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Colorectal Cancer Screening 20% Less Likely With HIV in Large Medicaid Population
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IDWeek, October 2-6, 2013, San Francisco
Mark Mascolini
HIV-positive people using Medicaid in five US states had a 20% lower likelihood of colorectal cancer screening than a matched group of Medicaid recipients without HIV [1]. But colorectal cancer incidence did not differ significantly between the HIV-positive and negative groups. Screening rates in both groups of Medicaid recipients were half the US national average screening rate.
Some studies find that colorectal cancer--the second-leading cause of cancer death in the United States--is diagnosed in HIV-positive people at an earlier age and a later stage than in HIV-negative people, but other studies do not confirm those findings. Colorectal cancer screening can prevent these cancers or find them at an earlier stage, but people in the US underutilize this strategy. Some evidence indicates that HIV-positive people get screened less for colorectal cancer than the general population, even though they have more contact with healthcare professionals.
To analyze these issues, researchers at Temple University and the University of Pennsylvania turned to Medicaid records of colon cancer diagnosis and screening because Medicaid is the largest single source of healthcare coverage among people with HIV in the United States. The investigators focused on all HIV-positive people at least 40 years old and continuously enrolled in Medicaid in five states--California, Florida, New York, Ohio, and Pennsylvania. They matched each HIV-positive person to 5 randomly selected HIV-negative Medicaid patients according to 5-year age group, gender, and state. Participants used Medicaid between 1999 and 2007.
The researchers calculated colorectal cancer incidence in 2006 and screening by sigmoidoscopy, colonoscopy, or barium enema between 1999 and 2007. In statistical analyses to determine factors affecting colorectal cancer incidence or screening, dependent variables were HIV status, age, race/ethnicity, state of residence, time in dataset, and comorbidity assessed by the Chronic Illness Disability Payment System.
Among the 55,439 HIV-positive Medicaid recipients, age averaged 49.9 and 32.6% were women. Age in the HIV-negative group averaged 50.0, and 32.6% were women. The HIV group had a lower proportion of whites (27.1% versus 42.7%) and a higher proportion of blacks (42.2% versus 19.5%). Average comorbidity index was higher (worse) in HIV-positive people than in the 277,195 HIV-negative controls (7.45 versus 3.44).
In 2006 the researchers counted 94 colon cancer diagnoses in the HIV group and 271 in the HIV-negative group (0.2% versus 0.1%). Adjusted analysis determined that this difference stopped short of statistical significance (adjusted odds ratio [aOR] 1.29, 95% confidence interval [CI] 0.98 to 1.70).
Next the researchers focused on 22,928 HIV-positive people 50 or older matched to 114,640 HIV-negative controls. Age averaged 56.4 in the HIV group and 56.7 in HIV-negative controls. Women made up just under one third of each group (30.5%). The HIV group had a lower proportion of whites (25.2% versus 42.1%) and a higher proportion of blacks (44.1% versus 18.5%). Average comorbidity index was higher in people with HIV than in controls (7.92 versus 4.02).
Over the study period 1999-2007, low proportions of people with HIV (35.8%) and without HIV (33.7%) got screened for colon cancer. In unadjusted analysis, HIV-positive people were 10% more likely than HIV-negative people to get screened for colon cancer (OR 1.10, 95% CI 1.07 to 1.13). But after adjustment for comorbidities and years in the database, people with HIV had 20% lower odds of getting screened for colon cancer (aOR 0.80, 95% CI 0.77 to 0.83). In both groups, colorectal cancer screening rates were less than half the national rate.
The researchers concluded that their results support previous studies finding equivalent colorectal cancer incidence in people with and without HIV after statistical adjustment for age. But after adjusting for comorbidities, HIV-positive people 50 or older were less likely to be screened for colorectal cancer than their HIV-negative age peers. The investigators called for more work to identify and lower barriers to colorectal cancer screening among Medicaid patients with and without HIV.
Reference
1. Momplaisir F, Keller S, Lo Re V III, et al. Colorectal cancer incidence and screening in U.S. Medicaid patients with and without HIV infection. IDWeek 2013. October 2-6, 2013. San Francisco. Abstract 328.
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