Association between age, substance use, and outcomes in Medicare enrollees with prostate cancer.

OBJECTIVE: To analyze the association between age, substance use, and outcomes in fee-for-service Medicare enrollees with advanced prostate cancer.

METHODS: Retrospective longitudinal cohort study of elderly men diagnosed with advanced prostate cancer using SEER-Medicare data between 2000 and 2009. Substance use disorder was identified using claims for alcoholic psychosis, drug psychoses, alcohol dependence syndrome, drug dependence, and non-dependent use of drugs. We compared health service use, cost, and 5-year mortality across two age-groups: young-old (66-74years) and old-old (≥ 75years).

RESULTS: Cohort consisted of 8484 young-old and 5763 old-old patients with advanced prostate cancer. Prevalence of substance use was 12.4% in young-old and 7.4% in old-old group. For the young-old group, the 'drug psychoses and related' category had the highest inpatient, outpatient, and ER usage as well as the highest hazard of mortality (HR=2.2; CI=1.5, 3.1), compared to those without substance use. Compared to the no substance use group, those with substance use in the follow-up phase had higher inpatient and ER visits, and those with substance use in treatment phase had higher outpatient visits and highest hazard of mortality (HR=1.6; CI=1.4, 1.9). For the old-old group, the 'drug psychoses and related' category was associated with highest inpatient and outpatient use; and 'Non-dependent use of drugs' were associated with highest ER use, compared to those without substance use.

CONCLUSION: Intersection of cancer and substance use disorder in elderly patients with advanced prostate cancer covered by Medicare is age specific. An integrated and multidisciplinary approach to screen, refer, and treat substance use in patients with prostate cancer may improve outcomes and reduce costs.