The prognostic and diagnostic value of intraleukocytic malaria pigment: an individual patient data pooled meta-analysis of 32,000 patients with severe falciparum malaria in Africa and Asia

BackgroundSevere falciparum malaria is a major cause of death in tropical countries, particularly in African children. Accurate diagnosis and prognostic assessment are critical to clinical management.MethodsThe prognostic value of the malaria parasite count, and the proportions of polymorphonuclear leukocytes (PMNs) and monocytes (PMMs) containing malaria pigment in peripheral blood films were assessed in three randomized controlled trials conducted in severe malaria patients; two in Southeast Asia (AQ Vietnam; n=483 and SEAQUAMAT; n=1,330) and one in Africa (AQUAMAT; n=4,211). Following a systematic review of the literature, we incorporated these data into an individual patient data meta-analysis including published data from the Severe Malaria in African children (SMAC) network (n=25,845) and a study from Mali (n=166).FindingsThe proportion of pigment containing PMNs on peripheral blood films was strongly positively correlated with prognosis (odds-ratio for in-hospital mortality for a tenfold increase: 2.53 [95% CI: 2.13-3.00], p = 10−26). The meta-analytic odds-ratio estimate for in-hospital death in patients with >5% pigment containing PMNs compared with lower values was 2.67 (95% CI: 2.08-3.42; p = 10−14). Particularly in African children, the proportion of pigment containing PMNs added substantially to the prognostic assessment from simple bedside examination, and also to the conventional parasite count. In all analyses, the proportion of pigment containing monocytes had a lower prognostic value.InterpretationMicroscopy assessment of the proportion of pigment containing PMNs in a blood film is simple and rapid, and should be performed in all patients hospitalised with suspected severe malaria. Patients with >5% pigment containing PMNs have more than double the risk of death.OtherFunded by Wellcome. The systematic review was registered prospectively on PROS-PERO, number CRD42021284527Research in contextEvidence before this studySevere falciparum malaria remains a major cause of preventable childhood mortality in sub-Saharan Africa. In 2019 there were an estimated 274,000 deaths in children under 5 years. Rapidly identifying patients at the greatest risk of death and providing effective treatment is essential to saving lives. Based on data from our prospective studies of strictly defined severe falciparum malaria in Vietnamese adults, the proportions of peripheral blood neutrophils and monocytes containing malaria pigment (haemozoin) was proposed as a prognostic factor for mortality. We carried out a systematic review on PubMed of all articles published between database inception and October 11, 2021, using search terms “intraleukocytic pigment” and “severe malaria”. In addition to papers published by our research group, we found two other studies that reported the prognostic value of intraleukocytic pigment counts in severe malaria cohorts of at least 100 patients: the SMAC network study, the largest published cohort study conducted in over 25,000 African children with suspected severe malaria, and a cohort of 172 children from Mali. The SMAC study reported that intraleukocytic malaria pigment counts were not a useful predictor of outcome in African children diagnosed with severe malaria. This differed from the results from the Malian study and our original study in Vietnamese adults.Added value of this studyWe provide new data on the prognostic value of intraleukocytic malaria pigment counts in over 6,000 adults and children with a strict diagnosis of severe falciparum malaria studied prospectively in Asia and Africa. These patients were enrolled in three of the largest randomised controlled trials in severe malaria. These randomised trials have provided the main evidence base for current global therapeutic recommendations. Our data show that there is substantial prognostic value in counting intraleukocytic malaria pigment. This was significantly greater for neutrophil rather than monocyte associated pigment. Pooling all the individual patient data showed that the prognostic value was consistent across studies and countries, despite the substantial differences in study populations and study designs. Having more than 5% pigment containing neutrophils was associated with over double the risk of death from severe falciparum malaria.Implications of all the available evidenceIntraleukocytic malaria pigment counts have sub-stantial prognostic value in severe falciparum malaria. The proportion of neutrophils containing malaria pigment should be counted in thin blood films in all patients with suspected severe malaria. Patients with over 5% of pigment containing neutrophils have a high risk of death.

