Does this patient have strep throat?

Context Sore throat is a common complaint, and identifying patients with gr oup A P-hemolytic streptococcal pharyngitis (strep throat) is an important task for clinicians. Previous reviews have not systematically reviewed and synthesized the evidence. Objective To review the precision and accuracy of the clinical examination in diagnosing strep throat. Data Source MEDLINE search for articles about d iagnosis of strep throat using history-taking and physical examination. Study Selection Large blinded, prospective studies (having greater than or equal to 300 patients with sore throat) reporting history and physical exam ination data and using throat culture as the reference standard were includ ed. Of 917 articles identified by the search, 9 met ail inclusion criteria. Data Extraction Pairs of authors independently reviewed each article and us ed consensus to resolve discrepancies. Data Synthesis The most useful findings for evaluating the likelihood of st rep throat are presence of tonsillar exudate, pharyngeal exudate, or exposu re to strep throat infection in the previous 2 weeks (positive likelihood r atios, 3.4, 2.1, and 1.9, respectively) and the absence of tender anterior cervical nodes, tonsillar enlargement, or exudate (negative likelihood rati os, 0.60, 0.63, and 0.74, respectively). No individual element of history-t aking or physical examination is accurate enough by itself to rule in or ru le out strep throat. Three validated clinical prediction rules are describe d for adult and pediatric populations. Conclusions While no single element of history-taking or physical examinati on is sufficiently accurate to exclude or diagnose strep throat, a well-val idated clinical prediction rule can be useful and can help physicians make more informed use of rapid antigen tests and throat cultures.