Cohort-Defined Low Skeletal Muscle Mass and Functional Dependency After Critical Illness: A 12-Month Longitudinal...

To evaluate the association between low skeletal muscle mass at intensive care unit (ICU) enrollment and functional dependency at 1, 3, 6, and 12 months after enrollment.

Prospective longitudinal observational cohort with follow-up at 1, 3, 6, and 12 months after enrollment.

Sex-defined low muscle mass (LMM), using L3 skeletal muscle index (SMI) thresholds of <33.2 cm ² /m ² in men and <28.3 cm ² /m ² in women, derived from the cohort distribution.

Need for assistance with activities of daily living, transfers, or toileting. Logistic generalized estimating equations (GEE) included LMM-by-time interactions, adjustment for sepsis, sex, and age <65 years, and mortality-derived inverse probability weights.

Among 217 participants, 148 had SMI measurements and 15 had sex-defined LMM. The functional GEE included 404 assessments from 121 patients, including 12 with LMM. Observed dependency at 1 month was 8/12 (66.7%) with LMM versus 35/108 (32.4%) without LMM. The adjusted 1-month odds ratio (OR) was 3.52 (95% confidence interval [CI], 0.99-12.44; p=0.051); the 12-month OR was 1.67 (95% CI, 0.41-6.81; p=0.475). The joint LMM-by-time test gave p=0.076. A model imposing a common effect across visits gave OR 2.04 (95% CI, 0.79-5.24). Sensitivity analyses were imprecise and did not establish a persistent association.

Low muscle mass may identify patients with greater early functional dependency after critical illness. Sparse exposed numbers, mortality, and incomplete follow-up limit inference about persistence and recovery trajectories. The data do not establish equivalent recovery patterns or a causal effect of muscle mass.