Validation of a symptoms distress scale in a cirrhotic population using item response theory

Background The assessment of symptoms distress is an important strategy for symptoms management and treatment of patients with liver cirrhosis (LC); however, appropriate instruments are limited. Objective The objective of this study was to validate a symptoms distress scale (SDS) by confirming the appropriateness of each item using item response theory. Methods A cross-sectional and convenience sampling was conducted to recruit eligible cirrhotic outpatients from the gastroenterology outpatient department of a single medical university hospital. In total, 163 patients with LC completed the 21-item SDS. A graded response model with two-parameter (discrimination and difficulty) estimation was used for data analysis. Results The item response theory model identified the validity of the SDS and found that most of the items in the SDS represented a high level of symptoms distress; moreover, three items of bruising, drowsiness, and dark urine were reported in cirrhotic patients with severe symptom distress. Four items comprising bodily pain, right upper quadrant pain, muscle cramps, and change in appearance can be appropriately represented in cirrhotic patients with mild symptoms distress. Moreover, the amount of test information in the SDS was >0.70, indicating acceptable reliability. Discussion Items of the SDS can be useful for assessing different levels of symptoms distress; however, using the scale to assess mild symptoms distress in populations with LC should be done with great caution.