ImportanceElder mistreatment is common and has serious health consequences. Little is known, however, about patterns of health care utilization among older adults experiencing elder mistreatment.ObjectiveTo examine emergency department (ED) and hospital utilization of older adults experiencing elder mistreatment in the period surrounding initial mistreatment identification compared with other older adults.Design, Setting, and ParticipantsThis retrospective case-control study used Medicare insurance claims to examine older adults experiencing elder mistreatment initially identified between January 1, 2003, and December 31, 2012, and control participants matched on age, sex, race and ethnicity, and zip code. Statistical analysis was performed in April 2022.Main Outcomes and MeasuresWe used multiple measures of ED and hospital utilization patterns (eg, new and return visits, frequency, urgency, and hospitalizations) in the 12 months before and after mistreatment identification. Data were adjusted using US Centers for Medicare and Medicaid Services Hierarchical Condition Categories risk scores. Chi-squared tests and conditional logistic regression models were used for data analyses.ResultsThis study included 114 case patients and 410 control participants. Their median age was 72 years (IQR, 68-78 years), and 340 (64.9%) were women. Race and ethnicity were reported as racial or ethnic minority (114 [21.8%]), White (408 [77.9%]), or unknown (2 [0.4%]). During the 24 months surrounding identification of elder mistreatment, older adults experiencing mistreatment were more likely to have had an ED visit (77 [67.5%] vs 179 [43.7%]; adjusted odds ratio [AOR], 2.95 [95% CI, 1.78-4.91]; P < .001) and a hospitalization (44 [38.6%] vs 108 [26.3%]; AOR, 1.90 [95% CI, 1.13-3.21]; P = .02) compared with other older adults. In addition, multiple ED visits, at least 1 ED visit for injury, visits to multiple EDs, high-frequency ED use, return ED visits within 7 days, ED visits for low-urgency issues, multiple hospitalizations, at least 1 hospitalization for injury, hospitalization at multiple hospitals, and hospitalization for ambulatory care sensitive conditions were substantially more likely for individuals experiencing elder mistreatment. The rate of ED and hospital utilization for older adults experiencing elder mistreatment was much higher in the 12 months after identification than before, leading to more pronounced differences between case patients and control participants in postidentification utilization. During the 12 months after identification of elder mistreatment, older adults experiencing mistreatment were particularly more likely to have had high-frequency ED use (12 [10.5%] vs 8 [2.0%]; AOR, 8.23 [95% CI, 2.56-26.49]; P < .001) and to have visited the ED for low-urgency issues (12 [10.5%] vs 8 [2.0%]; AOR, 7.33 [95% CI, 2.54-21.18]; P < .001).Conclusions and RelevanceIn this case-control study of health care utilization, older adults experiencing mistreatment used EDs and hospitals more frequently and with different patterns during the period surrounding mistreatment identification than other older adults. Additional research is needed to better characterize these patterns, which may be helpful in informing early identification, intervention, and prevention of elder mistreatment.