Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Effectiveness of household lockable pesticide storage to reduce pesticide self-poisoning in rural Asia: a community-based, cluster-randomised controlled trial(London : J. Onwhyn, 2017) Pearson, M.; Metcalfe, C.; Jayamanne, S.; Gunnell, D.; Weerasinghe, M.; Pieris, R.; Priyadarshana, C.; Knipe, D.W.; Hawton, K.; Dawson, A.H.; Bandara, P.; de Silva, D.; Gawarammana, I.; Eddleston, M.; Konradsen, F.BACKGROUND: Agricultural pesticide self-poisoning is a major public health problem in rural Asia. The use of safer household pesticidestorage has been promoted to prevent deaths, but there is no evidence of effectiveness. We aimed to test the effectiveness of lockablehousehold containers for prevention of pesticide self-poisoning. METHODS: We did a community-based, cluster-randomised controlled trial in a rural area of North Central Province, Sri Lanka. Clusters of households were randomly assigned (1:1), with a sequence computer-generated by a minimisation process, to intervention or usual practice (control) groups. Intervention households that had farmed or had used or stored pesticide in the preceding agricultural season were given a lockable storage container. Further promotion of use of the containers was restricted to community posters and 6-monthly reminders during routine community meetings. The primary outcome was incidence of pesticide self-poisoning in people aged 14 years or older during 3 years of follow-up. Identification of outcome events was done by staff who were unaware of group allocation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT1146496. FINDINGS: Between Dec 31, 2010, and Feb 2, 2013, we randomly assigned 90 rural villages to the intervention group and 90 to the control group. 27 091 households (114 168 individuals) in the intervention group and 26 291 households (109 693 individuals) in the control group consented to participate. 20 457 household pesticide storage containers were distributed. In individuals aged 14 years or older, 611 cases of pesticide self-poisoning had occurred by 3 years in the intervention group compared with 641 cases in the control group; incidence of pesticide self-poisoning did not differ between groups (293·3 per 100 000 person-years of follow-up in the intervention group vs 318·0 per 100 000 in the control group; rate ratio [RR] 0·93, 95% CI 0·80-1·08; p=0·33). We found no evidence of switching from pesticide self-poisoning to other forms of self-harm, with no significant difference in the number of fatal (82 in the intervention group vs 67 in the control group; RR 1·22, 0·88-1·68]) or non-fatal (1135 vs 1153; RR 0·97, 0·86-1·08) self-harm events involving all methods. INTERPRETATION: We found no evidence that means reduction through improved household pesticide storage reduces pesticide self-poisoning. Other approaches, particularly removal of highly hazardous pesticides from agricultural practice, are likely to be more effective for suicide prevention in rural Asia. FUNDING: Wellcome Trust, with additional support from the American Foundation for Suicide Prevention, Lister Institute of Preventive Medicine, Chief Scientist Office of Scotland, University of Copenhagen, and NHMRC Australia.Item A Randomized controlled trial of fresh frozen plasma for coagulopathy in Russell's viper (Daboia russelii) envenoming(Wiley-Blackwell, 2017) Isbister, G.K.; Jayamanne, S.; Mohamed, F.; Dawson, A.H.; Maduwage, K.; Gawarammana, I.; Lalloo, D.G.; de Silva, H.J.; Scorgie, F.E.; Lincz, L.F.; Buckley, N.A.BACKGROUND: Russell's viper (Daboia russelii) envenoming is a major health issue in South Asia and causes venom induced consumption coagulopathy (VICC). OBJECTIVES: We investigated the effect of fresh frozen plasma (FFP) and two antivenom doses in correcting VICC. METHODS: We undertook an open-label randomized controlled trial in patients with VICC at two Sri Lankan hospitals. Patients with suspected Russell's viper bites and coagulopathy were randomly allocated (1:1) high-dose antivenom (20 vials) or low-dose antivenom (10 vials) plus 4U FFP. The primary outcome was the proportion of patients with an international normalized ratio (INR)<2, 6h post-antivenom. Secondary outcomes included anaphylaxis, major haemorrhage, death and clotting factor recovery. RESULTS: From 214 eligible patients, 141 were randomized; 71 to high-dose antivenom, 70 to low-dose antivenom/FFP; five had no post-antivenom bloods. The groups were similar except for a delay of 1h in antivenom administration for FFP patients. 