0

The full content of Annals is available to subscribers

Subscribe/Learn More  >
Original Research |

Improved Diagnostic Accuracy of Group A Streptococcal Pharyngitis With Use of Real-Time Biosurveillance

Andrew M. Fine, MD, MPH; Victor Nizet, MD; and Kenneth D. Mandl, MD, MPH
[+] Article and Author Information

From Children's Hospital Boston, Harvard Medical School, Harvard-MIT Health Sciences and Technology, Boston, Massachusetts, and University of California, San Diego, La Jolla, California.


Acknowledgment: The authors thank CVS/Caremark and MinuteClinic for use of the data.

Grant Support: By the Mentored Public Health Research Scientist Development Award K01HK000055 from the Centers for Disease Control and Prevention (CDC), by Public Health Informatics Center of Excellence Award P01HK000088 from CDC, and by grants 1G08LM009778 and R01 LM007677 from the National Library of Medicine, National Institutes of Health.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-0140.

Reproducible Research Statement:Study protocol and data set: Not available. Statistical code: Available from Dr. Fine.

Requests for Single Reprints: Andrew M. Fine, MD, MPH, Emergency Medicine-Main 1, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115.

Current Author Addresses: Dr. Fine: Emergency Medicine-Main 1, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115.

Dr. Nizet: Division of Pediatric Pharmacology and Drug Discovery, UCSD School of Medicine, Cellular & Molecular Medicine East, Room 1066, 9500 Gilman Drive Mail Code 0687, La Jolla, CA 92093-5611.

Dr. Mandl: Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115.

Author Contributions: Conception and design: A.M. Fine, K.D. Mandl.

Analysis and interpretation of the data: A.M. Fine, V.N. Nizet, K.D. Mandl.

Drafting of the article: A.M. Fine, K.D. Mandl.

Critical revision of the article for important intellectual content: A.M. Fine, V.N. Nizet, K.D. Mandl.

Final approval of the article: A.M. Fine, V.N. Nizet, K.D. Mandl.

Provision of study materials or patients: A.M. Fine, K.D. Mandl.

Statistical expertise: A.M. Fine.

Obtaining of funding: A.M. Fine, K.D. Mandl.

Administrative, technical, or logistic support: A.M. Fine, K.D. Mandl.

Collection and assembly of data: A.M. Fine.


Ann Intern Med. 2011;155(6):345-352. doi:10.7326/0003-4819-155-6-201109200-00002
Text Size: A A A

Background: Clinical prediction rules do not incorporate real-time incidence data to adjust estimates of disease risk in symptomatic patients.

Objective: To measure the value of integrating local incidence data into a clinical decision rule for diagnosing group A streptococcal (GAS) pharyngitis in patients aged 15 years or older.

Design: Retrospective analysis of clinical and biosurveillance predictors of GAS pharyngitis.

Setting: Large U.S.-based retail health chain.

Patients: 82 062 patient visits for pharyngitis.

Measurements: Accuracy of the Centor score was compared with that of a biosurveillance-responsive score, which was essentially an adjusted Centor score based on real-time GAS pharyngitis information from the 14 days before a patient's visit: the recent local proportion positive (RLPP).

Results: Increased RLPP correlated with the likelihood of GAS pharyngitis (r2 = 0.79; P < 0.001). Local incidence data enhanced diagnostic models. For example, when the RLPP was greater than 0.30, managing patients with Centor scores of 1 as if the scores were 2 would identify 62 537 previously missed patients annually while misclassifying 18 446 patients without GAS pharyngitis. Decreasing the score of patients with Centor values of 3 by 1 point for an RLPP less than 0.20 would spare unnecessary antibiotics for 166 616 patients while missing 18 812 true-positive cases.

Limitations: Analyses were conducted retrospectively. Real-time regional data on GAS pharyngitis are generally not yet available to clinicians.

Conclusion: Incorporating live biosurveillance data into clinical guidelines for GAS pharyngitis and other communicable diseases should be considered for reducing missed cases when the contemporaneous incidence is elevated and for sparing unnecessary antibiotics when the contemporaneous incidence is low. Delivering epidemiologic data to the point of care will enable the use of real-time pretest probabilities in medical decision making.

