Confirmation of self-reported non-smoking status by salivary cotinine among diabetes patients in Kerala, India

Problem considered: There are no studies of tobacco cessation reported from low and middle income countries that have tested cotinine against self report in a patient population. We confirmed the accuracy of self report of smoking cessation by matching self reports against salivary cotinine test in diabetes patients. Methods: The study was part of a randomized controlled trial among 224 diabetes patients in Kerala. Salivary cotinine level was measured among 35 diabetes patients who claimed to have not smoked even a single cigarette/bidi in the last 30 days before the test. Biochemical analysis of salivary cotinine was done using the Enzyme-Linked Immunosorbent Assay kit from Salimetrics. Cotinine value of >15 ng/ml was used as the cut-off point. Results: Among the 35 patients, 26 (74%) were found to have a saliva cotinine level <= 15 ng/ml confirming self reports of non smoking status. Among the remaining nine patients, four reported being routinely exposed to secondhand smoke in their household or work place prior to cotinine testing. Interviews revealed that 12% of the variance between self report and the cotinine test results was attributable to routine exposure to second hand smoke. Conclusion: Self report of non-smoking by diabetes patients in India was fairly reliable when validated against a cotinine test. Larger clinical trials are warranted to further evaluate the validity of self reported non-smoking status in different patient populations having different education levels. Copyright (C) 2014, INDIACLEN. Publishing Services by Reed Elsevier India Pvt Ltd. All rights reserved.