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Diagnostic accuracy of the APPY1 Test in patients aged 2–20 years with suspected acute appendicitis presenting to emergency departments
  1. Juan González del Castillo1,2,
  2. Francisco Javier Ayuso1,
  3. Victoria Trenchs3,
  4. Mikel Martinez Ortiz de Zarate4,
  5. Carmen Navarro5,
  6. Kinda Altali6,
  7. Cristina Fernandez7,
  8. David Huckins8,
  9. Francisco Javier Martín-Sánchez1,2
  10. representing INFURG-SEMES group
    1. 1Emergency Department, Hospital Universitario Clínico San Carlos, Madrid, Spain
    2. 2Health Research Institute, Hospital Universitario Clínico San Carlos, Madrid, Spain
    3. 3Emergency Department, Hospital Universitario Sant Joan de Deu, Barcelona, Spain
    4. 4Emergency Department, Hospital Universitario de Basurto, Bilbao, Spain
    5. 5Emergency Department, Hospital Universitario Virgen de la Macarena, Sevilla, Spain
    6. 6Pediatric Department, Hospital Universitario Clínico San Carlos, Madrid, Spain
    7. 7Research Unit, Preventive Medicine Department, Hospital Universitario Clínico San Carlos, Madrid, Spain
    8. 8Division of Emergency Medicine, Newton-Wellesley Hospital, Newton, Massachusetts, USA
    1. Correspondence to Dr Juan González del Castillo, Emergency Department, Hospital Universitario Clínico San Carlos, Calle Professor Martín-Lagos s/n, Madrid 28040, Spain; jgonzalezcast{at}


    Objective Evaluate the diagnostic accuracy of the APPY1 Test alone and in combination with the Alvarado score (AS) to rule out acute appendicitis (AA) in patients presenting to EDs with abdominal pain suspicious for AA.

    Methodology Observational study in a prospective consecutive cohort including all patients from 2 to 20 years with abdominal pain suggestive of AA in four EDs. The APPY1 Test was performed and AS was calculated to determine risk stratification for each patient.

    Results 321 patients enrolled (mean age 11.8 (SD 3.8) years, 52.0% male), with 32.4% low risk, 23.7% intermediate risk and 43.9% high risk according to the AS. 111 (34.6%) had AA, of whom 1 (0.9%) had a false-negative APPY1 Test result. The APPY1 Test had a sensitivity (Se) of 99.1% (95% CI 94.4% to 99.9%), specificity (Sp) of 32.9% (95% CI 26.6% to 39.7%), negative predictive value (NPV) of 98.6% (95% CI 91.2% to 99.9%) and negative likelihood ratio (LHR−) of 0.03 (0.00 to 0.19) in this population. For patients at low risk by AS, the APPY1 Test had a Se of 100% (95% CI 62.9% to 100%), NPV of 100% (95% CI 91.1% to 100%) and LHR− of 0.0 (not calculable), and for patients at intermediate risk by AS, the APPY1 Test had a Se of 94.4% (95% CI 70.6% to 99.7%), NPV of 94.7% (95% CI 71.9% to 99.7%) and LHR− of 0.18 (0.0 to 1.2), respectively.

    Conclusions APPY1 Test is a potentially useful diagnostic tool to rule out AA in this population, with clinical utility primarily in those patients classified as having low clinical risk of appendicitis according to the AS.

    • abdomen
    • diagnosis
    • paediatrics

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