What a difference a day makes: a decision analysis of adult streptococcal pharyngitis

Rapid antigen group A streptococcus test to diagnose pharyngitis: a systematic review and meta-analysis

Background

Pharyngitis management guidelines include estimates of the test characteristics of rapid antigen streptococcus tests (RAST) using a non-systematic approach.

Objective

To examine the sensitivity and specificity, and sources of variability, of RAST for diagnosing group A streptococcal (GAS) pharyngitis.

Data Sources

MEDLINE, Cochrane Reviews, Centre for Reviews and Dissemination, Scopus, SciELO, CINAHL, guidelines, 2000–2012.

Study Selection

Culture as reference standard, all languages.

Data Extraction and Synthesis

Study characteristics, quality.

Main Outcome(s) and Measure(s)

Sensitivity, specificity.

Results

We included 59 studies encompassing 55,766 patients. Forty three studies (18,464 patients) fulfilled the higher quality definition (at least 50 patients, prospective data collection, and no significant biases) and 16 (35,634 patients) did not. For the higher quality immunochromatographic methods in children (10,325 patients), heterogeneity was high for sensitivity (inconsistency [I²] 88%) and specificity (I² 86%). For enzyme immunoassay in children (342 patients), the pooled sensitivity was 86% (95% CI, 79–92%) and the pooled specificity was 92% (95% CI, 88–95%). For the higher quality immunochromatographic methods in the adult population (1,216 patients), the pooled sensitivity was 91% (95% CI, 87 to 94%) and the pooled specificity was 93% (95% CI, 92 to 95%); however, heterogeneity was modest for sensitivity (I² 61%) and specificity (I² 72%). For enzyme immunoassay in the adult population (333 patients), the pooled sensitivity was 86% (95% CI, 81–91%) and the pooled specificity was 97% (95% CI, 96 to 99%); however, heterogeneity was high for sensitivity and specificity (both, I² 88%).

Conclusions

RAST immunochromatographic methods appear to be very sensitive and highly specific to diagnose group A streptococcal pharyngitis among adults but not in children. We could not identify sources of variability among higher quality studies. The present systematic review provides the best evidence for the wide range of sensitivity included in current guidelines.

Primary Prevention of Acute Rheumatic Fever and Rheumatic Heart Disease With Penicillin in South African Children With Pharyngitis

Background—

Acute rheumatic fever and subsequent rheumatic heart disease remain significant in developing countries. We describe a cost-effective analysis of 7 strategies for the primary prevention of acute rheumatic fever and rheumatic heart disease in children presenting with pharyngitis in urban primary care clinics in South Africa.

Methods and Results—

We used a Markov model to assess the cost-effectiveness of treatment with intramuscular penicillin using each of the following strategies: (1) empirical (treat all); (2) positive throat culture (culture all); (3) clinical decision rule (CDR) score ≥2 (CDR 2+); (4) CDR score ≥3 (CDR 3+); (5) treating those with a CDR score ≥2 plus those with CDR score <2 and positive cultures (CDR 2+, culture CDR negatives); (6) treating those with a CDR score ≥3 plus those with CDR score <3 and positive cultures (CDR 3+, culture CDR negatives); and (7) treat none. The strategies ranked in order from lowest cost were treat all ($11.19 per child), CDR 2+ ($11.20); the CDR 3+ ($13.00); CDR 2+, culture CDR negatives ($16.42); CDR 3+, culture CDR negatives ($23.89); and culture all ($27.21). The CDR 2+ is the preferred strategy at less than $150/quality-adjusted life year compared with the treat all strategy. A strategy of culturing all children compared with the CDR 2+ strategy costs more than $125 000/quality-adjusted life year gained.

Conclusions—

Treating all children presenting with pharyngitis in urban primary care clinics in South Africa with intramuscular penicillin is the least costly. A strategy of using a clinical decision rule without culturing is overall the preferred strategy. A strategy of culturing all children may be prohibitively expensive.

