INTRODUCTION: Measuring quality of life has growing importance in the field of health technology assessment. It is especially true for chronic diseases, like ankylosing spondylitis, which results in significant impact on patients' quality of life through the intensity and duration of the disease. OBJECTIVES: To measure the reliability and validity of the Hungarian version of Ankylosing Spondylitis Quality of Life instrument with the intention of its use in clinical and health economic trials and burden of disease studies in Hungary via the introduction of a certain validation process. METHODS: One of the most important criteria for the validity of quality of life instruments is the standard method used for adapting the questionnaire to foreign languages. The dual method was applied for the Hungarian adaptation of the Ankylosing Spondylitis Quality of Life questionnaire, which was followed by psychometric testing. RESULTS: High test-retest correlation (0.85) indicated an acceptable degree of reliability with no evidence of excessive random measurement error. The internal consistency of the measure was confirmed (Cronbach's alpha coefficients were 0.87 and 0.91 at Time 1 and Time 2 respectively), with strong evidence that all items were adequately inter-related. The correlations with the NHP at both time points were at the expected levels, providing evidence of convergent and divergent validity. CONCLUSION: On the basis of results shown above, it is concluded that the Hungarian Ankylosing Spondylitis Quality of Life questionnaire is a reliable and valid measure of quality of life.
