Lamon A, Peterson-Layne C, Cooter M, Grimsley A, Swamy G, Hopkins TJ, Aronson S, Jimenez M, Guinn NR. Value of a preoperative anemia clinic in a high-risk obstetric population. Poster presented at the American Society of Anesthesiologists 2016 Annual Conference; October 23, 2016. Chicago, IL.

INTRODUCTION: Anemia in pregnancy, defined by the World Health Organization as hemoglobin (Hb)<11g/dL, affects up to 30% of pregnancies and is associated with significant maternal and fetal morbidity. The most common etiology of anemia in this population is iron deficiency. Oral iron is poorly tolerated in the obstetric (OB) population due to GI side effects, and a recent systemic review showed intravenous (IV) iron to be more effective in treating iron-deficiency anemia of pregnancy. Thus, obstetricians, OB anesthesia, and blood conservation collaborated to coordinate care for anemic pregnant women, with the goal of improving hemoglobin and reducing blood transfusions.

METHODS: As of January 2015, patients at our High-Risk Obstetric (HROB) Clinic noted during routine screen to have iron-deficiency or other risk factor for transfusion, were referred to the Preoperative Anemia Clinic (PAC) for evaluation of anemia and consideration of IV iron. With IRB approval, we retrospectively identified PAC patients referred from HROB between January 2015 and December 2015, and a control cohort of HROB clinic patients from January 2014 and December 2014 with evidence of antepartum anemia (Hb <11g/dl within 3 months of delivery). Recorded data include demographics, lowest antepartum Hb, Hb at delivery, peripartum RBC transfusions, and number of iron infusions (PAC group only). Comparison of demographics between the cohorts was performed with Wilcoxon rank sum tests, Chi-Square or Fisher exact tests as appropriate. Group difference in Hb change was assessed univariately via a Wilcoxon Rank Sum test and multivariately in a linear regression model adjusting for lowest antepartum Hb. Difference in the rate of RBC transfusion was compared univariately with a chi-square test and multivariately via stratified logistic regression controlling for lowest antepartum Hb and stratifying by delivery mode.

RESULTS: 106 parturients referred to the PAC were compared to 190 in the control cohort. Of the 106 in the PAC group, 77 (71.3%) received one dose, and 9 (8.33%) received two doses of IV iron. 20 patients missed their appointment, delivered prior to treatment, or opted for oral iron. The only significant difference in baseline characteristics between the two cohorts was the lowest pre-admission Hb, which was lower in the PAC group 10.2 vs 9.3 (p<.001). The increase in Hb between lowest antepartum and delivery was significantly greater in the PAC group than the controls 1.0 vs 0.4 (p<.001). In the multivariate model adjusting for lowest antepartum Hb, treatment in the PAC was independently associated with greater Hb change (Beta 0.53; 95% CI 0.3-0.8; p<.0001). We found that peripartum transfusion rates were similar in both the univariate (4.7% control, 5.7% PAC, p=0.7) and multivariate analysis (OR 0.74; 95% CI 0.2-2.3; p=0.6).

CONCLUSION: This study shows that patients with antepartum anemia receiving care from the PAC had significantly greater increases in Hb level than those that did not. While there was not a statistically significant difference in transfusion rates, the PAC cohort group had lower starting hemoglobin, possibly representing a higher risk group.

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