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Antibiotics for Upper Respiratory Tract Infections
Follow-up Utilization and Antibiotic Use
William J. Hueston, MD;
Arch G. Mainous III, PhD;
Steven Ornstein, MD;
Qin Pan, MS;
Ruth Jenkins, MS
Arch Fam Med. 1999;8:426-430.
ABSTRACT
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Objectives To examine the effects of antibiotic prescribing during an initial visit for viral respiratory tract infections on future care seeking and the cost of care.
Materials and Methods Retrospective analysis of recorded visits for viral respiratory tract infections (N=49,862) between January 1, 1995, and December 31, 1997, to practices in a large network of affiliated practices that use the same electronic medical record.
Results Patients receiving antibiotics at the initial visit were less likely to return for a second visit, but this difference was small (15.4% vs 17.4%, P<.001). When returning for the second visit, those who received an antibiotic on the initial visit were prescribed more expensive antibiotics than those who had not received an antibiotic on the initial consultation. Overall, cost from initial antibiotic use outweighed any benefit from reduced utilization in adults and children.
Conclusions Antibiotic prescribing at an initial contact for a viral respiratory tract illness may reduce the likelihood that an individual will return for a subsequent visit, but adds substantial costs to care for the initial antibiotic and for more expensive antibiotics used on subsequent visits.
INTRODUCTION
ALTHOUGH VIRAL respiratory tract infections are seen by many as trivial conditions, they are a leading cause of acute morbidity and have substantial associated costs. While viral respiratory tract infections are generally mild, self-limited, and short term, they are a primary reason for industrial and school absenteeism.1-3 Each year in the United States, upper respiratory tract infections (URIs) alone account for 170 million days of restricted activity, 23 million days of school absence, and 18 million days of work absence.3
According to estimates from the US National Ambulatory Medical Care Survey,4 acute URIs accounted for 17 million visits in 1991 and were the fifth most common reason for seeking care.In addition, microbiologic and laboratory diagnostic tests of dubious clinical value are often performed and contribute additional unnecessary costs to the care of patients' URIs.5 The cost of antibiotics prescribed unnecessarily further increases the expense for these conditions.6 Finally, the direct costs for URIs include nonprescription treatments. Americans spend between $1 and $2 billion annually on the more than 800 over-the-counter cough and cold preparations.7-8 Together, viral respiratory tract diseases constitute a substantial economic drain on health care systems.
While multiple factors contribute to the use of resources in patients with URIs, the factor under the most control of physicians is the prescribing of antibiotics in cases of viral respiratory tract infections. Because the overwhelming majority of URIs are caused by viruses,1, 9 antibiotics are not indicated for their treatment.10-15 Nor do antibiotics prevent complications16-17 as evidenced by a double-blind, placebo-controlled trial in which complications developed in 12% of those receiving placebo and 11% of those receiving antibiotics.17 Yet, antibiotics are widely prescribed for URIs.18-19 Recent studies using claims data18 and physician surveys20 indicate that more than 50% of episodes for URIs are treated with antibiotics. Antibiotic overuse is not limited to URIs. Antibiotics have shown no benefit in the treatment of acute bronchitis,21-22 yet studies have shown antibiotic prescribing rates ranging from 66% to 75% of the cases.20, 23
One reason physicians may prescribe antibiotics for viral conditions is to reduce subsequent office visits for the same complaints. However, it is unclear what effect prescribing antibiotics has on reconsultation rates. This study investigated the effectof receipt of antibiotics on follow-up utilization for viral respiratory tract infections and examined the treatment rendered at second visits.
MATERIALS AND METHODS
Data were compiled in primary care practices participating in the Practice Partner Research Network (PPRNet). Practice Partner Research Network is a national network of practices that share a common electronic medical record system (Practice Partner; Physicians MicroSystems Inc, Seattle, Wash) and combines data regarding diagnoses, preventive services, selected laboratory and radiology services, and prescriptions for research purposes. Practice Partner Research Network practices include 53 primary care practices and 4 specialty practice in 24 states in the United States. Each month the practice collects data on a self-running program that is then submitted to a central site for inclusion in a longitudinal database. The database includes more than 380,000 patients with data on 2.3 million outpatient contacts and 3.9 million diagnoses. For this study, the database containing patient visit data between January 1, 1995, and December 31, 1997, was included for analysis.
Forty-five (79%) of the 57 practices in the PPRNet participated in this study. Of the 12 practices excluded, 5 had few contacts for viral illnesses (4 were specialty practices and 1 was primarily for patients with chronic illnesses), 5 practices had incomplete data for 1995, and 2 practices did not record prescriptions for acute illnesses. All active patients were considered eligible for study. An active patient was one whose medical record had been updated since January 1, 1994.