Improving the diagnosis of severe malaria in African children using platelet counts and plasma PfHRP2 concentrations

Background Severe falciparum malaria is difficult to diagnose accurately in children in high transmission settings. Platelet counts and plasma concentrations of P. falciparum histidine-rich protein-2 (PfHRP2) are potential biomarkers to increase diagnostic accuracy. Methods We fitted Bayesian latent class models to platelet counts and PfHRP2 concentrations in 2,649 patients enrolled in four studies of severe illness in three countries (Bangladesh, Kenya, and Uganda). We estimated receiver operating characteristic curves and compared parasite densities, haematocrits, total white blood cell counts, blood culture positivity rates, and haemoglobin S genotypes (HbAS and HbSS) across the subgroups defined by the probabilistic models. Findings The platelet count and the plasma PfHRP2 concentration have substantial diagnostic value in severe malaria. In severely ill patients with clinical features consistent with severe malaria, a combined platelet count ≤150,000 per μL and a plasma PfHRP2 concentration ≥1,000 ng/mL had an estimated sensitivity of 74\% and specificity of 93\% in identifying `true' severe falciparum malaria. We estimate one third of African children enrolled in the two clinical studies of severe malaria had another cause of severe illness. Under the model, patients with severe malaria had higher parasite densities, lower haematocrits, lower rates of invasive bacterial disease, and a lower prevalence of both HbAS and HbSS than children misdiagnosed. Mortality in `true' severe malaria was consistent across the African sites at ≈10%. Interpretation Studies of severe falciparum malaria in African children would be improved by including only patients with platelet counts ≤150,000 per μL and plasma PfHRP2 concentrations ≥1,000 ng/mL. Funding Wellcome

Identifying prognostic factors of severe metabolic acidosis and uraemia in African children with severe falciparum malaria: a secondary analysis of a randomized trial

Background Severe metabolic acidosis and acute kidney injury are major causes of mortality in children with severe malaria but are often underdiagnosed in low resource settings. Methods A retrospective analysis of the ‘Artesunate versus quinine in the treatment of severe falciparum malaria in African children’ (AQUAMAT) trial was conducted to identify clinical features of severe metabolic acidosis and uraemia in 5425 children from nine African countries. Separate models were fitted for uraemia and severe metabolic acidosis. Separate univariable and multivariable logistic regression were performed to identify prognostic factors for severe metabolic acidosis and uraemia. Both analyses adjusted for the trial arm. A forward selection approach was used for model building of the logistic models and a threshold of 5% statistical significance was used for inclusion of variables into the final logistic model. Model performance was assessed through calibration, discrimination, and internal validation with bootstrapping. Results There were 2296 children identified with severe metabolic acidosis and 1110 with uraemia. Prognostic features of severe metabolic acidosis among them were deep breathing (OR: 3.94, CI 2.51–6.2), hypoglycaemia (OR: 5.16, CI 2.74–9.75), coma (OR: 1.72 CI 1.17–2.51), respiratory distress (OR: 1.46, CI 1.02–2.1) and prostration (OR: 1.88 CI 1.35–2.59). Features associated with uraemia were coma (3.18, CI 2.36–4.27), Prostration (OR: 1.78 CI 1.37–2.30), decompensated shock (OR: 1.89, CI 1.31–2.74), black water fever (CI 1.58. CI 1.09–2.27), jaundice (OR: 3.46 CI 2.21–5.43), severe anaemia (OR: 1.77, CI 1.36–2.29) and hypoglycaemia (OR: 2.77, CI 2.22–3.46) Conclusion Clinical and laboratory parameters representing contributors and consequences of severe metabolic acidosis and uraemia were independently associated with these outcomes. The model can be useful for identifying patients at high risk of these complications where laboratory assessments are not routinely available.

STUDY OF ADRENAL INSUFFICIENCY IN SEVERE FALCIPARUM MALARIA WITH SHOCK KEY WORDS: Falciparum Malaria, Shock, Adrenal

Malaria remains a serious health problem in South East Asian Region (SEAR) with nearly 290 million people are estimated to be at high risk.India accounts for 77% of the regional total malarial cases.Most of deaths in malaria are due to severe falciparum malaria. Odisha is a unique state in the eastern region of India, which contributes 4% of the population and counting up to >40% of total falciparum malaria cases of India. Malaria is one of the most important public health disease in Odisha. In spite of such an important disease, there are many areas on severe falciparum malarias where research work is scanty. One among of them is detection of relative adrenal insufficiency in severe falciparum malaria. As there is limited work about the relative adrenal insufficiency in severe falciparum malaria with shock and its relation to mortality. This study has been undertaken with the following aims and objectives, firstly detection of relative adrenal insufficiency in severe falciparum malaria with shock and secondly to establish the relation of mortality with or without adrenal insufficiency in severe falciparum malaria.The present study has established that relative adrenal insufficiency is an important cause contributing to shock and increased mortality. Thus addition of corticosteroid saves life and must be used in the relative adrenal insufficiency. However the firm diagnosis of relative adrenal insufficiency depends upon estimation of basal serum cortisol level & post ACTH serum cortisol level. As corticosteroid reduces the mortality rate, it should be empirically used in critically ill severe falciparum malaria cases with shock.

