Concordance of clinical findings and clinical judgment in the diagnosis of streptococcal pharyngitis
Academic Emergency Medicine
Diagnostic, standards; Pharyngitis, microbiology; Reagent kits; Streptococcal infections, diagnosis
Objective: It is uncertain how reliably clinicians apply clinical predictors of group A beta hemolytic streptococcal pharyngitis (GABHSP) to form a clinical impression, and how reliably this impression predicts culture results. The objective was to study clinician accuracy in diagnosing GABHSP. Methods: This was a prospective cohort study, conducted at an urgent care center of a major university. A convenience sample of 218 patients, aged 9-83 years, presenting with sore throat, was enrolled. Symptoms and signs of pharyngitis were documented on a standardized form; the likelihood of GABHSP was plotted on a visual analog scale; and throat culture was obtained. A comparison was then made between the clinical impression on presentation and the throat culture result. Results: Throat cultures were positive for GABHSP in 41 patients (19%). The probability of GABHSP was related to node size and tenderness, tonsillar exudate and hypertrophy, and pharyngeal erythema (p < 0.05); but not throat soreness, degree of fever, or cough. A strong clinical impression of GABHSP (>50% on the visual analog scale) was associated with tonsillar exudate and hypertrophy, tender nodes, and pharyngeal, erythema. Together, these four predictors had a sensitivity of 71%, a specificity of 77%, and a positive predictive value of 46%. Conclusions: Clinicians in this study based their impression of GABHSP on the most reliable symptoms and signs. While a strong clinical suspicion of GABHSP predicted a greater probability of positive culture, the clinicians consistently overestimated the probability of GABHSP. Symptoms and signs predict GABHSP unreliably when used alone; they are helpful in modifying estimates of disease probability to facilitate optimal use of laboratory tests and antibiotics.
Nawaz, H., Smith, D., Mazhari, R., & Katz, D. (2000). Concordance of clinical findings and clinical judgment in the diagnosis of streptococcal pharyngitis. Academic Emergency Medicine, 7 (10). http://dx.doi.org/10.1111/j.1553-2712.2000.tb01259.x