The Effects of Comorbid Asthma and Long-term Use of Corticosteroids on Clinical Outcomes of Prostate Cancer Patients
Type of DegreePhD Dissertation
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Objectives: This study 1) examined burden of asthma among prostate cancer patients, asthma and prostate cancer treatment patterns, and factors associated with concurrent asthma, 2) assessed the associations between comorbid asthma and clinical outcomes among patients with prostate cancer, and 3) assessed the associations between long-term use of inhaled corticosteroids and clinical outcomes for patients with prostate cancer and comorbid asthma. Methods: Three retrospectives, population-based cohort analyses used the 2007-2014 Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database to identify newly diagnosed patients with prostate cancer. Comorbid asthma was identified in a 12-month baseline period prior to the prostate cancer diagnosis. Types of asthma and prostate cancer treatments were identified in 12 months after prostate cancer diagnosis. The exposure to corticosteroids use was identified in an up to 18 months observation period before and after prostate cancer diagnosis and further classified as different levels based on exposure periods (long vs. short) and dosages (high vs. low/intermediate). Two simple linear regression models were applied to test the trends in the annual prevalence of comorbid asthma among prostate cancer patients and the non-cancer comparison group. Cumulative rates of clinical outcomes (i.e., all-cause, prostate cancer related, and cardiovascular-related hospitalizations and emergency department (ED) visits) were estimated, and Cox proportional hazards models were used to identify the association between asthma and corticosteroids use with clinical outcomes. Results: The trend in the prevalence of comorbid asthma (15.71% in 2014) was stable in prostate cancer patients in 2007-2014 (P=0.35). Compared with prostate cancer patients without asthma, risks of all-cause and prostate cancer related hospitalizations, ED visits, and mortality (all-cause only) were higher in patients with asthma. Exposing to long-term (≥6 months) and/or high dosage (≥7.5 mg/day) of corticosteroids put patients with higher risks of all-cause hospitalizations, ED visits, and mortality compared to those without corticosteroids use. Conclusions: The existence of comorbid asthma and long-term and/or high dosage of exposure to corticosteroids put prostate cancer patients at higher risks in hospitalization, ED visits, and mortality. It is important for healthcare providers to screen and understand the burden and needs of managing comorbidities such as asthma among patients with prostate cancer.