February 24, 2005
Additionally, the potential impact of age on the response to highly active antiretroviral therapy (HAART) is important, since people living with HIV now survive longer. Age is also a vital issue as new infections in older individuals continue to occur at a steady rate. Previous studies have reported that despite better adherence and perhaps higher rates of viral suppression, CD4+ cell count response is blunted in older individuals.
Kristine Patterson from the University of North Carolina at Chapel Hill and colleagues studied age and gender-related differences in immunologic and virologic responses to an initial HAART regimen in a cohort of antiretroviral therapy-naive individuals from 2 observational cohorts.
All study participants were men or women older than 50 years of age who had entered HIV care between 1998 and 2004, were antiretroviral naive and were put on HAART.
Controls were randomly selected from patients who were younger than 50 years of age and were matched for gender. Of the 246 patients, 28% were women, with a median age of 54 years for the older cohort and 38 years for the controls. No other details on differences between the groups, including adherence, active substance use, hepatitis C virus coinfection or other factors that have been previously linked to response to treatment were available.
Similar to other studies, the researchers found that HIV-infected women tended to have a higher CD4+ cell count at entry into care in both age groups, while viral loads were similar in HIV-infected men and women. At 6 months there were no significant differences in CD4+ cell count increase (defined as an increase greater than 25%) or suppression of viral load at less than 400 copies/mL (range 66%-78%, P = .68) adjusted for baseline CD4+ cell count, viral load and HAART type.
These data suggest that HIV-infected women continue to access care at higher CD4+ cell counts. It further confirmed no gender-associated difference in response to treatment for HIV-infected women. Additionally, the study did not find any age-related blunting of immunologic response, which has been reported by other study groups.
In another study, Sonya Hadrigan and colleagues from the University of Miami School of Medicine, Miami, Florida, examined possible gender-associated differences in 539 HIV-infected patients who underwent 2 years of follow-up after initial hospitalization at Jackson Memorial Hospital, a large urban hospital in Florida. There were no differences seen in CD4+ cell count or HAART use, although less than 50% of the entire cohort was on HAART.
The researchers found that HIV-infected women had higher hospitalization rates than HIV-infected men (3.9 versus 1.9 per 100 person-years, respectively), and were more likely to have emergency admissions and longer duration of hospitalizations, despite similar use of outpatient visits.
However, there were higher death rates in HIV-infected men compared with HIV-infected women, including higher rates due to malignancy and renal insufficiency. Among the subgroup of patients over 50 years of age, no significant gender-associated differences were seen, although the statistical power was limited by the numbers.
These data confirm that HIV-infected women continue to access care and treatment at similar rates to HIV-infected men. Furthermore, despite higher rates of emergency admissions, HIV-infected women experience lower in-hospital mortality. The differences seen in numbers of and types of hospitalizations need to be compared with rates in HIV-uninfected patients to determine whether this pattern is unique to HIV-infected patients. Otherwise, these rates may be just reflecting the underlying rates and causes seen in age-matched controls.
In addition, more information on other comorbidities, such as hepatitis and cardiovascular disease, would help to better explain whether these hospitalizations are due to HIV, HIV-related medications or underlying conditions. Finally, this information could identify which hospitalizations, if any, could be prevented by changes in care and treatment.