Underweight and Obese Individuals Experience Smaller CD4 Cell Gains on Antiretroviral Therapy

		SUMMARY: Before the advent of highly active antiretroviral therapy (HAART), people with a high body mass index (BMI) experienced less CD4 cell loss than lighter weight individuals, but in the HAART era, both being underweight and obesity were associated with poorer CD4 cell recovery after starting treatment, according to a study presented at the recent 47th Annual Meeting of the Infectious Diseases Society of America (IDSA 2009) in Philadelphia.

By Liz Highleyman

As people with HIV stay healthier and live longer thanks to effective therapy, the proportion classified as obese has increased -- as it has in the U.S. general population. It is well known that excess weight contributes to a host of medical problems including cardiovascular diseased and diabetes, but its effect on CD4 count and immunological recovery is not well understood.

To explore this issue, Nancy Crum-Cianflone from the Infectious Disease Clinical Research Program and colleagues estimated the association between BMI and changes in CD4 counts from the time of HIV diagnosis onward using longitudinal models adjusted for demographic and HIV-related variables.

The study included 1119 documented HIV seroconverters (average window of infection 16 months) in a prospective natural history study during 1986-2008. Almost all (96%) were men, 44% were white, 41% were African-American, and the mean age was 29 years. Participants were followed for an average of nearly 5 years.

BMI was categorized as underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), or obese (>30 kg/m2). At the time of HIV diagnosis, 441 participants (39%) were overweight and 96 (9%) were obese.

Results

	Mean CD4 counts at the time of HIV diagnosis were statistically similar regardless of body weight (P = 0.31):
	Underweight individuals: 526 cells/mm3; Normal weight individuals: 551 cells/mm3; Overweight individuals: 542 cells/mm3; Obese individuals: 499 cells/mm3.
	Baseline CD4 results were similar during the pre-HAART and HAART eras.
	In the longitudinal models for participants diagnosed in the pre-HAART era, the mean decrease in CD4 count after diagnosis was significantly less as BMI increased (P < 0.001):
	Underweight individuals: -158 cells/mm3; Normal weight individuals: -125 cells/mm3; Overweight individuals: -95 cells/mm3; Obese individuals: -50 cells/mm3.
	Among participant diagnosed during the ART era, the mean change in CD4 count after diagnosis varied with body weight:
	Underweight individuals: -1 cells/mm3; Normal weight individuals: +103 cells/mm3; Overweight individuals: +116 cells/mm3; Obese individuals: +69 cells/mm3.
	Obese participants had significantly smaller increases in CD4 count compared with those of normal weight (P = 0.02).

"Although higher BMI was associated with less reduction in CD4 counts over time in the pre-HAART era, excessive weight was not similarly associated with benefit in the HAART era," the study authors concluded. "Being either underweight or obese in the HAART era was associated with smaller CD4 count rises. These data suggest that lower CD4 counts may be another adverse consequence of obesity."

Infectious Disease Clinical Research Program, Bethesda, MD.

11/10/09

Reference
NF Crum-Cianflone, M Roediger, and LE Eberly. Obesity among HIV-Infected Persons: Impact of Weight on CD4 Cell Counts. 47th Annual Meeting of the Infectious Diseases Society of America (IDSA 2009). Philadelphia, PA. October 29-November 1, 2009. Abstract 052-HIV.