Analysis of reoperation rate after strabismus surgery

Abstract

Benson et al. analyzed reoperations among strabismus patients. 1 They stated that "the historical strabismus reoperation rate over a 21-year period was 15.7%" and hoped that their results might "benefit in the preoperative counseling of patients." Unfortunately, if a patient asks about the likelihood that he or she will require reoperation over the next 21 years, the answer is probably much higher than 15.7%. The reoperation rate in just the first postoperative year is about 7.7% in children, 2 and 8.5% in adults. 3 The only way to know the true reoperation rate over 21 years in all patients is to wait until 21 years after the last patient has surgery. The survival curve in their paper is labelled "Kaplan-Meier-like." A correct survival curve has the number of years since an individual patient had surgery on the x-axis. For instance, at the 21-year postoperative mark, the survival curve should only show patients who had surgery in 1995. Instead, the last point on their survival curve includes every patient operated on at the hospital since 1995. In reality, a patient who had surgery in 2015 (for example) will not teach us anything about the 21-year reoperation rate until the year 2036. Could the authors provide the reoperation rate at 1, 2, 5, 10, 15, and 20 years after a patient had surgery, excluding all patients who had surgery less than 1, 2, 5, 10, 15, and 20 years (respectively) before the data were collected?