[Mortality and factors associated with phosphide poisoning: prospective cohort study]

Abstract

Background: Aluminum and zinc phosphides are solid fumigants for pest control. Metal phosphide poisoning (PP) is common in suicide and suicide attempts. In Mexico, zinc phosphide is easily available, and is a common agent in poisonings.

Objective: To identify mortality in PP, and associated factors in a poison control center.

Material and methods: Prospective cohort study. The starting point was the exposure (PP) and it was made a follow-up on the outcome (mortality and non-mortality). Main factors associated to PP outcome were assessed (e.g.: personal and clinical factors, duration of poisoning, detoxification, and radiographic evidence of poisoning). It was used relative risk (RR) as a risk estimator with 95% CI, as well as chi-squared with Fisher’s exact test, Kaplan-Meier survival curves, and Log- Rank test as a comparative mean.

Results: 44 exposed patients, and 88 non-exposed were followed up. Mortality rate in PP was of 16% in acute phase patients; there were no deaths in either subacute or chronic phases. Mortality risk was 14 (95% CI, 2 110). Main factors associated with increased mortality were: time of first medical assistance > 6 hours, RR = 15 (95% CI, 1.7-128); dose of poison ≥ 1 bottle or 1 tablet, RR = 14 (95% CI, 1.8-108); radiographic evidence of poisoning, RR = 10 (95% CI, 1.3 77).

Conclusion: Metal PP has a high mortality rate and is associated to long periods of exposure to the toxic chemical due to ineffective detoxification.

Keywords: Zinc Compounds; Aluminum Compounds; Aluminum and Zinc Phosphide; Mortality; Radiographic Evidence.