Five-Year Changes in Health-Related Quality of Life and Related Factors Among Iranian Adults: Evidence from a Population-Based Cohort

Abstract

Background: Health-related quality of life (HRQoL) reflects individuals’ perceptions of their health and daily functioning and has become a widely used outcome measure in population health research. Objectives: This study investigated factors associated with changes in HRQoL between baseline assessment and the 5-year follow-up in an adult cohort. Methods: A population-based cohort study was conducted among 106 adults in Shiraz, Iran, who completed HRQoL assessments at baseline in 2019 and at the five-year follow-up in 2024. Participants were recruited using multistage cluster sampling. Data on HRQoL and demographic, socioeconomic, behavioral, and clinical characteristics were collected using the Persian version of the 36-Item Short Form Health Survey (SF-36) questionnaire, physical examinations, laboratory measurements, and self-reported information. Changes in HRQoL were calculated, and factors associated with these changes were examined using multivariable linear regression models. Results: Among the 106 participants included in the analysis, 59 were female. At baseline, participants had a mean age of 48.4 ± 12.1 years. Comparisons between baseline and follow-up assessments indicated that total HRQoL remained largely unchanged, and the observed increase in mean Mental Component Summary (MCS) was not statistically significant. In regression analyses, older age was associated with greater improvement in MCS (β = 0.48, P = 0.006). Compared with participants who remained married, those who remained single experienced greater declines in total HRQoL (β = −16.04, P = 0.01) and MCS (β = −15.88, P = 0.02). Supplementary insurance status was associated with changes in HRQoL. Compared with participants who remained insured, those who gained supplementary insurance had greater changes in total HRQoL, MCS, and the Physical Component Summary (PCS) (β = 17.55, P < 0.001; β = 14.27, P = 0.003; and β = 21.02, P < 0.001, respectively). Participants who remained uninsured also showed greater changes in MCS (β = 12.41, P = 0.01). Self-rated health status was also associated with changes in HRQoL, with better ratings corresponding to improvements in both total HRQoL (β = −3.59, P = 0.01) and MCS (β = −4.23, P = 0.005). Conclusions: Over the five-year follow-up period, overall HRQoL remained relatively stable. Although the mean MCS increased slightly, this change was not statistically significant. Age, marital status, supplementary insurance status, and self-rated health were associated with changes in HRQoL. To confirm these findings and improve understanding of the factors influencing changes in HRQoL over time, further long-term studies with larger and more diverse populations are warranted.