A Concordance Study between IDH1-R132H Immunohistochemistry and PCR for Gliomas in one of the healthcare settings in Malaysia.

Abstract

Introduction: Mutations in the isocitrate dehydrogenases (IDH) 1 gene occur in most gliomas and thus show better prognostic value. Both immunohistochemistry (IHC) and polymerase chain reaction (PCR) are available in one of the healthcare settings in Malaysia to detect IDH1 mutation. PCR was preferred due to accuracy, but it was less cost-effective to perform. This study is primarily to analyse the concordance between IDH1-R132H IHC and PCR testing; secondarily, to evaluate demographic characteristics of IDH-mutant gliomas in one of the healthcare settings in Malaysia. Methodology: This is a single-centre retrospective study. Data of IDH1 PCR performed in brain tumours received by one of the healthcare settings in Malaysia between January 2021 and December 2021 were collected. Samples tested with both IDH1-R132H IHC and PCR were included. Non-glioma cases and IDH2 PCR positive were excluded. Concordance between IDH1-R132H IHC and PCR was evaluated according to Cohen's kappa coefficient and was interpreted according to the Landis and Koch scale. Results: 31 samples were able to meet the inclusion criteria and revealed a kappa coefficient of 0.86 with a concordance rate of 97%. There was a total of 46 brain tumour samples performed for IDH PCR in 2021. IDH1/2 mutation was detected in 21(45.6%) PCR tests, with the majority IDH1 R132H mutation 19(90%), male patients 16(76%), gliomas of WHO grade 2-3 (18.25%) and 3(25%) cases of WHO grade 4 showed IDH mutants. Conclusion: IDH1-R132H immunohistochemistry testing shows high concordance with IDH1 PCR testing. Hence, IDH1-R132H IHC testing alone in one of the healthcare settings in Malaysia is sufficient and cost-effective for diagnosing glioma with IDH1 mutation. Therefore, the concordance study is required in healthcare settings which have a surrogate marker to ensure the reliability and validity of the test offered and the diagnosis given.