Associations Between Self-Rated Health and Mortality in the Norwegian Women and Cancer (NOWAC) Study

Abstract

Purpose

We investigated the association between self-rated health (SRH) and cancer incidence and SRH and all-cause mortality among Norwegian women.

Population and Methods

We used data from 110,104 women in the Norwegian Women and Cancer (NOWAC) cohort aged 41–70 years at baseline. We used flexible parametric survival analysis with restricted cubic splines to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between SRH and mortality in the entire cohort. We employed the same method in a multistate design to assess associations between baseline SRH and 1) cancer incidence, and 2) all-cause mortality in subgroups of women who did and did not receive a cancer diagnosis during follow-up.

Results

With very good SRH as reference category for all associations and median age at end of follow-up, lower SRH was associated with increased mortality (HR_{good SRH} 1.19, 95% CI 1.12–1.26) and HR_{poor SRH} 1.81, 95% CI 1.66–1.97). Lower SRH at baseline was associated with cancer incidence (HR_{good SRH} 1.14, 95% CI 1.08–1.20 and HR_{poor SRH} 1.44, 95% CI: 1.32–1.58). Poor baseline SRH was associated with increased mortality for women who received a cancer diagnosis (HR_{poor SRH} 1.20, 95% CI 1.04–1.39), and SRH showed a strong association with increased mortality for women who stayed cancer free (HR_{good SRH} 1.59, 95% CI 1.44–1.77 and HR_{poor SRH} 3.34, 95% CI 2.91–3.84).

Conclusion

Lower SRH at baseline predicted increased cancer risk and all-cause mortality in middle-aged to older women. Poor SRH at baseline predicted all-cause mortality in women who later received a cancer diagnosis. Both good and poor SRH at baseline predicted all-cause mortality in women who stayed cancer-free, and the association was stronger for these women compared to both the entire cohort and to women who were subsequently diagnosed with cancer.

Keywords:

• self-rated health
• cohort study
• multistate
• cancer
• mortality
• women

Acknowledgments

The authors would like to thank Ms. Trudy Perdrix-Thoma for reading, language editing, and providing valuable input to this manuscript. We would also like to thank all the women who participated in the NOWAC study, contributing their valuable time and efforts to our research.

Disclosure

The authors report no competing interests in this work.