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Deaths associated with ivermectin for scabies

1997; Elsevier BV; Volume: 350; Issue: 9072 Linguagem: Inglês

10.1016/s0140-6736(05)62378-1

1474-547X

Philip E. Coyne, David G. Addiss,

Health Systems, Economic Evaluations, Quality of Life

In selecting controls Robert Barkwell and Susanne Shields1Barkwell R Shields S Deaths associated with ivermectin treatment of scabies.Lancet. 1997; 349: 1144-1145Summary Full Text Full Text PDF PubMed Scopus (158) Google Scholar matched for age and sex, but not for concomitant illnesses. Although they state that the residents of the Special Care Unit were "younger… and physically healthier than residents in the rest of the Lodge", the 15 who died had an average age of 84 (range 77–90) years and various chronic illnesses. The 15 deaths occurred 17–177 days after treatment. Neither the variable interval after treatment nor the reported causes of death would seem consistent with ivermectin being a contributing factor. Furthermore, all of the residents of the special care unit had previously been treated with other anti-scabies drugs, including lindane and crotamiton, which makes it difficult, if not impossible, to separate alleged effects of ivermectin from those of other drugs. Finally, although Barkwell admittedly had the benefit of direct clinical observation, the adverse event reports provided to the US Food and Drug Administration (FDA) suggest that the health of several of these patients had begun to decline well before administration of ivermectin. We used the data shown by Barkwell and Shields and assumed a 100% bed occupancy to calculate rates of death in Wentworth Lodge residents: Tabled 1Area of facilityDeaths per bed per month of observationNov, 1992, to Nov, 1995Nov, 1995 to May, 1996Special care (47 beds)0·01650·0456All other units (163 beds)0·02450·0087Total (210 beds)0·02270·0170 Open table in a new tab Death rates were 33% lower for special care unit residents during the 3 years before Nov 1, 1995. After that date the higher death rate among all other unit residents dropped to about one-third of its previous level; overall, the facility-wide death rate declined slightly. Was there a change in admission criteria, so that patients with more chronic illnesses were shifted from other units into the special care unit? Within 24 hours of being notified by local authorities of the event at Wentworth Lodge, the manufacturer of ivermectin alerted the FDA. This event was given immediate and careful scrutiny. An extensive review of adverse event reports and other documents provided no evidence of a causal association between ivermectin and increased risk of death, despite the apparent temporal association reported by Barkwell and Shields. In view of its record of safety and efficacy, the FDA approved ivermectin for treatment of onchocerciasis and strongyloidiasis on Nov 22, 1996 (the New Drug Application did not include scabies as an indication for treatment). Neither the considerable experience with this drug for onchocerciasis nor the data presented by Barkwell and Shields support the conclusion that an association exists betwen ivermectin administration and increased risk of death at Wentworth Lodge. We would nonetheless agree that continued pharmacovigilance is warranted. Deaths associated with ivermectin for scabiesAuthors' reply Full-Text PDF