The Massachusetts Hospitalization Puzzle

For everyone dealing with the coronavirus, there is both a societal and personal calculation. The societal calculation revolves around the enormous global and national costs of the pandemic – the staggering number of illnesses, hospitalization, and deaths, as well as the economic toll – massive unemployment, shuttered businesses, and food insecurity.

But there is a personal calculation with which most people wrestle. How likely am I or the people close to me to get sick; and if they get sick, how sick will they be? What are the odds that they will be hospitalized, or obviously even worse, how likely are they to die? This calculation clearly is highly dependent on personal circumstance – age, type of work, underlying health conditions, etc. But a starting point for understanding this is the number of people hospitalized from the coronavirus. (Obviously, this is an incomplete measure of severe illness, as many ill people in long-term care are never hospitalized regardless of how severely ill they become). And here, the available information in Massachusetts is confusing.

The Commonwealth has published a running total of the number of confirmed and suspected Covid-19 cases, total hospitalizations, and total deaths through time. (According to the Dashboard, this information comes from the Bureau of Infectious Disease and Laboratory Sciences). However, when the state changed the definition of probable cases earlier this month, they restated the cumulative number of hospitalizations without providing the details of the historical revisions – unlike what they did for cases and deaths. The number of confirmed and suspected hospitalizations dropped from 13,386 on September 1 to 13,295 the next day.

Fortunately, there is another source of hospitalization data – that provided by hospitals themselves and submitted to the state Department of Public Heath and federal government. Hospitals report both the number of patients currently hospitalized for Covid, and the number of new hospitalizations. Unfortunately, these data on new hospitalizations do not track the data collected by the state – in fact, the number of new probable case hospitalizations reported don’t make much sense if taken at face value.

For the week ending September 3, hospitals in Massachusetts reported an average of 312 patients hospitalized with Covid, an average of 19 new confirmed case admissions, and an average of 126 suspected case admissions, for a total of 145 new admissions. These statistics do not square with what we know about the hospital stays of Covid patients. Since the only way patients leave the hospital is if they are discharged or die, this would imply an average hospital stay of roughly two days, much shorter than what one would expect.

It is unclear exactly what these suspected hospital admissions are tracking, but the definition seems overly broad. According to the dashboard, these suspected cases “are those with symptoms who have not had a test result yet”. Perhaps many of these originally suspected cases turn out to not be Covid patients at all, or there is something else not transparent about this reporting.

However, the number of confirmed hospital admissions does closely track the number of newly hospitalized cases reported by the state up to the point at which the probable case definition was changed, as shown below. Both figures also reinforce the idea that the state has been in rough equilibrium for about the past five or six weeks (this is true for cases, hospitalizations, and deaths), with relatively low case and hospitalization rates.


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