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February 1994

Rigor of Research Methods in Studies of the Effectiveness and Safety of Cataract Extraction With Intraocular Lens Implantation

Author Affiliations

From The Johns Hopkins Program for Medical Technology and Practice Assessment (Drs Powe, Luthra, and Steinberg) and the Dana Center for Preventive Ophthalmology of The Wilmer Ophthalmological Institute (Drs Tielsch and Schein), The Johns Hopkins Health Institutions; the Departments of Ophthalmology (Drs Tielsch and Schein) and Medicine (Drs Powe and Steinberg), The Johns Hopkins University School of Medicine; and the Departments of Epidemiology (Dr Tielsch) and Health Policy and Management (Drs Powe and Steinberg), The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Md.

Arch Ophthalmol. 1994;112(2):228-238. doi:10.1001/archopht.1994.01090140104032

Objective:  To assess the rigor of research methods reported in studies of the safety or effectiveness of contemporary cataract surgery.

Design:  Formal systematic identification of pertinent studies and critical appraisal of each study's research methods.

Subjects:  From 6113 unique, potentially relevant citations that we identified, 90 original studies published between 1979 and 1991 that addressed visual acuity or complications following standard extracapsular cataract extraction with posterior chamber intraocular lens implantation, phacoemulsification with posterior chamber intraocular lens implantation, or intracapsular cataract extraction with flexible anterior chamber intraocular lens implantation.

Main Outcome Measures:  Strength of study design, performance, and reporting in 11 methodologic areas assessed with a standardized abstraction form by two reviewers masked to authors, their institutions, and the journal of publication. Results of reviews were tallied to produce an overall quality score (measure of rigor in research methods) for each study.

Results:  The mean (±SD) quality score was 43.1±20.1 out of a maximum possible score of 100. Studies received intermediate scores on description of baseline ocular disease and low scores on descriptions of other characteristics of enrolled patients, standardization of outcome assessment and follow-up duration, and handling of patient attrition. Eighty-three studies (92%) lacked a comparison group. The rigor of research methods in studies varied by the journal of publication, did not improve over time, and was no greater for studies with larger vs smaller sample sizes.

Conclusions:  The rigor of research methods in studies of cataract surgery can be improved if more attention is paid to fundamental principles of study design, data analysis, and reporting.

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