Subjective health and mortality in a population-based cohort: Study of Health In Pomerania (SHIP)

Objectives: This study examined the association between health-related quality of life (HRQoL) and mortality risk. Therefore, the predictive ability of the 12-Item Short-Form Health Survey (SF-12) with self-rated health (SRH) were analyzed. Furthermore, we adjusted our results for IGF-I and IGFBP-3 levels as confounder, which might be associated with HRQoL as well as mortality. Methods: Data from 4261 subjects aged 20–79 recruited for the prospective population-based Study of Health in Pomerania was used. During an average 7.2 year follow-up 322 deaths (7.5%) occurred. The study population was compared with regard to vital status at follow-up. HRQoL was assessed by the Physical Component Summary (PCS-12) and Mental Component Summary (MCS-12) of the SF-12. Results: Deceased subjects were older, more often male, less educated, scored significantly lower at PCS-12, higher at MCS-12, and rated their general health more often poor or very poor compared to survivors. Sex- and age-adjusted Cox regression analyses revealed a higher risk of all-cause mortality from for subjects who scored PCS-12 in the lowest quartile (HR, 2.17; 95% CI, 1.52; 3.09). Further adjustments did not change this result much. Adjusting for levels of IGF-I elevated mortality risk for subjects who scored PCS-12 in the lowest quartile (HR, 2.26; 95% CI, 1.56; 3.27). Cox regression analyses in quartiles of MCS-12 did not expose any association with all-cause mortality in the different models. Conclusion: The results suggest that SRH and HRQoL may be independent predictors of mortality in a population-based study. The adjustment for biological variables like IGF-I can be questioned as they might represent mediating mechanisms in a possible causal chain of events.