Key finding
Never smoker = reference; current smoking ~2.18–2.81× mortality in large cohorts; former smokers can approach never-smoker risk after prolonged cessation
Evidence & causal status
Strong
Causal support strong; mortality evidence mostly prospective
Caveats & limitations
Reliability / bias notes: Self-report; pack-years and cessation timing matter; reverse causation can affect recent quitters
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.