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CHANGES IN ANTIMICROBIAL PRESCRIBING PATTERNS FOLLOWING A HEALTH CARE PROVIDER EDUCATIONAL INTERVENTION
Nadia Shalauta Juzych, ScD, MS*, Mousumi Banerjee, PhD**, Lynnette Essenmacher**, Stephen A Lerner, MD**
*Michigan Public Health Institute ,**Wayne State University School of Medicine
CHANGES IN ANTIMICROBIAL PRESCRIBING PATTERNS FOLLOWING A
HEALTH CARE PROVIDER EDUCATIONAL INTERVENTION
Table 1. Changes in Antibiotic Prescribing Rates Among Internists and Pediatricians
Nadia Shalauta Juzych, ScD, MS1, Mousumi Banerjee, PhD2, Lynnette Essenmacher2, Stephen A Lerner, MD2
1Michigan Public Health Institute, 2Wayne State University School of Medicine
Intervention Group
Abstract
Problem Statement: Inappropriate use of antimicrobials in the treatment of acute upper
respiratory tract infections, which usually have a viral etiology, contributes to emergence
and spread of antimicrobial resistance in Streptococcus pneumoniae and other human
pathogens.
Objective: To reduce antimicrobial use for management of acute upper respiratory tract
infections in adult and pediatric patients.
Design: Prospective, non-randomized control trial, including baseline (November 15,
1999 to March 31, 2000) and study (November 16, 2000 to March 31, 2001) periods.
Setting: Four primary care clinics within a staff model health maintenance organization in
Detroit, Michigan.
Study Population: Twenty-one primary care physicians at two clinics where the
educational intervention was implemented, and nine primary care physicians at two control
clinics where no educational programs were presented.
Intervention: Interactive case-based educational program on appropriate use of
antimicrobials in the treatment of upper respiratory tract infections for pediatric and adult
medicine physicians and their staff was presented at two inner city health maintenance
organization (HMO) clinics for indigent patients.
Outcome Measure: Antibiotic prescribing for acute upper respiratory tract infections
during the baseline and study years among the intervention and control groups.
Results: Antimicrobial prescribing among the physicians who received the educational
intervention decreased 24.6% between the baseline and study years (p<0.0001) for both
pediatric and adult medicine physicians. There was no significant decline in rates of
antimicrobial prescribing for the control group of physicians between the baseline and
study years for pediatric (p=0.35) or adult medicine (p=0.42) physicians. There was a
significant difference in the decline in rates of antimicrobial prescribing between the
control and intervention groups (p<0.0003) for pediatricians and (p<0.01) for adult
medicine physicians.
Conclusion: An interactive case-based educational program for physicians and their staff
appeared to be an effective means for reducing the prescribing of antibiotics for the
treatment of upper respiratory tract infections by primary care physicians in an indigent
HMO setting.
Funding Source: Blue Cross Blue Shield of Michigan
Background and Setting
The rise in resistance to penicillin and other classes of antibiotics in
Streptococcus pneumoniae, the most frequent bacterial cause of
community-acquired pneumonia, otitis media, and meningitis, is due
principally to selection from exposure to penicillins and other
antibacterial agents. Since S. pneumoniae is often present in the upper
respiratory tract of healthy individuals, each course of antibiotic therapy
contributes to the selective pressure for emergence and proliferation of
antibiotic-resistant strains. An estimated 75% of all antibiotic usage in
outpatients in the US is prescribed for respiratory tract infections. The
majority of upper respiratory tract infections (URIs), including the
common cold, acute bronchitis, and many cases of otitis media, are
caused by viruses, for which antimicrobials are not indicated.
Previous studies that have documented changes in antimicrobial use for
treating a number of uncomplicated viral upper respiratory tract infections
through physician education have utilized population-based evaluations to
determine the efficacy of their approaches in changing antimicrobial
prescribing practices. In this study, we have been able to link diagnosis
to antibiotic prescriptions and, therefore, to demonstrate the efficacy of
our educational intervention in altering prescribing practices among
individual physicians for both pediatric and adult patient populations.
