News: A rare large scale study from ICMR is making news even in the mainstream media. (https://indianexpress.com/article/health-wellness/covid-19-vaccines-sudden-deaths-risk-icmr-study-9036761/)
A casual read of the original paper threw up some thoughts.
India’s apex medical body, ICMR, initiated a study primarily on sudden deaths among young people in covid times . The primary intention of this study was to find what causes sudden unexplained deaths . and also test the hypothesis that the deaths were not probably related to covid vaccination. The study did prove that. (I am not an expert to assess the statistical validity and scrutiny of the study. It is too complex a model. Still, I do have a primitive query as shown in the title )
But, we expected a minimum revelation. What caused these 729 deaths (filtered out of 29000 deaths) I understand physical autopsy could not be done in majority of deaths (Even in witnessed , in hospital deaths). So, the question remains . Is it sudden cardiac death ? Is it sudden “non cardiac ” death ? or can it be a “non sudden” masquerading as sudden in any way.
.A preformed hypothesis
Though this is not a hypothesis-proving study, it is apparent that the intention of the study primarily revolves around removing the stigma and fear associated with vaccination. (The fact that only a fraction of patients, (less than 2%,) were hospitalized for COVID indicates that this study primarily intended to test the risk of COVID vaccination, which was around 85% in both groups.) It makes sense, for the study group , they created a good methodology accordingly and indirectly proved the hypothesis right. As physicians and cardiologists, we wished also look into the data of what caused these deaths by performing autopsies in all possible cases. The results of these autopsies need to be known.
Conclusion is fair
It is traditional (and acceptable ) to blame the heart for all unexplained sudden deaths. The study suggests that heavy drinking, along with with intense physical activity in the background of positive family history, is behind many of the deaths. It is a fair assumption that they are all cardiac. Sudden neurological and pulmonary deaths are under reported. In fact many of the SCD is an arrhythmic event originating from CNS or electro-ionic triggers in blood with the healthy heart
Is this not a major limitation*
When you want to know whether COVID vaccination is related to sudden death in any way ,is not ideal, we need to have a control /cohort arm who have had no vaccination? In this study, both groups had nearly 82-88 % vaccination. In fact, the control group had few percent extra vaccination, and this helped the study, to claim that vaccination prevented some of the sudden deaths. This seems far-fetched with any statistical methodology. This, I feel is a serious limitation. It can even nullify the study conclusion to a large extent. (Experts please clarify , It may be an entirely wrong perception and lack basic knowledge in statistics.)
One more possiblity , can we combine a case-control study with add on accessory cohort and follow up as a dual mode study ?
Final message
It is a landmark attempt to study the mysterious deaths among young Indians in covid & post covid times. Two things .This study can talk about only vaccinated population. Does this study prove, people who have not vaccinated had more or less sudden deaths ? No. this study has no scientific grounds to talk about either positive or negative status of unvaccinated population , because there is no, unvaccinated cohort and follow-up.
At the end of the day, an unexplained death remains unexplained because we couldn’t do autopsy (Of course we have found the same known risk factors responsible , except probably new one vigorous physical activity , )
Dr.S.Venkatesan MD 