Chloroquine poisoning in Zimbabwe: a toxicoepidemiological study

Chloroquine is commonly implicated in pharmaceutical poisonings in Zimbabwe. A retrospective hospital record review was performed to describe the epidemiology of chloroquine poisoning compared with that of other medicines. All records of admissions to eight referral hospitals in Zimbabwe due to poisoning with single pharmaceutical agents were collated and separated into those involving either chloroquine or other medicines. Case characteristics were compared and a retrospective cohort study performed to investigate the association of pregnancy with chloroquine overdose. Of 544 cases, antimalarials accounted for the largest proportion of admissions (53.1%), with chloroquine accounting for 96.2% (279 cases) of these. The latter were compared with the remaining 265 cases. The median length of hospital stay for the chloroquine group was significantly lower (1 vs 2 days; P = 0.001) and a greater proportion of patients took chloroquine deliberately (80.3% vs 68.7%; P < 0.05). The mortality rate due to chloroquine poisoning was significantly higher than that of poisoning due to other drugs (5.7% vs 0.7%; P < 0.0001). There was no significant gender bias in mortality. Women of childbearing age admitted with chloroquine poisoning (188 cases) were twice as likely to be found pregnant (relative risk = 2.3, 95% CI = 1.2-4.5) than similar women admitted due to other medicines (157 cases). In conclusion, chloroquine is the most common cause of pharmaceutical poisoning admission at referral hospitals in Zimbabwe. It is normally taken deliberately with significant mortality. In women of childbearing age admitted with chloroquine poisoning, pregnancy should be suspected.