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Colorectal screening cost effective in cystic fibrosis patients



Screening for colorectal cancer in patients with cystic fibrosis is cost effective, and should be started at a younger age and performed more often, new research suggests.

While colorectal cancer (CRC) screening traditionally begins at age 50 years in people at average risk for the disease, those at high risk usually begin undergoing colonoscopies at an earlier age. Patients with cystic fibrosis fall under the latter category, wrote Andrea Gini, of the department of public health at Erasmus Medical Center in Rotterdam, the Netherlands, and colleagues, with an incidence of CRC up to 30 times higher than the general population, but their shorter lifespan has led to a “different trade-off between the benefits and harms of CRC screening.”

Between 2000 and 2015, the median predicted survival age for patients with cystic fibrosis increased from 33.3 years to 41.7 years; this increased survival has brought increased risk for other diseases, particularly in the GI tract, Mr. Gini and colleagues wrote in Gastroenterology. By using the Microsimulation Screening Analysis–Colon model – a joint project between Erasmus Medical Center and Memorial Sloan Kettering Cancer Center in New York – the investigators assessed the cost-effectiveness of CRC screening in patients with cystic fibrosis.

Three cohorts of 10 million patients each were simulated, with one cohort having undergone transplant, one cohort not having transplant, and one cohort of individuals without cystic fibrosis. The simulated patient age was 30 years in 2017. A total of 76 different colonoscopy-screening strategies were assessed, with each differing in screening interval (3, 5, or 10 years for colonoscopy), age to start screening (30, 35, 40, 45, or 50 years), and age to end screening (55, 60, 65, 70, or 75 years). The optimal screening strategy was determined based on a willingness-to-pay threshold of $100,000 per life-year gained, the investigators wrote.

In the absence of screening, the mortality rate for nontransplant cystic fibrosis patients was 19.1 per 1,000 people, and the rate for cystic fibrosis patients who had undergone transplant was 22.3 per 1,000 people. The standard screening strategy prevented more than 73% of CRC deaths in the general population, 66% of deaths in nontransplant cystic fibrosis patients, and 36% of deaths in cystic fibrosis patients with transplant; however, the model predicted that only 22% of individuals who received a transplant and 36% of those who did not would reach the age of 50 years.

According to the model, the optimal colonoscopy-screening strategy for nontransplant patients was one screen every 5 years, starting at 40 and screening until the age of 75. The incremental cost-effectiveness ratio (ICER) was $84,000 per life-year gained; CRC incidence was reduced by 52% and CRC mortality was reduced by 79%. For transplant patients, the best strategy was one screen every 3 years between the ages of 35 and 55, which reduced CRC mortality by 82% at an ICER of $71,000 per life-year gained.

In a separate analysis of fecal immunochemical testing, a less-demanding alternative to colonoscopy, the optimal screening strategy was an annual test between the age of 35 and 75 years for nontransplant cystic fibrosis patients, for an ICER of $47,000 per life-year gained and a CRC mortality reduction of 78%. The best strategy for transplant patients was once a year between the ages of 30 and 60, which reduced CRC mortality by 77% at an ICER of $86,000 per life-year gained. While fecal immunochemical testing may be more cost effective than colonoscopy, “specific evidence of its performance in the cystic fibrosis population is required before considering this screening modality,” the investigators noted.

“This study indicates that there is benefit to earlier CRC screening in the cystic fibrosis population and [that it] can be done at acceptable costs,” the investigators wrote. “The findings of this analysis support clinicians, researchers, and policy makers who aim to define a tailored CRC screening for individuals with cystic fibrosis in the United States.”

The study was funded by the Cystic Fibrosis Foundation, the Cancer Intervention and Surveillance Modeling Network consortium, and Memorial Sloan Kettering Cancer Center. The investigators reported no conflicts of interest.

SOURCE: Gini A et al. Gastroenterology. 2017 Dec 27. doi: 10.1053/j.gastro.2017.12.011.

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