GE Healthcare offers this calculator, based on data from the Society of Actuaries, to show the cost of medical errors for a given population. I inserted the population of Massachusetts from the most recent US Census to see what would pop up. Here is the result.
I suspect this figure of $260+ million is actually an underestimate because there is a lot of preventable harm that does not get counted as such. For example, we reduced our rate of ventilator associated pneumonia at BIDMC considerably over the last three years by rigorous application of the VAP bundle. Likewise at Cooley Dickinson Hospital in Northhampton, MA.
As best as I can tell, VAP is not included in the statistics above. Chances are those cases previously would not have been counted as medical errors. They were just part of the mentality of "these things happen," a belief by many that the current level of harm caused by hospitals is a statistically irreducible number.
Notice that I say "caused by hospitals," and not "occurring in hospitals." Until we take ownership of the fact that a great degree of harm that occurs in hospitals is caused by failures in the manner of delivering care, we will not make progress.