S
The Influence of Context on Antimicrobial
Prescribing for Febrile Respiratory Illness
A Cohort StudyAnnals of Internal Medicine
7 August, 2012 Volume 157 Number 3Courtney Hebert, MD; Jennifer Beaumont, MS;
Gere Schwartz, MD; and Ari Robicsek, MD
Danelle BlumeUniversity of Georgia College of Pharmacy
2013 Pharm.D. Candidate
Background
Patient presentation is often ambiguous Former studies have shown that antibiotic use
peaks during the flu seasons, fall and spring Epidemics such as the H1N1 pandemic can give
clinicians a diagnostic cue which suggests viral illness Decreases improper use of antibiotic therapy
http://www.rodale.com/antibiotics-sinus-infection
Funding
Research Career Development Award from NorthShore University HealthSystem to Dr. Robicsek, MD Funding source had no role in the design, conduct,
analysis, or decision to submit the study for publication
Purpose
Large-scale, retrospective review of prescribing practices
Primary: Compare antibiotic and antiviral prescribing in the primary care setting for febrile respiratory illness (FRI) during a seasonal influenza period and a pandemic influenza period
Secondary: Examine the effect of patient and physician characteristics and of a physician’s personal context on the likelihood of antibiotic prescribing
MethodsSetting/Inclusion
Setting: NorthShore University HealthSystem, an academic care system in metropolitan Chicago
Inclusion: Patients who presented to an eligible outpatient provider between January 1, 2006 and May 15, 2011 Eligible outpatient providers: primary care, internal
medicine, family practice, and pediatric physicians who worked within the NorthShore network and saw >100 outpatients with FRI during the study period
MethodsData Collection
Encounter: chief symptom, diagnosis, or temperature measurement in the office consistent with fever and patient had chief symptom or diagnosis of respiratory illness including: cough, sore throat, or rhinorrhea
Provider Data: Practice information (family practice, internal medicine, pediatric
physician) Medical school graduation date Volume of patients seen during year of encounter Number of patients with FRI seen in the week before a given visit Quintiles: Based on volume physicians saw during study period
Statistics
Estimated odds ratios (ORs)Definition: Probability of event occurring
Probability of event not occurringExample :
• The observed odds ratio = [40 x 3023] / [239 x 1287] = 0.39• The 0.39 represents a 39% odds of a hip fracture occurring in a
postmenopausal woman currently on HRT in comparison to a woman that has never used HRT or a former user of HRT.
• Another way of looking at the odds of 0.39 or 39% is to say that being a current user of HRT decreased the odds of a hip fracture by 61%
Current HRT User Never used HRT of Former user of HRT
With hip fracture 40 1287
Without hip fracture 239 3023
http://www.nutridesk.com.au/odds-ratio.phtml
ResultsBaseline Characteristics
ResultsTime Period Antibiotic
prescribing (%)P-value
Entire study 45.2Seasonal 47.5Pandemic 39.2 <0.001
Physician Characteristics: Rate of antibiotic prescribing ranged from 17.9% to 83.7% Individual physicians consistent from year to year Individual physician factors (i.e. graduation date, volume of patient
encounters, etc.) did not statistically influence primary outcome Patient Characteristics:
Older age, body mass index (BMI) greater than 35 kg/m2, asthma, and chronic obstructive pulmonary disease (COPD) were associated with increased likelihood of antibiotic prescribing
Chief complaints of cough, ear, nose, sinus, and chest symptoms as well as fever in office associated with increased likelihood of antibiotic prescribing Flu-like symptoms, gastrointestinal symptoms and headache associated with
decreased likelihood
Results
Finding OR or P-value
Patients seen in pandemic period significantly less likely to receive antibiotics
OR 0.72 [CI, 0.68 to 0.77]
Significant reduction in prescribing occurred in 23 of 69 physicians. Only 1 had significant increase
P<0.002
As number of patients with FRI seen by physician in the previous week increased, the likelihood of antibiotic prescribing for physicians next patient decreased
2 to 3 patients: OR 0.93 [CI, 0.86 to 1.01]4 to 6 patients: OR 0.84 [CI, 0.77 to 0.91]7 to 11 patients: OR 0.71 [CI, 0.64 to 0.78]12 or more: OR 0.57 [CI, 0.51 to 0.63]
Physicians more likely to prescribe antivirals during pandemic period
OR 6.43 [CI, 5.02 to 8.25]
The odds of prescribing antivirals was 4.25 [CI, 3.42 to 5.28] if the physician had seen 12 or more patients with FRI in the previous week
OR 4.25 [CI, 3.42 to 5.28]
Limitations
Retrospective Nonrandomized FRI cases differed in clinical presentation from one
period to another Design did not allow for the removal of cases of FRI
for which antibiotics were clearly appropriate Study included more pediatric patients than adults
or elderly patients
Conclusions
Overall rating IIIC The context in which a patient presented was
strongly associated with the likelihood that an antimicrobial agent would be prescribed
The presence of 1 or more medical comorbid conditions has been shown to be associated with antibiotic prescribing
References
Herbert C, Beaumont J, Schwartz G, Robicsek A. The influence of context on antimicrobial prescribing for febrile respiratory illness. Annals of Internal Medicine. 2012;157:160-68.
