Prevalence of iron deficiency and red blood cell transfusions in surgical patients

Soluble transferrin receptor is associated with red blood cell transfusion in infant cardiac surgery

Background

Iron deficiency (ID) is linked to an increased need for perioperative red blood cell (RBC) transfusion in cardiac surgery. Traditional markers used to assess ID are often influenced by inflammation, whereas soluble transferrin receptor (sTfR) is less affected by inflammation. Therefore, the purpose of this study is to explore the relationship between sTfR levels and the need for high-volume RBC transfusion in pediatric cardiac surgery patients.

Methods

From August 2021 to July 2022, 236 low-weight infants (≤10 kg) who underwent cardiac surgery were included in this study. Preoperative sTfR levels and the volume of RBCs perioperatively transfused were recorded. Receiver operating characteristic (ROC) curve analysis and multivariable logistic model were used to explore the association between sTfR levels and the need for a high-volume of RBC transfusion in this study.

Results

In our study, 29 (12.3%) patients received more than 2 units during the perioperative period. sTfR level was the most accurate marker for predicting the need for RBC transfusion [area under the curve (AUC) =0.643; 95% confidence interval (CI): 0.531-0.756]. Moreover, in both the continuous and categorical variable-adjusted models, a high sTfR level was associated with a greater need for RBC transfusion (P=0.006; P<0.001).

Conclusions

RBC transfusion is common for low-weight infants undergoing cardiac surgery. Furthermore, a high preoperative sTfR level is associated with the need for a high-volume perioperative RBC transfusion.

Reported outcomes in patients with iron deficiency or iron deficiency anemia undergoing major surgery: a systematic review of outcomes

BACKGROUND

Iron deficiency (ID) is the leading cause of anemia worldwide. The prevalence of preoperative ID ranges from 23 to 33%. Preoperative anemia is associated with worse outcomes, making it important to diagnose and treat ID before elective surgery. Several studies indicated the effectiveness of intravenous iron supplementation in iron deficiency with or without anemia (ID(A)). However, it remains challenging to establish reliable evidence due to heterogeneity in utilized study outcomes. The development of a core outcome set (COS) can help to reduce this heterogeneity by proposing a minimal set of meaningful and standardized outcomes. The aim of our systematic review was to identify and assess outcomes reported in randomized controlled trials (RCTs) and observational studies investigating iron supplementation in iron-deficient patients with or without anemia.

METHODS

We searched MEDLINE, CENTRAL, and ClinicalTrials.gov systematically from 2000 to April 1, 2022. RCTs and observational studies investigating iron supplementation in patients with a preoperative diagnosis of ID(A), were included. Study characteristics and reported outcomes were extracted. Outcomes were categorized according to an established outcome taxonomy. Quality of outcome reporting was assessed with a pre-specified tool. Reported clinically relevant differences for sample size calculation were extracted.

RESULTS

Out of 2898 records, 346 underwent full-text screening and 13 studies (five RCTs, eight observational studies) with sufficient diagnostic inclusion criteria for iron deficiency with or without anemia (ID(A)) were eligible. It is noteworthy to mention that 49 studies were excluded due to no confirmed diagnosis of ID(A). Overall, 111 outcomes were structured into five core areas including nine domains. Most studies (92%) reported outcomes within the 'blood and lymphatic system' domain, followed by "adverse event" (77%) and "need for further resources" (77%). All of the latter reported on the need for blood transfusion. Reported outcomes were heterogeneous in measures and timing. Merely, two (33%) of six prospective studies were registered prospectively of which one (17%) showed no signs of selective outcome reporting.

CONCLUSION

This systematic review comprehensively depicts the heterogeneity of reported outcomes in studies investigating iron supplementation in ID(A) patients regarding exact definitions and timing. Our analysis provides a systematic base for consenting to a minimal COS.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020214247.