A 9-year follow-up study of participants and nonparticipants in sigmoidoscopy screening: importance of self-selection
2008 (English)In: Cancer Epidemiology, Biomarkers and Prevention, ISSN 1055-9965, Vol. 17, no 5, 1163-1168 p.Article in journal (Refereed) Published
BACKGROUND: Self-selection may compromise cost-effectiveness of screening programs. We hypothesized that nonparticipants have generally higher morbidity and mortality than participants. METHODS: A Swedish population-based random sample of 1,986 subjects ages 59 to 61 years was invited to sigmoidoscopy screening and followed up for 9 years by means of multiple record linkages to health and population registers. Gender-adjusted cancer incidence rate ratio (IRR) and overall and disease group-specific and mortality rate ratio (MRR) with 95% confidence intervals (95% CI) were estimated for nonparticipants relative to participants. Cancer and mortality rates were also estimated relative to the age-matched, gender-matched, and calendar period-matched Swedish population using standardized incidence ratios and standardized mortality ratios. RESULTS: Thirty-nine percent participated. The incidence of colorectal cancer (IRR, 2.2; 95% CI, 0.8-5.9), other gastrointestinal cancer (IRR, 2.7; 95% CI, 0.6-12.8), lung cancer (IRR, 2.2; 95% CI, 0.8-5.9), and smoking-related cancer overall (IRR, 1.4; 95% CI, 0.7-2.5) tended to be increased among nonparticipants relative to participants. Standardized incidence ratios for most of the studied cancers tended to be >1.0 among nonparticipants and <1.0 among participants. Mortality from all causes (MRR, 2.4; 95% CI, 1.7-3.4), neoplastic diseases (MRR, 1.9; 95% CI, 1.1-3.5), gastrointestinal cancer (MRR, 4.7; 95% CI, 1.1-20.7), and circulatory diseases (MRR, 2.3; 95% CI, 1.2-4.2) was significantly higher among nonparticipants than among participants. Standardized mortality ratio for the studied outcomes tended to be increased among nonparticipants and was generally decreased among participants. CONCLUSION: Individuals who might benefit most from screening are overrepresented among nonparticipants. This self-selection may attenuate the cost-effectiveness of screening programs on a population level.
Place, publisher, year, edition, pages
2008. Vol. 17, no 5, 1163-1168 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-98968DOI: 10.1158/1055-9965.EPI-07-2764ISI: 000256012800021PubMedID: 18483338OAI: oai:DiVA.org:uu-98968DiVA: diva2:201742