Title:
Validation of the chronic liver disease questionnaire in Serbian patients.

Abstract:
To translate into Serbian and to investigate the validity of the cross-culturally adapted the chronic liver disease questionnaire (CLDQ).
The questionnaire was validated in 103 consecutive CLD patients treated between October 2009 and October 2010 at the Clinic for Gastroenterology, Clinical Centre of Serbia, Belgrade (Serbia). Exclusion criteria were: age < 18 years, psychiatric disorders, acute complications of CLD (acute liver failure, variceal bleeding, and spontaneous bacterial peritonitis), hepatic encephalopathy (grade > 2) and liver transplantation. Evaluation of the CLDQ was done based on the following parameters: (1) acceptance is shown by the proportion of missing items; (2) internal reliabilities were assessed for multiple item scales by using Cronbach alpha coefficient; and (3) in order to assess whether the allocation of items in the domain corresponds to their distribution in the original questionnaire (construction validity), an exploratory factor analysis was conducted. Discriminatory validity was determined by comparing the corresponding CLDQ score/sub-score in patients with different severity of the diseases.
The Serbian version of CLDQ questionnaire completed 98% patients. Proportion of missing items was 0.06%. The total time needed to fill the questionnaire was ranged from 8 to 15 min. Assistance in completing the questionnaire required 4.8% patients, while 2.9% needed help in reading, and 1.9% involved writing assistance. The mean age of the selected patients was 53.8 ± 12.9 years and 54.4% were men. Average CLDQ score was 4.62 ± 1.11. Cronbach's alpha for the whole scale was 0.93. Reliability for all domains was above 0.70, except for the domain "Activity" (0.49). The exploratory factor analysis model revealed 6 factors with eigenvalue of greater than 1, explaining 69.7% of cumulative variance. The majority of the items (66%) in the Serbian version of the CLDQ presented the highest loading weight in the domain assigned by the CLDQ developers: "Fatigue" (5/5), "Emotional function" (6/8), "Worry" (5/5), "Abdominal symptoms" (0/3), "Activity" (0/3), "Systemic symptoms" (3/5). The scales "Fatigue" and "Worry" fully corresponded to the original. The factor analysis also revealed that the factors "Activity" and "Abdominal symptoms" could not be replicated, and two new domains "Sleep" and "Nutrition" were established. Analysis of the CLDQ score/sub-score distribution according to disease severity demonstrated that patients without cirrhosis had lower total CLDQ score (4.86 ± 1.05) than those with cirrhosis Child's C (4.31 ± 0.97). Statistically significant difference was detected for the domains "Abdominal symptoms" [F (3) = 5.818, P = 0.001] and "Fatigue" [F (3) = 3.39, P = 0.021]. Post hoc analysis revealed that patients with liver cirrhosis Child's C had significantly lower sub-score "Abdominal symptoms" than patients without cirrhosis or liver cirrhosis Child's A or B. For domain "Fatigue", patients with cirrhosis Child's C had significantly lower score, than non-cirrhotic patients.
The Serbian version of CLDQ is well accepted and represents a valid and reliable instrument in Serbian sample of CLD patients.