Patients undergoing reconstructive surgery versus unburned children as "controls" in studies of pediatric patients with burns.

A valid control group is an essential part of any patient study. We asked whether burned children returning for reconstructive surgery could be used as "controls" in a study of seven proteolytic elements in the circulation. Functional levels of elastase, plasminogen, prekallikrein, antithrombin, alpha 2-antiplasmin, alpha 2-macroglobulin, and total proteolytic activity in 30 healthy unburned children were compared with levels in 29 patients admitted for reconstructive surgery an average of 7.9 years after burn. The two groups were not statistically different in distributions of sex and race but differed in mean age. Levels of six of the seven parameters were equal in the two groups. However, even when correction for the age difference was done between the groups, alpha 2-macroglobulin in the patients undergoing reconstructive surgery still was significantly less (p < 0.021) than in the unburned group. Therefore caution may be needed when readily available patients undergoing reconstructive surgery are used as "controls" in studies of patients with acute burns.