Survival following alpha particle pituitary irradiation for diabetic retinopathy

The purpose of this study was to evaluate the mortality experience of persons with longstanding diabetes who had received pituitary irradiation for diabetic retinopathy compared to a matched group of persons with diabetes who had not had pituitary ablation. The irradiated cohort consisted of 167 patients treated at the Donner Pavilion (Lawrence Berkeley Laboratory, University of California, Berkeley), and the comparison cohort was the population evaluated in the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR). Survival analyses were performed comparing the two cohorts using three different sets of matching criteria, each more restrictive than the previous analyses. The three different strategies were (1) matched only on severity of diabetic retinopathy; (2) matched on severity of retinopathy and age; and (3) matched on severity of retinopathy, age, gender, and hypertension status. Tests of comparison were the log-rank test, the Wilcoxon test, and the likelihood ratio test. For the model matching only on severity of retinopathy, mean survival was 8.3 years for the WESDR group and 9.4 years for the ablated group (p > 0.05 for all three statistical tests). For the model matched on retinopathy and age, mean survival was 8.9 years for the WESDR group and 9.2 years for the ablated group (p=0.05 log-rank test, 0.32 Wilcoxon test, and 0.06 likelihood ratio test). For the model matching on retinopathy, age, gender, and hypertension status, mean survival was 8.9 years for the WESDR group and 11.6 years for the ablated group (p=0.72 log-rank test, 0.08 Wilcoxon test, and 0.82 likelihood ratio test). These data are compatible with the notion that pituitary ablation, and therefore induced pituitary growth hormone deficiency, may not decrease survival in those with severe diabetic retinopathy.