Last week, a paper was published in the Lancet that drew some alarming conclusions about the number of complications associated with COVID-19 hospital patients, generating a predictable number of alarming headlines. However, our in-house doctor has cast his eye over it and has spotted a number of flaws. Here is an extract:
My main criticism of this paper lies in the conclusions drawn from the data. The majority of the discussion section concentrates on the incidence of complications from acute Covid in hospitalised younger patients – defined as under 50 years of age. Yet only 12.6% of the sample size were under 50 years of age. Very little discussion is made of the other 87.4% of patients in the older age groups, who actually had the worst outcomes.
Major emphasis is laid on the incidence of renal complications seen in the younger subgroup and what implications that might have for the future health of the patients. Inference is drawn that such acute kidney injury may lead to higher risks of subsequent renal failure and heart disease in later life.
Yet the authors extrapolate those conclusions based on citations of other papers which do not reflect the subgroup of younger patients referred to in their own figures. In my view it is not reasonable to compare a group of patients under 50 experiencing transient acute kidney injury in the context of another acute disease with a cohort of much older patients having AKI after recent heart attacks (as in one of their citations). Equating the long-term outcomes from these two distinct groups is likely to be a flawed assumption.
I note with interest that the incidence of acute kidney injury as a proportion of overall complications in each age group decile up to the over 90s was remarkably consistent at between 32% and 35%. No distinction was made in the analysis between people requiring renal replacement with dialysis or filtration and those experiencing transient biochemical renal dysfunction that was correctable with intravenous fluid replacement and other simple interventions. This observation supports my suspicion that the parameters of ‘renal injury’ have been set too wide to distinguish between mild dysfunction of no long-term consequence and serious renal damage.
Worth reading in full.