Validation of EncephalApp, Smartphone-Based Stroop Test, for the Diagnosis of Covert Hepatic Encephalopathy.
OBJECTIVE
Detection of covert hepatic encephalopathy (CHE) is difficult, but point-of-care testing could increase rates of diagnosis. We aimed to validate the ability of the smartphone app EncephalApp, a streamlined version of Stroop App, to detect CHE. We evaluated face validity, test-retest reliability, and external validity.


METHODS
Patients with cirrhosis (n = 167; 38% with overt HE [OHE]; mean age, 55 years; mean Model for End-Stage Liver Disease score, 12) and controls (n = 114) were each given a paper and pencil cognitive battery (standard) along with EncephalApp. EncephalApp has Off and On states; results measured were OffTime, OnTime, OffTime+OnTime, and number of runs required to complete 5 off and on runs. Thirty-six patients with cirrhosis underwent driving simulation tests, and EncephalApp results were correlated with results. Test-retest reliability was analyzed in a subgroup of patients. The test was performed before and after transjugular intrahepatic portosystemic shunt placement, and before and after correction for hyponatremia, to determine external validity.


RESULTS
All patients with cirrhosis performed worse on paper and pencil and EncephalApp tests than controls. Patients with cirrhosis and OHE performed worse than those without OHE. Age-dependent EncephalApp cutoffs (younger or older than 45 years) were set. An OffTime+OnTime value of >190 seconds identified all patients with CHE with an area under the receiver operator characteristic value of 0.91; the area under the receiver operator characteristic value was 0.88 for diagnosis of CHE in those without OHE. EncephalApp times correlated with crashes and illegal turns in driving simulation tests. Test-retest reliability was high (intraclass coefficient, 0.83) among 30 patients retested 1-3 months apart. OffTime+OnTime increased significantly (206 vs 255 seconds, P = .007) among 10 patients retested 33 ± 7 days after transjugular intrahepatic portosystemic shunt placement. OffTime+OnTime decreased significantly (242 vs 225 seconds, P = .03) in 7 patients tested before and after correction for hyponatremia (126 ± 3 to 132 ± 4 meq/L, P = .01) 10 ± 5 days apart.


CONCLUSIONS
A smartphone app called EncephalApp has good face validity, test-retest reliability, and external validity for the diagnosis of CHE.
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia. Electronic address: jsbajaj@vcu.edu.
Jasmohan S
JS
Bajaj
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Douglas M
DM
Heuman
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Richard K
RK
Sterling
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Arun J
AJ
Sanyal
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Muhammad
M
Siddiqui
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Scott
S
Matherly
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Velimir
V
Luketic
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
R Todd
RT
Stravitz
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Michael
M
Fuchs
Department of Biostatistics, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Leroy R
LR
Thacker
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
HoChong
H
Gilles
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Melanie B
MB
White
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Ariel
A
Unser
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
James
J
Hovermale
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Edith
E
Gavis
Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
Nicole A
NA
Noble
Department of Psychiatry, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia.
James B
JB
Wade
D000328:Adult; D006501:Hepatic Encephalopathy / Q000175:diagnosis*; D006801:Humans; D008103:Liver Cirrhosis / Q000150:complications*; D008875:Middle Aged; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D000068997:Smartphone; D057190:Stroop Test; D017216:Telemedicine / Q000379:methods*
Minimal Hepatic Encephalopathy; Screening; Stroop Test; TIPS