Epidemiology of Cleistanthus collinus (oduvan) poisoning: clinical features and risk factors for mortality

Cleistanthus collinus (local name: oduvan) poisoning is a common suicidal poisoning method used in rural southern India. There are few studies on this issue and they have small sample sizes. This study examines the epidemiology of oduvan poisoning in a large sample, highlighting socio-demographic and clinical profile, complications, and risk factors for mortality. This study is a retrospective case series of 127 oduvan intentionally poisoned patients presenting at a tertiary care teaching hospital between the years 1990-1999. Descriptive statistics, cumulative case fatality rates and time to death from ingestion of poison were calculated. Cox regression adjusting for left truncation was used to investigate the effects of covariates on death. Patients' average (sd) age was 29.1 (10.9), 62% were female, 76% were married and 49% were housewives. The cumulative case fatality rate was 30%. The median time to death after oduvan ingestion was 3 days. Common signs and symptoms included hypokalaemia, vomiting, hyponatraemia, altered sensorium, bradycardia and abnormal ECG. There was a 58% risk reduction (95% CI: 29-75) in death with each 1 mmol/l increase in plasma potassium level. Patient's age was associated with an increased risk of death and the estimated hazard ratio for an increase of 10 years in age was 1.56 (95% CI: 1.18-2.07). Use of boiled oduvan extract was associated with an increased mortality (HR: 2.71, 95% CI: 1.17-6.32) compared to ingesting fresh leaves. Risk factors for oduvan poisoning mortality were hypokalaemia, older age, mode of consumption and an elevated risk for death with presence of chronic disease. When consumed as a boiled extract, oduvan is more lethal. We recommend close monitoring, correction of plasma potassium and appropriate supportive measures.