So 1 baby dies and because myocarditis is rare and they assume "cannabis exposure" is rare that they are probably linked? This seems pretty far from anything like science.
They report this possible case. Maybe there is never another association and the issue is forgotten, because there is no causal link. But maybe, someone else, some place else, who never read this paper, notices something similar and reports it. And maybe this happens several more times. And then, along the way, one of these reporters does a detailed search and finds the other reports. He collects the cases and maybe contacts the doctors who wrote the reports and writes what we call a Case-Series on these.
Maybe a couple case-series get written independently in various places. Someone finds these series and convinces someone else to fund a Case Control study.
Usually with environmental exposure literature this is exactly how "science" happens. Medicine is messy and serendipity is more than involved.
Hierarchy of evidence: http://ebm.bmj.com/content/early/2016/06/23/ebmed-2016-11040...
Their argument is “Specifc myocardial complications related to cannabis toxicity that are well documented in adolescence through older adulthood include acute coronary syndrome, cardiomyopathy, myocarditis, pericarditis, dysrhythmias and cardiac arrest.2-4 To date, there are no reported pediatric deaths from myocarditis after confrmed, recent cannabis exposure“, therefore “this pediatric patient with death due to myocarditis may have died because cannabis exposure caused that myocarditis.”
And yes, if you get a highly anomalous event, it’s not at all unreasonable to point out that it immediately followed a highly anomalous input. If you’re looking for causality, x -> rare Y Is more likely if x is rare than if it isn’t. It inherently explains why Y is rare.
> The progressive clinical presentation of this patient during the prior 24-48 hours, including symptoms of somnolence, lethargy, irritability, nausea, seizure and respiratory depression are consistent with previously documented, known complications of recent cannabis exposure in the pediatric population.
Their source is here: https://alanflashman.files.wordpress.com/2014/02/piis0196064...
Those symptoms are consistent with exposure - it's too bad the case report didn't include any data from the parents (maybe I missed that).