Pharyngitis management: defining the controversy

Despite numerous controlled trials, clinical practice guidelines and cost-effective analyses, controversy persists regarding the appropriate management strategy for adult pharyngitis. In this perspective, we explore this controversy by comparing two competing clinical guidelines. Although the guidelines appear to make widely diverging recommendations, we show that the controversy centers on only a small proportion of patients: those presenting with severe pharyngitis. We examine recently published data to illustrate that this seemingly simple problem of strep throat remains a philosophical issue: should we give primacy to relieving acute time-limited symptoms, or should we emphasize the potential societal risk of antibiotic resistance? We accept potentially over treating a minority of adult pharyngitis patients with the most severe presentations to reduce suffering in an approximately equal number of patients who will have false negative test results if the test-and-treat strategy were used.

Optimal management of adults with pharyngitis--a multi-criteria decision analysis

BACKGROUND

Current practice guidelines offer different management recommendations for adults presenting with a sore throat. The key issue is the extent to which the clinical likelihood of a Group A streptococcal infection should affect patient management decisions. To help resolve this issue, we conducted a multi-criteria decision analysis using the Analytic Hierarchy Process.

METHODS

We defined optimal patient management using four criteria: 1) reduce symptom duration; 2) prevent infectious complications, local and systemic; 3) minimize antibiotic side effects, minor and anaphylaxis; and 4) achieve prudent use of antibiotics, avoiding both over-use and under-use. In our baseline analysis we assumed that all criteria and sub-criteria were equally important except minimizing anaphylactic side effects, which was judged very strongly more important than minimizing minor side effects. Management strategies included: a) No test, No treatment; b) Perform a rapid strep test and treat if positive; c) Perform a throat culture and treat if positive; d) Perform a rapid strep test and treat if positive; if negative obtain a throat culture and treat if positive; and e) treat without further tests. We defined four scenarios based on the likelihood of group A streptococcal infection using the Centor score, a well-validated clinical index. Published data were used to estimate the likelihoods of clinical outcomes and the test operating characteristics of the rapid strep test and throat culture for identifying group A streptococcal infections.

RESULTS

Using the baseline assumptions, no testing and no treatment is preferred for patients with Centor scores of 1; two strategies--culture and treat if positive and rapid strep with culture of negative results--are equally preferable for patients with Centor scores of 2; and rapid strep with culture of negative results is the best management strategy for patients with Centor scores 3 or 4. These results are sensitive to the priorities assigned to the decision criteria, especially avoiding over-use versus under-use of antibiotics, and the population prevalence of Group A streptococcal pharyngitis.

CONCLUSION

The optimal clinical management of adults with sore throat depends on both the clinical probability of a group A streptococcal infection and clinical judgments that incorporate individual patient and practice circumstances.

Diagnosis and management of pharyngitis in a pediatric population based on cost-effectiveness and projected health outcomes

BACKGROUND

Pharyngitis is a common childhood complaint. Current management for children and adolescents includes 1 of 6 strategies, ie, (1) observe without testing or treatment, (2) treat all suspected cases with an antibiotic, (3) treat those with positive throat cultures, (4) treat those with positive rapid tests, (5) treat those with positive rapid tests and those with positive throat cultures after negative rapid tests, or (6) use a clinical scoring measure to determine the diagnosis/treatment strategy. The sequelae of untreated group A hemolytic streptococcal (GAS) pharyngitis are rare, whereas antibiotic treatment may result in side effects ranging from rash to death. The cost-utility of these strategies for children has not been reported previously.

METHODS

A decision tree analysis incorporating the total cost and health impact of each management strategy was used to determine cost per quality-adjusted life-year ratios. Sensitivity analyses and Monte Carlo simulations assessed the accuracy of the estimates.

