Existing clinical decision rules (CDRs) to diagnose group A streptococcal (GAS) pharyngitis have not been validated in sub-Saharan Africa. We developed a locally applicable CDR while evaluating existing CDRs for diagnosing GAS pharyngitis in South African children.
We conducted a prospective cohort study and enrolled 997 children 3–15 years of age presenting to primary care clinics with a complaint of sore throat, and whose parents provided consent. Main outcome measures were signs and symptoms of pharyngitis and a positive GAS culture from a throat swab. Bivariate and multivariate analyses were used to develop the CDR. In addition, the diagnostic effectiveness of 6 existing rules for predicting a positive culture in our cohort was assessed.
A total of 206 of 982 children (21%) had a positive GAS culture. Tonsillar swelling, tonsillar exudates, tender or enlarged anterior cervical lymph nodes, absence of cough and absence of rhinorrhea were associated with positive cultures in bivariate and multivariate analyses. Four variables (tonsillar swelling and one of tonsillar exudate, no rhinorrhea, no cough), when used in a cumulative score, showed 83.7% sensitivity and 32.2% specificity for GAS pharyngitis. Of existing rules tested, the rule by McIsaac et al had the highest positive predictive value (28%), but missed 49% of the culture-positive children who should have been treated.
The new 4-variable CDR for GAS pharyngitis (ie, tonsillar swelling and one of tonsillar exudate, no rhinorrhea, no cough) outperformed existing rules for GAS pharyngitis diagnosis in children with symptomatic sore throat in Cape Town.
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From the *Department of Medicine, Groote Schuur Hospital and University of Cape Town; and †Division of Clinical Pharmacology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa; ‡Division of Medical Microbiology, Department of Pathology, Faculty of Medicine & Health Sciences, Stellenbosch University & NHLS Tygerberg, Tygerberg, South Africa; §College of Public Health & Health Informatics, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; and ¶Division of Infectious Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee.
Accepted for publication July 21, 2016.
G.M. conceived the study and together with J.B.D. and B.M.M. gave conceptual advice, interpreted the data and edited the manuscript; M.E.E., K.C. and R.G. wrote the protocol and designed the study. M.E.E. implemented and managed the study, conducted the analysis with K.C., A.P.K., M.B. and A.S., interpreted the data and wrote the manuscript; K.C. contributed to the design of the study; V.F. recruited participants; D.D.B. collected and managed the data and assisted with the analysis. All authors read and approved the final draft of the manuscript. B.M.M. and G.M. contributed equally to this work.
This work was supported by the USPHS National Institutes of Health, UO1AI060592 and RO1AI010085 (to J.B.D.), the Medical Research Council of South Africa grant (to M.E.E. and B.M.M), the Lily and Ernst Hausmann Research Trust and the Medtronic Foundation. The authors have no conflicts of interest to disclose.
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Address for correspondence: Mark E. Engel, PhD, Department of Medicine, J46, Old Groote Schuur Hospital, Groote Schuur Drive, Observatory, Cape Town, South Africa. E-mail: firstname.lastname@example.org or Bongani M. Mayosi, DPhil, Department of Medicine, J46, Old Groote Schuur Hospital, Groote Schuur Drive, Observatory, Cape Town, South Africa. E-mail: email@example.com.