Prognostic value of a nomogram model for pancreatic cancer incorporating the systemic immune-inflammation and prognostic nutritional indices

Figure 2 Calculation for the optimal systemic immune inflammation index and prognostic nutritional index cutoff values. The basic principle of the surv-cutpoint function was based on patient overall survival, and the Kaplan-Meier curve was used to determine the best cutoff value. The survival differences between the two groups were tested by a log-rank test. The survival rates on both sides of a specific point had the greatest difference when the χ² statistic of the log-rank test was the largest. The measured values corresponding to the maximum χ² statistic were the optimal systemic immune inflammation index and prognostic nutritional index cutoff values. SII: Systemic immune inflammation index; PNI: Prognostic nutritional index; grps: Groups.