Outpatient Parenteral Antibiotic Therapy—What’s the Risk?
Abstract & Commentary
Source: Hoffman-Terry ML, et al. Adverse effects of outpatient parenteral antibiotic therapy. Am J Med 1999;106:44-49.
Hoffman-terry and colleagues report a series of 269 patients who received 291 courses of outpatient parenteral antimicrobial therapy (OPAT) over two years. This was a retrospective study of patients treated through the Thomas Jefferson University Hospital Home Infusion Program in Philadelphia during 1992 and 1993. Their model was self-administration through a hospital-based OPAT program. All patients were initially hospitalized. Patients were seen two or three times per week by nurses of the infusion service and by the prescribing doctor as deemed necessary. Blood monitoring specimens were drawn at least weekly in the home. Medications were delivered on a weekly basis.
The average age was 49 years, although ages ranged from newborn to 86 years of age. Most patients had complicating medical illnesses (81%). The mean duration of therapy was 40 days with a median of 42 and a range from three to 141 days. The majority of patients were treated for bone and joint infections (59%), followed by endovascular infections (16%), and abscesses (9%). Patients with HIV were excluded. Nearly half of the patients received more than one intravenous antibiotic. Vancomycin was the most frequently prescribed antibiotic, with beta-lactams second.
Hoffman-Terry et al did a detailed chart review with careful assessment of a number of factors that were linked to adverse effects. They defined "leukopenia" as a total leukocyte count of 4000 per mm3 or less, "neutropenia" as an absolute neutrophil count of 1500 per mm3 or less, and "eosinophilia" as an absolute eosinophil count of 500 per mm3 or more. "Thrombocytopenia" was defined as a total platelet count of 140,000 mcg or less. Nephrotoxicity was defined as an increase in creatinine concentration of 1 mg/dL or more if the baseline serum creatinine was less than 3 mg/dL or an increase of 0.5 mg/dL or more if the creatinine was more than 3 mg/dL.
Hoffman-Terry et al found a surprisingly high incidence of adverse effects and problems during the OPAT program. The most frequent problems were leukopenia and eosinophilia—which occurred in 16% and 12% of cases, respectively. Venous access was a problem in 31 (11%) cases, with 12 patients requiring hospitalization. The fourth most frequent problem was nephrotoxicity, which occurred in 8%, followed by diarrhea, which was noted in 7% of patients.
Twenty-two patients required rehospitalization, 12 for venous access-related problems. Four patients died during therapy, but in no case were the deaths attributed to complications of infusion therapy.
Comment by Alan D. Tice, MD
This study reinforces the concern that OPAT has as many or more associated adverse effects as intravenous antibiotic therapy in the hospital. Complications and problems of OPAT have been reported previously but investigations have not been as detailed as this one.1,2
Of concern is the finding that many of the adverse effects occurred well into the course of therapy. The mean time until leukopenia and eosinophilia were found was 30 days. Even the rashes appeared after an average of 29 days. Diarrhea and vomiting did not become a problem until 18 and 19 days, respectively. This points out the need for increased vigilance and close physician monitoring late in the course of therapy—even though the patient may be improving from an infection stand- point.3
Blood was drawn weekly to monitor for toxicity. This is the minimum frequency recommended by the guidelines of the Infectious Diseases Society of America (IDSA).4 It is also of concern that there were no standards for physician follow-up visits. The IDSA guidelines recommend these visits should be at least weekly as well.
Hoffman-Terry et al also recognized the problems with vascular access with complications in 11% of 180 permanent indwelling catheters. Thirteen of them had to be removed. Peripherally inserted central catheters (PICCs) had a lower complication rate (9 of 99), seven required removal. Five percent of permanent in-dwelling catheters and 3% of PICCs had complications that required rehospitalization.
This study points out the relatively high incidence of side effects and problems with intravenous therapy. While they may be no greater than in the hospitalized patient, the ability to evaluate and control them outside the hospital is considerably less—particularly if there is not close follow-up by a knowledgeable physician. In addition to the usual side effects of antibiotics, vascular access is a significant problem and may cause life-threatening complications, such as sepsis and central vein thrombosis. It is notable that approximately 4% of the patients were rehospitalized because of vascular access problems and complications. This poses a significant risk to patients who are not seen by a physician on a regular basis and who may be receiving potentially toxic medications. As the financial incentive to send people home on OPAT increases, the concerns about the quality of care and monitoring for even the expected problems may become lax.
As for infectious disease specialists, this article raises further concerns about who is to manage OPAT and what the role of the physician should be. On the one hand, infectious disease physicians are sought for responsibility and liability for OPAT but they are often not compensated for their efforts and risks. This points to the need to set and follow standards for monitoring in the infectious diseases community in regard to the care and quality assurance for these patients—particularly as the compensation for OPAT and patient care continue to decline.
References
1. Williams DN. Home intravenous anti-infective therapy (HIVAT)—do the benefits outweigh the risks. Drug Safety 1996;14:1-7.
2. Poretz DM. Treatment of skin and soft-tissue infections utilizing an outpatient parenteral drug delivery device: A multicenter trial. Am J Med 1994;97:23-27.
3. Tice AD. Antimicrobial selection for outpatient parenteral antibiotic therapy. In: Handbook of Outpatient Parenteral Therapy for Infectious Diseases. New York: Scientific American, Inc.; 1997:43-57.
4. Williams DN, et al. Practice guidelines for community-based parenteral anti-infective therapy. Clin Infect Dis 1997;25:787-801.
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