Background Associations of socioeconomic status (SES) and smoking-related diseases depend on uniform validity of self-reported smoking habits in different SES groups. We investigated the influence of SES on validity of self-reported smoking status by means of urinary cotinine.
Methods We determined total urinary cotinine in the baseline population of the Heinz Nixdorf Recall Study. Participants with cotinine>200 µg/L were potential current smokers. We defined upper and lower 20% of the gender-specific distribution of the International Socio-Economic Index (ISEI) as high and low SES, respectively, else as intermediate. We analysed the association of self-reported smoking status and cotinine by ISEI and additional SES measures, stratified by gender. In self-reported non-smokers, we estimated age-adjusted ORs with 95% CI to detect differences by SES in the validity of self-reported smoking status.
Results In 2004 men and 1887 women, 78% and 80%, respectively, reported to be non-smokers. Median cotinine concentrations were 2 µg/L in non-smokers, and 3651 µg/L in male and 3127 µg/L in female smokers. Based on cotinine in non-smokers, 2.0 % of men (n = 32) and 1.8 % of women (n = 27) were potential smokers, with lower proportions in the subgroup of never-smokers (men: 0.7%, women: 0.5%). The validity of self-reported smoking status did not substantially differ by SES. Tendencies for increased underreporting were indicated for women with low ISEI (OR 1.35; 95% CI 0.54 to 3.39) and men in blue-collar jobs (OR 1.39; 95% CI 0.67 to 2.87).
Conclusion Validity of self-reported smoking status in this elderly German cohort was high and did not depend on SES.
- self-report validity
- socioeconomic status
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Presented at Some preliminary results of the study have been presented at the annual conference of the German Society for Epidemiology in 2017.
Contributors JH, TW, HK, BP, TBe, TBr and K-HJ conceived the study and the analyses. K-HJ, SM and ND, among others, were responsible for the overall design of this part of the Heinz-Nixdorf Recall study (HNR), K-HJ, MA and BS for the coordination of HNR. TW and HK were responsible for the analysis of urinary cotinine. Manual coding of occupations was conducted by JH and BK. JH analysed the data. JH wrote the initial draft of the manuscript, together with BP, TBe, BK and K-HJ. All authors critically revised and approved the final version of this paper.
Funding The Institute for Medical Informatics, Biometry and Epidemiology received a grant from the German Social Accident Insurance (FP 295).
Competing interests The authors from the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Ruhr University Bochum (IPA) are employed at the 'Berufsgenossenschaft Rohstoffe und chemische Industrie' (BG RCI), a public body, which is a member of the German Social Accident Insurance. The authors are independent from the German Social Accident Insurance in study design, access to the collected data, responsibility for data analysis and interpretation and the right to publish. The views expressed in this paper are those of the authors and not necessarily those of the German Social Accident Insurance. All other authors have disclosed any potential conflicts of interests.
Patient consent for publication Obtained.
Ethics approval Approval for the study was obtained from the ethics commission of the Medical
Faculty of the University Duisburg-Essen.
Provenance and peer review Not commissioned; externally peer reviewed.