Emergency cancer diagnoses in an integrated HMO: Novel insights from a managed care setting.

165 Background: Patients diagnosed with cancer during emergency presentation (EP) face worse outcomes than those diagnosed as outpatients. While established studies show increased mortality in this population, this phenomenon has not yet been studied in the integrated care setting, where preventative care is expected to be higher than in the general US population. We studied EP for cancer in Kaiser Permanente Northern California (KPNC), a large, California-representative HMO serving adults of all ages, with robust clinical data, including smoking status, marital status, BMI, and cancer screening. Methods: We studied all adult patients diagnosed with any type of cancer at KPNC (2018-2022). Patients were stratified by diagnostic setting: outpatient or EP; subcategorized as diagnosis during inpatient admission (ED-IP) or outpatient diagnosis following ED referral (ED-OP). Key patient characteristics were compared across groups, and logistic regressions were used to evaluate factors associated with diagnostic setting. Results: A total of 56,383 adult patients were included, with 22% diagnosed as EPs (10% ED-IP and 12% ED-OP). Compared with outpatient diagnoses, ED-IP and ED-OP were older (median age: 71; 68 vs 65 years), had higher comorbidity burden (median Elixhauser score: 5; 3 vs 2), and were more frequently in the most socioeconomically deprived neighborhoods (21%; 21% vs 16%). After adjustment, independent increased EP risk factors included: age 18-45 vs 46-60 (ED-IP OR 1.71; ED-OP OR 1.37), age 81+ vs 46-60 (ED-IP OR 1.59; ED-OP OR 1.57), single/divorced status vs married (ED-IP OR 1.31; ED-OP OR 1.12), BMI 30 vs 18-5-24.5 (ED-IP OR 0.50; ED-OP OR 0.83). EP varied by cancer type, ranging from 4% (melanoma) to 78% (brain). EP was associated with more metastatic disease compared with outpatient diagnoses (41%; 39% vs 14%). All p-values < 0.01. Conclusions: Even within an integrated healthcare system with robust screening and preventative care access, over one in five adult cancer diagnoses occurred during EP, highlighting a persistent reliance on acute care pathways. EP patients differed significantly from those diagnosed in routine settings in unique ways, underscoring diagnostic setting is a consequence of systemic inequities, necessitating targeted interventions, like optimized outpatient referral pathways for symptomatic presentations, to facilitate earlier detection and improve outcomes.