] and
9. Male gender [1.41(1.22-1.63)].

Authors noted that future research in this field would benefit from a standard definition for endophthalmitis and the design of quality prospective studies with appropriate methodologies.

Methodology

Authors included studies which reported cataract surgery as covariate, had exogenous acute endophthalmitis as the outcome measure, including the suspected and/or confirmed cases by positive culture. If a positive culture of a vitreous sample was obtained, authors defined the case as a proven acute endophthalmitis. In all proven and unproven cases, the patients had swollen lids, pain and an opaque vitreous. Studies also had to report a measure of association either as odds ratio (OR) or relative risk (RR) with 95% confidence Interval (CI), or allowed for the calculation of the same from raw data presented in the article.

Authors conducted a search of six databases including PUBMED, EMBASE, Web of Science, Cochrane library, Association for Research in Vision and Ophthalmology and the National Institutes of Health Clinical Trial Databases. Bibliographies and reference lists of full text articles were also reviewed. No language restrictions or year of publication were put in place.

The search strategy used both keywords and medical subject headings. The terms were: ‘endophthalmitis’ and ‘cataract surgery’ or ‘cataract extraction’ or ‘cataract or intracapsular cataract extraction’ or ‘extracapsular cataract extraction’ or ‘phacoemulsification’ and ‘risk factors or association’. Data extraction and evaluation of included studies were performed independently by two reviewers.

A systematic review and meta-analysis of observational studies was performed.

Applicability/external validity

Many studies included in the review were from Asian populations and thus, authors believe that results from this review can be generalizable to different populations in different countries around the world.

Geographic focus

Authors did not restrict their search to any particular country. They included studies from across the world including India, Thailand, USA, United Kingdom, Spain, Sweden, Canada, Arabia, Belgium, Germany, Italy, Singapore, Taiwan, and many others.  Authors noted that results might be applicable to other countries, including low- and middle-income countries, as most of included studies were from Asian populations including Chinese, Malay, Asians, Thai and Indian.

Quality assessment

Authors conducted a thorough search of the literature, avoiding risk of bias. This review had minor limitations, as it was not clear if two reviewers independently screened full text articles. Data analysis of included studies was appropriately analysed, taking into account the inclusion of the diverse study designs.  Other limitations were acknowledged by the authors including those related to the quality of included studies. Therefore, high confidence was attributed in the conclusions about the effects of this review.