Association of the Charlson comorbidity index and hypertension with survival in men with metastatic castration-resistant prostate cancer

Abstract

Objectives: The independent prognostic effect of comorbidities on outcomes in men with metastatic castration-resistant prostate cancer (mCRPC) is unclear. We sought to determine whether the Charlson comorbidity index (CCI) and hypertension (HTN) are associated with overall survival (OS) independent of known clinical prognostic factors in mCRPC.

Patients and methods: A retrospective analysis was conducted on 221 patients with mCRPC treated with docetaxel plus prednisone combined with AT-101 (bcl-2 antagonist) or placebo on a prospective randomized phase II trial. The Cox regression analysis was performed to identify whether the CCI or HTN or both (by medical history) independently predicted OS after adjusting for baseline variables known to be associated with OS. The Wilcoxon rank sum test and the Fisher exact test were used to compare data by comorbidity groups (CCI as a continuous variable, CCI = 6 vs. CCI ≥ 7 and HTN vs. no HTN).

Results: The CCI was 6 in 116 patients (52.7%), 7 in 70 (31.8%), 8 in 23 (10.5%), 9 in 4 (1.8%), and 10 in 7 patients (3.2%). HTN was present in 107 (48.6%) patients. Patients with CCI of ≥ 7 were older and exhibited worse performance status and anemia than patients with CCI of 6 (P<0.05). The CCI was not independently predictive of OS on univariable and multivariable analyses. HTN alone or in combination with the CCI was borderline significantly associated with OS (P ~ 0.09) on both univariable and multivariable analyses.

Conclusions: The CCI did not predict OS independent of known prognostic factors in mCRPC. Age, performance status, and anemia may adequately capture comorbidities in the context of mCRPC, given their association with higher CCI. Further prospective study of comorbidities in a larger data set may be warranted. The study of HTN in a larger data set may also be warranted given its borderline-independent association with OS.

Keywords: Charlson comorbidity index; Docetaxel; Hypertension; Metastatic castration-resistant prostate cancer; Overall survival; Progression-free survival.