The aim of this study was to evaluate validity and reliability of the WHOQOL-100 questionnaire in the middle-aged Kaunas population and to assess quality of life among men and women and age groups.
Material and methods: The random sample consisted of 1347 Kaunas men and women aged 35-64 and stratified by age and sex (response rate 62%). They were examined in 2001-2002 using self-administered of the WHOQOL-100 questionnaire. Approval from the Ethics Committee of Kaunas University of Medicine was obtained and participants signed a written informed consent prior to filling in a questionnaire. The direct method was used for age standardization using European population as a standard. Validity and reliability of the questionnaire were evaluated by Pearson's correlation coefficients and by Cronbach's alfa.
Results: The reliability of the questionnaire among items was found to be very high for all domains (Cronbach's alfa from 0.77 to 0.91). The retest reliability was high or very high for all domains (0.64-0.89). Women scored lower in all domains as compared to men, except spirituality (p<0.001). The scores of the questionnaire decreased with age among both men and women. Women aged 45-54 scored lower in the quality of life, physical and independence level domains, whereas men were lower in the social relationship and spirituality domains as compared to the youngest group (p<0.05).
Conclusion: The WHOQOL-100 questionnaire is a reliable and valid measure of quality of life in the middle-aged Kaunas population; older age and female gender are the determinants of worse quality of life.