Purpose: To test the measurement equivalence (i.e., invariance) of osteoporosis-specific and general health-related quality-of-life (HRQOL) instruments in Canadian Aboriginal and non-Aboriginal women.
Methods: A total of 258 Aboriginal and 181 non-Aboriginal women were recruited to the First Nations Bone Health Study from rural and urban sites in the province of Manitoba, Canada. The Medical Outcomes Study Short Form-36 (SF-36) and the mini-Osteoporosis Quality of Life Questionnaire (mini-OQLQ) were administered to study participants by trained interviewers. Confirmatory factor analysis techniques were adopted to test hypotheses about four forms of invariance for the two groups using likelihood ratio tests and other goodness-of-fit indices.
Results: For the mini-OQLQ instrument configural and metric invariance were satisfied, indicating that both groups have the same conceptualization of osteoporotic quality of life and the concepts have equivalent meaning. However, scalar and complete invariance were not satisfied for this instrument. The SF-36 exhibited complete invariance in the two groups.
Conclusions: Measurement equivalence, which is required to conduct valid group comparisons, was not demonstrated for the disease-specific quality-of-life instrument but was supported for the general instrument. Ethnicity appears to influence responses about the effects of osteoporosis on quality of life.