Original English questionnaires--Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Patient Global Score, and Bath Ankylosing Spondylitis Disease Activity Index--are designed to evaluate health, physical and psychical state of patients with spondyloarthropathies and to assess efficiency of the treatment.
Objective: The objective of the study was to adapt Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Patient Global Score, Bath Ankylosing Spondylitis Disease Activity Index questionnaires to the Lithuanian context and examine their psychometric aspects: reliability and validity.
Patients and methods: Validation and linguistic and cultural adaptation of Lithuanian questionnaires were performed according to the requirements for adaptation of the international questionnaires. Psychometric features of Lithuanian questionnaires were examined in 139 patients with spondyloarthropathies. The validity of questionnaires was tested by comparing these questionnaires with Health Assessment Questionnaire Modified for Spondyloarthropathies, metrology indices (tragus-to-wall distance, lateral flexion, modified Schober's distance, intermalleolar distance), pain intensity, patient's well-being, physician's assessment of the disease activity, and total enthesis count. The reliability of questionnaires was assessed by determining internal consistency of scales and scale stability and by calculating the intraclass correlation coefficient.
Results: The linguistic and cultural adaptation of these questionnaires was made during the study. Internal consistency was high for functional and disease activity index (Cronbach alpha>/=0.80) and moderate for the Bath Ankylosing Spondylitis Patient Global Score (Cronbach alpha=0.58). High stability in regard to time was characteristic of all three questionnaires (intraclass correlation coefficient >0.95). A significant association between the separate questions of examined instruments, their joint results and other factors reflecting patient's health was established.
Conclusions: Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Patient Global Score, and Bath Ankylosing Spondylitis Disease Activity Index questionnaires in Lithuanian fully correspond to psychometric requirements. They are appropriate and relevant in assessing the influence of spondyloarthropathies on a patient's health.