The association of social network factors with healthcare use and outcomes among persons who inject drugs in Baltimore, Maryland
Sacamano, Paul L
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Background The prevalence of past year injection drug use has been estimated to be 15.6 million adults globally and 2.6 million in North America. Persons who inject drugs (PWID) are disproportionately burdened with a high prevalence of health and socioeconomic disparities and barriers to care. High rates of emergency department (ED) use among PWID indicate disparities in access to and use of primary care. The National Institute of Drug Abuse domestic research funding priorities include eliminating disparities in the HIV continuum of care for persons who use substances. Further, the National HIV/AIDS Strategy has set a goal to increase the number of PLWH with HIV viral suppression. While social network factors are known to influence health behaviors, it is not known how social networks may differ between PWID with current or former injection drug use and most studies do not focus on the very close ties that may be the most influential on health behaviors. Objectives The goal of this study is to characterize the social support available to PWID from their closest network members and determine associations of social network factors with HIV viral suppression and emergency department (ED) use. Methods We developed a social network survey to gather network characteristics among PWID participating in the AIDS Linked to the IntraVenous Experience (ALIVE) study in Baltimore, Maryland. The interviews were conducted from April 1, 2016 to June 30, 2017. Egocentric social network data were derived from participant report about their network members’ attributes and relationship characteristics. Emotional, instrumental and informational support constructs were based on responses to seven support indicator questions. Latent class analysis was implemented with a multilevel approach based on the probabilities for each of the social support indicators. Associations with class membership were identified through multinomial logistic regression. The types of social support and the sources of support from different types of alters within ego-networks then became the primary exposures of interest in determining associations with emergency department use categorized as none, one or two or more visits in the prior six months use for the entire sample and with HIV RNA <50 at the last visit among PWID living with HIV. Results Data were available from 970 participants who completed the social network survey. Persons with injection drug use within the previous 12 months had smaller networks of close ties that were more likely to include a partner compared to persons with more remote injection drug use. Based on model fit statistics and in the interest of model interpretability and parsimony, the three-class model was selected: 1) Moderate support: probabilities of support were below 0.40; 2) High support: probabilities of support ranged from 0.58 to 0.82; 3) Very high support: probabilities of support ranged from 0.91 to 0.99. Compared to moderate support, the odds of membership in the very high support class was greater with each increasing mean year age of alters and lower with less than three very close network members and each additional network member who ever injected drugs. Compared to the moderate class of support, greater odds of membership in the high support class were observed with each additional alter with daily contact and lower odds with each additional alter that ever used non-injection drugs. For the entire sample, compared to no ED visits in the prior six months, the odds of having one ED visit were lower for participants having informational support (AOR: 0.64; 95% CI: 0.41, 1.00) and the odds of two or more visits were lower for participants having a partner (AOR: 0.56; 95% CI: 0.35, 0.90). For PWID living with HIV, the key social network factor associated with HIV viral suppression was having at least one HIV-positive alter (AOR: 2.02; 95% CI: 1.12, 3.64). Conclusions There were high levels of perceived support overall from the closest network ties, while the highest level of support was less likely with current non-injection drug use by participants or ever injection drug use by network members. It is both the type of support -- informational -- and sources of support -- partners and HIV-positive alters -- that represent opportunities for network level interventions that aim to improve health outcomes and promote optimal use of healthcare resources among PWID.