6h post-antivenom 23/69 (33%) patients allocated high-dose antivenom had an INR<2 compared with 28/67 (42%) allocated low-dose antivenom/FFP [absolute difference 8%;95%Confidence Interval:-8% to 25%]. 15 patients allocated FFP did not receive it. Severe anaphylaxis occurred equally frequently in each group. One patient given FFP developed transfusion related acute lung injury. Three deaths occurred in low-dose/FFP patients including one intracranial haemorrhage. There was no difference in recovery rates of INR or fibrinogen, but more rapid initial recovery of factor V and X in FFP patients. CONCLUSION: FFP post-antivenom in Russell's viper bites didn't hasten recovery of coagulopathy. Low-dose antivenom/FFP did not worsen VICC, suggesting low-dose antivenom is sufficient. This article is protected by copyright. All rights reserved.Item Mechanism-specific injury biomarkers predict nephrotoxicity early following glyphosate surfactant herbicide (GPSH) poisoning(Elsevier, 2016) Mohamed, F.; Endre, Z.H.; Pickering, J.W.; Jayamanne, S.; Palangasinghe, C.; Shahmy, S.; Chathuranga, U.; Wijerathne, T.; Shihana, F.; Gawarammana, I.; Buckley, N.A.Acute kidney injury (AKI) is common following glyphosate surfactant herbicide (GPSH) self-poisoning. Serum creatinine (sCr) is the most widely used renal biomarker for diagnosis of AKI although a recent study in rats suggested that urinary kidney injury molecule-1 predicted AKI earlier and better after GPSH-induced nephrotoxicity. We explored the utility of a panel of biomarkers to diagnose GPSH-induced nephrotoxicity in humans. In a prospective multi-centre observational study, serial urine and blood samples were collected until discharge and at follow-up. The diagnostic performance of each biomarker at various time points was assessed. AKI was diagnosed using the Acute Kidney Injury Network (AKIN) definitions. The added value of each biomarker to sCr to diagnose AKI was assessed by the integrated discrimination improvement (IDI) metric. Of 90 symptomatic patients, 51% developed AKI and 5 patients who developed AKIN ≥ 2 died. Increased sCr at 8 and 16 hours predicted moderate to severe AKI and death. None of the 10 urinary biomarkers tested increased above normal range in patients who did not develop AKI or had mild AKI (AKIN1); most of these patients also had only minor clinical toxicity. Absolute concentrations of serum and urinary cystatin C, urinary interleukin-18 (IL-18), Cytochrome C (CytoC) and NGAL increased many fold within 8 hours in patients who developed AKIN ≥ 2. Maximum 8 and 16 hour concentrations of these biomarkers showed an excellent diagnostic performance (AUC-ROC ≥0.8) to diagnose AKIN ≥ 2. However, of these biomarkers only uCytoC added value to sCr to diagnose AKI when assessed by IDI metrics. GPSH-induced nephrotoxicity can be diagnosed within 24 hours by sCr. Increases in uCytoC and uIL-18 confirm GPSH-induces apoptosis and causes mitochondrial toxicity. Use of these biomarkers may help to identify mechanism specific targeted therapies for GPSH nephrotoxicity in clinical trials.Item High lethality and minimal variation after acute self-poisoning with carbamate insecticides in Sri Lanka - implications for global suicide prevention(Informa Healthcare, 2016) Lamb, T.; Selvarajah, L.R.; Mohamed, F.; Jayamanne, S.; Gawarammana, I.; Mostafa, A.; Buckley, N.A.; Roberts, M.S.; Eddleston, M.BACKGROUND: Highly hazardous organophosphorus (OP) insecticides are responsible for most pesticide poisoning deaths. As they are removed from agricultural practice, they are often replaced by carbamate insecticides of perceived lower toxicity. However, relatively little is known about poisoning with these insecticides. METHODS: We prospectively studied 1288 patients self-poisoned with carbamate insecticides admitted to six Sri Lankan hospitals. Clinical outcomes were recorded for each patient and plasma carbamate concentration measured in a sample to confirm the carbamate ingested. FINDINGS: Patients had ingested 3% carbofuran