Among this HIV-infected cohort, concurrent MI and DU was associated with a lower odds of viral suppression compared to those with either MI or DU alone, or those with neither, suggesting that co-occurring substance use and MI are a significant barrier to positive treatment outcomes among HIV-infected individuals. The finding that MI alone was not significantly associated with lower HAART receipt or viral suppression suggests that a diagnosis of MI among individuals engaged in care should not impede appropriate treatment of HIV.
Our finding of decreased HAART receipt among individuals with co-occurring DU and MI is consistent with an earlier study in the HIVRN (Himelhoch et al., 2007
). Using data from four HIVRN sites in 2001, Himelhoch and colleagues also found that patients with either DU or both DU and SMI were less likely to receive HAART than those with neither DU nor MI. Similar to our results, they found that patients with MI alone were not significantly less likely to receive HAART compared to those with neither MI nor DU.
In contrast to a recent study among HIV-infected women (15), we did not find an interaction between DU and MI suppressing HAART use. Cook and colleagues, using data from the Women’s Interagency HIV Study (WIHS) examined the interaction of DU and depressive symptoms on the likelihood of HAART receipt among 1710 women. They found that probable depression plus crack, cocaine or heroin use was associated with 51% decrease in their odds of receiving HAART compared to those with neither. Moreover, they found that the effects of depression interacted with DU to suppress the initiation of HAART over time. There are several reasons our results may differ from the WIHS cohort. First, we did not limit our sample to women, and a previous study in both men and women did not find an interaction between MI and DU and HAART use (Turner et al., 2001
). In addition, MI was defined more broadly and classified by a medical record diagnosis in our study, while the WIHS cohort used a depression symptom scale. Thus individuals in the HIVRN with a diagnosis of MI may have been more likely to be in care for their MI.
Individuals with concurrent MI and DU had decreased odds of viral suppression compared to those with MI alone and those with neither MI nor DU, which is consistent with mental health literature describing worse treatment outcomes in individuals with concurrent MI and DU compared to those with MI alone (Akincigil et al., 2007
; Buckley, 2006
; Drake & Wallach, 1989
; Olfson et al., 2000
; Watkins, Paddock, Zhang, & Wells, 2006
; Wilk et al., 2006
). Similarly, we found that HAART use and viral suppression was lower among those with MI and DU compared to DU only. Among DUs psychiatric illness has been found to be a barrier to HAART access and adherence (Wood, Kerr, Tyndall, & Montaner, 2008
We limited our analysis of viral suppression to only those individuals receiving HAART. Part of the effect of MI and DU on viral suppression operates through affecting who receives HAART. MI and DU have an indirect effect on viral suppression by reducing the likelihood of receiving HAART in the first place. Thus, limiting the analysis of suppression to those on HAART likely underestimates the total effect of MI and DU.
MI independent of DU was not associated with decreased HAART receipt or viral suppression. That persons with MI alone did not differ in HAART receipt from those with neither MI nor DU is consistent with the WIHS study, where women with depression were as likely to receive HAART compared to those without depression (Cook et al., 2007
). Similarly, Himelhoch et al., using 2001 data from the HIVRN, found that SMI alone was not significantly associated with decreased HAART compared to neither SMI nor DU (Himelhoch et al., 2007
). However, our finding of no difference in viral suppression among those with MI only compared to those with neither MI nor DU is in contrast to current literature focusing on HIV-infected individuals with depression (Anastos et al., 2005
; Li et al., 2005
; Parienti et al., 2004
; Pence, Miller, Gaynes, & Eron, 2007
). Pence and colleagues recently demonstrated delayed virological suppression among individuals with a higher probability of depression (Pence, Miller, Gaynes, & Eron, 2007
). One possible explanation for the difference in viral suppression between our study and others may be level of engagement in care. MI diagnoses were made by practitioners within the clinical settings, which may be reflective of a high level of engagement in care and perhaps adherence among those with MI only.
Our finding of lower viral suppression among those with DU is consistent with the current literature on viral suppression among HIV-infected DUs (Lucas, Gebo, Chaisson, & Moore, 2002
; Palepu et al., 2003
; Wood et al., 2003
). Wood and colleagues, longitudinally evaluating virological suppression among 1583 antiretroviral naïve individuals, 25% of whom had a history of DU, reported a 12 month cumulative suppression rate of 51% among DUs compared to 71% in non-DUs (Wood et al., 2003
). Another study reported that on-going DU was associated with a 70% decrease in viral suppression in current DUs compared to non-DUs (Palepu et al., 2003
Notably, four or greater outpatient visits was associated with increased odds of HAART use compared to those with three or fewer visits, implying greater engagement in care is associated with HAART utilization. However, when the sample was limited to individuals on HAART, seven or greater visits was associated with decreased odds of virological suppression, suggesting that very frequent visits may be secondary to viral failure and or non-adherence.
Our study has several implications. Individuals with substance abuse and MI experience several barriers that may affect their HAART uptake and response to HIV treatment, including difficulties with appointment and medication adherence, self-care, homelessness, and incarceration (Brunette & Mueser, 2006
; Compton, Weiss, West, & Kaslow, 2005
; Drake & Wallach, 1989
; Hurlburt, Hough, & Wood, 1996
). Consequently, interventions targeted toward the special needs of this population may be necessary. One such intervention that has been put forward in the literature is integrated HIV care, which has been described by Soto, Bell, and Pillen, et al. as follows: “Integrated HIV care combines HIV primary care with mental health and substance abuse services into a single coordinated treatment program that simultaneously, rather than in parallel or sequential fashion, addresses the clinical complexities associated with having multiple needs and conditions” (Soto et al., 2004
). The literature on integrated care among this population is limited. However, simultaneously addressing psychiatric, substance use, HIV and psychosocial issues, using a multidisciplinary collaborative approach may result in better clinical outcomes in this population.
Limitations of our study include its cross-sectional design. Because this is a cross-sectional study, we cannot assess the directionality of the association between co-occurring MI and DU and viral suppression. Our study is also limited by the lack of a measure of adherence; thus, we could not assess if inadequate medication adherence accounted for the decreased viral suppression among those with MI and/or DU. In addition, it is possible that there was undiagnosed MI and substance use in this sample, leading to some misclassification of individuals in this study. In addition, years in clinical care may be an underestimate as our definition included years in care at an HIVRN site, and it is possible an individual received treatment at a different site prior to switching to an HIVRN site. In addition, the HIVRN sample is not nationally representative and does not generalize to all HIV care sites. The sites in the HIVRN were all highly experienced in the treatment of HIV with high rates of HAART use (Gebo et al., 2005
) and opportunistic infection prophylaxis (Gebo, Fleishman, Reilly, & Moore, 2005
); results may differ at sites with less provider experience with HIV or a smaller caseload of patients with HIV. Finally, not all of the sites in the HIVRN collect comprehensive mental health and utilization data; therefore we were only able to include seven of the 19 adult sites in the Network. Although patients in these seven sites were similar to patients in the excluded sites in terms of demographic characteristics, differences in other (unmeasured) characteristics could limit generalizeability.
In summary, we found that the concurrent MI and DU was associated with decreased HAART receipt and virological suppression among HIV-infected individuals compared to those with either MI or DU or neither. These data suggest that targeted interventions incorporating integrated substance abuse, psychiatric, and HIV care among HIV-infected individuals may be useful in improving HIV treatment outcomes, but longitudinal studies are needed to accurately assess whether concurrent MI and DU is a risk factor for low HAART uptake and viral suppression.