Original Research

Adherence to Evidence-Based Outpatient Antimicrobial Prescribing Guidelines at a Tribal Health System

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Background: In 2019, the Tuba City Regional Health Care Corporation on the Navajo Reservation in northeastern Arizona established facility-wide, evidence-based outpatient antimicrobial guidelines. We aimed to evaluate adherence to these guidelines.

Methods: A retrospective chart review of the electronic health record for all ages was conducted from August 1, 2020, to August 1, 2021, to evaluate antimicrobials prescribed for indications covered by the facility prescribing guidelines. The appropriateness of the antimicrobial prescribed was assessed and reported as a percentage. An educational intervention and a survey were then distributed from March 2, 2022, to March 31, 2022, to all prescribers.

Results: Overall adherence to prescribing guidelines over the period assessed was 86%, 4% short of the study goal of 90%. Before the educational intervention, 61.5% of prescribers used the prescribing guidelines to guide their antibiotic choice, while after the educational intervention, 87.1% of prescribers indicated a willingness to use the guidelines to guide their antibiotic choice.

Conclusions: Adherence to the facility guidelines was already high at 86%. Educational interventions were performed but their efficacy could not be assessed within the time constraints of the study.



Tuba City Regional Health Care Corporation (TCRHCC) is located on the Navajo Reservation in northeastern Arizona and provides medical coverage to a 6000-square-mile area, serving more than 33,000 residents of the Navajo, Hopi, and San Juan Southern Paiute tribes.1,2 In 2021, there were 334,497 outpatient visits. TCRHCC departments involved in prescribing outpatient antibiotics include the emergency, internal medicine, family medicine, pediatrics, dentistry, surgery, podiatry, obstetrics and gynecology, and midwifery.

Antimicrobial resistance is one of the largest public health threats, causing an estimated 2 million infections and 23,000 deaths every year in the United States.3 This can lead to increased health care costs, morbidity, and mortality. A large, modifiable risk factor is the inappropriate prescribing of antibiotics: An estimated half of all outpatient antibiotics prescribed may be inappropriate in some manner, such as antibiotic choice, dosing, or duration. In addition, at least 30% of US antibiotic prescriptions are unnecessary, leading to significant overuse.3 As such, antimicrobial stewardship is a cornerstone of improving antibiotic use, patient care, and safety.

The goals of antimicrobial stewardship are to measure antimicrobial prescribing, improve clinician prescribing, minimize misdiagnosis or delayed diagnoses, and ensure the right drug, dose, and duration are selected when antimicrobial therapy is appropriate.3 The Centers for Disease Control and Prevention recommends 4 core elements of outpatient antimicrobial stewardship: commitment, action for policy and practice, tracking and reporting, and education and expertise.3 This study focuses on the pillars of action for policy and practice and tracking and reporting.


The study objectives were not designed to achieve statistical power. A retrospective chart review was performed for patients of any age who were seen in an ambulatory care setting at TCRHCC from August 1, 2020, to August 1, 2021, with a visit diagnosis included in the outpatient antimicrobial prescribing guidelines.4,5 A random sample of 10% of charts of each diagnosis code was used for analysis. An Excel spreadsheet with all patient charts, separated by diagnosis code, was created. Each chart was then assigned a number, and the Excel function RAND was used to select a random number from the pool. This was continued until 10% of each category, or at least 1 chart from diagnosis code categories with less than 10 total charts available, were selected.

Inclusion criteria were patients seen in ambulatory clinics or the emergency department, an infectious disease diagnosis addressed in the facility guidelines, diagnosis and treatment occurred between August 1, 2020, and August 1, 2021, and the patient was discharged home after the visit. Exclusion criteria were patients who required inpatient admission, patient visits to the clinic established solely for COVID-19 vaccination or testing as no other care was ever provided at this location, patients who refused treatment, patients who failed empiric therapy and required treatment adjustments, or patients who were initially treated and received an antibiotic prescription at a facility outside the TCRHCC system.

After chart review and analysis were completed, a prescriber survey and educational intervention were performed from March 2, 2022, to March 31, 2022. This consisted of an anonymous survey to gather demographic data and prescribing habits pre-education, a short educational brief on the existence, location, and recommended use of the outpatient antimicrobial prescribing guidelines, and a posteducation survey to assess knowledge of the guidelines and willingness to adhere to them after the educational intervention.


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