“…This heterogeneity limits the precision of our estimates. We cannot adjust for a number of clinical factors known to be associated with outcome, such as age, 1,11,15,21,27,28 timing of surgery, 15,24,27 admission GCS score, preoperative pupillary examination, and other features. 12,21 We chose QOL as an outcome measure over GOS scores because of its almost universal use in quantitative studies of medical outcomes 10 and because of its conformance to mathematical calculations, such as determining mean values and confidence intervals.…”