Self-Administered Outpatient Antimicrobial Infusion by Uninsured Patients Discharged from a Safety-Net Hospital: A Propensity-Score-Balanced Retrospective Cohort Study

Background: Outpatient parenteral antimicrobial therapy (OPAT) is accepted as safe and effective for medically stable patients to complete intravenous (IV) antibiotics in an outpatient setting. Since, however, uninsured patients in the United States generally cannot afford OPAT, safety-net hospitals are often burdened with long hospitalizations purely to infuse antibiotics, occupying beds that could be used for patients requiring more intensive services. OPAT is generally delivered in one of four settings: infusion centers, nursing homes, at home with skilled nursing assistance, or at home with self-administered therapy. The first three—termed healthcare-administered OPAT (H-OPAT)—are most commonly used in the United States by patients with insurance funding. The fourth—self-administered OPAT (S-OPAT)—is relatively uncommon, with the few published studies having been conducted in the United Kingdom. With multidisciplinary planning, we established an S-OPAT clinic in 2009 to shift care of selected uninsured patients safely to self-administration of their IV antibiotics at home. We undertook this study to determine whether the low-income mostly non-English-speaking patients in our S-OPAT program could administer their own IV antimicrobials at home with outcomes as good as, or better than, those receiving H-OPAT. Methods and Findings: Parkland Hospital is a safety-net hospital serving Dallas County, Texas. From 1 January 2009 to 14 October 2013, all uninsured patients meeting criteria were enrolled in S-OPAT, while insured patients were discharged to H-OPAT settings. The S-OPAT patients were trained through multilingual instruction to self-administer IV antimicrobials by gravity, tested for competency before discharge, and thereafter followed at designated intervals in the S-OPAT outpatient clinic for IV access care, laboratory monitoring, and physician follow-up. The primary outcome was 30-d all-cause readmission, and the secondary outcome was 1-y all-cause mortality. The study was adequately powered for readmission but not for mortality. Clinical, sociodemographic, and outcome data were collected from the Parkland Hospital electronic medical records and the US census, constituting a historical prospective cohort study. We used multivariable logistic regression to develop a propensity score predicting S-OPAT versus H-OPAT group membership from covariates. We then estimated the effect of S-OPAT versus H-OPAT on the two outcomes using multivariable proportional hazards regression, controlling for selection bias and confounding with the propensity score and covariates. Conclusions: S-OPAT was associated with similar or better clinical outcomes than H-OPAT. S-OPAT may be an acceptable model of treatment for uninsured, medically stable patients to complete extended courses of IV antimicrobials at home. In a propensity score-balanced retrospective cohort study, Kavita Bhavan and colleagues compare health outcomes for patients undergoing self-administered versus healthcare-administered outpatient parenteral antimicrobial therapy.Background: Patients sometimes need lengthy courses of antimicrobial agents to treat life-threatening infections. For example, patients who develop endocarditis (an infection of the inner lining of the heart usually caused by bacteria entering the blood and traveling to the heart) need to be given antimicrobial drugs for up to six weeks. Initially, these patients require intensive diagnostic and therapeutic care in the hospital. But once the antimicrobial treatment starts to work, most patients only need regular intravenous antimicrobial infusions. Patients who stay in the hospital to receive this low intensity care occupy beds that could be used for patients requiring more intensive care. Moreover, they are at risk of catching a hospital-acquired, antibiotic-resistant infection. For these reasons, and because long-term administration of antimicrobial agents in the hospital is costly, outpatient parenteral (injected or infused) antimicrobial therapy (OPAT) is increasingly being used as a safe and effective way for medically stable patients to complete a course of intravenous antibiotics outside the hospital. Why Was This Study Done?: In the US, OPAT is usually delivered in infusion centers, in nursing homes, or at home by visiting nurses. But healthcare-administered OPAT (H-OPAT) is available only to insured patients (in the US, medical insurance provided by employers or by the government-run Medicare and Medicaid programs funds healthcare). Uninsured people cannot usually afford H-OPAT and have to stay in safety-net hospitals (public hospitals that provide care to low-income, uninsured populations) for intravenous antibiotic treatment. In this propensity-score-balanced retrospective cohort study, the researchers investigate whether uninsured patients discharged from a safety-net hospital in Texas to self-administer OPAT at home (S-OPAT) can achieve outcomes as good as or better than those achieved by patients receiving H-OPAT. A retrospective cohort study compares recorded clinical outcomes in groups of patients who received different treatments. Because the patients were not chosen at random, such studies are subject to selection bias and confounding. Propensity score balancing is used to control for selection bias—the possibility that some members of the population are less likely to be included in a study than others. Adjustment for covariates (patient characteristics that may affect the outcome under study) is used to control for confounding—the possibility that unknown characteristics shared by patients with a specific outcome, rather than any treatment, may be responsible for that outcome. What Did the Researchers Do and Find?: Between 2010 and 2013, 994 uninsured patients were enrolled in the hospital’s S-OPAT program, and 224 insured patients were discharged to an H-OPAT program. Patients in the S-OPAT group were trained to self-administer intravenous antimicrobials, tested for their ability to treat themselves before discharge, and then monitored by weekly visits to the S-OPAT outpatient clinic. The researchers estimated the effect of S-OPAT versus H-OPAT on 30-day all-cause readmission and one-year all-cause mortality (the primary and secondary outcomes, respectively) after adjusting for covariates and controlling for selection bias with a propensity score developed using baseline clinical and sociodemographic information collected from the patients. The 30-day readmission rate was 47% lower in the S-OPAT group than in the H-OPAT group (a significant result unlikely to have arisen by chance), and the one-year mortality rate did not differ significantly between the two groups. Notably, because the S-OPAT program resulted in patients spending fewer days having inpatient infusions, 27,666 inpatient days were avoided over the study period. What Do These Findings Mean?: These findings indicate that, after adjusting for preexisting differences between those patients receiving S-OPAT and those receiving H-OPAT and for potential confounders, the risk of readmission within 30 days of discharge was lower in the S-OPAT group than in the H-OPAT group and the risk of dying within one year of hospital discharge did not differ significantly between the two groups (the study did not include enough participants to detect any subtle difference that might have existed for this end point). Thus, S-OPAT was associated with similar or better outcomes than H-OPAT. Note that there may be residual selection bias and confounding by characteristics not included in the propensity score. This study did not address whether S-OPAT actually improves outcomes for patients compared with H-OPAT; a randomized controlled trial in which patients are randomly assigned to receive the two treatments is needed to do this. Nevertheless, these findings suggest that S-OPAT might make it possible for uninsured, medically stable patients to have extended courses of intravenous antimicrobials at home rather than remaining in the hospital until their treatment is complete. Additional Information: This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001922.