Development and psychometric properties of Iranian Women’s Quality of Life Instrument (IWQOLI): mixed exploratory study

Abstract

Background To determine the health needs and promote women's health, their quality of life should be investigated. For this purpose, a valid tool is needed, that has credible validity and reliability, and its concepts are clearly defined and culturally appropriate. This study aimed to develop and assess the psychometric properties of “Iranian Women’s Quality of Life Instrument (IWQOLI)”. Methods The items of “IWQOLI” were generated from themes extracted (150 items) from a content analysis approach with the participation of 40 women. Face validity of the questionnaire with the participation of 10 women and content validity by 10 experts was approved. To determine the domains of the questionnaire, exploratory factor analysis (principal component extraction method) was performed. Internal consistency and test—retest reliability methods with 14-day intervals (30 women) were used to assess the reliability of WQOLI. Results After performing the face and content validity, 32 items were deleted. S-CVI/Ave was obtained for the instrument (0.93). The factor structure of the inventory was identified by undertaking a principal component analysis in a sample of 590 women. Five factors were extracted with a total variance account of 56.24% and 28 items dropped at this point. The IWQOLI score was significantly correlated with the SF-36 (r = 0.717, p < 0.001). Reliability was demonstrated with Cronbach’s alpha coefficient of 0.919 for the entire scale (90-item). Consistency of the instrument was established with test–retest reliability with an interval of 2 weeks (intra-cluster correlation = 0.889, P < 0.001). Conclusions The Iranian women’s Quality of life Instrument “IWQOLI”, consisting of 90 items representing 5 domains (sense of peace in life, sense of security, health responsibility, pleasant communication, received comprehensive support), demonstrated excellent psychometric properties, so it may be used for measuring women’s QOL in practical research.