Incorrect study design and analysis: visual acuity outcomes after deep anterior lamellar keratoplasty: a case-control study.

摘要

The recently published study by Tan et al is described as a retrospective case-control study; however, this is incorrect. The study participants were selected on the basis of an exposure of interest, that is, deep anterior lamellar keratoplasty versus penetrating keratoplasty and matched with respect to age, race and diagnosis. The study participants were followed (retrospectively) for the occurrence of visual and refractive outcomes as well as complications and graft survival. This describes a retrospective matched cohort study, not a retrospective case-control study. This error is not merely a semantic issue as it .has implications for the appropriate statistical analysis and therefore the proper interpretation of the observed results. And, with respect to the current manuscript, not only is the statistical analysis incorrect for the study design the authors thought they used (ie, a retrospective case-control study), it is also incorrect for the study design they actually conducted (ie, a retrospective matched cohort study).