Using salivary cotinine to validate self-reports of tobacco use by Indian youth living in low-income neighborhoods.

BACKGROUND Self-reported tobacco use among young people can underestimate the actual prevalence of tobacco use. Biochemical validation of self-reports is particularly recommended for intervention studies where cessation outcomes are to be measured. Literature on biochemical validation of self-reports of multiple forms of tobacco use in India is sparse, particularly among young people. METHODS The study was conducted during the baseline household survey of a community-based tobacco prevention and cessation intervention trial for youth (10-19 years old) residing in slum communities in Delhi, India in 2009. Salivary cotinine measurement on 1,224 samples showed that youth were under-reporting use of chewing and smoking tobacco. RESULTS Self-reports had a low sensitivity (36.3%) and a positive predictive value of 72.6%. No statistically significant difference in under- reporting was found between youth in the control and intervention conditions of the trial, which will be taken into consideration in assessing intervention outcomes at a later time point. CONCLUSION Biochemical validation of self-reported tobacco use should be considered during prevention and cessation studies among youth living in low-income settings in developing countries like India. IMPACT The future results of biochemical validation from Project ACTIVITY (Advancing Cessation of Tobacco in Vulnerable Indian Tobacco Consuming Youth) will be useful to design validation studies in resource-poor settings.