P089: Frequency of substance abuse in Albertan emergency departments: a retrospective NACRS analysis

Abstract

Introduction: Substance abuse is strongly correlated with frequent ED use, which is a known risk factor for mortality. This study aimed to examine epidemiologic trends in ED visit frequency, and visit and patient characteristics among all patients presenting to Albertan EDs with visits related to substance abuse over a five-year period. Methods: This is a retrospective analysis of National Ambulatory Care Reporting System (NACRS) administrative ED data for Alberta. All ED visits related to substance abuse made by adults from fiscal year 2010/11 to 2014/15 were included. Using a validated definition enhanced by expert consultation, ED visits were classified as visits related to substance abuse if a set of ICD-10 codes determined a priori were present within the primary or secondary diagnostic fields. Data are reported as means (with SD), medians (with IQR) and proportions. Visit and admission frequencies were compared using Chi square and Chi square trend tests. All analysis was performed using SAS 9.4. Results: Over the study period, 177,287 visits related to substance abuse were made to Alberta EDs. These visits were made by 77,291 unique patients, and annual patient numbers increased consistently from 17,660 in 2010/11 to 24,737 in 2014/15; 62% of patients were male and median age was 38 years (IQR 24, 49). Visits increased from 27,839 in 2010/11 to 42,965 in 2014/15 (p<0.001). 50% arrived by ambulance, and were mostly triaged as CTAS 3 to 5 (32% CTAS 1 or 2, 43% CTAS 3, and 23% CTAS 4 or 5). While most of the patients were discharged, 15.6% of visits resulted in admission; statistical but not clinically meaningful differences were detected in proportions of admitted visits across the study years. Compared to the overall population of patients with substance abuse presentations, frequent presenters (with a visit number greater than the 95^th percentile) appeared to be older (median age 40 years [IQR 31, 49]) and had a higher proportion of males (69%). Conclusion: ED presentations for substance abuse increased from 2010 to 2015 in Alberta, and frequent presenters appear to have a different demographic profile. Future study is needed to determine whether patients who present frequently with substance abuse are at increased risk for mortality as this may justify targeted intervention.