Rigor of research methods in studies of the effectiveness and safety of cataract extraction with intraocular lens implantation. Cataract Patient Outcome Research Team
N. R. Powe, J. M. Tielsch, O. D. Schein, R. Luthra and E. P. Steinberg
Johns Hopkins Program for Medical Technology and Practice Assessment, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Md.
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.
