INTRODUCTION Patients who make 5 or more visits per year to hospital emergency departments (EDs) are usually considered ED frequent users (FUs). This study aims to better characterize the influence of alcohol and other drug use-related disorders in this phenomenon in a European Mediterranean country with public, universal, tax-financed healthcare system.

METHODS Matched case-control study. Cases were adults between 18 and 65 years old who consulted 5 or more times the ED of a tertiary hospital in Spain between December 2018 and November 2019. Each case was assigned a control of the same age and gender, who appeared to the ED on the same day, but who made 4 visits or less to the service during the study period. The electronic record of the first ED visit during this period was used to extract the variables of interest: emergency care received, clinical and social characteristics. Predictors of frequent ED use were identified with conditional logistic regression.

RESULTS 609 case-control pairs (total n = 1,218) were selected. History of alcohol-related conditions (adjusted odds ratio [AOR] = 1.82 [95% CI: 1.26-2.64] p = 0.001) and also other drug use-related disorders (AOR = 1.50 [95% CI: 1.11-2.03] p = 0.009) significantly increased the probability of frequent use of emergency services.

DISCUSSION/CONCLUSION Alcohol-related conditions and other drug use-related disorders must be evaluated in all ED FUs. Specific action protocols to concurrently address repeated attendance and addictions in the emergency room could be a good tool to reduce frequent ED use.