RESUMO
Background: Utilizing multidimensional item response theory (MIRT) and genetic algorithm (GA) we aimed to design and test the psychometric properties of the short form Postpartum Quality of Life Questionnaire (PQOL). Methods: In this methodological study, 500 women aged 18 to 42 were enrolled through a multistage random sampling scheme in Tabriz, Iran. We used MIRT model and GA to identify a short form of the 40-item PQOL measure (SF-PQOL). Construct and criterion validity of the SF-PQOL was assessed by confirmatory factor analysis (CFA) and the correlation between SFPQOL scores with a 12-item short form of QOL (SF-12) and Edinburg Postnatal Depression Scale (EPDS) scores, respectively. The internal consistency, test-retest reliability and feasibility of the measure were evaluated. Results: sixteen- and 13-item SF-PQOL were identified based on MIRT and GA, respectively.The results indicate the better performance of the MIRT based 13-item SF-PQOL; Construct and criterion validity, the test-retest and internal consistency reliability, and the feasibility were confirmed in the MIRT based SF-PQOL, but not in the GA-based SF-PQOL. Conclusion: The MIRT suggests a 13-item SF-PQOL with adequate content which demonstrated satisfactory validity, reliability, and feasibility. SF-PQOL could be used across the population for both research and clinical objectives.
RESUMO
BACKGROUND: There are some specific measures for the evaluation of postpartum quality of life, and each have some limitations. OBJECTIVES: This study investigated the validity and reliability of the Persian version of a postpartum women's quality of life (PQOL) questionnaire at the eighth week of postpartum. PATIENTS AND METHODS: This was a methodological research, and subjects were 500 women, ages 18 - 42, eight weeks postpartum, randomly selected from half of the public centers in Tabriz, Iran, who completed questionnaires in a self-administered manner. Data was collected during a two-month period during 2014 - 2015. A standard forward - backward translation procedure was used to translate the English version of the PQOL into Persian. Content, construct, discriminant, and criterion validity was assessed. The reliability was evaluated by internal consistency and test-retest reliability. RESULTS: The PQOL showed good content validity; content validity ratio (CVR) ranged from 0.67 to 1.00 and content validity index (CVI) ranged from 0.78 to 1.00. Construct validity evaluation by exploratory factor analysis (EFA) led to extraction of six factors from the data. Due to the lack of theoretical justification for items' relocation in the extracted factors and poor-fitting indices obtained by confirmatory factor analysis (CFA), the exploratory model was eliminated, and the original model was presented and incorporated into the CFA, indicating an acceptable fit for the model (root mean square error of approximation [RMSEA] = 0.038 [0.034; 0.042]; comparative fit index [CFI] = 0.90; normed fit index [NFI] = 0.80; non-normed fit index [NNFI] = 0.90; incremental fit index [IFI] = 0.90). The intergroup differences in total and all dimensions of the PQOL, except for social support, indicated the discrimination ability of the questionnaire. The questionnaire indicated a medium correlation with the short form health survey (SF-12) questionnaire (r ≥ 0.50). Cronbach's alpha coefficient (0.70 - 0.88) indicated a good internal consistency, and the intraclass correlation coefficients (0.87 - 0.92) showed good test - retest reliability. CONCLUSIONS: The findings of this study confirmed the validity and reliability of the Iranian version of the PQOL questionnaire in Iranian women as a specific measure to evaluate the women's quality of life.
