Social Inequality and Structural Vulnerability as Predictors of Health-Related Quality of Life: A Prospective Cohort Study.

Background Social inequality and structural vulnerability are increasingly recognized as important social determinants of health; however, longitudinal evidence regarding their impact on health-related quality of life (HRQoL) remains limited, particularly in low- and middle-income countries. This study explored associations between social inequality, structural vulnerability, and HRQoL over a six-month follow-up period in adults in Pakistan. Methods We conducted a prospective cohort study of 600 adult participants recruited through healthcare facilities and community-based settings in Karachi, Pakistan, using non-probability convenience sampling. Baseline assessments comprised a composite social inequality index, the Structural Vulnerability Assessment Tool (SVAT), and the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire. We reassessed HRQoL after six months, with 593 participants completing follow-up. We used Spearman correlation analysis, linear mixed-effects modelling, and analysis of covariance to examine associations between social inequality, structural vulnerability, and HRQoL. Results Higher social inequality was significantly associated with lower HRQoL at baseline (ρ = -0.530, p < 0.001), and higher structural vulnerability was significantly associated with lower HRQoL at baseline (ρ = -0.691, p < 0.001). Quality of life(QoL) declined significantly over six months (B = -6.09, p < 0.001). Structural vulnerability (B = -1.48, p < 0.001) and chronic disease burden (B = -2.08, p < 0.001) independently predicted poor HRQoL over time. However, after adjustment, structural vulnerability remained an independent predictor of HRQoL six months later, whereas social inequality was not. Conclusion Structural vulnerability was the strongest independent predictor of HRQoL, underscoring the need to address structural determinants of health and well-being alongside clinical care to minimize health inequities and improve HRQoL over time.