Lipid therapy in oral poisoning: a not-so-systematic review
December 27, 2016, 4:12 pm
No support for lipid rescue in oral poisoning: A systematic review and analysis of 160 published cases. Forsberg M et al. Hum Exp Toxicol 2016 Nov 24 [Epub ahead of print]
The authors’ goal was “to present a systematic review and case analysis of practically all published reports on humans treated with lipid rescue for LAST [local anesthetic systemic toxicity] or oral poisoning.”
The focus of the paper is on oral poisonings. The authors report that they identified 94 reported cases of oral poisoning with “alleged” positive response to lipid rescue therapy (LRT.) Two authors reviewed each case and rated causality (that is, LRT -> positive response) using a modified WHO-UMC scale. (As the authors note, the WHO-UMC scale was actually designed to determine causality in adverse drug reactions, not antidote response.) If the two authors disagreed as to the causality score, “consensus was obtained through discussion.”
The authors report that all 94 oral poisonings received scores of 2 (probable causality,) 3 (possible causality,) and 4 (unlikely causality.) in fact, 86% received a score of 3 or 4. They note that 91% of these cases received other treatment modalities at approximately the same time they received LRT.
The authors conclude:
“Considering the findings of the present study, the weak and contradictory scientific evidence for lipid rescue being an effective antidote and its increasingly reported adverse effects, it is reasonable to strictly limit its use in clinical practice. We would not recommend its use at all in cases of oral poisoning.”
There are several significant problems with this conclusion:
- Because of the nature of case reports, it is most often impossible to determine causality, especially using a scale that was not designed for this purpose. There are few methods describe as to how the authors assigned a score to each case. One could go back to original cases and make one’s own conclusions, but the reference list has only 22 citations and does not include all or most of the relevant papers. The paper says this information is contained in online appendices at http://het.sagepub.com/supplemental, but my efforts to reach that material through the link came back with either a blank page or an error message. This is really inexcusable. While it’s true that this paper was posted online before it appears in print, it should not in my opinion have been posted until the crucial supplemental material was available.
- It is completely unclear how the “discussions” of disputed cases were handled. Was one author more pessimistic and more persuasive than the other?
- Of course many of these patients received multiple, nearly simultaneous, treatment modalities. This certainly would make determining causality more uncertain, but not to the extent of concluding that LRT should not be used at all in oral poisoning.
I would add that the Cochrane Review states that a systematic review “summarizes the results of available carefully designed healthcare studies (controlled trials) and provides a high level of evidence on the effectiveness of healthcare interventions.” Case reports are not “carefully designed healthcare studies.” This is no systematic review, and this paper totally misappropriates the term.