Effect of Non-Routine Perioperative Laboratory Values on 30 Day Mortality after Non-Cardiac Surgery

Background: It is known that certain laboratory value abnormalities may increase mortality in patient populations with specific risk factors and specific procedures. The purpose of this paper was to investigate the effect of drawing a non-routine lab (regardless of its result) on 30 day mortality and to investigate the effect of an abnormal non-routine laboratory value on 30 day mortality. Methods: The electronic medical records of adult patients undergoing non-cardiac surgery from 2011-2014 at LAC + USC Medical Center were reviewed retrospectively as approved by our institutional review board. Demographic data, surgical risk assessment, and routine and non-routine laboratory values (TSH, Troponin, Creatine Kinase, Hb A1c) were recorded; patients were grouped according to the single non-routine lab they had drawn. Multivariate logistic regression analysis was used to determine significant risk factors associated with increased 30 day mortality. Results: 11,306 patients met our inclusion criteria. Drawing a non-routine lab was associated with a statistically significant increase in mortality in the Troponin group (OR = 3.05, P < 0.001) but not in the TSH, Creatine Kinase, or Hb A1c groups. An abnormal non-routine lab value was associated with a statistically significantly increase in mortality in the TSH group (OR = 11.07, P = 0.008) but not in the other three groups. Conclusions: Drawing a non-routine lab was associated with a statistically significant increase in mortality in the Troponin group but not in the TSH, Creatine Kinase, or Hb A1c groups. An abnormal TSH value was associated with a statistically significant increase in mortality but not an abnormal Troponin, Creatine Kinase, or Hb A1c. Routine and non-routine laboratory testing may guide perioperative patient care and result in improved post-surgical outcome.