In Reply We thank Grzybowski and Lee et al for their interest in our recent studies of postoperative endophthalmitis (POE) using the French Medico-Administrative database SNIIR-AM (Système national d’information inter-régime de l’assurance maladie).1,2 This will allow us to discuss the precautions that we must consider when using “big data.” This is of importance because it seems likely to us that big data will increasingly be used in future studies.3