Figure 2. Association between the duration of tracheal intubation and adjusted (for covariates and covariate-DRG interactions) intensive care unit (ICU) length of stay (LOS) after intubation after adjustment using our statistical model. Data are plotted on a logarithmic scale. The line represents the best quadratic fit to the covariate-adjusted data set (n = 952). The quadratic model predicted minimal ICU LOS after extubation with a 7.3-h intubation time. Schwartz-Bayesian criterion selected the quadratic over the linear model (Table 3). Our quadratic model does not predict a positive association between duration of intubation and increasing ICU LOS after extubation when tracheal intubation lasted <7.3 h.