Concordance of clinical findings and clinical judgment in the diagnosis of streptococcal pharyngitis.
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
H
Department of Preventive Medicine, Griffin Hospital, Derby, CT 06418, USA. haqnawaz@pol.net
Smith
D S
DS
Mazhari
R
R
Katz
D L
DL
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D015331:Cohort Studies; D015169:Colony Count, Microbial; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010612:Pharyngitis / Q000175:diagnosis* / Q000382:microbiology / Q000503:physiopathology; D010808:Physical Examination; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000503:physiopathology; D013297:Streptococcus pyogenes / Q000302:isolation & purification*