Personalizing colonoscopy screening for elderly individuals based on screening history, cancer risk, and comorbidity status could increase cost effectiveness

Abstract

Background & aims: Colorectal cancer (CRC) screening decisions for elderly individuals are often made primarily on the basis of age, whereas other factors that influence the effectiveness and cost effectiveness of screening are often not considered. We investigated the relative importance of factors that could be used to identify elderly individuals most likely to benefit from CRC screening and determined the maximum ages at which screening remains cost effective based on these factors.

Methods: We used a microsimulation model (Microsimulation Screening Analysis-Colon) calibrated to the incidence of CRC in the United States and the prevalence of adenomas reported in autopsy studies to determine the appropriate age at which to stop colonoscopy screening in 19,200 cohorts (of 10 million individuals), defined by sex, race, screening history, background risk for CRC, and comorbidity status. We applied a willingness-to-pay threshold of $100,000 per quality-adjusted life-year (QALY) gained.

Results: Less intensive screening history, higher background risk for CRC, and fewer comorbidities were associated with cost-effective screening at older ages. Sex and race had only a small effect on the appropriate age to stop screening. For some individuals likely to be screened in current practice (for example, 74-year-old white women with moderate comorbidities, half the average background risk for CRC, and negative findings from a screening colonoscopy 10 years previously), screening resulted in a loss of QALYs, rather than a gain. For some individuals unlikely to be screened in current practice (for example, 81-year-old black men with no comorbidities, an average background risk for CRC, and no previous screening), screening was highly cost effective. Although screening some previously screened, low-risk individuals was not cost effective even when they were 66 years old, screening some healthy, high-risk individuals remained cost effective until they reached the age of 88 years old.

Conclusions: The current approach to CRC screening in elderly individuals, in which decisions are often based primarily on age, is inefficient, resulting in underuse of screening for some and overuse of screening for others. CRC screening could be more effective and cost effective if individual factors for each patient are considered.

Keywords: Colon Cancer Screening; Individualized Care; MISCAN; Tumor.

Figure 1

The Effect of Age on the Effectiveness (A), Costs (B), and Cost Effectiveness (C) of Colonoscopy Screening: Results for Average Risk Individuals with a Negative Screening Colonoscopy 10 Years Prior and No Comorbidities (QALYs gained and costs per 1,000 individuals; 3% discounted).¹ QALY = quality-adjusted life-year ¹Detailed results on the effectiveness and costs of screening can be found in Appendix 3. ²The effect of screening on quantity and quality of life incorporated in one measure (i.e. the net health benefit of screening). A negative value indicates that screening is associated with a net harm, rather than a net health benefit. ³The costs of screening and surveillance colonoscopies, complications of colonoscopy, and overtreatment of CRC minus the savings associated with preventing CRC treatment.

Figure 1

The Effect of Age on the Effectiveness (A), Costs (B), and Cost Effectiveness (C) of Colonoscopy Screening: Results for Average Risk Individuals with a Negative Screening Colonoscopy 10 Years Prior and No Comorbidities (QALYs gained and costs per 1,000 individuals; 3% discounted).¹ QALY = quality-adjusted life-year ¹Detailed results on the effectiveness and costs of screening can be found in Appendix 3. ²The effect of screening on quantity and quality of life incorporated in one measure (i.e. the net health benefit of screening). A negative value indicates that screening is associated with a net harm, rather than a net health benefit. ³The costs of screening and surveillance colonoscopies, complications of colonoscopy, and overtreatment of CRC minus the savings associated with preventing CRC treatment.

Figure 1

The Effect of Age on the Effectiveness (A), Costs (B), and Cost Effectiveness (C) of Colonoscopy Screening: Results for Average Risk Individuals with a Negative Screening Colonoscopy 10 Years Prior and No Comorbidities (QALYs gained and costs per 1,000 individuals; 3% discounted).¹ QALY = quality-adjusted life-year ¹Detailed results on the effectiveness and costs of screening can be found in Appendix 3. ²The effect of screening on quantity and quality of life incorporated in one measure (i.e. the net health benefit of screening). A negative value indicates that screening is associated with a net harm, rather than a net health benefit. ³The costs of screening and surveillance colonoscopies, complications of colonoscopy, and overtreatment of CRC minus the savings associated with preventing CRC treatment.

