Towards a combined prognostic index for survival in HIV infection: the role of 'non-HIV' biomarkers.

BACKGROUND: As those with HIV infection live longer, 'non-AIDS' condition associated with immunodeficiency and chronic inflammation are more common. We ask whether 'non-HIV' biomarkers improve differentiation of mortality risk among individuals initiating combination antiretroviral therapy (cART). METHODS: Using Poisson models, we analysed data from the Veterans Aging Cohort Study (VACS) on HIV-infected veterans initiating cART between 1 January 1997 and 1 August 2002. Measurements included: HIV biomarkers (CD4 cell count, HIV RNA and AIDS-defining conditions); 'non-HIV' biomarkers (haemoglobin, transaminases, platelets, creatinine, and hepatitis B and C serology); substance abuse or dependence (alcohol or drug); and age. Outcome was all cause mortality. We tested the discrimination (C statistics) of each biomarker group alone and in combination in development and validation data sets, over a range of survival intervals, and adjusting for missing data. RESULTS: Of veterans initiating cART, 9784 (72%) had complete data. Of these, 2566 died. Subjects were middle-aged (median age 45 years), mainly male (98%) and predominantly black (51%). HIV and 'non-HIV' markers were associated with each other (P < 0.0001) and discriminated mortality (C statistics 0.68-0.73); when combined, discrimination improved (P < 0.0001). Discrimination for the VACS Index was greater for shorter survival intervals [30-day C statistic 0.86, 95% confidence interval (CI) 0.80-0.91], but good for intervals of up to 8 years (C statistic 0.73, 95% CI 0.72-0.74). Results were robust to adjustment for missing data. CONCLUSIONS: When added to HIV biomarkers, 'non-HIV' biomarkers improve differentiation of mortality. When evaluated over similar intervals, the VACS Index discriminates as well as other established indices. After further validation, the VACS Index may provide a useful, integrated risk assessment for management and research.

Association of hypocholesterolaemia with hepatitis C virus infection in HIV-infected people.

OBJECTIVE: To study the impact of hepatitis C virus (HCV) status on serum cholesterol levels in HIV-infected patients. METHODS: We retrospectively analysed data from the 881 participants of the Veterans Ageing Cohort 3 Site Study. Four different models were constructed using total cholesterol, low-density lipid (LDL) cholesterol, high-density lipid (HDL) cholesterol and triglycerides as dependent variables. The relevant covariates included HCV antibody status, HIV medication class, CD4 count, HIV viral load, glucose level, lipid-lowering drug use, gender, race, age, liver function test results, ethanol use, drug use, and HIV exposure category. Variables excluded from the final model included niacin use, gender, race, age, current ethanol use, and HIV exposure category. RESULTS: Of the 881 HIV-positive patients enrolled in the study, 700 (79%) were screened for HCV antibody, with 300 (42.8%) HCV antibody positive and 400 (57.2%) HCV antibody negative. A positive HCV antibody status was independently associated with lower total cholesterol levels (P=0.001) and LDL cholesterol levels (P<0.001) but not with lower HDL cholesterol or triglyceride levels. HCV-positive patients had predicted LDL levels 19 mg/dL lower than those of HCV-negative subjects. HCV infection was also associated with a decreased use of lipid-lowering medication, and protease inhibitor use was associated with increased LDL and total cholesterol levels. CONCLUSIONS: HCV infection has been associated with lower cholesterol levels in HIV-negative individuals, and the same appears to be true with HIV-infected patients. This is an interesting finding given that HCV particles bind to LDL receptors in vitro and also because HCV-lipid interactions appear to be important in the HCV replication cycle.

Therapeutic substitution of cimetidine for nizatidine was not associated with an increase in healthcare utilization.

OBJECTIVE: To examine changes in healthcare utilization resulting from a formulary switch to cimetidine from nizatidine at the Veterans Affairs Pittsburgh Healthcare System. STUDY DESIGN: A retrospective analysis of administrative and clinical data 6 months before and 6 months after the therapeutic substitution. METHODS: The 704 patients who were switched from nizatidine to cimetidine were included in the study. Administrative data included total and primary care clinic visits, emergency room visits, gastrointestinal (GI)-related radiological studies, and GI endoscopic procedures. Discharge summaries were examined, and rates of total and GI-related hospitalizations were calculated. RESULTS: There was no evidence of increased utilization of healthcare resources during the 6 months after the formulary switch. Estimated monthly pharmaceutical savings for the Veterans Affairs Pittsburgh Healthcare System were $7260. CONCLUSIONS: A formulary switch from nizatidine to cimetidine can be accomplished at significant pharmaceutical cost savings, and this retrospective study suggests that this can be done without increasing other aspects of healthcare resource utilization.