Sedation level variability as an indicator for mortality in mechanically ventilated critically ill patients: a propensity score-weighted cohort study

Objective: To investigate the impact of low versus high sedation level variability (SLV), measured during the first 72-h intensive care unit (ICU) stay, on clinical outcomes in ventilated critically ill patients. Methods: Patients were identified from the Medical Information Mart for Intensive Care IV database from 2008 to 2019. The SLV was quantified by calculating the coefficient of variation (CV) using 18 time-series exponentially transformed Richmond Agitation-Sedation Scale (RASS) scores for each patient. Based on the median of the CV, patients were divided into the low and high SLV groups, which were subsequently balanced by a stabilized inverse probability of treatment weighting method. Results: < 0.001]. However, these two study groups had similar outcomes regarding prolonged mechanical ventilation on ICU Day 14 and ventilation-free days on ICU Day 21. The negative impact of the low SLV on mortality was evident only in the subgroup with < 60% of RASS scores within the target range, but not in the subgroup with ≥ 60%. Conclusion: A reduced SLV, measured during the first 72-h ICU stay, is associated with an increased risk of both 28-day and 90-day ICU mortality in ventilated critically ill patients. Patients with < 60% of RASS scores within the target range are especially vulnerable to this negative impact.