Examining the factor structure of the Pittsburgh Sleep Quality Index and its determinants among GI cancer patients

Background: Poor sleep quality is one of the prevalent manifestations experienced by cancer patients. There is a lack of research focusing specifically on sleep quality and affecting factors in Gastrointestinal (GI) cancer patients. This study aimed to assess the potential interaction between dietary, comorbid conditions, demographic, and socioeconomic determinants of sleep quality in GI cancer patients.

Methods: In a cross-sectional study, the Pittsburg Sleep Quality Index (PSQI) was completed for 875 adult patients suffering from GI cancer in a referral hospital. We conducted structural equation modeling analyses to evaluate the potential interaction between dietary and socioeconomic determinants of sleep quality in GI cancer patients.

Results: This study demonstrated that the PSQI encompasses two factors (perceived sleep quality and sleep disturbances) in GI cancer patients in Iran. Based on the standardized coefficients for the structural paths, the wealth index (WI) partially mediated the effect of food insecurity (FI) on the sleep quality index. There was a direct predictive effect of the WI on the PSQI (β = 0.10, P = 0.01). In addition, WI indirectly through FI (effect of WI on FI: β = -0.21, P = 0.01 & effect of FI on PSQI: β = 0.07, P = 0.03) had a negative effect on PSQI. Our finding suggested the full mediation effect of age on PSQI through the number of comorbidities (effect of age on number of comorbidities: β = 0.25, P < 0.001 & the effect of number of comorbidities on PSQI: β = 0.13, P < 0.001). Structural path outputs for gender-model indicated the full mediation effect of age on PSQI through the number of comorbidities among males and through the FI among females.

Conclusion: These findings highlight the importance of considering the bi-dimensional construct of the PSQI for assessing sleep quality among GI cancer patients. The current study demonstrated that food insecurity and comorbidity prevalence mediated the relationship between socio-demographic determinants of sleep quality in patients with GI cancer.