Factor Structure of the Pittsburgh Sleep Quality Index among Women Undergoing Infertility Treatment: A Confirmatory Factor Analysis

Abstract

Background and Objective: People that undergo assisted infertility treatments experience more sleep problems. Although Pittsburgh Sleep Quality Index (PSQI) frequently has been used as a sleep quality assessment scale in different clinical and non-clinical settings, different sample characteristics may account for different structures. The current study aimed to evaluate the factor structure of PSQI among women seeking infertility treatment in Iran.

Materials and Methods: Using a convenience sampling method, 157 infertile women or women whose husbands had infertility problems were included in a cross-sectional study in Royan Institute, a main referral infertility center in Tehran, Iran. The factor structure of PSQI was evaluated through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA).

Results: The Cronbach’s alpha coefficient for PSQI was 0.65. A two-factor model was extracted by EFA; 56% of the total variance was accounted for by this model. The results of CFA indicated that extracted model obtained acceptable fit statistics [comparative fit index (CFI) = 0.942, standardized root mean square residual (SRMR) = 0.042, root mean square error of approximation (RMSEA) = 0.128, χ2 = 19.8, degree of freedom (df) = 12, P = 0.071] compared to other original single-factor or 3-factor models.

Conclusion: Our results revealed the limited usefulness of single-factor structure of PSQI. A two-factor model of Persian version of PSQI should be used to assess sleep problems among women seeking assisted infertility treatments.