Jeremy Darling.

Our analyses, which were performed by using Medicare data, are at the mercy of several limitations, including the known fact that the data are observational, are subject to potential coding error, and lack anatomical information plus some clinical details which may be important determinants of patient selection and outcomes. Although our set of confounders was comprehensive, propensity analyses cannot account for selection bias related to unmeasured characteristics. To conclude, our analysis verified the findings of prior studies which have shown that perioperative mortality and rates of complications are lower with endovascular repair than with open repair of stomach aortic aneurysms.Nearly identical results were observed in similar analyses of cataract-extraction surgery , with the glycated hemoglobin level or development of nonproliferative diabetic retinopathy explaining most of the between-group difference. All elements were also associated with the risk of vitrectomy, retinal-detachment surgery, or both, and the between-group difference was no longer significant after adjustment for many of these factors owing to the smaller amount of such operations .