A retrospective study presented at MAD-ID 2025 suggests that immunocompromised (IC) patients receiving outpatient parenteral antimicrobial therapy (OPAT) are at significantly greater risk for unplanned 30-day hospital readmissions compared with non-immunocompromised (non-IC) patients, though rates of infection-related readmissions and central venous access device (CVAD) complications were not significantly different between groups.
Christina Lee, PharmD, and Julia Donahue, PharmD, PGY1 pharmacy residents at the University of North Carolina Medical Center, led the research. “We’re really excited to be sharing a little bit about our research project titled The Comparison of Outcomes Between Immunocompromised and Non-Immunocompromised Patients on Outpatient Parenteral Antimicrobial Therapy,” Lee said.
The single-center, observational study evaluated 533 adult OPAT encounters between August 1, 2023, and August 31, 2024. Patients receiving therapy through skilled nursing facilities, dialysis, or infusion centers were excluded. The presence of a solid organ transplant, hematologic malignancy, or a left ventricular assist device defined immunocompromised status.
Among the 533 encounters, 144 (27%) involved immunocompromised patients and 389 (73%) involved non-IC patients. At least one unplanned readmission occurred in 27.1% of IC patients versus 14.1% of non-IC patients (adjusted OR 1.85; 95% CI, .99–3.47). The unadjusted 30-day risk of all-cause readmission for IC patients was more than double that of non-IC patients (2.32; 95% CI, 1.55–3.47).
“In general, immunocompromised patients may be more likely or have a lower threshold for readmission, but that might not be the only reason,” Lee noted. “Our immunocompromised patients specifically had less bone and joint infections, more concomitant bacteremia, higher use of high-risk antimicrobials such as vancomycin and aminoglycosides, and more non-tuberculosis mycobacterium. This, coupled with their immunocompromised status, could likely be the reason for their increased risk in readmissions.”
Infection-related readmission occurred in 11.8% of IC and 6.4% of non-IC patients (adjusted OR 1.31; 95% CI, .52–3.29). Unadjusted 30-day risk of infection-related readmission was 2.55 times higher in IC patients (95% CI, 1.26–5.16). Although, these differences did not reach statistical significance. Similarly, CVAD complication rates were not significantly different (adjusted OR 2.01; 95% CI, .9–4.48).
“These patients have their own unique vulnerabilities that make them more susceptible to readmissions and complications,” said Donahue. “One important strategy is establishing the goals of therapy early on—whether curative or palliative—because that affects how aggressively we manage them. These nuances are particularly important in immunocompromised populations.”
Donahue emphasized that immunocompromised patients often receive more frequent clinical follow-up, especially those with complex conditions like stem cell or solid organ transplants. “If they come in weekly for infusions over eight weeks, we see them much more often than traditional OPAT patients,” she said. “That gives us a valuable opportunity to monitor side effects, detect treatment failures, and adjust therapy promptly.”
The UNC team credits their institution’s specialized Immunocompromised Host OPAT Program for enabling more proactive care. “We’re very lucky to have this program,” Lee said. “Having immunocompromised patients managed by an infectious diseases pharmacist or provider, alongside a multidisciplinary team—solid organ transplant, hematology/oncology, and heart failure specialists—has been really beneficial.”
The researchers cited earlier institutional data showing reduced readmissions among transplant patients when followed by the immunocompromised OPAT team. “We want to emphasize the importance of having a dedicated pharmacist and a team for this patient population,” Donahue added. “They have very unique vulnerabilities. A targeted team can help optimize therapy and set them up for success.”