powder (719), carbosulfan EC25 liquid (25% w/v, 389), or fenobucarb EC50 liquid (50% w/v, 127) formulations, carbamate insecticides of WHO Toxicity Classes Ib, II, and II, respectively. Intubation and ventilation was required for 183 (14.2%) patients while 71 (5.5%) died. Compared with carbofuran, poisoning with carbosulfan or fenobucarb was associated with significantly higher risk of death [carbofuran 2.2%; carbosulfan 11.1%, OR 5.5 (95% CI 3.0-9.8); fenobucarb 6.3%, OR 3.0 (1.2-7.1)] and intubation [carbofuran 6.1%; carbosulfan 27.0%, OR 5.7 (3.9-8.3); fenobucarb 18.9%, OR 3.6 (2.1-6.1)]. The clinical presentation and cause of death did not differ markedly between carbamates. Median time to death was similar: carbofuran 42.3 h (IQR 5.5-67.3), carbosulfan 21.3 h (11.5-71.3), and fenobucarb 25.3 h (17.3-72.1) (p = 0.99); no patients showed delayed onset of toxicity akin to the intermediate syndrome seen after OP insecticide poisoning. For survivors, median duration of intubation was 67.8 h (IQR 27.5-118.8) with no difference in duration between carbamates. Reduced GCS at presentation was associated with worse outcome although some patients with carbosulfan died after presentation with normal GCS. CONCLUSIONS: We did not find carbamate insecticide self-poisoning to vary markedly according to the carbamate ingested although the case fatality varied according to the concentration and formulation of the insecticide. Carbamate poisoning did not appear to be much less toxic than poisoning with some liquid OP insecticide formulations, e.g., chlorpyrifos EC40, that we have previously noted in these same hospitals (Lancet 2005, 366:1452-1459; QJM 2006, 99:513-522). Replacement of WHO Class II Toxicity OP insecticides in agriculture with high-strength liquid carbamate formulations may not substantially reduce case fatality after pesticide poisoning and, therefore, global suicide rates.Item Acute human self-poisoning with imidacloprid compound: a neonicotinoid insecticide(Public Library of Science, 2009) Mohamed, F.; Gawarammana, I.; Robertson, T.A.; Roberts, M.S.; Palangasinghe, C.; Zawahir, S.; Jayamanne, S.; Kandasamy, J.; Eddleston, M.; Buckley, N.A.; Dawson, A.H.; Roberts, D.M.BACKGROUND: Deliberate self-poisoning with older pesticides such as organophosphorus compounds are commonly fatal and a serious public health problem in the developing world. The clinical consequences of self-poisoning with newer pesticides are not well described. Such information may help to improve clinical management and inform pesticide regulators of their relative toxicity. This study reports the clinical outcomes and toxicokinetics of the neonicotinoid insecticide imidacloprid following acute self-poisoning in humans. METHODOLOGY/PRINCIPAL FINDINGS: Demographic and clinical data were prospectively recorded in patients with imidacloprid exposure in three hospitals in Sri Lanka. Blood samples were collected when possible for quantification of imidacloprid concentration. There were 68 patients (61 self-ingestions and 7 dermal exposures) with exposure to imidacloprid. Of the self-poisoning patients, the median time to presentation was 4 hours (IQR 2.3-6.0) and median amount ingested was 15 mL (IQR 10-50 mL). Most patients only developed mild symptoms such as nausea, vomiting, headache and diarrhoea. One patient developed respiratory failure needing mechanical ventilation while another was admitted to intensive care due to prolonged sedation. There were no deaths. Median admission imidacloprid concentration was 10.58 ng/L; IQR: 3.84-15.58 ng/L, Range: 0.02-51.25 ng/L. Changes in the concentration of imidacloprid in serial blood samples were consistent with prolonged absorption and/or saturable elimination. CONCLUSIONS: Imidacloprid generally demonstrates low human lethality even in large ingestions. Respiratory failure and reduced level of consciousness were the most serious complications, but these were uncommon. Substitution of imidacloprid for organophosphorus compounds in areas where the incidence of self-poisoning is high may help reduce deaths from self-poisoning.Item Population pharmacokinetics of an Indian F(ab')2 snake antivenom in patients with Russell's Viper (Daboia russelii) bites(Public Library of Science, 