Figure 1.

CONSORT diagram. ^aSum of exclusion reasons totals greater than 117 because individuals could be ineligible for more than one reason. ^bSmoking inclusion criteria were: 1) lifetime smoking of ≥100 cigarettes, 2) current daily smoking of ≥5 cigarettes per day, and 3) exhaled carbon monoxide level of ≥8 parts per million on 2 separate occasions.