RESULTS

From a societal perspective with current Medicaid reimbursements for testing, performing a throat culture for all patients had the best cost-utility. For private insurance reimbursements, rapid antigen testing had the best cost-utility. Observing without testing or treatment had the lowest morbidity rate and highest cost from a societal perspective but the lowest cost from a payer perspective. The model was most sensitive to the incidence of acute rheumatic fever and peritonsillar abscess after untreated GAS pharyngitis. Monte Carlo simulations demonstrated considerable overlap among all of the options except for treating all patients and observing all patients.

CONCLUSIONS

Observing patients with pharyngitis had the lowest morbidity rate. The costs of this option were primarily from parental time lost from work. Before recommending observation rather than treatment of GAS pharyngitis, accurate estimates of the risk of developing acute rheumatic fever and peritonsillar abscess after GAS pharyngitis are needed.

The effect of erythromycin on resolution of symptoms among adults with pharyngitis not caused by group A streptococcus

OBJECTIVE

To determine the effect of treatment with erythromycin on the resolution of symptoms among adults with pharyngitis not caused by group A streptococcus (GAS).

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Ambulatory setting (hospital-based general internal medicine practices, walk-in clinic, employee health service, and university health service).

PATIENTS

One hundred and eighty-six adults who met eligibility criteria and whose chief complaint included sore throat. Patients with positive cultures for GAS were excluded.

INTERVENTION

Ninety-three patients received erythromycin (333 mg three times daily for 10 days) and 93 control patients received placebo.

MEASUREMENTS AND MAIN RESULTS

Major outcome measurements included time to improvement in sore throat, time to improvement in cough, time to improvement in activity level, and subjective sense of well-being. The average age of the patients studied was 26.6 years; 35% were men. Patients given erythromycin had more rapid resolution of sore throat symptoms (hazard ratio 1.43: 95% confidence interval [CI] 1.00, 2.03: p = .049). Cough also resolved more rapidly in patients receiving erythromycin (hazard ratio 2.22: 95% CI 1.01, 4.88: p = .05). There were no differences between the two treatment groups in improvement of activity level or how sick patients felt in general. Most of the benefit in resolution of sore throat was conferred on patients who sought medical care within 2 days of onset.

CONCLUSIONS

Our results suggest that the benefit of erythromycin treatment for patients with non-GAS pharyngitis is small and of borderline statistical significance. Because of the small size of the effect and because widespread use of erythromycin could promote drug resistance, we do not recommend routine use of erythromycin in adult patients with this type of pharyngitis.

Should nurses in Israeli primary care clinics be expected to manage streptococcal throat infections?

INTRODUCTION

Legal regulations in Israel allow nurses to perform only limited clinical procedures.

OBJECTIVE

To determine the probability of streptococcal infection in adults with sore throat, as assessed clinically by standard nursing procedures.

DESIGN

Using throat culture as the standard, the contribution of various clinical findings (fever, exudate, erythrocyte sedimentation rate (ESR), white blood count) to the determination of the diagnosis of streptococcal infection was assessed, using logistic regression analysis.

SETTING

Israeli general practice.

PATIENTS

100 consecutive adult patients presenting with a red, sore throat.

RESULTS

Six patients showed the full clinical picture of exudate, increased ESR and leukocytosis, with an 82% probability of streptococcal infection. Forty-nine patients showed none of these three findings, and only one of them (among the three patients with rhinitis) had a positive throat swab. Forty-five patients showed an intermediate clinical picture which did not provide a reliable basis for the diagnosis or exclusion of streptococcal infection. Fever alone did not significantly (P < 0.05) predict streptococcal infection.

CONCLUSIONS

Nurses may safely discharge adult patients with a red, sore throat without antibiotic treatment only if they have no additional signs or symptoms. The few patients with all the clinical findings may be treated with antibiotics without a throat swab. All other patients should be referred for examination by a doctor.

