ASSESSMENT OF CLINICAL-FEATURES PREDICTING STREPTOCOCCAL PHARYNGITIS

A total of 133 patients who consulted 4 general practitioners in Berge n 1988/89 for sore throat were examined. 8 clinical parameters with ex pected predictive value for identifying streptococcal tonsillopharyngi tis were recorded. Clinical examination was validated against bacterio logic examination at a microbiological laboratory. The prevalence of s treptococcal infection (group A, C and G) was 29%. An algorithm was co nstructed which identifies 3 groups with varying probabilities of stre ptococcal infection. A positive predictive value of 62% in the group w ith highest prevalence and a negative predictive value of 90% in the g roup with lowest prevalence was found. The consequences of performing a confirmative test only on patients in the group with uncertain predi ction for streptococcal disease was elaborated. Although slightly redu ced accuracy was demonstrated, due to diminished sensitivity, selectiv e testing is recommended. Another algorithm was constructed for use in situations where no confirmative testing is available. The positive p redictive value in the group with highest probability of streptococcal infection was 51%, and the negative predictive value in the group wit h lowest probability was 84%.