Accuracy of Self-reported Smoking Exposure Among Bladder Cancer Patients Undergoing Surveillance at a Tertiary Referral Center

Abstract

BackgroundSmoking is a risk factor for developing bladder cancer (BCa). Even though continued exposure after diagnosis may adversely affect prognosis, patients may be reluctant to disclose to their physicians that they are currently smoking, leading to inaccurate reporting of exposure and missed opportunities to deliver smoking-cessation advice and treatment in the context of cancer care. ObjectiveWe examined the extent of misclassification of recent smoking exposure among patients undergoing BCa surveillance. Design, setting, and participantsA consecutive sample of 145 patients with a self-reported smoking history and prior initial diagnosis of BCa was recruited from a tertiary referral urology clinic. Outcome measurements and statistical analysisPatients were asked if they had smoked a cigarette or used nicotine replacement therapy (NRT) within the past week and whether they lived with a smoker. At the same visit, we collected urine under a biospecimen protocol. We used urinary cotinine, the primary metabolite of nicotine, as an objective biomarker of recent smoking exposure. Nine patients whose urine could not be interpreted for cotinine were excluded. We calculated the smoking status misreporting rate by comparing biochemically verified smoking status (≥31.5 ng/ml vs <31.5 ng/ml) against self-reported current smoking status (yes vs no) while considering recent NRT use. Results and limitationsOverall, 11% (15 of 136) of patients had cotinine values consistent with current smoking. Of these 15 patients, 7 reported being former smokers, resulting in a 47% misclassification rate. However, three of the seven patients who denied smoking in the past week were currently using NRT. Excluding NRT users, the misclassification rate was 33%. ConclusionsFuture studies investigating the impact of postdiagnosis nicotine exposure on BCa outcomes should use biochemical verification combined with self-reported smoking exposure to classify patients accurately. Patient summaryBladder cancer patients may misreport smoking exposure, thereby missing opportunities for smoking cessation.