Maximum heart rate and mortality in sepsis patients: a retrospective cohort study

The effects of maximum heart rate (MHR) on the prognosis of sepsis patients are still being determined, and the most optimal MHR is yet to be recommended. We aimed to determine the association between MHR and 28-day mortality in sepsis patients. A total of 269 patients with sepsis were enrolled in this retrospective cohort study. The patients were all from a 28-bed multi-disciplinary ICU in a tertiary teaching hospital. Relevant information about sepsis patients was extracted according to specific inclusion and exclusion criteria. Examined parameters such as the MHR, blood pressure, laboratory variable, primary disease, and comorbidities were collected. The study outcome was a 28-day death. A Cox proportional hazard model and restricted cubic splines (RCS) were used to elucidate the association between MHR and the 28-day mortality of sepsis patients. Sensitivity analyses were also conducted on our results. Finally, we test and verify our results using a validation cohort from a large public database. In patients with sepsis, the 28-day survivors have the lower MHR than the non-survivors (106 vs. 118, P<0.001). After univariate and multivariate Cox regression analyses, the MHR was significantly correlated with 28-day mortality [hazard ratio 1.013, 95% confidence interval (CI) 1.004-1.022, P = 0.004; hazard ratio 1.013, 95% CI 1.004-1.021, P = 0.004]. The patients in the highest quartile of MHR had a higher risk for 28-day mortality than other patients based on the Kaplan-Meier survival curves (log-rank P<0.001). This correlation remained remarkable in subgroup analysis. A typical U-shaped curve relationship was observed between MHR and the 28-day mortality as a continuous variable using the RCS model. The curve shows that either too high or too low MHR will increase the risk of death. The sepsis patients who had a MHR ranging from approximately 70 to 110 beats per minute (bpm) had the lowest 28-day mortality rate. A similar trend was identified in the validation cohort. High or low MHR was associated with an elevated risk for 28-day mortality in patients with sepsis.