 |
|
|
| |
Do People Over 50 Get Less or More From Antiretrovirals?
|
| |
| |
Mark Mascolini
XVI International AIDS Conference, Toronto
August 16, 2006
People who start potent antiretroviral combinations (HAART) at age 50 or older control HIV replication better than 40- to 49-year-olds, probably because of better adherence to their regimen [1]. But the older people in this California cohort proved more likely to endure viral rebounds. After 6 years of follow-up the 50-plus group had gained as many CD4 cells as people in their 40s.
Clinicians in the Kaiser Permanente system in northern California studied treatment responses in 997 people in their 50s or older who started a three-drug combination and in 1834 people in their 40s. The median year for starting HAART was 1998 in both groups, and both started with a median CD4 count around 220 cells/mm3.
While 53.6% of the 50-plus group had tried nucleoside therapy before HAART, 50.9% in the 40-something group had taken nuke monotherapy or dual therapy. About one third in each group took a HAART regimen not including a protease inhibitor. Similar proportions (18.9% of the 50 group and 15.8% of the 40 group) had a viral load below 500 copies/mL when they began HAART. Adherence measured by pharmacy refill records was at least 75% in 65.4% of the 50-plus group and in 61.2% of the 40-to-49 contingent.
One year after starting their first three-drug regimen, people 50 years old or older had a better chance of pushing their viral load under 500 copies/mL than the 40- to 49-year-olds in statistical models considering (1) only age, (2) age plus adherence, (3) age plus Charlson comorbidity index (see note 2), and (4) age, adherence, and Charlson score. Hazard ratios (HR) predicting a sub-500-copy load for the four analyses always favored the 50-and-over group:
- Only age: HR 1.15 for 50 group versus 0.97 for 40 group
- Age plus adherence: HR 1.03 for the 50 group versus 0.95 for the 40 group
- Age plus Charlson index: HR 1.15 for the 50 group versus 0.97 for the 40 group
- All three factors: HR 1.07 for the 50 group versus 0.97 for the 40 group
But people 50 and older had a higher risk of rebound to more than 1000 copies/mL 2 years after going under 500 copies/mL in all four models:
- Only age: HR 0.88 for 50 group versus 0.81 for 40 group
- Age plus adherence: HR 0.92 for the 50 group versus 0.79 for the 40 group
- Age plus Charlson index: HR 0.87 for the 50 group versus 0.81 for the 40 group
- All three factors: HR 0.83 for the 50 group versus 0.75 for the 40 group
Compared with 40-to-49-year-olds, people 50 or older regained CD4 cells more slowly after starting HAART. But statistical analysis by all four models described above found no difference in chances of CD4 gains through 6 years of follow-up. The Kaiser team figured that stricter regimen adherence in the 50-plus group accounted for their better early virologic response and helped explain how they pulled even with the younger group in CD4 gains.
Michael Silverberg and Kaiser colleagues urged close monitoring of older people starting triple therapy to make sure tight adherence gives them a good shot at a durable response.
References
1. Silverberg M, Leyden W, Horberg M, et al. Older age, therapy adherence, comorbidities and variable response to antiretrovirals. XVI International AIDS Conference. August 13-18. Toronto. Abstract TUPE0135.
2. According to wikipedia.org, the Charlson comorbidity index predicts 1-year mortality in people with an array of conditions such as heart disease, AIDS, and cancer. Charlson ME, Pompei P, Ales KL, McKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373-383.
|
| |
|
|
|
|
|
