Improving the prediction of streptococcal pharyngitis; time to move past exudate alone

Palatal petechiae are predictive of Group A streptococcal (GAS) pharyngitis. We sought to (a) quantify the value of considering petechiae in addition to exudate, and (b) assess provider incorporation of petechiae's predictive nature for GAS into clinical decision making.

We conducted a cross-sectional study of patients 3-21 years with sore throat and GAS testing performed in a pediatric emergency department (ED) in 2016. Patients were excluded if immunosuppressed, nonverbal, medically complex, had chronic tonsillitis, or received antibiotics in the preceding week. As a proxy of provider incorporation of petechiae into clinical decision making we assessed how often petechiae were documented, compared with exudate. We performed univariate analysis using χ² analysis for categorical data and Mann-Whitney U test for continuous data.

1574 patients met inclusion criteria. Median age 8 years [IQR 5, 13]; 54% female. 372 patients (24%) were GAS positive. Both palatal petechiae and tonsillar exudates were predictive of GAS [OR 8.5 (95% CI 5.2-13.9), and 1.9 (95% CI 1.4-2.6) respectively]. Examining petechiae or exudate vs. exudate alone increases OR from 1.9 to 2.9 (95% CI 2.2-3.8). Sensitivity improves (23% to 34%) with minimal change to specificity (87% to 85%). Among those with a normal or erythematous throat exam, petechiae were mentioned as a pertinent negative in 28%; absence of tonsillar exudate was mentioned in 78% (p = .02).

Palatal petechiae are highly associated with GAS, yet rarely addressed in documentation. Incorporating palatal petechiae into common scoring systems could improve prediction and disseminate this knowledge into practice.