Information available in the PPRNet data set included the date of service, diagnosis, prescriptions written, duration of therapy, and demographic information about the patient. Because some practices did not include all radiology and laboratory services in their medical records, this information was not included in the study. Diagnoses investigated in this study included those for viral conditions coded under the following conditions: URI/nasopharyngitis, acute bronchitis, influenza, and multiple viral illnesses (which was used when more than one of the index viral illnesses was diagnosed in the same visit, eg, URI and acute bronchitis).
To evaluate how treatment with an antibiotic influenced subsequent care, rather than analyzing the data based on individual visits, it was necessary to construct "episodes of illness" that served as the unit of analysis. An episode of illness was conceptualized to include all care related to one discrete viral illness. The definition was constructed to assure that subsequent visits could be related to a previous index visit and that visits that signaled a new episode were not likely to be related to a previous viral illness. To meet these criteria, we defined an index visit for a new episode as a visit with the diagnosis of URI, acute bronchitis, or influenza with no other contact in the preceding 14 days that included a diagnosis of URI, acute bronchitis, influenza, pharyngitis, or viral disease not otherwise specified. All subsequent contact for a respiratory condition or follow-up for potential complications such as adverse drug reactions in the next 14 days was considered part of the episode. An example of relevant diagnoses included any of the index diagnoses plus viral infection, pneumonia, rhinosinusitis, otitis media, nausea, diarrhea, tonsillitis, "follow-up," and "medical examination."
Bivariate analyses of categorical data were performed using  2 statistic. Estimates of antibiotic costs for episodes when antibiotics were prescribed were calculated using what we considered the most conservative estimate of the potential price of an antibiotic, ie, the average wholesale price,24 assuming a 7-day course of therapy. Radiology and laboratory use were excluded from the model because we could not determine how antibiotic prescribing influenced the use of these ancillary services. An  level of .05 was considered statistically significant.
RESULTS
The characteristics of the 45 participating practices are given in Table 1. Most were single-specialty family physician practices and viral respiratory tract diseases constituted 38% of any type of encounter that involved a respiratory complaint.
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Table 1. Characteristics of Participating Practices
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Table 2 lists the number of contacts and episodes for viral respiratory tract infections in adults and children. The vast majority of viral illnesses resulted in a single contact and only 17% of the patients returned for a second visit. The rate of return was no different for children compared with adults. Table 2 also gives the percentage of episodes in which an antibiotic was prescribed on the initial visit. Antibiotics were more likely to be used on initial visits for adults than for children (P<.001)
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Table 2. Episodes of Viral Illnesses in the Practice Partner Research Network Population
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The effect of prescribing antibiotics during the initial visit on the likelihood of seeking additional care at the same practice is given in Table 3. Prescribing an antibiotic at the initial visit reduced the percentage of individuals who returned for a second appointment in adults and children. For children, individuals who returned for a second visit were no more likely to receive an antibiotic prescription on the second visit if they had received an antibiotic initially. Just the opposite was found for adults; those who did not receive an antibiotic on the first encounter were more likely to receive an antibiotic if they made a second visit (P<.001).
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Table 3. Frequency of Repeat Visits and Treatment on Second Visit*
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The types of antibiotics used during initial and second visits are listed in Table 4. Differences in drug selection for initial and return visits resulted in substantial variations in the average cost of drugs for each type of visit. When prescribed on an initial visit, the average price per prescription for initial visits was $18.85 for adults and $11.57 for children. When patients who received an antibiotic returned and were given another antibiotic, the average price increased to $28.18 for adults and $29.28 for children. If a patient had not received an antibiotic on the initial visit, but was prescribed an antibiotic at the second visit, the cost was $21.51 for adults and $16.38 for children.
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Table 4. Antibiotics Used on Initial and Second Visits of Episode*
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The use of antibiotics on the initial encounter had a notable effect on the overall cost of visits. Figure 1 and Figure 2 show a hypothetical population of 100,000 adults and children seeking care for viral respiratory tract diseases. Based on the data from our population and an estimated cost of $35 per patient visit, the average cost of the episode increased 43% for adults and 26% for children when antibiotics were used on the initial visit. Antibiotics costs accounted for 33% of the episode cost in adults and 24% in children when antibiotics were prescribed on the initial visit; when antibiotics were not used on the initial visit, the overall cost of antibiotics contributed only 2% to the cost of the entire episode.
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Figure 1. Treatment of viral upper respiratory tract diseases in adults.
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Figure 2. Treatment of viral upper respiratory tract diseases in children.
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Because patients could seek care outside the PPRNet of physicians in this study, we also performed a sensitivity analysis to determine how patients who sought care at other sites would alter our results. We found that 32% of adults and 24% of children who had initial visits in which they did not receive an antibiotic would have had to make visits to other sources of care and all would have to receive antibiotics for the cost of episodes in which antibiotics were not used initially to exceed the cost when antibiotics were prescribed on the initial visit.
Finally, we examined the diagnoses associated with second visits in patients who did and did not receive antibiotics. Regardless of whether patients received an antibiotic on the initial visit, they were more likely to be diagnosed with another viral infection or a bacterial infection if they received antibiotics on the second visit than if no antibiotic was prescribed on the second visit (71% vs 35%, P<.001). However, those who received an antibiotic on the initial visit were more likely to have a bacterial diagnosis on the second visit than those who did not receive an antibiotic (31% vs 28%, P=.002).
