Effect of Ruboxistaurin on the Visual Acuity Decline Associated with Long-standing Diabetic Macular Edema

Abstract

We read with interest the article, “Effect of Ruboxistaurin on the Visual Acuity Decline Associated with Long-standing Diabetic Macular Edema,” by Davis et al., in the January 2009 issue. Although we congratulate them for addressing a pertinent topic, we seek a few clarifications regarding the methodology and conclusions. Baseline data for factors such as diabetes type, body mass index, hemoglobin A1C, systolic and diastolic blood pressure, angiotensin-converting enzyme (ACE) inhibitor use, insulin use, serum lipid profile, and anemia are not compared between the two groups. These factors affect both the incidence of diabetic macular edema and its response to any kind of therapy. In Figure 2, it is evident that the two arms of the study differed significantly after 18 months of therapy, but because in the prior (PKC-DRS2) study only 75% of the patients completed follow-up, it is important to know how many of the patients with diabetic macular edema completed the follow-up. The authors briefly mention this issue in discussion, but the conclusions appear overdrawn and based on few data. The authors also gave the confidence limits in Figure 2 for the drug-induced change in visual acuity, but they did not provide a confidence interval for the same statistic after regression analysis, which is likely to have overlapping results. It would have been appropriate to mention the confidence intervals of both arms and the power of the study. We would appreciate having the authors clarify these aspects for the benefit of the readers. Atul Kumar Sahu Ajit Babu Majji