# Optimizing Testing Time for Methaemoglobin Reduction Test in G6PD Screening: A Comparative Study of Monica Cheesbrough’s Protocol and a Modified Approach at a Hospital in a Resource‐Restraint Country, Ghana

## TL;DR

This study finds that a 120-minute testing time is optimal for diagnosing G6PD deficiency in a hospital in Ghana, improving efficiency and reducing blood volume needed.

## Contribution

The study identifies 120 minutes as the optimal reaction time for Methaemoglobin Reduction Test in G6PD screening in resource-limited settings.

## Key findings

- ICC values were very low at T90 but high from T120 onwards, showing excellent reliability.
- Kappa values indicated slight agreement at T90 but perfect agreement from T120 onwards.
- The optimal MRT reaction time was found to be 120 minutes with lesser blood and reagent volumes.

## Abstract

Glucose‐6‐phosphate dehydrogenase (G6PD) deficiency is an inherited disorder caused by a genetic defect in the red blood cell enzyme G6PD, affecting around 500 million people worldwide. The study investigated the optimum Methaemoglobin Reduction Test (MRT) reaction time for diagnosing G6PD deficiency among patients at Asutifi North District Hospital using Monica Cheesbrough protocol and Asutifi North District Hospital Protocol.

The study was an experimental study conducted with 643 participants from April, 2024 to July, 2024. The Monica Cheesbrough MRT and the modified approach (Asutifi North Hospital MRT protocols), were compared at various time points (T90, T120, T150, and T180 min). Intraclass Correlation Coefficient (ICC) and Kappa statistics were used to assess reliability and agreement between the results from the two protocols. McNemar’s test was utilized to analyse G6PD status differences between the protocols. The prevalence of G6PD deficiency was also determined. Data analyses were done using IBM Statistical Package for the Social Sciences version 26.0 (2019. Armonk, NY: IBM Corp). p‐value less than 0.05 was considered statistically significant for all analyses.

T90 ICC values were very low (0.005–0.007), indicating poor agreement. From T120 onwards, ICC values were high (0.967–0.996, p < 0.001), demonstrating excellent reliability. Significant differences in G6PD status were found at T90 (p < 0.001), with diminishing differences at later time points. Kappa values indicated slight agreement at T90 (K = 0.164, p < 0.001) and perfect agreement from T120 onwards (K = 1.000, p < 0.001). The majority of participants 606 (94.2%) had normal G6PD status, 29 (4.5%) had a fully defective enzyme, and 8 (1.2%) had a partially defective enzyme activity.

The study found the optimum MRT reaction to be 120 min. The study also emphasized lesser volumes of blood samples and reagent give accurate results in the optimum time established. These insights can contribute to faster turnaround times and efficient sample and reagent management especially amongst paediatric patients where it is difficult taking very large volumes of blood for testing.