You can lead a horse to water--improving physicians' knowledge of probabilities may not affect their decisions

OBJECTIVES

To determine whether improving physicians' judgments of the probability of streptococcal pharyngitis for patients with sore throats would affect their use of antibiotics and affect the variation in such use.

DESIGN

Post-hoc retrospective analysis of data previously collected as part of a controlled trial.

SETTINGS

University student health services in Pennsylvania and Nebraska.

PATIENTS

Sequential patients with pharyngitis seen before and after the time clinicians received either an experimental educational intervention designed to improve probabilistic diagnostic judgments (at the Pennsylvania site) or a control intervention, a standard lecture (at the Nebraska site). The clinician-subjects were the primary case physicians practicing at either site.

MEASUREMENTS

Clinical variables prospectively recorded by the clinicians, probability assessments, and treatment decisions.

RESULTS

At the experimental site, despite marked decreases in clinicians' overestimations of disease probability after the intervention, the proportion of patients prescribed antibiotics showed a trend toward increasing: 100/290 (34.5%) pre-intervention, 90/225 (40%) post-intervention. The intervention did not decrease practice variation between individual doctors. Univariable and multivariable analyses showed no major change in the relationships between clinical variables and treatment decisions after the intervention. At the control site there was no major change in probability judgments or treatment decisions after the intervention.

CONCLUSIONS

Teaching physicians to make better judgments of disease probability may not alter their treatment decisions.

Streptococcal pharyngitis: a review of pathophysiology, diagnosis, and management

Pharyngitis is an illness frequently treated by emergency physicians and primary care practitioners. It is the subject of much controversy regarding optimal treatment in the acute care setting. This review discusses pertinent aspects of the pathophysiology, clinical features, diagnosis, and treatment based on available literature. This review is also meant to serve as a bibliographic resource for some of the controversies of this complex topic.

Using treatment-tradeoff preferences to select diagnostic strategies: linking the ROC curve to threshold analysis

Selection of optimal diagnostic strategies depends on the accuracy of diagnostic tests, the prevalence of disease, and the relative benefits and harms resulting from test/treatment choices. One can characterize diagnostic strategies according to their net benefit-to-harm ratios. Within the framework of expected-utility theory, the benefit-to-harm ratio is equivalent to the marginal tradeoff between erroneous and correct treatment choices. Consequently, a physician can identify his or her preferred strategy by asking the question: "How many additional treatment errors am I willing to make in order to treat one additional person correctly?" Family physicians were asked to indicate their lowest and highest acceptable tradeoff ratios in a survey about streptococcal pharyngitis. All 53 respondents indicated uncertainty about their preferred treatment-tradeoff ratios. For 58% of respondents, the midpoints of the acceptable range of tradeoff ratios corresponded to generally accepted diagnostic strategies: 1) test all or 2) treat if classic, test all others. In contrast, previously published patient utilities yield a treatment-tradeoff ratio that corresponds to the strategy of treating all cases. The analysis illustrates the linkage between the optimal operating point on a receiver operating characteristic (ROC) curve and the selection of a preferred diagnostic strategy based on treatment thresholds derived from benefit-to-harm ratios. The survey results indicate that physicians can respond directly to questions assessing their preferences for such treatment thresholds. Differences between patients and physicians have significant impacts on choices of test and treatment strategies.

Facts and fallacies about streptococcal infection and rheumatic fever

Recent outbreaks of acute rheumatic fever (ARF) in the United States are drawing attention to a previously declining disease. Authorities agree that penicillin treatment of group A beta-hemolytic streptococcus (GABHS) pharyngitis contributed to the decline in incidence and severity of ARF. However, because the pathogenic mechanism that links GABHS and ARF is still a debatable issue, the cause of the recent outbreaks is unknown. A review of the current literature generates interesting questions about the current status of ARF and common GABHS testing and treatment practices. Facts about GABHS and ARF and current recommendations for the diagnosis and treatment of GABHS pharyngitis are presented.