OBJECTIVES: Low-value esophagogastroduodenoscopies (EGDs) for uncomplicated gastro-oesophageal reflux disease (GERD) can harm patients and raise patient and payer costs. We developed an electronic health record (EHR) eMeasure to detect low-value EGDs. DESIGN: Retrospective cohort of 518 adult patients diagnosed with GERD who underwent initial EGD between 1 January 2019 and 31 December 2019. SETTING: Outpatient primary care and gastroenterology clinics at a large, urban, academic health centre. PARTICIPANTS: Adult primary care patients at the University of California Los Angeles who underwent initial EGD for GERD in 2019. MAIN OUTCOME MEASURES: EGD appropriateness criteria were based on the American College of Gastroenterology 2012 guidelines. An initial EGD was considered low-value if it lacked a documented guideline-based indication, including alarm symptoms (eg, iron-deficiency anaemia); failure of an 8-week proton pump inhibitor trial or elevated Barretts oesophagus risk. We performed manual chart review on a random sample of 204 patients as a gold standard of the eMeasures validity. We estimated EGD costs using Medicare physician and facility fee rates. RESULTS: Among 518 initial EGDs performed (mean age 53 years; 54% female), the eMeasure identified 81 (16%) as low-value. The eMeasures sensitivity was 42% (95% CI 22 to 61) and specificity was 93% (95% CI 89 to 96). Stratifying across clinics, 62 (74.6%) low-value EGDs originated from 2 (12.5%) out of 16 clinics. Total cost for 81 low-value EGDs was approximately US$75 573, including US$14 985 in patients out-of-pocket costs. CONCLUSIONS: We developed a highly specific eMeasure that showed that low-value EGDs occurred frequently in our healthcare system and were concentrated in a minority of clinics. These results can inform future QI efforts at our institution, such as best practice alerts for the ordering physician. Moreover, this open-source eMeasure has a much broader potential impact, as it can be integrated into any EHR and improve medical decision-making at the point of care.