B55-07 Assessing the Construct Validity of Electronic Health Record-Based Definitions of Early Deep Sedation

Abstract Rationale Early deep sedation (EDS), defined as a Richmond Agitation-Sedation Scale (RASS) score of -3 to -5 during the first 48 hours of invasive mechanical ventilation (IMV), has been associated with adverse clinical outcomes (e.g., duration of IMV) and higher resource utilization metrics (e.g., length of stay). However, substantial heterogeneity exists regarding the operationalization of EDS in observational studies, which complicates their comparability, interpretability, and generalizability. To address this gap, we developed multiple electronic health record (EHR)-based EDS definitions and evaluated their construct validity by examining associations with clinical outcomes and resource utilization. Methods We conducted a retrospective cohort study across six hospitals of one academic health system. Adult patients receiving IMV for ≥24 hours with at least one RASS assessment per 12-hour period during the first 48 hours of IMV were included; those with pre-existing tracheostomy, receipt of continuous neuromuscular blockade, or admission to a neurologic intensive care unit (ICU) were excluded. We derived seven EHR-based definitions of EDS using RASS values from the first 48 hours of IMV (e.g., proportion of time at RASS -3 to -5, median RASS value, and time-weighted mean RASS value). We fit multivariable regression models including each EDS definition separately as independent variables for the following outcomes: 28-day ventilator free days (primary) and 28-day ICU and hospital free days (secondary). Models were adjusted for patient demographics, co-morbidities, severity of illness, and location. The performance of EDS definitions was assessed via model fit statistics and effect size. Results Among 10,044 patients, the median age was 64.5 years, 57.5% were male, and 50.6% identified as White. Severity of illness was high (median LAPS2 177), and sedation was frequently assessed (median 2.82 RASS scores per 12-hour period). For our primary outcome of 28-day ventilator free days, the variance explained by the reference model (R2 = 0.262) improved following the addition of EDS definitions (R2 = 0.311-0.343) (Figure 1). The model including sedation index score (sum of RASS scores divided by the number of RASS measurements) most improved model fit (R2 = 0.343). Conclusions These findings demonstrate that several EHR-based EDS definitions improve the fit of multivariable regression models for important clinical outcomes, providing evidence of construct validity. Further work is needed to evaluate the causal relationship between EDS and clinically meaningful outcomes. This abstract is funded by: T32-HL-007891