November 9, 2009 (Philadelphia, Pennsylvania) — A natural history study of people with HIV has found that obesity has a negative effect on immunity. Obese patients with HIV treated with highly active antiretroviral therapy (HAART) gained fewer CD4 cells compared with their nonobese counterparts.
"This study, as well as other findings, suggests that we should look at HIV patients' body mass index [BMI] and encourage those who are overweight or obese to achieve and maintain normal weight. This is prudent for overall health, for cardiovascular health, for cancer prevention, and now we see it's prudent for the immune system," said lead author Nancy Crum-Cianflone, MD, Infectious Disease Clinical Research Program, San Diego, California. She presented her findings here at the 47th Annual Meeting of the Infectious Diseases Society of America (IDSA).
While at the Infectious Disease Clinical Research Program of the National Institutes of Health in Bethesda, Maryland, Dr. Crum-Cianflone and colleagues initiated the study after noticing a growing trend toward obesity and weight gain among the HIV patients they were treating. "In the HAART era, wasting has become less common and patients are increasingly overweight or obese," she noted. Although they were well aware of the adverse health consequences of obesity, the investigators were interested to find out whether obesity had adverse effects on the immune system, in particular, on CD4 cell counts, in patients with HIV.
The study included 1119 HIV patients followed up from date of seroconversion over time. Mean follow-up was 4.6 years (range, 1-10 years). Weight was recorded for patients diagnosed as having HIV in the pre-HAART and HAART eras to determine the effect of medication on CD4 cell count. Of the 1119 patients, 441 (39%) were overweight and 96 (9%) were obese. Mean age was 29 years, 96% were male, 41% were black, and 44% were white.
Patients were categorized according to BMI as follows: underweight, less than18 kg/m2; normal weight, 18.5 to 24.9 kg/m2; overweight, 25 to 29.9 kg/m2; and obese, 30 kg/m2 or higher. At HIV diagnosis, mean CD4 cell counts were 526, 551, 542, and 499 cells/µL, respectively, for the 4 different weight groups in both the pre-HAART (1986-1995) and HAART (1996-2008) eras. Patients showed fewer CD4 cell count increases with increasing BMI.
For those whose HIV was diagnosed in the pre-HAART era, the mean postdiagnosis decrease in CD4 cell count was less as BMI category increased: –158, –125, –95, and –50 cells/µL, respectively (P < .001). Compared with normal weight persons, those who were overweight and obese had smaller reductions in CD4 cell count over time (P = .005 and P < .001, respectively).
"This finding is consistent with lower weight, in the absence of HAART, being associated with faster-progression of HIV and death," Dr. Crum-Cianflone said.
In the HAART era, she announced, excessive weight was no longer beneficial. For those whose HIV was diagnosed in the HAART era, the mean postdiagnosis change in CD4 cell count was −1, +103, +116, and +69 cells/µL, respectively, for the 4 BMI groups (P < .001). Obese patients had significantly smaller increases in CD4 cell count compared with normal weight patients: 69 vs 103 cells/µL (P = .01). Obese HIV patients also gained fewer CD4 cells after HAART initiation than overweight patients (a mean of 43 fewer cells, P = .005). No significant difference was found in gain of CD4 cells after HAART initiation between normal weight and overweight persons.
HIV Patients at Increased Cardiovascular Risk
These findings about the effect of obesity on immunity are in line with what is known about patients with HIV infection, explained Kenneth Mayer, MD, cochair of the IDSA Center for Global Health Policy's Scientific Advisory Committee and professor of medicine at Brown University in Providence, Rhode Island.
"They have increased cardiovascular risk from the disease itself and from the antiretroviral medications as well. Clinicians who treat patients with HIV should encourage them to attend to modifiable lifestyle factors, including weight, tobacco use, alcohol consumption, and exercise. Monitoring of patients with a chronic infectious disease such as HIV should include diet and weight control," he said.
Dr. Crum-Cianflone has disclosed no relevant financial relationships. Dr. Mayer disclosed financial ties with Gilead and Merck.
Infectious Diseases Society of America (IDSA) 47th Annual Meeting: Abstract 342. Presented October 30, 2009.
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