Review of available evidence supporting different transfusion thresholds in different patient groups with anemia

Use of point-of-care haemoglobin tests to diagnose childhood anaemia in low- and middle-income countries: A systematic review

OBJECTIVES

Anaemia is a major cause of mortality and transfusion in children in low- and middle-income countries (LMICs); however, current diagnostics are slow, costly and frequently unavailable. Point-of-care haemoglobin tests (POC(Hb)Ts) could improve patient outcomes and use of resources by providing rapid and affordable results. We systematically reviewed the literature to investigate what, where and how POC(Hb)Ts are being used by health facilities in LMICs to diagnose childhood anaemia, and to explore challenges to their use.

METHODS

We searched a total of nine databases and trial registries up to 10 June 2022 using the concepts: anaemia, POC(Hb)T, LMIC and clinical setting. Adults ≥21 years and literature published >15 years ago were excluded. A single reviewer conducted screening, data extraction and quality assessment (of diagnostic studies) using QUADAS-2. Outcomes including POC(Hb)T used, location, setting, challenges and diagnostic accuracy were synthesised.

RESULTS

Of 626 records screened, 41 studies were included. Evidence is available on the use of 15 POC(Hb)Ts in hospitals (n = 28, 68%), health centres (n = 9, 22%) and clinics/units (n = 10, 24%) across 16 LMICs. HemoCue (HemoCue AB, Ängelholm, Sweden) was the most used test (n = 31, 76%). Key challenges reported were overestimation of haemoglobin concentration, clinically unacceptable limits of agreement, errors/difficulty in sampling, environmental factors, cost, inter-observer variability and supply of consumables. Five POC(Hb)Ts (33%) could not detect haemoglobin levels below 4.5 g/dL. Diagnostic accuracy varied, with sensitivity and specificity to detect anaemia ranging from 24.2% to 92.2% and 70% to 96.7%, respectively.

CONCLUSIONS

POC(Hb)Ts have been successfully utilised in health facilities in LMICs to diagnose childhood anaemia. However, limited evidence is available, and challenges exist that must be addressed before wider implementation. Further research is required to confirm accuracy, clinical benefits and cost-effectiveness.

Executive Function and Processing Speed in Children Living with Sickle Cell Anemia

Executive function and processing speed difficulties are observed in children living with sickle cell anemia (SCA). The influence of processing speed on executive function is not well understood. We recruited 59 children living with SCA and 24 matched controls aged 8-18 years between 2010 and 2016 from clinics in the UK. Children completed tests in processing speed and cognitive flexibility, subdomains of executive function. MRI scans were conducted within one year of testing; oxygen saturation was obtained on the day of testing. Hemoglobin levels were obtained from medical records. Caregivers completed the executive function questionnaire. Hierarchical linear regressions found that hemoglobin, oxygen saturation, age, infarct status, and processing speed were not independent predictors for any model. However, for all cognitive flexibility tests, there was a significant interaction between infarct status and processing speed; children without silent cerebral infarction (SCI) with faster processing speed had better cognitive flexibility. Our findings indicate that, when interpreting executive function difficulties, it is important to account for the relationship between SCI status and processing speed. More research is needed to elucidate the mechanisms, but clinically, including executive function testing as part of clinic visits by embedding psychologists within the healthcare team would appear to be a critical step.

Passive order auditing associated with reductions in red blood cell utilization: National blood shortage experience

BACKGROUND

Decreased blood collection during the Coronavirus Disease 2019 (COVID-19) pandemic resulted in long-term red blood cell (RBC) shortages in the United States. In an effort to conserve RBCs, the existing passive alert system for auditing inpatient transfusions was modified to activate at a lower hemoglobin threshold (6.5 g/dL instead of 7.0 g/dL for stable, nonbleeding inpatients) during a 9-month shortage at an academic medical center. Hemoglobin levels prior to RBC transfusions were compared for inpatients receiving RBC transfusions to determine whether RBC utilization changed during the intervention.

STUDY DESIGN AND METHODS

This retrospective study compared the number of single-unit RBC transfusions and hemoglobin levels prior to RBC transfusion among inpatients during the 9 months of the intervention (Period 2, 06/01/2021-2/28/2022) to the same period of the previous year (Period 1, 06/01/2020-2/28/2021).

RESULTS

Overall full unit RBC transfusions to inpatients decreased by 15% from 5182 to 4421. Of all transfusions, 50.3% and 49.8% were single-unit RBC transfusions in Period 1 and Period 2, respectively. The incidence rate difference and incidence rate ratio of single RBC units transfused per 1000 patient days were significantly decreased (p = 0.0007). The average pre-transfusion hemoglobin level significantly decreased from 7.18 g/dL to 7.05 g/dL (p = 0.0002), largely due to significant decreases in hemoglobin transfusion triggers for adult inpatient ward transfusions.

DISCUSSION

Modification of the passive alert system was associated with significantly decreased RBC utilization during a long-term RBC shortage. Modification of transfusion criteria recommended by passive alerts may be a feasible option to decrease RBC utilization at centers during long-term RBC shortages.