Setting
The Wellness Plan (TWP) is a staff model health maintenance
organization (HMO) that manages four primary care clinics and an
outpatient urgent care center in Detroit, Michigan. The Wellness Plan
HMO includes approximately 50,000 covered lives, and has a patient
population that is more than 90% African-American. Members receive
primary care services primarily from TWP physicians, staff, and
laboratories. In addition, both clinicians and patients are assigned to one
of the four clinics, and rarely do patients see clinicians from one of the
other clinic sites.
The Wellness Plan clinics contain in-house pharmacies that fill
approximately 95% of the prescriptions. Patients with acute illnesses are
given same-day appointments at each of the four clinics, and are seen
only at the urgent care center when the clinics are closed.
Study Aim
To evaluate the efficacy of a health care provider educational intervention
in reducing unwarranted prescribing of antibiotics for probable viral upper
respiratory tract infections.
Methods
 Prospective, non-randomized control trial of an educational
intervention program at two of the health plan’s clinics.
 The program involved a half-day educational session that provided an
overview of antimicrobial resistance, and
 Utilized case study presentations to review appropriate treatment and
diagnosis of bronchitis, pharyngitis, sinusitis, and otitis media.
The in-service educational program was conducted with health care
staff of two of TWP’s four clinics, designated “intervention” clinics.
 Staff of the other two TWP clinics did not participate in the
educational intervention and served as a concurrent control population.
Data on antimicrobial prescribing for the treatment of select URIs were
collected from each of the clinics and evaluated for the periods
November 16, 1999 to March 31, 2000 (baseline period) and November
16, 2000 to March 31, 2001 (study period).
Intervention
• Twenty-six pediatricians, internists, and obstetricians participated in
the educational programs, along with nurses, physician assistants, and
pharmacists of two health plan clinics.
• The sessions were structured to provide an overview of antimicrobial
resistance, followed by a case-based interactive review of appropriate
diagnosis and treatment of a number of upper respiratory tract infections:
bronchitis, pharyngitis, otitis media, and sinusitis.
• The participants were divided into “pediatric” and “adult medicine”
groups for the case-based review portion of the program.
Subjects
The evaluation was conducted to determine changes in prescribing of
antimicrobials in the treatment of bronchitis, pharyngitis, otitis media,
and URIs not otherwise specified (nos) among the physicians of the TWP
clinics between the baseline and study years, and between physicians at
the intervention and control clinics. For each diagnosis, physicians were
included in the analysis if they conducted at least 10 patient visits in each
of the baseline and study years for that diagnosis.
Measurements
Data were gathered from all incident office visits for both pediatric and adult
patients during which a diagnosis of one of the following URIs was made:
bronchitis, otitis media, pharyngitis, or URI nos. The data were extracted from
the administrative database files of TWP as identified by ICD-9 codes recorded
for medical billing.
• Data were extracted for the periods November 16, 1999 to March 31, 2000
(baseline year) and November 16, 2000 to March 31, 2001 (study year).
• Incident visits were defined as representing the first office visit for any of the
diseases of interest. Return visits within 30 days of an incident visit were
excluded from the analysis.
•Patients were excluded for any of the following co-morbidities: asthma,
chronic obstructive pulmonary disease (COPD), diabetes, HIV, congestive heart
failure, or chronic ischemic heart disease.
•Calculations were also performed to evaluate the potential for diagnostic
shifting.
 Prescribing data were extracted from a pharmacy administrative database,
linked to each patient visit by date of prescription.
 Additional data were collected for each office visit: patient sex, age, and
attending physician.
 Data were also collected for the year in which each attending physician
completed residency training.
Statistical Analysis
• Univariate measures were used to compare the control versus the intervention
group with respect to patient demographics.
•Antibiotic prescribing rate was calculated as the proportion of incident office
visits where the patient received an antibiotic prescription.
