Prolonged acute care and post-acute care admission and recovery of physical function in survivors of acute respiratory failure: a secondary analysis of a randomized controlled trial

BACKGROUND: The proportion of survivors of acute respiratory failure is growing; yet, many do not regain full function and require prolonged admission in an acute or post-acute care facility. Little is known about their trajectory of functional recovery. We sought to determine whether prolonged admission influenced the trajectory of physical function recovery and whether patient age modified the recuperation rate. METHODS: We performed a secondary analysis of a randomized clinical trial of intensive physical therapy for patients with acute respiratory failure requiring mechanical ventilation for ≥4 days. The primary outcome was Continuous Scale Physical Functional Performance, short form (CS-PFP-10), score. Predictor variables included prolonged admission in an acute or post-acute care facility at 1 month, time, and patient age. To determine whether the association between admission and functional outcome varied over time, a multivariable mixed effects linear regression model was fit using an interaction between prolonged admission and time with a primary outcome of total CS-PFP-10 score. RESULTS: Of the 89 patients included, 56% (50 of 89) required prolonged admission. At 1 month, patients who remained admitted had CS-PFP-10 scores that were 20.1 (CI 10.4–29.8) points lower (p < 0.0001) than patients who were discharged to home. However, there was no difference in the rate at which physical function improved from 3 to 6 months for patients who required prolonged admission compared with those who returned home (p = 0.24 for interaction between prolonged admission and time). Adjusted for age, Acute Physiology and Chronic Health Evaluation II score, and sex, both groups had CS-PFP-10 scores that were 8.2 (CI 4.5–12.0) points higher at 6 months than at 3 months (p < 0.0001). For each additional year in patient age, CS-PFP-10 recovered 0.36 points slower (95% CI 0.12–0.61; p = 0.004). CONCLUSIONS: Patients who require prolonged admission after acute respiratory failure have significantly lower physical functional performance than patients who return home. However, the rates of physical functional recovery between the two groups do not differ. The majority of survivors do not recover sufficiently to achieve functional independence by 6 months. Older age negatively influences the trajectory of functional recovery. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01058421. Registered on 26 January 2010. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13054-017-1791-1) contains supplementary material, which is available to authorized users.