2015) Isbister, G.K.; Maduwage, K.; Saiao, A.; Buckley, N.A.; Jayamanne, S.F.; Seyed, S.; Mohamed, F.; Chathuranga, U.; Mendes, A.; Abeysinghe, C.; Karunathilake, H.; Gawarammana, I.; Lalloo, D.G.; de Silva, H.J.BACKGROUND: There is limited information on antivenom pharmacokinetics. This study aimed to investigate the pharmacokinetics of an Indian snake antivenom in humans with Russell's viper bites. METHODS/PRINCIPAL FINDINGS: Patient data and serial blood samples were collected from patients with Russell's viper (Daboia russelii) envenoming in Sri Lanka. All patients received Indian F(ab')2 snake antivenom manufactured by VINS Bioproducts Ltd. Antivenom concentrations were measured with sandwich enzyme immunoassays. Timed antivenom concentrations were analysed using MONOLIXvs4.2. One, two and three compartment models with zero order input and first order elimination kinetics were assessed. Models were parameterized with clearance(CL), intercompartmental clearance(Q), central compartment volume(V) and peripheral compartment volume(VP). Between-subject-variability (BSV) on relative bioavailability (F) was included to account for dose variations. Covariates effects (age, sex, weight, antivenom batch, pre-antivenom concentrations) were explored by visual inspection and in model building. There were 75 patients, median age 57 years (40-70y) and 64 (85%) were male. 411 antivenom concentration data points were analysed. A two compartment model with zero order input, linear elimination kinetics and a combined error model best described the data. Inclusion of BSV on F and weight as a covariate on V improved the model. Inclusion of pre-antivenom concentrations or different batches on BSV of F did not. Final model parameter estimates were CL,0.078 Lh-1, V,2.2L, Q,0.178Lh-1 and VP,8.33L. The median half-life of distribution was 4.6h (10-90%iles:2.6-7.1h) and half-life of elimination, 140h (10th-90th percentilesx:95-223h). CONCLUSION: Indian F(ab')2 snake antivenom displayed biexponential disposition pharmacokinetics, with a rapid distribution half-life and more prolonged elimination half-life.Item Community-based cluster randomised trial of safe storage to reduce pesticide self-poisoning in rural Sri Lanka: study protocol(BioMed Central, 2011) Pearson, M.; Konradsen, F.; Gunnell, D.; Dawson, A.H.; Pieris, R.; Weerasinghe, M.; Knipe, D.W.; Jayamanne, S.; Metcalfe, C.; Hawton, K.; Wickremasinghe, A.R.; Atapattu, W.; Bandara, P.; de Silva, D.; Ranasinghe, A.; Mohamed, F.; Buckley, N.A.; Gawarammana, I.; Eddleston, M.A.BACKGROUND: The WHO recognises pesticide poisoning to be the single most important means of suicide globally. Pesticide self-poisoning is a major public health and clinical problem in rural Asia, where it has led to case fatality ratios 20-30 times higher than self-poisoning in the developed world. One approach to reducing access to pesticides is for households to store pesticides in lockable "safe-storage" containers. However, before this approach can be promoted, evidence is required on its effectiveness and safety. METHODS/DESIGN: A community-based cluster randomised controlled trial has been set up in 44,000 households in the North Central Province, Sri Lanka. A census is being performed, collecting baseline demographic data, socio-economic status, pesticide usage, self-harm and alcohol. Participating villages are then randomised and eligible households in the intervention arm given a lockable safe storage container for agrochemicals. The primary outcome will be incidence of pesticide self-poisoning over three years amongst individuals aged 14 years and over. 217,944 person years of follow-up are required in each arm to detect a 33% reduction in pesticide self-poisoning with 80% power at the 5% significance level. Secondary outcomes will include the incidence of all pesticide poisoning and total self-harm. DISCUSSION: This paper describes a large effectiveness study of a community intervention to reduce the burden of intentional poisoning in rural Sri Lanka. The study builds on a strong partnership between provincial health services, local and international researchers, and local communities. We discuss issues in relation to randomisation and contamination, engaging control villages, the intervention, and strategies to improve adherence.