Regardless of patient sex or BMI, initiating colorectal cancer screening with colonoscopy at age 45 years or with fecal immunochemical testing at age 40 years was cost-effective, according to new research.

In addition, researchers reported CRC screening with colonoscopy at age 40 years was cost-effective in men with class 2 and 3 obesity, whom investigators noted have the highest risk for CRC and all-cause mortality.

“Initiating CRC colonoscopy-based screening at age 45 years is likely to be cost-effective for women and men irrespective of BMI, initiating colonoscopy-based screening at age 40 years may be cost-effective in men with obesity [class 2 to 3], and FIT-based screening may be cost-effective starting at age 40 years in both sexes across the range of BMI,” Aaron Yeoh, MD, and colleagues from the division of gastroenterology and hepatology at Stanford University School of Medicine, wrote in Clinical Gastroenterology and Hepatology.

As obesity is a suspected risk factor for CRC, researchers sought to determine whether intensified CRC screening would be cost-effective in overweight and obese individuals, noting that obesity also is associated with increased morbidity and mortality risks and incremental costs. “Given these competing risks, our aim was to estimate the potential clinical impact and cost-effectiveness of earlier initiation or more intensive CRC screening in overweight and obese persons,” they wrote.

Using a decision analytic model that was recalibrated to avoid double-counting the impact of BMI and birth cohort effect of increasing CRC incidence at younger ages, investigators compared CRC screening initiated at ages 45 or 40 years vs. 50 years in men and women with BMI that ranged from normal weight to class 3 obesity.

They analyzed 10 cohorts, grouped by age and BMI, and studied the impact of annual fecal immunochemical testing (FIT) and colonoscopy every 5 and 10 years. Incremental costs and quality of life-years (QALY) gained were calculated using a payer perspective, with cost-effectiveness defined as no more than $100,000/QALY gained.

Without CRC screening, investigators reported comparable sex-specific total CRC mortality for individuals who were overweight or had class 1 to 3 obesity, “reflecting the counterbalancing of higher CRC risk by lower life expectancy as BMI rises.”

Across BMI categories and sex groups, initiating colonoscopy at age 45 vs. 50 years with routine screening every 10 years through age 75 years cost $33,400 to $85,900/QALY gained. However, researchers reported starting screening at age 40 vs. 45 years with subsequent colonoscopies at 10-year intervals was only cost-effective for men with class 2 or 3 obesity ($93,300/QALY gained vs. $80,400/QALY gained, respectively). In addition, starting FIT at age 40 vs. 45 years cost $22,000/QALY to $58,800/QALY gained for both sexes and across BMI groups.

“Our finding that initiating CRC screening at age 45 years appears cost-effective across

the range of BMI groups, and that even earlier initiation at age 40 years appears cost-effective in men with obesity [class 2 to 3], suggests that the benefits of earlier CRC screening are substantial even when the higher CRC risks in overweight and obese persons are balanced against the higher risk of competing morbidity and mortality, and overweight- and obesity-associated costs that are incurred when CRC death is averted,” researchers wrote. “These findings have implications for CRC screening in overweight and obese persons specifically, and for risk-adjusted CRC screening more generally.”