Hiroshi Igarashi, Naoki Nago, Hiromichi Kiyokawa, Motoharu Fukushi

This study was designed to assess the accuracy of gastrointestinal symptoms, including abdominal pain, nausea, and vomiting, in the diagnosis of Group A streptococcal (GAS) pharyngitis in children and to determine differences in diagnostic accuracy in boys versus girls. This retrospective cross-sectional study included 5,755 consecutive patients aged <15 years with fever in the electronic database at a primary care practice. Gastrointestinal symptoms were recorded in the database according to the International Classification of Primary Care codes, and the data were extracted electronically. The reference standard was GAS pharyngitis diagnosed with a rapid test. Patients with a clinical diagnosis of probable GAS pharyngitis were excluded from the primary analysis. Among the 5,755 children with fever, 331 (5.8%) were coded as having GAS pharyngitis, including 218 (65.9%) diagnosed with rapid tests and 113 (34.1%) clinically diagnosed with probable GAS pharyngitis. Among patients with fever and abdominal pain, rapid-test-confirmed GAS pharyngitis was significantly more common in boys (11/120, 9.2%) than in girls (3/128, 2.3%; p=0.026). The positive likelihood ratio of abdominal pain was 1.49 (95% CI =0.88-2.51): 2.41 (95% CI =1.33-4.36) in boys and 0.63 (95% CI =0.20-1.94) in girls. The positive likelihood ratio of nausea was 2.05 (95% CI =1.06-4.00): 2.74 (95% CI =1.28-5.86) in boys and 1.09 (95% CI =0.27-4.42) in girls. The association between abdominal pain and GAS pharyngitis was stronger in boys aged <6 years than in boys aged 6-15 years. Abdominal pain and nausea were associated with GAS pharyngitis in boys, but not in girls. Abdominal pain and nausea may help determine the suitability of rapid tests in younger boys with fever and other clinical findings consistent with GAS pharyngitis, even in the absence of sore throat.