Comorbidity and survival of Danish ovarian cancer patients from 2000–2011: a population-based cohort study

Anne Fia Grann,¹ Reimar Wernich Thomsen,¹ Jacob Bonde Jacobsen,¹ Mette Nørgaard,¹ Jan Blaakær,² Mette Søgaard<sup>1

1</sup>Department of Clinical Epidemiology, ²Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark

Objective: To examine the prevalence of comorbidity among patients diagnosed with epithelial ovarian cancer in the Central Denmark Region and to study the impact of comorbidity on cancer survival over time.
Methods: We included women recorded with a first-time diagnosis of epithelial ovarian cancer in the Danish National Registry of Patients in the Central Denmark region between 2000 and 2011. We followed their survival through the Danish Civil Registration System. We estimated 1- and 5-year survival overall and stratified by Charlson Comorbidity Index score. We used Cox proportional hazard regression analyses to compute adjusted mortality rate ratios (MRRs) within different calendar time periods overall and by comorbidity level.
Results: We identified 1,540 patients. In 2000–2002, 25% of the newly diagnosed ovarian cancer patients had a comorbidity diagnosis compared with 35% in 2009–2011. Median age increased from 61 to 66 years. One-year overall survival changed from 73% (95% confidence interval [CI]: 69–78) in 2000–2002 to 69% (95% CI: 63–73) in 2009–2011, corresponding to an age- and comorbidity-adjusted MRR of 1.03 (95% CI: 0.79–1.36). Five-year survival changed only slightly during the study period, from 37% (95% CI: 32–42) in 2000–2002 to 39% (95% CI: 34–44) in 2009–2011. In patients with Charlson score ≥3, 1-year survival changed from 63% (95% CI: 35–81) in 2000–2002 to 41% (95% CI: 24–57) in 2003–2005 and thereafter stabilized. One-year survival changed from 56% (95% CI: 44–66) to 64% (95% CI: 53–74) in patients with Charlson score 1–2. Compared with Charlson score 0, adjusted 1-year MRRs for Charlson score ≥3 were 1.44 (95% CI: 0.62–3.36) in 2000–2002 and 2.11 (95% CI: 1.27-3.51) in 2009–2011, whereas adjusted 1-year MRRs for Charlson score 1–2 changed from 2.04 (95% CI: 1.33–3.14) in 2000–2002 to 1.09 (95% CI: 0.69–1.71) in 2009–2011.
Conclusion: Comorbidity increased among ovarian cancer patients over time and was associated with poor survival. One- and 5-year overall survivals changed only little and an expected decrease in survival, following increased prevalence of comorbidity and increasing age of patients, may have been counteracted by more aggressive surgery.

Keywords: ovarian neoplasm, comorbidity, mortality, survival, epidemiology