Aims
To estimate the prevalence and predictors of failed biochemical verification of self‐reported abstinence among participants enrolled in trials of hospital‐initiated smoking cessation interventions.
Design
Comparison of characteristics between participants who verified and those who failed to verify self‐reported abstinence.
Settings
Multi‐site randomized clinical trials conducted between 2010 and 2014 in hospitals throughout the United States.
Participants
Recently hospitalized smokers who reported tobacco abstinence 6 months post‐randomization and provided a saliva sample for verification purposes (n = 822).
Measurements
Outcomes were salivary cotinine‐verified smoking abstinence at 10 and 15 ng/ml cut‐points. Predictors and correlates included participant demographics and tobacco use; hospital diagnoses and treatment; and study characteristics collected via surveys and electronic medical records.
Findings
Usable samples were returned by 69.8% of the 1178 eligible trial participants who reported 7‐day point prevalence abstinence. The proportion of participants verified as quit was 57.8% [95% confidence interval (CI) = 54.4, 61.2; 10 ng/ml cut‐off] or 60.6% (95% CI = 57.2, 63.9; 15 ng/ml). Factors associated independently with verification at 10 ng/ml were education beyond high school education [odds ratio (OR) = 1.51; 95% CI = 1.07, 2.11], continuous abstinence since hospitalization (OR = 2.82; 95% CI = 2.02, 3.94), mailed versus in‐person sample (OR = 3.20; 95% CI = 1.96, 5.21) and race. African American participants were less likely to verify abstinence than white participants (OR = 0.64; 95% CI = 0.44, 0.93). Findings were similar for verification at 15 ng/ml. Verification rates did not differ by treatment group.
Conclusions
In the United States, high rates (40%) of recently hospitalized smokers enrolled in smoking cessation trials fail biochemical verification of their self‐reported abstinence.