Original Research

Outpatient Antimicrobial Practices of a Large Academic Center

Jose G. Castro, MD1 • Jennifer Quevedo, PharmD2 • Blanca Rivera, PharmD2

1Department of Medicine, Division of Infectious Diseases, University of Miami Miller School of Medicine
2Department of Pharmacy, University of Miami Miller School of Medicine

Castro JG, Quevedo J, Ribera B. Outpatient antimicrobial practices of a large academic center. Consultant. 2021;61(5):e1-e2.

Received August 18, 2020. Accepted January 11, 2021. Published online February 18, 2021.

The authors report no relevant financial relationships.

Jose G. Castro, MD, University of Miami Miller School of Medicine, 1120 NW 14th Street, Suite 857, Miami, FL, 33136 (jcastro2@med.miami.edu)


Antibiotic resistance leads to an estimated 2.8 million infections and 35,000 deaths per year in the United States, making it one of the greatest public health threats today.1 Prescribing antibiotics inappropriately is an important modifiable risk factor for antibiotic resistance.2 Antibiotic use in ambulatory settings represents the highest volume (85%-95%)3 and the majority of dollars spent on antibiotics for human health care. Thus, it is an important antibiotic stewardship target.4,5 However, data describing antimicrobial misuse in the outpatient setting are limited.6 We aimed to describe volume and patterns of antimicrobial prescription practices in a large university-owned outpatient practice in South Florida.

Methods. We reviewed the ambulatory antibiotic prescribing practices carried out in 2016 by the University of Miami Medical Group (UMMG) practitioners. Electronically prescribed antimicrobials were identified using codes from the Multum Lexicon Drug Database. Antimicrobials included in our search included antibiotics and antifungals but not antivirals or antiparasitic agents. We adopted a measure used in some outpatient antimicrobial stewardship reports that classifies antibiotics as narrow spectrum (NS) or broad spectrum (BS). NS antibiotics include first-generation cephalosporins, sulfonamides, tetracyclines, metronidazole, and penicillin. BS antibiotics include quinolones, macrolides, broad-spectrum cephalosporins and extended spectrum penicillins, and lincomycin derivatives.

Practitioners were MDs (including DOs) and advanced practitioners (PAs and APRNs). Provider specialties were characterized into 17 specialty groups based on the American Medical Association’s self-designated practice specialties. Five medical specialties were further analyzed with the following parameters: ratio of total number of antimicrobials/total medications and number of visits, as well as practitioner’s professional information (ie, foreign/domestic degree, years of practice after graduation, and rate of patient satisfaction with individual provider). The 5 medical specialty practices analyzed in more detail included urology (2 locations, 12 providers), family medicine (2 locations, 8 providers), internal medicine (5 locations, 10 providers), pediatrics (2 locations, 10 providers), and gynecology (1 practice, 5 providers).

Results. In 2016, 798 UMMG practitioners consulted patients in 4831 individual clinics. A total of 596,895 prescriptions were electronically prescribed, with 53,927 (9.03%) of those being antimicrobials. Quinolones, macrolides, and trimethoprim-sulfamethoxazole were the most commonly prescribed antimicrobials. Prescription rates for NS and BS were 47% and 53%, respectively. Volume and top-prescribing antimicrobials varied among different practices. Gynecology practitioners prescribed 3308 antimicrobials (fluconazole, metronidazole, doxycycline), urology practitioners prescribed 2610 (ciprofloxacin, trimethoprim-sulfamethoxazole, levofloxacin), internal medicine practitioners prescribed 1761 (azithromycin, cefuroxime, doxycycline), pediatric practitioners prescribed 1381 (amoxicillin, azithromycin, cefuroxime), and dermatology practitioners prescribed 1133 (doxycycline, minocycline and trimethoprim-sulfamethoxazole).

Antibiotic prescribing patterns and frequency were different according to the type of practice and the type of prescriber (MD/DO vs APRN/PA). The average ratio of number of antimicrobials prescribed per visit was 0.15 and varied from 0.03 (pediatricians) to 0.49 (gynecologists). The volume of antibiotic prescriptions varied between practices and depended on location and provider. No correlation was identified between number of antimicrobials prescribed and volume of visits per provider (0.09), number of years of practice (0.05), domestic or foreign degree, or global patient satisfaction score with the individual provider. The standard deviation for all these findings was 123. The average number of antimicrobial prescriptions per provider per year was 67. Only 1% of the providers wrote more than 43 antimicrobials prescriptions in a year. Three of the top 5 providers prescribing antimicrobials were advanced practitioners.

Discussion. Our report describes antimicrobial prescription practices of a single, large university-owned outpatient practice. Compared with previous findings among providers in large health care systems, providers in our practice had written fewer prescriptions for antimicrobials.6 In addition, fewer BS antibiotics were prescribed in our practice compared with large health care systems and recently published national study data.6 The national study also examined changes in BS and NS antibiotics.6 Findings showed no significant changes from 2011 to 2016 and that the BS antibiotic prescription rate was still 1.8 times higher than the NS prescription rate.6

The National Action Plan for Combating Antibiotic-Resistant Bacteria was established in 2015 and updated in 2020 to provide a roadmap for the United States to combat antimicrobial resistance.7 One of the significant goals of the National Action Plan is to lower the annual proportion and rate of antibiotic prescriptions for outpatient visits where antibiotics are not needed (according to evidence-based guidelines) and provide descriptive statistics for trends in unnecessary prescribing patterns. In order to comply with this objective, it is required that each institution determine the rate and appropriateness of antibiotic prescriptions in their outpatient services. Assessing appropriateness for all services may not be realistic in large practices where about a half a million antimicrobials were prescribed in a given year. A more realistic approach would be to perform random selection of services and providers. For our report, individual medical records were not reviewed, so the appropriateness of the antibiotic prescription practices in the institution was not assessed.

In the analyzed subgroup of practitioners, we found no association between the rate of antimicrobials/prescriptions and patient load, patient satisfaction rates, or type or location of practices. We also found that pediatricians prescribe fewer antibiotics, which is similar to previous reports.5 In addition, pediatricians had the lowest rate of antibiotic prescriptions. Our data confirm previous study findings8,9 that nonphysician practitioners (PAs and APRNs) prescribe antibiotics at the highest rates. This could be explained by the level of training, type of patients, or other factors. The reasoning behind some advanced practitioners prescribing antibiotics at high rates (up to 1 antibiotic every 2 patients) is unclear and requires a more detailed analysis. According to our study findings, however, this is not related to the volume of patients seen by the provider or patient satisfaction.

Limitations to this study include only electronic prescriptions being evaluated, and the appropriateness of antibiotic choice per patient was not identified. Nevertheless, the great majority of prescriptions in 2016 were electronic. Another limitation was that this analysis was done on a convenience sample rather than a random sample, and this methodology could lead to biased results. Nevertheless, this report provides important initial information about antimicrobial practices in this Institution.

Conclusion. In summary, this report establishes a baseline for the antimicrobial prescription practices of UMMG providers. The study highlights the providers who prescribe fewer antibiotics and explains that the level of prescribing is not predicted by the volume of patients or patient satisfaction.



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