Key finding
Low skeletal muscle mass index associated with 57% higher all-cause mortality risk (pooled RR 1.57, 95% CI 1.25–1.96) across 16 prospective studies, 81,358 participants
Evidence & causal status
Strong
Associational; prospective cohort evidence, biologically plausible via frailty/functional decline pathway
Caveats & limitations
Reliability / bias notes: Heterogeneous SMI definitions across studies; risk magnitude varies substantially by BMI subgroup
This describes a population-level association from published research. It is not a prediction about any one individual, and association is not the same as causation unless stated otherwise above.