Estimates show there are approximately 220,000 cases of bariatric surgery performed in the United States (US) each year. Malabsorption of nutrients, including vitamins and minerals following bariatric surgery is common and may lead to iron deficiency anemia (IDA), with some studies showing incidence rates up to 49% of bariatric surgery patients.


The purpose of this study was to evaluate the economic, medical resource use (MRU), and clinical outcomes of IDA in adult bariatric surgery patients having commercial insurance coverage, and to further evaluate the treatment of IDA in this population.


This study was based on the Truven Health MarketScanĀ® claims databases. Bariatric surgery patients were identified by ICD-9-CM and CPT procedure codes for restrictive, malabsorptive, and combined restrictive/malabsorptive bariatric surgeries; and further classified as an IDA patient if an IDA diagnosis was identified within two years of initial surgery. Intravenous (IV) iron treatment was determined by HCPCS codes. Prescription oral iron treatment was determined by NDC codes. Blood transfusions were determined by CPT and ICD-9-CM procedure codes. Clinical, MRU, and economic outcomes, including hospitalization, bariatric surgery complications, MRU and payer reimbursement for all-cause health services were evaluated over a two-year period following surgery and compared between patients with and without IDA. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression, controlling for demographic and clinical characteristics (including post-surgery IDA status, diabetes, cancer, sleep apnea, heart disease, stroke, hypertension, dyslipidemia, gallbladder disease, osteoarthritis, and chronic back pain) on the outcomes of bariatric surgery complications and hospitalization in the post-surgery period.


A total of 24,382 bariatric surgery patients were analyzed, and 2,845 (11.7%) patients were diagnosed with IDA in the two-year period following surgery (average days to IDA diagnosis = 279 days). Of the patients with IDA, nearly all (98.7%) developed their anemia following surgery. Most IDA patients received a test for iron in the post-index period, but only 9.3% of all IDA patients received IV iron treatement with either iron dextran (3.8%) and iron sucrose (3.4%) being the most common treatments (average days until IV iron treatment = 403 days). Prescription oral iron was found in 4.8% of all IDA patients (average days to oral iron treatment = 477 days). Approximately 9.0% of all IDA patients received a blood transfusion (average days until blood transfusion = 306 days).

Average age was 46 years for patients with and without IDA and more females were found in each group (83.8% in patients with IDA, 78.8% in patients without IDA). Clinical characteristics were similar between groups with the exception of heart disease (1.3% patients with IDA vs 0.8% patients without IDA; P = 0.003) and gallbladder disease (0.0% patients with IDA vs 0.2% patients without IDA; P = 0.037). More IDA patients were associated with a bariatric surgery complication than patients without IDA (40.4% vs 27.7%; P < 0.001) with most complications attributable to other and unspecified postsurgical complications: nonabsorption (22.4% vs 16.5%; P < 0.001), digestive system complications (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 surgical complication as compared to patients without IDA [OR (95 % CI) = 1.372 (1.262, 1.492)]. IDA patients were hospitalized more often than patients without IDA (42.9% vs 20.9%; P < 0.001) and adjusted results showed IDA patients to be more than twice as likely to be hospitalized [OR (95% CI) = 2.574 (2.370, 2.796)]. Total costs were twice as much among IDA patients as compared to those without IDA ($38,025 vs $19,245; P < 0.001) (Figure 1).


Bariatric surgery patients that develop IDA may be associated with higher complication rates as well as higher MRU and direct medical costs. Although most bariatric surgery patients that develop IDA are tested for their iron, most are not treated with IV iron, oral iron, and most do not receive blood transfusions. Further research is warranted to determine if IDA is a result of bariatric surgery complications or a predictor of increased MRU and costs.


Knight:Covance: Consultancy. D'Sylva:American Regent Inc.: Employment. Moore:Covance: Consultancy. Barish:Wake Gastroenterology/Wake Research Associates: Honoraria.

Author notes


Asterisk with author names denotes non-ASH members.