June 11, 2012
To determine whether the higher rate of lung cancer seen among HIV patients is due to biological effects of HIV, surveillance bias or excess smoking, the research team compared the incidence of lung cancer between patients with HIV and demographically similar but HIV-negative patients, accounting for smoking and lung cancer stage at diagnosis. An analytic cohort of 37,294 HIV-infected patients and 75,750 uninfected patients was created by linking data from the Veterans Aging Cohort Study Virtual Cohort and data from the Veterans Affairs Central Cancer Registry.
The incidence rates of pathologically confirmed lung cancer were calculated by dividing numbers of cases by numbers of person-years at risk. Incidence rate ratios (IRRs) -- adjusted for age, sex, race/ethnicity, smoking prevalence, previous bacterial pneumonia, and chronic obstructive pulmonary disease -- were determined using Poisson regression.
The results indicated a lung cancer incidence rate of 204 cases per 100,000 person-years among patients with HIV (95 percent confidence interval 167-249) and 119 cases per 100,000 person-years among uninfected patients (95 percent CI 110-129). Lung cancer stage at presentation did not differ between the two groups; however, the IRR of lung cancer associated with HIV infection remained significant after multivariable adjustment (IRR 1.7; 95 percent CI 1.5-1.9).
"In our cohort of demographically similar HIV-infected and uninfected patients, HIV infection was an independent risk factor for lung cancer after controlling for potential confounders including smoking," the authors concluded. "The similar stage distribution between the two groups indicated that surveillance bias was an unlikely explanation for this finding."
05.15.2012; Vol. 26; No. 8: P. 1017-1025; Keith Sigel; and others
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