Abstract
BACKGROUND: Both acute respiratory failure (ARF) and ICU delirium are risk factors for postintensive care syndrome but whether quality of life (QoL) differs between delirium and subsyndromal delirium (SSD) over time is not well quantified. RESEARCH QUESTION: In ARF ICU survivors, are delirium and SSD associated with longitudinal changes in QoL, mood, and cognition up to 12 months postdischarge? STUDY DESIGN AND METHODS: In this secondary analysis, delirium (exposure variable) and SSD were assessed 2 times per day using the Richmond Agitation-Sedation Scale and Confusion Assessment Method for the ICU. QoL was the primary outcome; 36-Item Short Form Health Survey (SF-36) Physical Component Summary, SF-36 Mental Component Summary (MCS), Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) scores were collected at discharge, 3 months, 6 months, and 12 months. Mixed effects models were used with delirium group (delirium vs SSD vs no delirium), time, and an interaction term for group × time as independent variables. RESULTS: Of 456 ARF ICU survivors, 227 (50%) experienced delirium, 110 (24%) had SSD, and 121 (26%) had no delirium. The 3 groups did not significantly differ by pattern of change in SF-36 Physical Component Summary, SF-36 MCS, Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, or RBANS scores over time. Delirium survivors had significantly lower SF-36 MCS scores vs SSD (predicted mean difference, -2.81; 95% CI, -5.03 to -0.59; P = .013) and no delirium (predicted mean difference, -2.93; 95% CI, -5.17 to -0.69; P = .011). Delirium survivors had significantly lower RBANS z scores than individuals with SSD (predicted mean difference, -0.19; 95% CI, -0.35 to -0.03; P = .023) and no delirium (predicted mean difference, -0.20; 95% CI, -0.36 to -0.03; P = .019). All outcomes showed improvement over time in all 3 groups. INTERPRETATION: Delirium, rather than SSD, was associated with lower SF-36 MCS and RBANS scores up to 12 months. Further research is needed to identify ideal time points for interventions aimed at these postintensive care syndrome-related outcomes. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT03053245; URL: www.clinicaltrials.gov.