Figure 2

The Relative Effect of Age, Screening History, Comorbidity Status, and Background Risk for CRC on the Effectiveness (A) and Cost Effectiveness (B) of Colonoscopy Screening (QALYs gained per 1,000 individuals; 3% discounted). CRC = colorectal cancer; QALY = quality-adjusted life-year; NSC = negative screening colonoscopy; SCR = screening; RR CRC = background risk for CRC; CM = comorbidities; FH = family history; CS = cost saving; NE = negative effect ¹The dashed lines indicate results for healthy, average risk, 75-year-old individuals with a negative screening colonoscopy 10 years prior. ²The effect of screening on quantity and quality of life incorporated in one measure (i.e. the net health benefit of screening). A negative value indicates that screening is associated with a net harm, rather than a net health benefit. ³See also Figure 1. ⁴Individuals are classified as having moderate comorbidities if diagnosed with an ulcer, rheumatologic disease, peripheral vascular disease, diabetes, paralysis, or cerebrovascular disease and in case of a history of acute myocardial infarction; as having severe comorbidities if diagnosed with chronic obstructive pulmonary disease, congestive heart failure, moderate or severe liver disease, chronic renal failure, dementia, cirrhosis and chronic hepatitis, or AIDS; and as having no comorbidities if none of these conditions is pre‘Moderate comorbidities’ corresponds with ‘low/medium comorbidity’ and ‘severe comorbidities’ corresponds with high comorbidity’ as used in the study by Cho and colleagues. ⁵The range of the background risk for CRC is based on the National Cancer Institute's Colorectal Cancer Risk Assessment Tool. This tool incorporates the following risk factors: the number of first-degree relatives with CRC, current leisure-time vigorous activity, aspirin/ NSAID use, vegetable intake, body mass index, current and past smoking (men only), and estrogen status within the last two years (women only). In white women, the minimum background risk for CRC is 0.5, the maximum background risk in the absence of a family history of CRC is 2.0, and the maximum background risk in the presence of a family history of CRC is 3.5. In white men, black women, and black men, the corresponding risks are 0.5, 2.0, and 4.9; 0.4, 1.8, and 3.5; and 0.5, 2.5, and 5.3, respectively. ⁶Cannot be calculated.

Figure 2

The Relative Effect of Age, Screening History, Comorbidity Status, and Background Risk for CRC on the Effectiveness (A) and Cost Effectiveness (B) of Colonoscopy Screening (QALYs gained per 1,000 individuals; 3% discounted). CRC = colorectal cancer; QALY = quality-adjusted life-year; NSC = negative screening colonoscopy; SCR = screening; RR CRC = background risk for CRC; CM = comorbidities; FH = family history; CS = cost saving; NE = negative effect ¹The dashed lines indicate results for healthy, average risk, 75-year-old individuals with a negative screening colonoscopy 10 years prior. ²The effect of screening on quantity and quality of life incorporated in one measure (i.e. the net health benefit of screening). A negative value indicates that screening is associated with a net harm, rather than a net health benefit. ³See also Figure 1. ⁴Individuals are classified as having moderate comorbidities if diagnosed with an ulcer, rheumatologic disease, peripheral vascular disease, diabetes, paralysis, or cerebrovascular disease and in case of a history of acute myocardial infarction; as having severe comorbidities if diagnosed with chronic obstructive pulmonary disease, congestive heart failure, moderate or severe liver disease, chronic renal failure, dementia, cirrhosis and chronic hepatitis, or AIDS; and as having no comorbidities if none of these conditions is pre‘Moderate comorbidities’ corresponds with ‘low/medium comorbidity’ and ‘severe comorbidities’ corresponds with high comorbidity’ as used in the study by Cho and colleagues. ⁵The range of the background risk for CRC is based on the National Cancer Institute's Colorectal Cancer Risk Assessment Tool. This tool incorporates the following risk factors: the number of first-degree relatives with CRC, current leisure-time vigorous activity, aspirin/ NSAID use, vegetable intake, body mass index, current and past smoking (men only), and estrogen status within the last two years (women only). In white women, the minimum background risk for CRC is 0.5, the maximum background risk in the absence of a family history of CRC is 2.0, and the maximum background risk in the presence of a family history of CRC is 3.5. In white men, black women, and black men, the corresponding risks are 0.5, 2.0, and 4.9; 0.4, 1.8, and 3.5; and 0.5, 2.5, and 5.3, respectively. ⁶Cannot be calculated.