Primary Funding Source: Centers for Disease Control and Prevention and the National Library of Medicine, National Institutes of Health.

Figures

Grahic Jump Location
Figure 1.
Proportion of cases positive for GAS pharyngitis, by study week for 9 locations.

The x-axis represents the time from 1 January 2007 to 31 December 2007, and the y-axis is the weekly proportion of cases positive for GAS pharyngitis. Each graph shows the proportion of patients who tested positive each week in 1 of 9 markets. The axes have been standardized to allow comparison across markets. The horizontal line is the average across all markets (0.25) and is provided for reference and to facilitate comparison. The hash marks on the x-axis display bimonthly intervals. GAS = group A streptococcal; NC = North Carolina.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Proportion of patients testing positive for GAS pharyngitis, by RLPP and grouped and labeled by Centor score.

Each line represents patients with the same Centor score across varying RLPPs. The proportion of patients who tested positive increases both as the clinical score and the RLPP increase. The Pearson coefficient was used to measure the strength of correlation. The r2 values, representing the proportion of the variation in GAS pharyngitis positivity that can be attributed to the RLPP, are 0.81 (P < 0.001) for a Centor score of 4, 0.86 (P < 0.001) for a Centor score of 3, 0.86 (P < 0.001) for a Centor score of 2, 0.70 (P < 0.001) for a Centor score of 1, and 0.47 (P < 0.001) for a Centor score of 0. The slopes of the lines for Centor scores of 4, 3, 2, 1, and 0 are 1.21, 0.88, 0.64, 0.37, and 0.29, respectively. Each data point represents a median of 223 patients (range, 41 to 1152 patients; interquartile range, 115 to 518 patients). GAS = group A streptococcal; RLPP = recent local proportion positive.

Grahic Jump Location
Grahic Jump Location
Appendix Figure.
Proportion of patients in the validation set (n = 27 081) testing positive for GAS pharyngitis, by RLPP and grouped and labeled by Centor score.

Each line represents patients with the same Centor score across varying RLPPs. The proportion of patients who tested positive increases both as the clinical score and the RLPP increase. The Pearson coefficient was used to measure strength of correlation. The r2 values, representing the proportion of the variation in GAS pharyngitis positivity that can be attributed to the RLPP, are 0.33 (P = 0.012) for a Centor score of 4, 0.70 (P < 0.001) for a Centor score of 3, 0.82 (P < 0.001) for a Centor score of 2, 0.68 (P < 0.001) for a Centor score of 1, and 0.35 (P = 0.005) for a Centor score of 0. The slopes of the lines for Centor scores of 4, 3, 2, 1, and 0 are 0.99, 0.80, 0.75, 0.43, and 0.28, respectively. Each data point represents a median of 140 patients (range, 45 to 555 patients; interquartile range, 82 to 290 patients). GAS = group A streptococcal; RLPP = recent local proportion positive.

Grahic Jump Location

Tables

References

Letters

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Comments

Submit a Comment
Submit a Comment

Summary for Patients

Clinical Slide Sets

Terms of Use

The In the Clinic® slide sets are owned and copyrighted by the American College of Physicians (ACP). All text, graphics, trademarks, and other intellectual property incorporated into the slide sets remain the sole and exclusive property of the ACP. The slide sets may be used only by the person who downloads or purchases them and only for the purpose of presenting them during not-for-profit educational activities. Users may incorporate the entire slide set or selected individual slides into their own teaching presentations but may not alter the content of the slides in any way or remove the ACP copyright notice. Users may make print copies for use as hand-outs for the audience the user is personally addressing but may not otherwise reproduce or distribute the slides by any means or media, including but not limited to sending them as e-mail attachments, posting them on Internet or Intranet sites, publishing them in meeting proceedings, or making them available for sale or distribution in any unauthorized form, without the express written permission of the ACP. Unauthorized use of the In the Clinic slide sets will constitute copyright infringement.

Toolkit

Buy Now

to gain full access to the content and tools.

Want to Subscribe?

Learn more about subscription options

Advertisement
Related Articles
Related Point of Care
Topic Collections
PubMed Articles
Forgot your password?
Enter your username and email address. We'll send you a reminder to the email address on record.
(Required)
(Required)