Objective: To asses the efficacy of near-to-patient laboratory testing in diagnosing group A beta haemolytic streptococci throat infection in adults, alone and in conjunction with the doctor's clinical judgement.
Setting and subjects: 174 primary care patients with a sore throat, of which 59 (34%) were identified as having group A streptococci.
Main outcome measures: The erythrocyte sedimentation rate, leucocyte count, and C-reactive protein, and a specific streptococcal immunological assay were evaluated separately and in conjunction with the doctor's clinical diagnosis. The presence of GAS throat infection, the reference standard, was defined as those patients presenting with a chief complaint of sore throat and having a positive GAS culture or a four-fold or more increase or fall of AST or ADNase B serum levels during a four-week observation period.
Results: The discriminatory ability of the sedimentation rate was not satisfactory and added little useful clinical information. Leucocytes and C-reactive protein both yielded clinically significant information and had similar test characteristics. The immunological test had the best characteristics of the tests evaluated.
Conclusion: Near-to-patient testing, except the erythrocyte sedimentation rate, may, in addition to the clinical evaluation, contribute to the differential diagnosis of streptococcal pharyngitis in adults.