•To evaluate the impact of the intervention on antibiotic prescribing rates within
and between the intervention and control groups, a generalized linear mixedeffects model was used to control for potential clustering (random effects) of
physicians by group.
•Antibiotic prescribing rates were modeled using binomial error distribution and
logit link function.
Prescribing
Rate
Baseline
Year
Study
Year
Control Group
%
Change
P value
Baseline
Year
Study
Year
% Change P value
All Physicians
49.9
37.6
-24.6
<0.0001
45
42.8
-4.9
0.25
Internists
62.6
45.1
-27.9
<0.0001
75.3
72.2
-4.1%
0.42
Pediatricians
37.1
27.5
-25.9
<0.0001
31.4
29.9
-4.8%
0.35
Table 2. Changes in Antibiotic Prescribing Rates For Treating Specific URIs
Intervention Group
Prescribing
Rate
Baseline
Year
Study
Year
%
Change
Control Group
P value
Baseline
Year
Study
Year
% Change P value
Pharyngitis
82.8
73.9
-10.7
0.007
82.6
74.5
-9.8
0.053
Bronchitis
79.6
78.2
-1.8
0.84
74.5
81.6
9.5
0.15
Otitis Media
84.3
74.1
-12.1
<0.0001
91.6
85.2
-7.0
0.007
URI Nos
26.1
16.9
-35.2
<0.0001
16.8
17.9
6.5
0.58
Figure 1.
Comparison of Antimicrobial Prescribing at Intervention Clinics: Baseline and Study Years
90
80
70
60
B aseline Year
Study Year
50
3-D C olumn 3
3-D C olumn 4
3-D C olumn 5
40
3-D C olumn 6
30
20
10
The model included physician-specific random effects. Time (i.e., baseline
versus study year), patient gender, and years since residency training had been
completed by physicians (categorized as in practice >15 years versus <15 years)
were included as fixed effects for the within-group analysis. For the betweengroup analysis, we added group (intervention versus control) as a fixed effect.
The interaction term between time and group was used to test if change in
prescription rates from baseline to study year differed between the intervention
and control groups. Estimates of variance components were obtained using
restricted maximum likelihood method. Model fit was assessed using deviance.
Analyses were performed using the GLIMMIX macro in SAS version 8. In
addition to the overall (unstratified) analysis, a stratified analysis was performed
by physician specialty (pediatrics versus adult medicine), and specific URI
diagnosis (pharyngitis, bronchitis, otitis media, and URIs nos).
0
A ll D iagnoses
Pharyngitis
B ronchitis
Otitis Media
U R I nos
Figure 2.
Comparison of Antimicrobial Prescribing at Control Clinics: Baseline and Study Years
Findings and Results
• Total number of physicians included in the evaluation for the study population
was 21 (9 pediatricians and 12 internists); control population had 9 physicians (6
pediatricians and 3 internists). A number of physicians were excluded because
they had not seen a minimum of 10 patients with a given diagnosis.
• Patient encounters included in the analysis: baseline year (4429 in study
population and 1970 in control population); study year (3338 in study population
and 1688 in the control population).
Tables 1 and 2 and Figures 1 and 2 summarize the overall findings for the
changes in prescribing practices among physicians in both the intervention and
control groups as well as the changes in prescribing for specific URIs..
 An evaluation of patient gender showed that there was no effect on
prescription rates of antibiotics for URIs among the physicians in either the
intervention or control groups. Similarly, years since residency training had been
completed had no effect on prescription rates by physicians.
 Return office visits were tracked within 30 days of the initial diagnosis to
evaluate whether the decreases in antibiotic prescription rates resulted in
complication of diseases. In the baseline year the mean number of follow-up
visits was 1.54 in the intervention group and 1.51 in the control group, with
standard deviations of 1.10 and 1.05, respectively. In the study year, the mean
was 1.26 follow-up visits in the intervention group and 1.33 in the control group,
with standard deviations of 0.66 and 0.67, respectively. Thus, the follow-up
visits of the study groups did not differ and declined from the baseline year to the
study year.
