Importance of Complete Parenteral Iron Replacement on Hemoglobin Normalization: A Retrospective Analysis

Introduction

Iron deficiency anemia (IDA) is the most common cause of anemia in the United States (US) and occurs most often in patients with chronic diseases and inflammation.

Although oral iron therapy is often prescribed for iron deficiency anemia, parenteral iron therapy is necessary for patients who cannot tolerate or are nonresponsive to oral iron. Parenteral iron therapy is also used in patients with chronic diseases such as inflammatory bowel disease, cancer or chronic kidney disease when rapid iron replacement is desirable. Currently, several parenteral iron therapies are available in the US and they vary in dose strengths and administration schedules. There are limited data on the dosing patterns of parenteral iron therapy and its effectiveness in the real world setting. The objective of this analysis was to assess the importance of parenteral iron dosing on serum hemoglobin (Hgb) level normalization in real world clinical practice.

Methods

Data was obtained from the Decision Resources Group (DRG) Real World Evidence Data Repository US database, which includes medical and pharmacy claims, and electronic health record data representing more than 300 million patient lives. Adult patients (≥18 years of age) who were treated with parenteral iron between 3/1/2015 and 2/28/2017 were included in the analysis. Eligible patients were required to have their most recent baseline Hgb level below normal (Hgb <12 g/dL for females and <13.5 g/dL for males) and recorded <30 days prior to or on the date of their index (first) parenteral iron therapy claim. Patients were excluded from the study if they received parenteral iron 6 weeks prior to the index date, received dialysis, or had insufficient data to identify comorbidities one year prior to index date.

Parenteral iron dose required to correct for iron deficit was calculated using the Ganzoni formula. Patients were categorized based on whether or not they received the full amount of parenteral iron required to correct for iron deficit during the 3 weeks after the index date. Patients were assessed to determine the proportions of patients achieving normalized Hgb levels (≥12 g/dL for females and 13.5 g/dL for males) within 8 weeks after index date and until the end of data availability. Logistic regression was used to estimate the effect of receiving the full amount of required parenteral iron dose within 3 weeks of treatment initiation on the likelihood of Hgb level normalization while controlling for gender, age, comorbid conditions, and use of prescription oral iron therapy.

Results

A total of 2,966 patients were included in the analysis (68.2% female, 58.4% ≥65 years; 60.1% chronic kidney disease, 50.1% congestive heart failure, 64.4% inflammatory bowel disease, and 59.5% cancer). Most (95%) patients did not receive prescription oral iron therapy within 3 months before or after index date. Mean (SD) number of injections during the 3-week period after index date was 2.5 (1.4).

Parenteral iron dose required to correct for iron deficit ranged from 343.7mg to 1915.0mg. Parenteral iron dose received during the first three weeks ranged from 600mg to 2000mg. About a third of patients (33.9%, n=1,006) received the full amount of required parenteral iron dose within the 3-week treatment course. A total of 582 (19.6%) patients had normalized Hgb levels within 8 weeks of treatment initiation and 53.9% (n=1,599) had normalized Hgb levels at any time during the entire study period (median study follow-up=108 weeks).

Patients who received the full amount of required dose to correct for iron deficit within 3 weeks of treatment initiation were significantly more likely to have normalized Hgb levels within 8 weeks of treatment initiation than those patients who did not receive the full amount of required dose over the same time period [adjusted odds ratio (95% CI) =2.67 (2.20, 3.24)]. Similarly, when normalized Hgb levels were analyzed using data available for the entire study period, patients who received the full amount of required dose within 3 weeks of treatment initiation were significantly more likely to have normalized Hgb levels than those patients who did not receive the full amount of required dose within 3 weeks of treatment initiation [adjusted odds ratio (95% CI) =2.32 (1.96, 2.75)].

Conclusion

The results of this analysis underscore the importance of initial complete iron replacement on rapidly improving clinical outcomes for IDA patients receiving parenteral iron therapy.