COMMENT
Our data suggest that, first, individuals not given antibiotics at the initial visit for a presumably viral condition are more likely to return for a second visit, but overall second visit rates are low for both groups. Second, the absolute differences between the groups are small. To reduce the revisit frequency by one individual, the number needed to treat with antibiotics would be 59 for adults and 30 for children. Based on the cost of antibiotics, the potential for side effects in the large number of patients treated just to discourage reconsultation, and our observation that even more expensive antibiotics are used if patients do return for another visit, antibiotics cannot be considered a harmless placebo prescribed simply to discourage a second visit.
In addition to immediate cost and side effects from antibiotic prescribing, antibiotic use for URIs may encourage patients to seek care for subsequent viral infections. Data suggest that providing courses of antibiotics for primarily viral illnesses encourages patient beliefs in the effectiveness of antibiotics for those illnesses.25-26 Patients associate the resolution of the self-limited illness in time with the receipt of the antibiotics and, thus, draw the conclusion that the antibiotics caused the resolution of the illness. Unfortunately, the results suggest that the second antibiotic tends to be a more expensive broad-spectrum agent, thereby increasing the cost substantially and conveying to the patient that they need the "strong" antibiotic on future episodes.
Clinicians may believe that in practice they use antibiotics selectively and choose to prescribe antibiotics only for patients who come into the visit with the expectation that they will receive an antimicrobial. However, evidence suggests that physicians are not accurate at assessing patients' expectations for antibiotics in URIs and when unsure assume that the patient wanted an antibiotic.26 This error in perception will lead to over-prescribing of antibiotics and will reduce the usefulness of this strategy. In fact, most patients consult physicians to clarify their symptoms and obtain a diagnosis.27-28 Patients are perfectly happy when they do not receive antibiotics for their viral illness so long as they are provided with an explanation of the rationale behind that decision.26, 29 Because most patients simply want a diagnosis for their conditions, physicians may be overestimating the desire for antibiotics; rather than writing a prescription to fulfull an unstated need, a focused discussion with the patient of the lack of benefits of antibiotic therapy and potential complications of antibotics is a useful alternative stategy.
While the net costs of antibiotic prescribing add appreciable cost to the episode, another additional cost that was not considered in this study is the indirect costs associated with the increased prevalence of antibiotic-resistant bacteria that has been linked to widespread use of antibiotics for primarily viral conditions. Recent data suggest that antimicrobial use is positively correlated with the nasopharyngeal carriage of penicillin-resistant pneumococci in children.30 Similarly, nationwide reductions of macrolide antibiotic use was shown to be associated with a notable decrease in erythromycin-resistant group A streptococci.31 The widespread development of antibiotic resistance means that use of antibiotics for URIs and other primarily viral respiratory tract infections can have serious repercussions and should not be viewed by the physician as simply a harmless placebo to pacify the presumed expectations of the patient.
There are several limitations of this study that should be considered in interpreting the results. First, we could not validate the diagnoses provided by the participating physicians. Because viral respiratory tract infections are part of a constellation of symptoms that is shared by other respiratory infections (eg, rhinosinusitis or pneumonia), the coded diagnosis may be inaccurate and may be an overestimate of ineffective antibiotic treatment. However, the coded diagnoses are what was determined by the participating physician according to clinical and diagnostic criteria. Second, we only examined whether an antibiotic was prescribed. Even though we used the most conservative estimate of a cost for each drug (ie, the wholesale price), our cost models may have overestimated the actual costs of antibiotic prescribing since other studies suggest that a large proportion of patients in the United States never get their medication prescription filled.
Finally, we could not account for utilization of sources of care outside the PPRNet of primary care physicians in the study. If individuals who did not receive antibiotics sought care at other sources more often than those who received antibiotics, the differences between these 2 groups would be an overestimate. However, as noted in the sensitivity analysis, those who did not receive antibiotics would have had to use other sources of care at a rate 150% to 200% higher to alter the overall conclusions of the study.
In summary, this study suggests that initial antibiotic prescribing may reduce subsequent visits in episode of viral respiratory tract illness. However, when patients who previously received antibiotics do return, they are likely to receive another antibiotic. This increases the cost of care and may have implications in the development of antibiotic resistance in common respiratory organisms.
AUTHOR INFORMATION
Accepted for publication October 6, 1998.
This project was supported by a Robert Wood Johnson Generalist Physician Faculty Scholar Award (Dr Hueston), Princeton, NJ, and support from IMS America, Philadelphia, Pa.
Corresponding author: William J. Hueston, MD, Department of Family Medicine, Medical University of South Carolina, 295 Calhoun St, Charleston, SC 29401.
From the Department of Family Medicine, Medical University of South Carolina, Charleston.
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