Age and increasing comorbidity also affected the mortality risk. At 5 years, age was associated with an increased risk of death (risk ratio 1.1 for each 5 years in age). For patients with a major comor-bidity, compared with those with no major comorbidities, the risk ratio was 1.4, and for patients with two or more comor-bidities, the risk ratio increased to 1.9.
Race and tumor site were not significantly associated with an increased risk of mortality, but both chemotherapy and radiation therapy were. This likely reflected more advanced disease in patients receiving this treatment, Dr. Fisher said.
"Overall medical utilization, which was measured by the total number of outpatient visits, was similar between the two groups," she said. This suggests that the reduced mortality risk was associated with colonoscopy itself and not with more intensive follow-up among the colonoscopy patients.