Table 1.

PICO^a criteria for inclusion of studies

Parameter	Study selection criteria
Population	Current smokers and non-smokers, both sexes, aged ≥18 years
Intervention	Smoking
Comparator	Non-smokers
Outcome measures	Primary outcome: Mean difference in direct health care costs between smokers and non-smokers Secondary outcome: mean annual incremental health care costs associated with smokers and non-smokers

^aPICO population, intervention, comparison, and outcome