Burden of Iron Deficiency Anemia in a Bariatric Surgery Population in the United States

BACKGROUND: Obesity is a serious condition affecting more than 35% of adults in the United States. In obese individuals for whom other weight control methods have been ineffective, bariatric surgery is a safe and effective method of weight control. An estimated 150,000 to 160,000 bariatric surgeries are performed in the United States yearly. Iron deficiency anemia is common in patients after bariatric surgery, with incidence rates up to 49%, and may be due to malabsorption of nutrients. OBJECTIVES: To (a) compare the medical resource utilization (MRU)—both medical care and treatment resources—and associated costs in a sample of commercially insured adult bariatric surgery patients with and without iron deficiency anemia (IDA), and (b) describe anti-anemia treatment patterns in those bariatric surgery patients diagnosed with IDA. METHODS: Using Truven Health MarketScan claims data, bariatric surgery patients were identified by the ICD-9-CM and CPT procedure codes for bariatric surgery and classified by surgery and IDA diagnosis within 2 years of initial surgery. Intravenous (IV) iron treatment was determined by HCPCS codes, prescription oral iron by NDC numbers, and blood transfusions by CPT and ICD-9-CM codes. Clinical, MRU, and economic outcomes for all-cause health services were compared between IDA and non-IDA patients. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression, controlling for demographic and clinical characteristics on outcomes of complications and hospitalization. RESULTS: Of the 24,344 bariatric surgery patients analyzed, 11.6% received an IDA diagnosis 2 years after surgery (average days to diagnosis = 279). Most IDA patients (78.5%) received a test for iron in the post-index period; only 9.1% received IV iron treatment, with iron dextran (3.8%) and iron sucrose (3.4%) being the most common (average days to IV iron treatment = 403 days). Prescription oral iron was found in 4.9% of all IDA patients (average days to oral iron treatment = 476.7). Approximately 9% of IDA patients received a blood transfusion (average days to transfusion = 304.8). For the total sample, the average age was 46 years with a higher percentage of females (83.9% IDA; 78.7% non-IDA). Most clinical characteristics were similar among patients with and without IDA, except heart disease (1.3% IDA vs. 0.8% non-IDA; P = 0.005) and gallbladder disease (0.0% IDA vs. 0.2% non-IDA; P = 0.037). More IDA patients had complications after surgery (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 that IDA patients were more likely to have a bariatric surgery complication over non-IDA patients (OR = 1.367, 95% CI = 1.257-1.487; P < 0.05). Adjusted results showed IDA patients more than twice as likely to be hospitalized (OR = 2.567, 95% CI = 2.363-2.790; P < 0.05). Total costs were twice as much in the IDA group compared with the non-IDA group ($37,882 vs. $19,253; P < 0.001). CONCLUSIONS: Bariatric surgery patients who develop IDA may be subject to higher complication rates, MRU, and direct medical costs. Although most bariatric surgery patients who develop IDA are tested for 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.