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
Outpatient parenteral antimicrobial therapy (OPAT) programs allow patients to receive antibiotic therapy at home or in other settings.1-3 Bacterial infections among people who inject drugs (PWID) and the homeless are common, leading to complicated treatment strategies. Those with opioid dependence have frequent hospitalizations.4 Bacteremia and endocarditis frequently require intravenous (IV) antibiotics5-7 and may be difficult to treat. Creating outpatient treatment plans for PWID and the homeless is challenging, and there is a paucity of data on OPAT effectiveness in these groups as they are often excluded from OPAT services.1,2,8
We evaluated treatment outcomes in PWID and the homeless in our OPAT program.
METHODS
We conducted a retrospective cohort study of hospitalized adults discharged from Harborview Medical Center (HMC) with OPAT from January 1, 2015 to April 30, 2016. HMC is a county hospital in Seattle, Washington, affiliated with the University of Washington (UW). Infectious disease specialists supervise our OPAT program and provide follow-up care. We partner with a medical respite facility, a discharge option for homeless patients.9 Respite is staffed by HMC nurses, mental health specialists, and case managers.
Patients aged >18 years were enrolled in OPAT if they were discharged with >2 weeks of IV therapy or required laboratory monitoring while on oral antibiotics. Patients with multiple hospitalizations were included for their initial OPAT encounter only. PWID discharged to respite were instructed not to use their vascular access to inject drugs, but drug abstinence was not required. A tamper-evident sticker was placed over lines that nurses evaluated daily. Patients violating line-tampering restrictions were discharged from respite, and OPAT providers developed alternative antibiotic plans.
The two primary exposures evaluated were patient-reported injection drug use and housing status, and our primary exposure measure was the four-category combination: (1) housed non-PWID, (2) housed PWID, (3) homeless non-PWID, and (4) homeless PWID. Current drug use was defined as use within three months of hospitalization. Homelessness was defined as lack of stable housing. Patients receiving chemotherapy, prolonged steroids, biologic agents, or those with organ transplant were considered immunocompromised.
The primary outcome was clinical cure, defined as completion of antibiotic therapy and resolution of infection, determined by OPAT providers. Patients who were placed on oral suppressive antibiotics or died before treatment completion were considered not cured. Unknown status, including care transfer and lost to follow-up, were noted separately. Lost to follow-up was assumed if patients did not return for care, their care was not formally transferred, and no other medical information was available.
