Impact of age and comorbidity on colorectal cancer screening among older veterans

Abstract

Background: The Veterans Health Administration, the American Cancer Society, and the American Geriatrics Society recommend colorectal cancer screening for older adults unless they are unlikely to live 5 years or have significant comorbidity that would preclude treatment.

Objective: To determine whether colorectal cancer screening is targeted to healthy older patients and is avoided in older patients with severe comorbidity who have life expectancies of 5 years or less.

Design: Cohort study.

Setting: Veterans Affairs (VA) medical centers in Minneapolis, Minnesota; Durham, North Carolina; Portland, Oregon; and West Los Angeles, California, with linked national VA and Medicare administrative claims.

Patients: 27 068 patients 70 years or older who had an outpatient visit at 1 of 4 VA medical centers in 2001 or 2002 and were due for screening.

Measurements: The main outcome was receipt of fecal occult blood testing (FOBT), colonoscopy, sigmoidoscopy, or barium enema in 2001 or 2002, on the basis of national VA and Medicare claims. Charlson-Deyo comorbidity scores at the start of 2001 were used to stratify patients into 3 groups ranging from no comorbidity (score of 0) to severe comorbidity (score > or =4), and 5-year mortality was determined for each group.

Results: 46% of patients were screened from 2001 through 2002. Only 47% of patients with no comorbidity were screened despite having life expectancies greater than 5 years (5-year mortality, 19%). Although the incidence of screening decreased with age and worsening comorbidity, it was still 41% for patients with severe comorbidity who had life expectancies less than 5 years (5-year mortality, 55%). The number of VA outpatient visits predicted screening independent of comorbidity, such that patients with severe comorbidity and 4 or more visits had screening rates similar to or higher than those of healthier patients with fewer visits.

Limitations: Some tests may have been performed for nonscreening reasons. The generalizability of findings to persons who do not use the VA system is uncertain.

Conclusion: Advancing age was inversely associated with colorectal cancer screening, whereas comorbidity was a weaker predictor. More attention to comorbidity is needed to better target screening to older patients with substantial life expectancies and avoid screening older patients with limited life expectancies. primary funding source: VA Health Services Research and Development.

Figure 1. Criteria used to define the final cohort of elderly patients eligible for a colorectal cancer screening during 2001–2002

*Eligibility criteria included having been seen in an outpatient clinic at 1 of 4 VA’s during 1/1/01–12/31/02 which indicated that the VA was at least partially responsible for medical care, but data on colorectal cancer screening was gathered during the entire 2-year interval from both national VA and Medicare claims. Additional eligibility criteria included having at least 1 outpatient visit during 1/1/00–12/31/00 to define comorbidity as of 1/1/01. ^†History was defined by searching VA and Medicare inpatient and outpatient claims prior to 1/1/01, dating as far back as 10/1/92 for VA claims and 1/1/99 for Medicare claims.

Figure 2. Colorectal cancer screening incidence versus 5-year mortality for different age groups as comorbidity increases (n=27,068)

Circles (●) indicate no comorbidity (Charlson score = 0); Triangles (▲) indicate average comorbidity (Charlson score 1–3); Squares (▪) indicate severe comorbidity (Charlson score > 4).* *Within each age group screening incidence declined only a small amount with worsening comorbidity. The lines are included in the figure to illustrate the relatively flat incidence of screening between patients without comorbidity (●), average comorbidity (▲), and severe comorbidity (▪) for each age group. This is despite the substantial increase in 5-year mortality that occurs with worsening comorbidity. If screening was targeted to older patients with substantial life expectancies and away from those with severe comorbidity all lines would start much higher and slope down more steeply.

Figure 3. Patients aged > 70 years who had colorectal cancer screening during 2001–2002, according to comorbidity and number of VA outpatient medical visits (n=27,068)*

*Number of visits was defined by the number of visits during 1/1/01–12/31/02 to VA primary care, gastroenterology, or general surgery clinics (clinic codes 301, 303, 305, 306, 307, 309, 312, 321–323, and 401).