Diagnostic accuracy of the APPY1 Test in patients aged 2-20 years with suspected acute appendicitis presenting to emergency departments.
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.


METHODS
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.
Emergency Department, Hospital Universitario Clínico San Carlos, Madrid, Spain.|Health Research Institute, Hospital Universitario Clínico San Carlos, Madrid, Spain.
Juan
J
González Del Castillo
Emergency Department, Hospital Universitario Clínico San Carlos, Madrid, Spain.
Francisco Javier
FJ
Ayuso
Emergency Department, Hospital Universitario Sant Joan de Deu, Barcelona, Spain.
Victoria
V
Trenchs
Emergency Department, Hospital Universitario de Basurto, Bilbao, Spain.
Mikel
M
Martinez Ortiz de Zarate
Emergency Department, Hospital Universitario Virgen de la Macarena, Sevilla, Spain.
Carmen
C
Navarro
Pediatric Department, Hospital Universitario Clínico San Carlos, Madrid, Spain.
Kinda
K
Altali
Research Unit, Preventive Medicine Department, Hospital Universitario Clínico San Carlos, Madrid, Spain.
Cristina
C
Fernandez
Division of Emergency Medicine, Newton-Wellesley Hospital, Newton, Massachusetts, USA.
David
D
Huckins
Emergency Department, Hospital Universitario Clínico San Carlos, Madrid, Spain.|Health Research Institute, Hospital Universitario Clínico San Carlos, Madrid, Spain.
Francisco Javier
FJ
Martín-Sánchez
D000208:Acute Disease; D000293:Adolescent; D001064:Appendicitis / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis*; D002097:C-Reactive Protein / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007223:Infant; D007958:Leukocyte Count; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D055815:Young Adult
D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex; D002097:C-Reactive Protein
abdomen; diagnosis; paediatrics