Outpatient Parenteral Antimicrobial Therapy in Vulnerable Populations—People Who Inject Drugs and the Homeless
Outpatient parenteral antimicrobial therapy (OPAT) programs can provide high-value care but may be challenging in people who inject drugs (PWID) and homeless individuals. We conducted a single-center, retrospective, cohort study of adults who received OPAT at an urban, public health hospital from January 1, 2015 to April 30, 2016, grouped by PWID and housing status. Outcomes included clinical cure, length of stay, secondary bacteremia, line-tampering, and readmission. A total of 596 patients (homeless PWID (9%), housed PWID (8%), homeless non-PWID (8%), and housed non-PWID (75%), received OPAT. Assuming that patients lost to follow-up failed therapy, homeless PWID were least likely to achieve cure compared with housed non-PWID, (odds ratio [OR] = 0.33, 95% CI 0.18-0.59; P < .001). Housed PWID were also less likely to achieve cure (OR = 0.37, 95% CI 0.20-0.67; P = .001). Cure rates did not differ in patients not lost to follow-up. OPAT can be effective in PWID and the homeless, but loss to follow-up is a significant barrier.
© 2019 Society of Hospital Medicine
DISCUSSION
Our study compares the outcomes of 596 OPAT patients, including PWID and the homeless. Among those retained in care, PWID achieved similar rates of cure compared with non-PWID groups. When assuming that all lost to follow-up had poor outcomes, the cure rates were markedly lower for PWID, with no difference noted by housing status.
Data on PWID and homeless enrolled in OPAT programs are limited.5,11,12 Few studies have reported the outcomes of infections in PWID and the homeless, as these populations often experience significant loss to follow-up due to transiency, lack of care continuity, and effective means of communication.
Cure was achieved in less than half of PWID, when lack of cure was assumed for unknown outcomes. This rate was substantially less than that for non-PWID groups. The assumption that those lost to follow-up did not achieve cure dramatically alters the inference; the truth may lie somewhere between the primary and sensitivity analyses. Homeless PWID remained at the highest risk for lost to follow-up, secondary bacteremia, line-tampering, and 30-day readmission related to OPAT.
PWID have traditionally been considered as a high-risk group for OPAT,1,2,8 but to completely restrict PWID from OPAT may not be appropriate. Ho et al. studied 29 PWID who were selectively enrolled to receive OPAT, and 28 completed IV therapy without any instances of line-tampering, death, or unknown clinical status.6 Recent literature suggests that some candidates can succeed with OPAT, despite drug use.13,14
Homelessness is also considered a barrier to OPAT.1,8 Medical respite is a harm-reduction model implemented for patients who require subacute care.9 In our study, among homeless patients, PWID status was the primary determinant of whether therapy was successful, rather than respite care.
Our study may have limited generalizability to other populations. We are a single-center facility in a large, urban city. PWID and housing status were self-reported but were verified before discharge. Most of our patients were men and white; thus, outcomes may differ for others. Due to the nature of the data, cost effectiveness could not be directly calculated. LOS and readmissions serve as proxy measures.
When patients remain engaged in care, PWID and the homeless achieved comparable clinical cure rates to those of housed non-PWID. Moving forward, OPAT can be more effective in PWID and the homeless with careful patient selection and close clinical support. Access to medication-assisted therapy, such as methadone or buprenorphine,15 may improve follow-up rates and linkage to outpatient care. Additional treatment strategies to improve retention in and adherence to care may promote successful outcomes in these vulnerable populations.
Disclosures
Presented at the Poster Abstract Session: Clinical Practice Issues at ID Week, October 26–30, 2016, New Orleans, LA. No conflicts of interested related to this work for all authors.
Funding
AW and AM received NIH NIAID grant K24 AI 071113-06 and UW Medicine Patient Safety Innovations Program Grant.
