Development And Evaluation Of Quality Of Life Instrument For Patients With Osteoarthritis.

Objectives To develop and validate the osteoarthritis scale of the system of Quality of Life Instruments for Chronic Diseases, QLICD-OA, based on the modular approach (combining a general QOL module and a disease-specific module) and Chinese culture. To explore influence factors of QOL in patients with osteoarthritis.Methods According to the theoretical framework of QLICD-OA, item pool was presented and screened to form a questionnaire for pre-test. A pre-test was administered to 32 doctors and 12 patients with osteoarthritis treated in the First Affiliated Hospital of Kunming Medical University in Kunming, Yunnan. Three statistical procedures (variation analysis-select items by comparing their score standard deviation, correlation analysis and importance ratings) and focus group discussion were used to re-screen the items based on pre-test data. Finally,21 items were selected to form the specific module. The QLICD-OA consisting of the general and the specific module described above was used for 140 patients with osteoarthritis in a field survey in order to study its psychometric properties.The study population was limited to osteoarthritis inpatients at any stage and with any treatment who were able to read and understand the questionnaires. The participating investigators were doctors and medical post-graduate students. The investigators explained the trial and the scale to the patients and obtained informed consent from those who agreed to participate in the study. Each respondent (n=140) answered the questionnaires at the time of admission to the hospital. Each patient was required to participate in a second assessment the following day or the second day after hospitalization to evaluate test-retest reliability. In addition, each patient was measured again at discharge (after about one weeks of treatment) to evaluate the responsiveness.The Chinese version of SF-36 was also used to provide data for assessing the criterion-related validity of the QLICD-OA. Construct validity was evaluated by Pearson's correlation coefficient r. among items and domains as well as by factor analysis. Internal consistency was evaluated using Cronbach's alpha coefficient for each domain/facet, and test-retest reliability by Pearson's correlation coefficient r. Responsiveness was assessed by comparing the mean difference between the first and third assessments as well as the standardized response mean (SRM).Comparisons of mean scores across different levels of factors were evaluated by t tests, analysis of variance. Analysis of influence factors of HRQOL employed correlation analysis and multiple linear regressions.Results (1) Development of QLICD-OA, a total of 57 entries, of 21spcific modules, common modules 36.(2) QLICD-OA Reliability:The coefficients of internal consistency Cronbach's Alpha of all domains were greater than 0.6 except three facets of energy, interpersonal relations and social role. The split-half were greater than 0.5 except social function domain. The results of test-retest reliability indicated that all domains correlation coefficients between the first and second measurements were greater than 0.7, and the differences of means scores of all domains had no statistical significance. The reliability of the questionnaire was good.(3) QLICD-OA Validity:Because the item pool was discussed by panels and expert in urology and it could reflect the definition of health related QOL proposed by WHO, the QLICD-OA had good content validity. Most of the correlation coefficients between item and its domain were greater than the correlation coefficients between items and other domains. Three components were explored by using factor analysis with varimax rotation, identified and explain 58.37% of the variance. The mentioned three methods indicate the specific module of QLICD-OA had good construct validity.(4) QLICD-OA Responsiveness:The differences of each domain between first and third time point had statistical significance. So the scale had good responsibility. (5) About 20 minutes were spent in completing the instrument and the qualified rate is 100%, demonstrating good feasibility of the instrument.(6) The multiple regression analysis showed that age, marital status, ethnicity, gender, rheumatoid factor affect different domains of QOL of osteoarthritis.Conclusions The QLICD-OA is of reliability, validity and responsiveness, and can be used to assess quality of life for patients with osteoarthritis. The influence factors of patients'quality of life were age, marital status, ethnicity, gender, rheumatoid factor, although quality of life scores did not show strong correlations with clinical objective indicators. However, there were still other influence factors.