Greater increases in total, HDL, and non-HDL cholesterol were seen with ddI/d4T compared with ZDV/3TC, while triglycerides were similar (Fig. 3b). There was no evidence for an interaction of the effect of nelfinavir or efavirenz assignment with the effect of the NRTI assignment for any glucose or lipid outcome. There were no between-arm differences in the proportion of subjects at week 64 with total cholesterol > 200 mg/dl, LDL cholesterol > 130 mg/dl, or triglycerides > 200 mg/dl (data not shown). Four subjects assigned to ddI/d4T and six assigned to ZDV/3TC started lipid-lowering drugs during the 64 weeks.
Subjects who had DEXA scans had similar baseline characteristics compared with the whole study population (data not shown).
At week 64, subjects assigned to nelfinavir had lost 13.1% (IQR, −30.2 to 6.1) of limb fat from baseline compared with an increase of 1.8% (IQR −21.2 to 31.1) with efavirenz. The time pattern was significantly different between groups (MMANOVA, P = 0.003). When the analysis was limited only to those subjects remaining on their original treatment arm assignment, the limb fat loss with nelfinavir was similar in magnitude but did not achieve statistical significance (MMANOVA, P = 0.053). Using logistic regression modeling to predict limb fat loss of at least 10% from baseline, after adjustment for age, sex, race/ethnicity, baseline BMI, log HIV RNA, CD4 cell count, and NRTI assignment, there was some evidence that the effect of assignment to nelfinavir or efavirenz on the percentage change in limb fat from baseline was important (P = 0.06).
This prospective metabolic and body composition study nested in a large randomized trial of potent antiretroviral regimens demonstrates clear differences between the tendency of particular antiretroviral drug-containing regimens to induce limb fat loss compared with baseline measurements. When combined with a protease inhibitor (nelfinavir), an NNRTI (efavirenz), or both, assignment to the combination of ddI/d4T was associated with greater loss of limb fat than was the combination of ZDV/3TC. When combined with dual NRTI, assignment to the protease inhibitor nelfinavir was associated with greater loss of limb fat than was the NNRTI efavirenz, although the magnitude of the difference was smaller than that with the NRTI drugs and the on-treatment analysis did not reach statistical significance. Contrary to our expectations, use of nelfinavir in combination with a pair of NRTI did not induce greater insulin resistance or dyslipidemia than use of efavirenz.
The use of antiretroviral therapy that includes protease inhibitors has been associated with new-onset diabetes mellitus [1,2,20] and insulin resistance [3–5,7,21,22]. However, indinavir is the only protease inhibitor clearly associated with early (within 8 weeks or less) reduction of insulin sensitivity [21–23], likely in part via inhibition of the function of the insulin-sensitive glucose transporter GLUT4 [24,25]. There is human clinical evidence that amprenavir  and atazanavir [27,28] do not cause early insulin resistance, while conflicting data exist for lopinavir–ritonavir [28,29]. There was no evidence of an effect on insulin sensitivity in this study with nelfinavir at 8 weeks, suggesting that an early, direct effect on insulin resistance also does not occur with this particular protease inhibitor.
Lipid measures, including total and non-HDL cholesterol and triglycerides, increased comparably with both nelfinavir- and efavirenz-based treatment. Similar results have been presented in another preliminary report . Of note were the substantial increases in HDL cholesterol with both treatments (median increase of 5–7 mg/dl, or approximately 20–25%). With efavirenz, there was a modest advantage in HDL cholesterol, resulting in a more favorable total cholesterol to HDL cholesterol ratio, suggesting lesser cardiovascular risk . Non-HDL cholesterol, a risk marker that may be more predictive than LDL cholesterol for cardiovascular events , increased comparably by approximately 25 mg/dl in both groups. The net effect of these changes on long-term cardiovascular risk in patients with HIV is unknown.
Protease inhibitors may contribute to an increased risk of lipoatrophy when administered with an NRTI. In a descriptive cohort study, dual NRTI therapy plus a protease inhibitor was associated with a more rapid time to fat wasting than was dual NRTI alone . Moreover, as compared with time on nevirapine, cumulative time on protease inhibitors was associated with an increased risk of fat wasting, suggesting that protease inhibitors may accelerate the fat wasting effects of NRTI drugs . When not administered with NRTI agents, the incidence of lipoatrophy with the protease inhibitor combination ritonavir plus saquinavir was low . In the present study, we report evidence from a prospective, randomized trial of an independent effect of assignment to the protease inhibitor nelfinavir on limb fat loss, albeit an effect smaller in magnitude than the effect of assignment to ddI/d4T. Our findings are consistent with in vitro studies in which certain protease inhibitors, including nelfinavir, have been shown to inhibit adipocyte differentiation [35–37]. These results, however, may not be generalizable to all protease inhibitors. The on-treatment analysis was limited by a high frequency of treatment switching, reducing the number of subjects observed. We feel that, because lipoatrophy represents a cumulative toxicity, the on-treatment analysis (which censors subjects after a treatment arm change) is less valuable than our primary, intent-to-treat analysis.
Randomization to ddI/d4T led to a greater loss of limb fat than did ZDV/3TC. A secondary analysis that censored subjects at the time of regimen changes was also statistically significant, and there was no evidence for interaction between treatment group assignments. Many studies have linked d4T use with lipoatrophy [13,33,38,39] and substitution of other NRTI for d4T has improved lipoatrophy [40–42]. A randomized trial that compared d4T or tenofovir in combination with 3TC and efavirenz reported greater limb fat by DEXA among tenofovir recipients at weeks 96 and 144, but did not include baseline DEXA measurements  and so could not evaluate the longitudinal patterns of fat gain or loss with the different therapies. The current report from a prospective randomized study among initially antiretroviral-naive subjects using objective measures clearly links use of a particular NRTI combination with loss of limb fat over time compared with baseline values. However, our data cannot address the relative contribution of the individual components (ddI or d4T) to the observed effects. Nonetheless, it is clear that d4T contributes to lipoatrophy risk even when combined with 3TC , while the individual contribution of ddI is less certain. Because of the risk of side effects, this drug combination is no longer recommended .
