Responsiveness and minimally important difference of a generic quality of life measure for complementary health practices

Abstract

Shorter and easier methods of conducting community health surveys would be useful. We conducted a study to demonstrate the responsiveness of the 10-item Mokichi Okada Association quality of life questionnaire (MQL-10) in a follow-up survey and to determine the minimally important difference (MID) for this measure. In 2007, Japanese adults participated in a survey on health prac- tices. We analyzed the MQL-10 scores (n=6365) together with the following factors: gender, age group, disease, reason for participation, and complementary health practices, such as food and eating. The mean baseline MQL-10 score was 26.4±5.83 [standard deviation (SD)] and the mean follow-up score was 27.6±5.45 SD with a mean change of 1.20±4.41 SD. The effect size for change was 0.21 and the standardized response mean was 0.27. The MQL-10 scores in the baseline condition were associated with gender, age group, disease, reason for participation and complementary health practices. Furthermore, the changes in the MQL-10 during the 12 weeks of study were associated with age group, disease, reason for participa- tion and complementary health practices. The increase in frequency of health practices was significantly associated with improvements in the participants’ quality of life (QOL). These results suggest that the MQL-10 is use- ful for assessing the effects of complementary health practices on QOL. The estimate of 3 points for the range of this measure (0-40) was higher than half of the SD of scores; therefore, it was considered reasonable for the MID.