Reliability of an Osteoporosis-Targeted Quality of Life Survey Instrument for Use in the Community: OPTQoL

A brief Osteoporosis-Targeted Quality of Life (OPTQoL) questionnaire was previously developed as a cross-sectional survey instrument to assess the community impact of osteoporosis on quality of life in women. The initial development process involving item generation through focus groups, item reduction, and content and construct validation yielded a 36-item questionnaire with three domains (physical difficulty, adaptations and fears) and 10 health-related questions. In the present study, test-retest reliability and internal consistency of the questionnaire were assessed in a mail-based study with two clinical sites. Two hundred women (50 with severe osteoporosis, 50 with osteopenia, 50 with normal bone mineral density (BMD) and 50 with osteoarthritis and normal BMD), aged 43-84 years, completed the self-administered questionnaire initially and again about 2 weeks later. Using weighted kappas, agreement between questionnaire administrations ranged from 0.60 to 0.80 for most of the individual items. Intraclass correlation coefficients to assess reliability for the domain scores were 0.93 (physical difficulty), 0.82 (adaptations) and 0.88 (fears). Internal consistency of each of the domains was also high, with Cronbach's alpha coefficients ranging from 0.89 to 0.91. Four items were dropped from the 36-item questionnaire due to high percentage of 'not applicable' responses. Results of the analyses support the validity and reliability of this instrument as a cross-sectional survey tool for assessing the impact of osteoporosis on quality of life in women living in the community. The questionnaire has been translated and culturally adapted into seven languages to allow cross-cultural studies of the community impact of osteoporosis.