Impact of Comorbidity on Survival of Danish Prostate Cancer Patients, 1995–2006: A Population-Based Cohort Study

ObjectivesThe existence of comorbid diseases among men with newly diagnosed prostate cancer may affect prostate cancer prognosis.MethodsWe identified patients (n = 8114) with a first-time discharge diagnosis of prostate cancer from Danish hospitals between 1995 and 2006. We measured comorbidity using the Charlson Comorbidity Index.ResultsThe number of patients doubled between 1995 and 2006. The proportion of patients with Charlson scores of 0 (no comorbidity) increased from 62% to 63% of total patients diagnosed, whereas the proportion of patients with Charlson scores of 1 to 2 (moderate comorbidity) decreased from 31% to 29%, and the proportion with Charlson scores of 3 or higher (severe comorbidity) increased from 106 to 227 (7% to 8%). Among patients with a Charlson score of 0, the 1-year survival rate improved from 79% to 94%; among patients with Charlson scores of 1 to 2, the 1-year survival rate increased from 68% to 83%; and in patients with a Charlson score of 3 or higher, this rate increased from 61% to 69%. Compared with patients with Charlson scores of 0, patients with scores of 1 to 2 had age-adjusted 1-year mortality rate ratios (MRRs) of 1.60 in 1995 to 1997, increasing to 2.67 in 2004 to 2006. For patients with Charlson scores of 3 or higher, the adjusted MRR increased from 3.11 in 1995 to 1997 to 5.08 in 2004 to 2006.ConclusionsComorbidity was present in more than one-third of prostate cancer patients and was a negative prognostic factor. Although prostate cancer survival generally has improved in Denmark in recent years, no improvement was found among those with high levels of comorbidity.