Prognostic significance of nonprotein respiratory quotient in patients with liver cirrhosis

The aim of this study was to examine the effect of nonprotein respiratory quotient (npRQ), as assessed using indirect calorimetry, on clinical outcomes in patients with liver cirrhosis (LC). A total of 244 LC patients were evaluated in this study. For the univariate analysis, for each continuous variable, the optimal cutoff value that maximized the sum of sensitivity and specificity was selected using receiver operating curve (ROC) analysis for survival. There were 137 men and 107 women with the median (range) age of 67 (25-90) years. Indirect calorimetry indicated that 54 patients (22.1%) had hepatocellular carcinoma (HCC) on radiological findings and 59 patients (24.2%) had protein energy malnutrition, as defined by npRQ <0.85 and serum albumin level <3.5 g/dL. In ROC analysis of npRQ for survival, the optimal cutoff point of npRQ was 0.849 for all cases (area under the ROC = 0.61272; sensitivity, 66.22%; and specificity, 57.06%). The median follow-up periods after indirect calorimetry were 4.35 years (range, 1.01-9.66 years) in patients with npRQ ≥0.85 (n = 122) and 3.71 years (range, 0.19-9.51 years) in patients with npRQ <0.85 (n = 122). The 1-, 3-, and 5-year cumulative OS rates in patients with npRQ ≥0.85 were 100%, 87.79%, and 77.24%, respectively, whereas those in patients with npRQ <0.85 were 94.26%, 73.65% and 57.78%, respectively (P = 0.0004). In the multivariate analysis, presence of HCC (P = 0.0045), body mass index (P < 0.0001), serum albumin (P = 0.0441), prothrombin time (P = 0.0463), npRQ (P = 0.0024), estimated glomerular filtration rate (P = 0.0086), and des-γ-carboxy prothrombin (P = 0.0268) were found to be significant predictors associated with OS. For all cases, risk stratification for survival was well performed using these significant variables. In conclusion, npRQ value, as assessed by indirect calorimetry, can be helpful for predicting clinical outcomes for LC patients.