Early in the HIV epidemic, researchers established an independent link between severe malnutrition and mortality among HIV-infected individuals. Death was found to occur, on average, when body weight fell below 66 percent of the ideal body weight (IBW) or when lean body mass (LBM) fell below 54 percent of the norm (Kotler et al., 1989
). Today, advances in understanding and treatment of HIV have markedly lowered the frequency of severe malnutrition in populations with access to highly active antiretroviral therapy (HAART). For example, data from the Adult and Adolescent HIV Disease Project indicate that the incidence of HIV wasting syndrome, as defined by the Centers for Disease Control and Prevention (CDC), declined from30.2 to 11.9 cases per 1,000 person-years of infection between 1992 and 1999, with most of the drop occurring after the introduction of HAART in late 1995 (Dworkin, Williamson, and Adult/Adolescent Spectrum of HIV Disease Project, 2003
). This progress notwithstanding, unintentional weight loss and wasting continue to contribute tomorbidity and mortality in the HIV-infected population. One study found that a drop of 5 to 10 percent from the patient’s initial body weight quadrupled his or her risk of death (Tang et al., 2002
). Conversely, in a cohort of HIV-positive women, none of whom were on HAART at baseline and almost half of whom had a history of injection drug use, a higher body mass index (BMI) and increases in BMI were associated with a decreased risk of disease progression (Jones et al., 2003
The most widely used standard for identifying individuals with HIV whose condition warrants nutritional or medical intervention to increase weight or body mass is the CDC AIDS surveillance case definition for wasting: profound involuntary weight loss of more than 10 percent of baseline body weight plus either chronic diarrhea (at least two loose stools per day for 30 days or more) or chronic weakness and documented fever (constant or intermittent for 30 days or more) in the absence of a concurrent illness or other condition that might cause such symptoms (e.g., cancer, tuberculosis, cryptosporidiosis, or other specific enteritis) (Centers for Disease Control and Prevention, 1987
A Department of Health and Human Services Working Group has suggested expanding the diagnosis of wasting to also include patients who weigh less than 90 percent of their IBW (or have a BMI less than 18.5), have lost more than 10 percent of their pre-illness maximum weight, or have experienced weight loss of more than 5 percent in the previous 6 months (Grinspoon, Mulligan, and Department of Health and Human Services Working Group on the Prevention and Treatment of Wasting and Weight Loss, 2003
). The aim of the proposed changes is to identify at-risk patients sooner, especially in light of evidence that HAART has altered the characteristics of wasting in ways that render the CDC definition a less sensitive predictor of nutritional risk. For example, the Multicenter AIDS Cohort Study of 5,622 men in Baltimore, Chicago, Los Angeles, and Pittsburgh found that patients reported diarrhea as frequently in the HAART era as before, but experienced less anemia, fever, fatigue, and thrush (Smit et al., 2002
). Using three of the newly proposed criteria—weight less than 90 percent of IBW, or a BMI less than 18.5, and weight loss of more than 10 percent—Campa and colleagues (2005)
found an 18 percent prevalence of wasting among 119 HIV-infected IDUs.
ETIOLOGY OF WASTING AND WEIGHT LOSS IN HIV-INFECTED INJECTION DRUG USERS
Decreased dietary intake related to abdominal pain, anorexia, chaotic lifestyle, dementia, depression, diarrhea, esophagitis, fatigue, food insecurity, mouth sores, nausea, and vomiting.
Malabsorption related to antibiotic-induced alterations in intestinal flora, enteropathy, HIV-induced mucosal changes, Kaposi’s sarcoma, medication effects on absorption of specific nutrients, and opportunistic gastrointestinal infections.
Altered metabolism related to drug effects (e.g., from cocaine), fever or cytokine-induced increase in basal metabolic rate, hormonal deficiencies, increased lean body mass breakdown, and medication (HAART) effects on metabolism.