A limitation of the body composition analyses in this report is the relatively short follow-up period, 64 weeks. This period was chosen to coincide with the available metabolic data, which were limited to 64 weeks. It is possible that with more extended observation, differences between treatment groups may become even greater, or they may equilibrate over time.
Unlike limb fat, trunk fat tended to remain above baseline values in all groups. Similar increases in DEXA-derived central abdominal fat have been reported in a prospective, non-randomized observational study . It is possible that the early increases in limb fat and the persistent increases in trunk fat represent a generalized ‘return-to-health’ phenomenon associated with viral suppression and immune reconstitution. This study provides evidence that the subsequent decreases in limb fat are related to use of particular antiretroviral drugs. The treatments that spared limb fat over 64 weeks (ZDV/3TC, efavirenz) were also associated with overall greater increases in trunk fat and total body fat. This may represent a generalized increase in adiposity that preferentially affects trunk fat. If such an increase reflects increased visceral fat, it is a potentially adverse consequence. DEXA scans, however, do not differentiate between visceral and subcutaneous trunk fat.
Our results illustrate the importance of prospective studies to determine the particular roles of individual antiretroviral agents and combinations in the development of metabolic and morphological complications. Extended follow-up will be necessary to define the long-term course of these complications, particularly as individuals are treated with multiple different antiretroviral agents from multiple drug classes. It will be crucial to develop new, less-toxic antiretroviral agents and combination regimens in order to minimize the cardiovascular risks associated with antiretroviral therapy [45,46] and the stigma, non-adherence [47–49], and metabolic disturbances  associated with lipodystrophy.
A5005s team members who contributed to the design and conduct of the trial were Thomas A. Buchanan (University of Southern California), Kevin Yarasheski, (Washington University, St Louis), and Jeff Taylor (ACTG Community Constituency Group representative, San Diego).
We are grateful to the subjects who volunteered for these experiments, without whom this work would not have been possible. The authors acknowledge the invaluable assistance of Gina-Bob Dubé and Kathy L. Flynn with managing the references, Lawrence A. Hirsch of Quest Diagnostics for coordinating laboratory assays, and Jodi L. Weiner, of the Friedman School of Nutrition Science and Policy at Tufts University for DEXA scan management.
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The following ACTG investigators and sites participated in this study: Barbara M. Gripshover and Kathleen Burgner (Case Western Reserve University, A2501), Ian Frank and Isabel Matozzo (University of Pennsylvania, Philadelphia, A 6201), Laura Laughlin and Diane Gochnour (Ohio State University, A2301, grant U01 AI025924); Tammy Powell and Pamposh Kaul (University of Cincinnati, A2401, grant AI25897); Debra deMarco and John Stoneman (Washington University, St Louis, A2101, grant AI25903 and RR-00036); Connie A. Funk and Kathleen E. Squires (University of Southern California, A1201, grant U01A127673); Margaret A. Fischl and Leslie Thompson (University of Miami, A0901, grant AI27675); Mitch Goldman and Helen Rominger (Indiana University Hospital, A2601, grant U01AI25859 and RR-00750); Linda Meixner and Tari Gilbert (University of California, San Diego, A0701, grant AI27670); Christine Fietzer and Kathy A. Fox (University of Minnesota, A1501), Eileen Chusid and Donna Mildvan (Beth Israel Medical Center, Mount Sinai Medical Center, New York, A1801, grant AI 46370; University of North Carolina, A3201; Howard University, A5301); Lynn Dumas (Beth Israel-Deaconess Hospital) and Betsy Adams (Boston Medical Center) (Harvard, Massachusetts General Hospital, A0101); Mallory Witt and Tomasa Maldonado (Harbor General/UCLA School of Medicine, A0601); Juan J. L. Lertora and Rebecca Clark (Tulane University, A1701, grant IU01AI3844 and GCRC grant PHS NCRR M01 RR05096); Pat Cain and Sylvia Stoudt (Stanford University, A0501; NYU/Bellevue, A0401); Harold A. Kessler and Ruth M. Davis (Rush-Presbyterian/St. Lukes, Chicago, A2702, grant UO1 AI025915); Santiago Marrero and Irma Torres (University of Puerto Rico, A5401, grant A134832-12); Diane Havlir and Jody Lawrence (San Francisco General Hospital, A0801; University of Hawaii, A5201; University of Rochester Medical Center, A1101); Clifford Gunthel and Ericka Patrick (Emory University, A5802); Michael J. Borucki and Gerianne Casey (University of Texas, Galveston, A6301, grant AI32782); Ilene Wiggins and Dorcas Baker (Johns Hopkins University, A0201, grant RR00052 and AI27668); Carol Dukes-Hamilton and Shelia Tedder (Duke University Medical Center, A1601); Valery Hughes and Todd Stroberg (Cornell University, A2201, grant AI46386); Sally Canmann and Cathi Basler (University of Colorado Health Sciences Center, Denver, A6101); Beck Royer and N. Jeanne Conley (University of Washington Seattle, A1401, grant AI27664).
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. Relationship between HAART adherence and adipose tissue alterations. J Acquir Immune Defic Syndr 2002; 31:S140–S144.