Unveiling the hidden burden: Prevalence and disparities of cancer diagnosed in emergency and hospital settings.

e13748 Background: Patients diagnosed with cancer while inpatient (Emergency Department [ED] or hospital) have worse outcomes than those diagnosed as outpatients. Prior studies have highlighted increased mortality in this population, but real-world, large-scale data comparing outcomes between clinical settings are lacking. This study aims to characterize patients diagnosed with cancer in the ED/hospital vs outpatient settings and describe differences in patient characteristics and outcomes. Methods: This retrospective cohort study included all patients diagnosed with cancer within Kaiser Permanente Northern California between January 1, 2018, and December 31, 2022. Patients were stratified by diagnostic setting: outpatient, ED, or inpatient after admission from the ED (hereafter categorized simply as hospital). Key patient characteristics were compared across groups. Survival analysis was conducted using Kaplan-Meier methods. Results: A total of 58,591 patients were included, of whom 46,025 (75.6%) were diagnosed in the outpatient, 6,622 (11.3%) ED, and 5,944 (10.1%) hospital settings. Compared with patients diagnosed as outpatients, those diagnosed in the ED or hospital were older (median age: 68 / 71, vs 65 years), had higher comorbidity burden (median Elixhauser score: 3 / 5, vs 2), and were more likely to be in the most deprived neighborhood deprivation index quartile (21.3% / 20.7%, vs 15.9%). The proportion of cancers diagnosed in the ED or hospital varied by cancer type from 3.8% (melanoma) to 77.6% (brain). Screened cancers (breast, prostate, lung, colorectal) were more likely to be diagnosed as outpatients (84.4%) compared with unscreened cancers (68.6%). Patients diagnosed in the ED or hospital were more likely to have metastatic disease (38.7% / 41.1%) compared with outpatient diagnoses (13.5%). Among 11,213 patients with stage IV cancer, median overall survival differed by diagnostic setting: outpatient, ED, or hospital (28.8 / 9.8 / 4.3 months). All p-values < .001. Conclusions: Patients diagnosed with cancer in the ED or hospital differ significantly from those diagnosed as outpatients in terms of demographics, socioeconomic factors, and clinical outcomes. The markedly lower survival rates observed in ED/hospital diagnoses emphasize the need for further research to better understand these disparities and develop targeted interventions to improve outcomes. Survival outcomes of patients with stage IV cancer by diagnostic setting. Follow-up Time Diagnostic Setting Survival Probability (%) Unadjusted HR vs Outpatient (95% CI) 6 months Outpatient 79.0 Reference ED 58.7 2.30 (2.12, 2.49) Hospital 44.8 3.76 (3.48, 4.06) 1 year Outpatient 68.1 Reference ED 46.9 2.04 (1.90, 2.19) Hospital 34.3 3.16 (2.96, 3.38) 5 years Outpatient 35.4 Reference ED 18.9 1.80 (1.70, 1.91) Hospital 12.5 2.62 (2.47, 2.78) ED: Emergency department; HR: Hazard ratio; CI: Confidence interval.