Physical Function Trajectories in Survivors of Acute Respiratory Failure

Abstract

Rationale: Survivorship from critical illness has improved; however, factors mediating the functional recovery of persons experiencing a critical illness remain incompletely understood.

Objectives: To identify groups of acute respiratory failure (ARF) survivors with similar patterns of physical function recovery after discharge and to determine the characteristics associated with group membership in each physical function trajectory group.

Methods: We performed a secondary analysis of a randomized controlled trial, using group-based trajectory modeling to identify distinct subgroups of patients with similar physical function recovery patterns after ARF. Chi-square tests and one-way analysis of variance were used to determine which variables were associated with trajectory membership. A multinomial logistic regression analysis was performed to identify variables jointly associated with trajectory group membership.

Results: A total of 260 patients enrolled in a trial evaluating standardized rehabilitation therapy in patients with ARF and discharged alive (NCT00976833) were included in this analysis. Physical function was quantified using the Short Physical Performance Battery at hospital discharge and 2, 4, and 6 months after enrollment. Latent class analysis of the Short Physical Performance Battery scores identified four trajectory groups. These groups differ in both the degree and rate of physical function recovery. A multinomial logistic regression analysis was performed using covariates that have been previously identified in the literature as influencing recovery after critical illness. By multinomial logistic regression, age (P < 0.001), female sex (P = 0.001), intensive care unit (ICU) length of stay (LOS) (P = 0.003), and continuous intravenous sedation days (P = 0.004) were the variables that jointly influenced trajectory group membership. Participants in the trajectory demonstrating most rapid and complete functional recovery consisted of younger females with fewer continuous sedation days and a shorter LOS. The participant trajectory that failed to functionally recover consisted of older patients with greater sedation time and the longest LOS.

Conclusions: We identified distinct trajectories of physical function recovery after critical illness. Age, sex, continuous sedation time, and ICU length of stay impact the trajectory of functional recovery after critical illness. Further examination of these groups may assist in clinical trial design to tailor interventions to specific subgroups.

Keywords: ARDS; critical illness; intensive care unit; mechanical ventilation; skeletal muscle.

Figures

Figure 1.

Mean Short Physical Performance Battery (SPPB) Score during 6-month follow-up period. SPPB evaluates gait speed, balance, and lower extremity strength, with scores ranging from 0 to 12. Scores of 0 to 3 denote physical function disability, 4 to 6 low physical function, 7 to 9 intermediate physical function, and 10 to 12 high physical function. CI = confidence interval.

Figure 2.

Trajectories of physical function recovery based on Short Physical Performance Battery (SPPB) scores over 6 months after critical illness. Four distinct recovery trajectories are identified. The rate and degree of physical function recovery is highly variable in the first 6 months after critical illness. CI = confidence interval.