Examining participant characteristics according to food security status, a significantly higher proportion of women and individuals of aboriginal descent were food insecure. Food insecurity was also significantly associated with lower median ages, lower median CD4 cell counts, and higher viral loads, fewer years on HAART, history of injection drug use, history of enrollment in an alcohol or drug treatment program, lower education, and unstable housing (Table 1). In addition, 29% of individuals who were food insecure were non-adherent with their HAART regimens compared with 16% of individuals who were food secure (P < 0.001). Nineteen percent of individuals who were food insecure died by nonaccidental deaths, compared with 9% of individuals who were food secure (P < 0.001).
Although malnutrition has been found to be associated with mortality for individuals both on and off HAART in both developed and developing countries,39-47 no previous studies to our knowledge have examined the association between food insecurity and mortality. We found that HAART-treated individuals who were food insecure were significantly more likely to die of nonaccidental deaths compared with individuals who were not food insecure. The very high prevalence of food insecurity in our study sample (48%) has been previously reported in this population,16 and suggests that the negative impacts of food insecurity on health outcomes may be experienced by a large proportion of urban poor HIV-infected individuals. These results are also consistent with our previous work in San Francisco, where we found that 49% of HIV-infected individuals on HAART were food insecure and that food insecurity was significantly associated with incomplete viral load suppression among homeless and marginally housed individuals.27 Taken together, these results argue that food insecurity should be an important target for intervention for HIV-infected individuals on HAART to improve clinical outcomes and decrease mortality. Our findings support recommendations by the World Health Organization, the Joint United Nations Programme on HIV/AIDS, and the World Food Program that food assistance should be integrated into HIV AIDS programming where possible.48-50 Although these recommendations are typically aimed at underresourced settings, our findings suggest that targeted food supplementation coupled with other measures to alleviate poverty should also be a priority among urban poor HIV-infected individuals in well-resourced settings.
Another key finding was that BMI modified associations between food insecurity and mortality in that the effects of food insecurity on mortality were most pronounced among individuals who were also underweight. There is a rich body of literature examining the impacts of malnutrition on HIV clinical, immunological, and virological outcomes. Studies from both westernized and developing settings have shown that malnutrition, measured by low BMI and low albumin, hastens progression to immunologic decline, opportunistic infections, AIDS, and death in untreated individuals.39-43,51-56 In terms of the impact of malnutrition on HIV outcomes for patients on HAART, Tang et al44 has shown that loss of weight and of lean body mass remain independent predictors of mortality in the HAART era among patients in Massachussets. Similarly, studies from westernized settings have found associations between weight loss or low BMI and higher HIV RNA levels.57,58 Negative impacts of poor nutritional status have also been shown in sub-Saharan Africa, where several studies reported that low BMI and low hemoglobin were predictive of mortality, especially in the early phases of HAART initiation.45-47 Our findings, coupled with those of others, suggests that interventions using targeted food supplementation or sustainable food production strategies may have the most benefit among individuals who are both food insecure and underweight.
It is interesting that associations between low BMI and mortality in this study were not seen among individuals who were food secure and that there was a trend toward increased risk of mortality among individuals who were food insecure but not underweight. This suggests that associations seen between nutritional status and mortality among HAART-treated individuals in other studies may be mediated to some extent by food insecurity. It also suggests that the adverse impact of food insecurity on mortality may be explained in part by mechanisms other than poor nutritional status. In terms of possible additional biologic mechanisms to explain associations between food insecurity and mortality, food insecurity may also impede optimal absorption of certain ARV drugs, which may contribute to treatment failure, progression to AIDS and death. For instance, several protease inhibitors such as nelfinavir and ritonavir require food for maximal absorption, and the absence of food may negatively affect the pharmacokinetics of these drugs.59-61
As for behavioral mechanisms, we found that food insecurity was significantly associated with ARV adherence at baseline, so it is likely that lower adherence to HAART may have contributed to negative clinical impacts of food insecurity. Because we did not collect longitudinal data on food insecurity, we were unable to better explore interactions between food insecurity and adherence over time and how they may have affected mortality. Other studies have also found associations between food insecurity and HAART nonadherence. A number of qualitative and small quantitative studies have reported that food insecurity is an important barrier to HAART adherence in underresourced settings.62-64 Similarly, in a study among nearly 5000 HIV-infected individuals in France, food privation was associated with increased odds of HAART nonadherence among heterosexual men and a trend toward increased odds of nonadherence among heterosexual women.65 Associations between food insecurity and nonadherence have also been reported for other diseases such as tuberculosis.66,67 More studies are needed to better understand the role of HAART nonadherence and treatment interruptions in mediating the negative clinical impacts of food insecurity.
Food insecurity was strongly associated with both baseline drug and alcohol use and with markers of socioeconomic status such as low income, lower education, and unstable housing. Although these factors were controlled for in our confounder models, socioeconomic status is a complex concept that may not be adequately captured by income, education, and housing status, and we did not evaluate all drugs of abuse. Consequently, it is possible that low socioeconomic status and drug abuse may in part account for associations seen between food insecurity and mortality. In addition, other studies have found associations between food insecurity and depression,17,18,20 and depression is well known to be associated with worse clinical outcomes and mortality among individuals on HAART.68 Consequently, it is possible that depression and other mental illnesses may also be on the causal pathway between food insecurity and poor health outcomes.
There were a number of other important limitations that may affect interpretation of our results. As previously mentioned, we did not gather longitudinal data on food insecurity and so were unable to better assess interactions between food insecurity, BMI, adherence, and viral load suppression over time to better understand mechanisms for how food insecurity may impact upon mortality. In addition, we did not use more comprehensive measures of nutritional status such as anthropometry, lab markers of overall nutrition, nutrient assays, and body composition measures. Future studies should use more rigorous measures of nutritional status in further exploring interactions between food insecurity, nutritional status, and clinical outcomes. Few patients were HAART naive at the time of the food security interview, and it is likely that the impacts of food insecurity on clinical outcomes and mortality may be different among people first initiating HAART. Finally, as with all observational studies, bias is inherent due to uncontrolled confounders.
In conclusion, we found that nearly half of HAART-treated patients from the British Columbia HIV Drug Treatment Program were food insecure and that food insecurity strongly and significantly increased the likelihood of mortality. The effect of food insecurity on mortality was most pronounced in individuals who were also underweight. Addressing food insecurity and relieving hunger among the urban poor is an important goal by itself to improve quality of life and overall health. The potential impact of food support on mortality for HIV-infected individuals on HAART provides additional rationale for meeting broad needs, including food provisions, for urban poor individuals living with HIV/AIDS. Novel interventions to alleviate food insecurity and poverty among urban poor individuals in resource-rich settings are needed to avoid clinical deterioration and excess mortality. Toward this goal, clinicians caring for HIV-infected individuals may consider working in multidisciplinary teams that include both case managers and nutritionists. These teams can screen individuals for food insecurity and poor nutritional status, inquire about barriers to food access, and help individuals who are food insecure identify reliable sources of good quality food in their communities.
We would like to thank Svetlana Draskovic for administrative assistance and Keith Chan for statistical support.
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