2. The study included an evaluation of both pediatric and adult patient populations, as well as
an evaluation of male and female patients. The study found that there were no differences
among antibiotic prescription rates for male and female patients, and that, overall, antibiotic
prescription rates were lower among pediatricians prescribing for children (<15 years old).
3. Tracking of follow-up visits showed that the average number of follow-up visits were very
similar between the intervention and control populations in both the baseline and study
years. This indicates that the decreased prescription of antibiotics for the treatment of URIs
within the intervention group did not result in an increase in the number of return visits.
This study of the effects of educational intervention has confirmed the results of previous
studies of educational interventions to reduce antimicrobial use and has demonstrated the
effectiveness of an educational intervention with physicians and their staff in a large, innercity, staff-model HMO primary care clinic. Although the overall reduction of antimicrobial
use by 24.6% among the intervention population is a large step forward in reducing
inappropriate use, there is still much room for improvement. In this study, following the
educational intervention, nearly 80% of patients who were diagnosed as having bronchitis
still received antibiotic prescriptions. Because bronchitis is largely a viral disease, few
patients benefit from treatment with antimicrobial therapy and this number should have been
close to zero. Similarly, because streptococcal pharyngitis, which does require antimicrobial
treatment, is relatively rare in adults, the number of prescriptions of antibiotics for
pharyngitis in adults should have been lower.
Conclusions and Implications
Limitations
Recognizing the rise in the rates of antibiotic resistance in Michigan, particularly
among S. pneumoniae, we have demonstrated the efficacy of a physician and
health care provider educational intervention on reducing antibiotic use in the
treatment of uncomplicated viral URIs. This study demonstrated a statistically
significant decline of 24.6% in the number of prescriptions for URIs among the
intervention clinic physicians. Both the intervention and control groups exhibited
a decline in the number of patient encounters for URIs and the number of
prescriptions for treating URIs between the baseline and study years. The decline
in the control group was likely due to the mild flu and cold season that occurred
during the winter of 2000-2001. The decreases in prescriptions for treating URIs
may also reflect the impact of both national and local efforts to promote
appropriate antibiotic use.
 Potential for coding errors - data were derived from administrative data files for medical
billing
 One of the pediatric physicians in the control group inadvertently participated in the
educational program. Baseline prescribing rates of antibiotics for treating URI nos for this
physician were very low (5%), and changed to 4% in the study year. The overall effect of
this physician’s participation in the intervention on the control group is not known, but
would have likely served to limit the differences in prescribing rates between the study and
control populations.
 This study was conducted in partnership with a Medicaid HMO in Detroit, Michigan.
Because the patients at these clinics are of lower socioeconomic status, it is unknown
whether similar effects would be seen among patients of higher socioeconomic status.
 The intervention was conducted during the winter of 2000-2001, when anti-pneumococcal
vaccine for children became widely available. We were not able to track immunization rates
among the patients in the study and are not able to account for potential decreases in patient
encounters or reductions in antimicrobial prescriptions that may have resulted due to the
vaccinations.
1. 14 of the 21 physicians in the intervention group whose antimicrobial prescribing
patterns were evaluated in this study participated in the educational program. No
significant difference was found between the changes in antimicrobial prescribing
patterns of the seven physicians who did not receive the education, compared to
the 14 who did attend.
 Improvements seen in the antimicrobial prescribing for treating probable viral
URIs may have been due to education of other members of the health care staff,
as well as peer influence of physicians in the clinic who did participate in the
sessions. This finding is particularly interesting, given that the baseline
prescribing rates of the physicians who participated in the educational sessions
were lower than those of the physicians who did not participate in the program.
In addition to the public health implications of unnecessary antimicrobial use, cost
considerations are significant. In 2001, the cost of prescription drugs rose 17%. From 20012002, the use of prescription drugs accounted for 22% of the total rise in gross healthcare
expenditures in the US. In light of the significant impact of prescription medication costs on
healthcare expenditures, the development of methods to reduce the use of prescription
medications without compromising patient care or outcomes will take on great significance.