Accuracy of Smoking Status Reporting: Proxy Information in a Rapidly Fatal Cancer Setting

Objective

To assess whether patients and relatives can serve as reliable proxy reporters of other family members’ cigarette-smoking history.

Patients and Methods

Two samples (325 patients, 707 relatives) were identified from the Mayo Clinic Biospecimen Resource for Pancreas Research, enrolled from November, 6, 2000, to March 15, 2018. Smoking-history data, including categorical (ever/never) and quantitative (packs per day and years smoked) smoking measures, were obtained from self-completed questionnaires by patients and relatives. Relative reports were compared with patient reports on self; patient reports were compared with relative reports on self.

Results

Overall, spouses and first-degree relatives (FDRs) were accurate (94.5%) when reporting patient ever smoking; spouse reports were 98.6% sensitive and 97.7% accurate. Accuracy of patient reports was 97.8% for spouse smoking and 85.5% for FDR smoking; accuracy varied by relationship of FDR. When not concordant, patients generally over-reported daily packs smoked by relatives and under-reported years smoked. Within a 25% agreement range, spouse reports about patients’ daily packs smoked was 46.7%, and years smoked was 69.6%, whereas FDRs were 50% and 64.6%, respectively. When not concordant, relatives generally over-reported daily packs smoked by patients, but no consistent pattern was observed of over- or under-reporting years smoked by patients.

Conclusions

Patients and relatives can be reliable proxies for smoking history (ever/never) in their family members, especially spouses. An accurate reporting of smoking status will help physicians to better gauge performance status and family smoking exposures to inform disease management.