BACKGROUND: An estimated 220,000 bariatric surgeries are performed in the US yearly. Malabsorption of nutrients after bariatric surgery is common and may lead to IDA, with incidence rates of up to 49%. OBJECTIVE: To evaluate the economic, MRU, clinical outcomes, and treatment of IDA in adult bariatric surgery patients with commercial insurance coverage. METHODS: Using Truven Health MarketScan® claims data, bariatric surgery patients were identified by ICD-9-CM and CPT codes then classified by surgery and IDA diagnosis within two years of initial surgery. Intravenous (IV) iron treatment was determined by HCPCS codes, prescription oral iron by NDC codes, and blood transfusions by CPT and ICD-9CM codes. Clinical, MRU, and economic outcomes for all-cause health services were compared between IDA and non-IDA patients. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression, controlling for demographic and clinical characteristics on outcomes of complications and hospitalization. RESULTS: Of the 24,382 bariatric surgery patients analyzed, 11.7% received an IDA diagnosis 2 years post-surgery (avg days to diagnosis=279). Most (98.7%) of the IDA group developed anemia post surgery. Most IDA patients received a test for iron in the post-index period; only 9.3% received IV iron treatment, with iron dextran (3.8%) and iron sucrose (3.4%) being the most common (avg days to IV iron treatment=403 days). Prescription oral iron was found in 4.8% of all IDA patients (avg days to oral iron treatment=477). Approximately 9% of IDA patients received a blood transfusion (avg days to transfusion=306). Average age was 46 years with a higher percentage of females (83.8% IDA, 78.8% non-IDA). Most clinical characteristics were similar, except heart disease (1.3% IDA vs 0.8% non-IDA; P=0.003) and gallbladder disease (0.0% IDA vs 0.2% non-IDA; P=0.037).More IDA patients had post-surgery complications (40.4% vs 27.7%; P<0.001), such as nonabsorption (22.4% vs 16.5%; P<0.001), digestive (15.6% vs 10.2%; P<0.001), and gastrojejunal ulcer (7.6% vs 2.0%; P<0.001). Multivariate results showed IDA patients were more likely to have a bariatric surgery complication over non-IDA patients (OR [95 % CI]=1.372 [1.262, 1.492]]. Adjusted results showed IDA patients over twice as likely to be hospitalized (OR [95% CI]=2.574 [2.370,2.796]]. Total costs were twice as much in IDA over non-IDA groups ($38,025 vs $19,245; P<0.001). CONCLUSIONS: Bariatric surgery patients who develop IDA may have higher complication rates, MRU, and direct medical costs. Though most bariatric surgery patients who develop IDA are tested for their iron, most are not treated with IV iron or oral iron and do not receive blood transfusions. Further research is needed to determine if IDA is a result of bariatric surgery complications or a predictor of increased MRU and costs.