Applications of statistical quality control to cardiac surgery

Background. Although originally developed for use in manufacturing, statistical quality control techniques may be applicable to other frequently performed, standardized processes. Methods. We employed statistical quality control charts (X¯ — s, p, and u) to analyze perioperative morbidity and mortality and length of stay in 1,131 nonemergent, isolated, primary coronary bypass operations conducted within a 17-quarter time period. Results. The incidence of the most common adverse outcomes, including death, myocardial infarction, stroke, and atrial fibrillation, appeared to follow the laws of statistical fluctuation and were in statistical control. Postoperative bleeding, leg-wound infection, and the summation of total and major complications were out of statistical control in the early quarters of the study period but showed progressive improvement, as did postoperative length of stay. Conclusions. The incidence of morbidity and mortality after primary, isolated, nonemergent coronary bypass operations may be described by standard models of statistical fluctuation. Statistical quality control may be a valuable method to analyze the variability of these adverse postoperative events over time, with the ultimate goal of reducing that variability and producing better outcomes.