Development and validation of an in silico decision-tool to guide optimisation of intravenous artesunate dosing regimens for severe falciparum malaria patients

Most deaths from severe falciparum malaria occur within 24 hours of presentation to hospital. Intravenous (i.v.) artesunate is the first-line treatment for severe falciparum malaria, but its efficacy may be compromised by delayed parasitological responses. In patients with severe malaria the life-saving benefit of the artemisinin derivatives is their ability to clear circulating parasites rapidly, before they can sequester and obstruct the microcirculation. To evaluate the dosing of i.v. artesunate for the treatment of artemisinin-sensitive and reduced ring stage sensitivity to artemisinin severe falciparum malaria infections Bayesian pharmacokinetic-pharmacodynamic modelling of data from 94 patients with severe malaria (80 children from Africa and 14 adults from Southeast Asia) was performed. Assuming delayed parasite clearance reflects a loss of ring stage sensitivity to artemisinin derivatives, the median (95% credible interval) percentage of patients clearing ≥99% parasites within 24 hours (PC24≥99%) for standard (2.4 mg/kg i.v. artesunate at 0 and 12 hours) and simplified (4 mg/kg i.v. artesunate at 0 hours) regimens were 65% (52.5%-74.5%) versus 44% (25%-61.5%) for adults, 62% (51.5%-74.5%) versus 39% (20.5%-58.5%) for larger children (≥20 kg) and 60% (48.5%-70%) versus 36% (20%-53.5%) for smaller children (<20 kg). The upper limit of the credible intervals for all regimens was below a PC24≥99% of 80%, a threshold achieved on average in clinical studies of severe falciparum malaria infections. Rapid clearance of parasites, where there is loss of ring stage sensitivity to artemisinin, in patients with severe falciparum malaria is compromised with the currently recommended and proposed simplified i.v. artesunate dosing regimens.

Identifying Prognostic Factors of Severe Metabolic Acidosis and Acute Kidney Injury in African Children with Severe Falciparum Malaria: A Secondary Analysis of A Randomised Trial

IntroductionSevere metabolic acidosis and acute kidney injury are major causes of mortality in children with severe malaria but are often underdiagnosed in low resource settings. MethodsWe conducted a retrospective analysis of the ‘Artesunate vs Quinine in the treatment of severe falciparum malaria in African children’ (AQUAMAT) trial to identify clinical features of severe metabolic acidosis and acute kidney injury in 5425 children from nine African countries. Separate models were fitted for acute kidney injury and severe metabolic acidosis. Separate univariable and multivariable logistic regression were performed to identify prognostic factors for severe metabolic acidosis (SMA) and acute kidney injury (AKI). Both analyses adjusted for the trial arm. A forward selection approach was used for model building of the logistic models and a threshold of 5% statistical significance was used for inclusion of variables into the final logistic model. Model performance was assessed through calibration, discrimination, and internal validation with bootstrapping. ResultsThere were 2296 children identified with Severe metabolic acidosis and 1110 with Acute Kidney Injury. Prognostic features of SMA among them were: deep breathing (OR: 5.41, CI: 4.26 – 6.89), hypoglycaemia (OR: 5.22, CI: 3.80 – 7.18), AKI (OR: 3.99, CI: 3.30 – 4.81), coma ( OR: 1.79 CI: 1.36 – 2.35), respiratory distress (OR: 1.49, CI: 1.21 – 1.83), prostration (OR: 1.64 CI: 1.30 – 2.03) and severe anaemia (OR: 1.40, CI: 1.11 – 1.77). Features associated with AKI were; older children(OR: 1.20, CI: 1.15 – 1.25), coma (2.47, CI: 1.78 – 3.42), Prostration (OR: 1.52 CI: 1.14 – 2.02), decompensated shock (OR: 1.74, CI: 1.15 – 2.63), black water fever (CI: 1.81. CI: 1.22 – 2.69), jaundice (OR: 3.31 CI: 2.01 – 5.47), SMA (OR: 4.02 CI:3.30 – 4.89), mild anaemia (OR: 1.36, CI: 1.05 – 1.76), severe anaemia (OR: 1.48, CI: 1.11 – 1.96), hypoglycaemia (OR: 2.02, CI: 1.58 – 2.59), hypernatremia (OR: 5.74, CI: 2.69 – 12.26) and hyperkalaemia (OR: 5.31. CI: 4.15 – 6.80). ConclusionClinical and laboratory parameters representing contributors and consequences of severe metabolic acidosis and acute kidney injury were independently associated with these outcomes. The model can be useful for identifying patients at high risk of these complications where laboratory assessments are not routinely available.