Reviews of wasting and malnutrition in HIV-positive IDUs indicate that the causes are multifactorial and may be secondary to decreased dietary intake, malabsorption, or increased resting energy expenditure (see Etiology of Wasting and Weight Loss in HIV-Infected Injection Drug Users
) (Mangili et al., 2006
; Smit and Tang, 2000
). Injection drug use promotes each of these factors independently of HIV. In one study among Hispanic HIV- negative women, IDUs reported more food insecurity, fewer meals per week, lower intake of vegetables and fish, and more ingestion of sweets and fried foods than non-IDUs from the same relatively low socioeconomic stratum (Himmelgreen et al., 1998
) (). The IDUs registered lower scores in all anthropometric measures except height.
Injection Drug Use and Levels of Food Insecurity
The combined impact of HIV and injection drug use on weight loss and wasting appears synergistic. The inadequate nutrient intake associated with chronic drug use leads to decreased nutritional status and impaired immunity. In turn, weakened immunity allows viral loads to increase, leading to more frequent secondary infections. New infections increase nutritional needs, further widening the gap between nutritional requirements and attainment. Several studies suggest that HIV and injection drug use together exert amore deleterious effect on weight and body mass than either alone:
- Smit and colleagues (1996) surveyed 107 IDUs and found that those who were HIV-positive had a higher prevalence of involuntary weight loss than those who were HIV-negative, even though their self-reported intakes of macro- and micronutrients and calories were higher and exceeded estimated needs.
- Studies of Hispanics in the Bienestar cohort (n = 285) disclosed that HIV-positive IDUs had lower BMIs than HIV-positive non-IDUs (Forrester, Tucker, and Gorbach, 2004, 2005). Use of cocaine and concurrent use of cocaine and opiates were both associated with weight loss over time, while use of other illicit drugs was associated with weight stability. Infection with HIV or hepatitis, intestinal malabsorption, resting energy expenditure, diet and physical activity, as measured in these studies, did not explain the observed differences in weight and BMI. Studies are needed to evaluate more precisely how different illicit drugs affect metabolism and whether they have a role in wasting.
- A study using data from the Nutrition for Healthy Living (NFHL) cohort found that injection drug use predicted lower BMI and fat mass among HIV-positive women, but not men (Forrester et al., 2000). Both male and female IDUs in this study reported adequate dietary energy intake, on average, although male IDUs’ intakes of iron and zinc were significantly lower than those of male non-IDUs.
Several other reports from the NFHL cohort shed additional light on HIV-positive IDUs’ diets. Woods and colleagues (2002)
linked injection drug use to greater dietary vulnerability among HIV-positive women in the sample; overall, 25 to 35 percent of infected women, half of whom were drug users, reported intakes below 75 percent of the recommended dietary allowance for key micronutrients. Woods also found that dietary intake increased as weight and CD4 cell count decreased, perhaps because individuals needed more nutrients to maintain weight as their disease progressed. Another analysis (Kim et al., 2001
) revealed that 36 percent of the NFHL cohort met formal assessment criteria for food insecurity as defined by Radimer, Olson, and Campbell (1990
; see U.S.D.A. Food Security Survey
) and that an additional 8 percent described themselves as persistently hungry. IDUs consumed less energy than nonusers, and dietary inadequacy correlated with lifestyle and behavioral factors (Kim et al., 2001
). Minorities, subjects without an adult caregiver, subjects with dependent children, and those without food shopping assistance had less adequate diets.
Data from other studies also indicate that lifestyle and socioeconomic issues contribute to the nutritional vulnerability of IDUs with HIV. Food insecurity and viral load were independent predictors of wasting in HIV-positive IDUs in a study that also identified heavy alcohol consumption, heavy cocaine use, and inability to hold a job as contributors to the syndrome (Campa et al., 2005
). HIV infection also has been independently associated with food insecurity; in a Canadian study, the problem was five times as prevalent among HIV-positive individuals as in the general population (Normén et al., 2005
). The impact of lifestyle and socioeconomic factors on HIV-related care, including adherence to HAART, is likely important but has not been well studied.