Although overcrowding in the prisons is a longstanding problem, inadequacy of health care really has not been scientifically established in spite of the court rulings.
There is a certain death rate in any population, and studies were never shown that proved that the death rate among inmates exceeded that of a similar-sized population. Inmates in general also are not a healthy group, and they tend to have chronic illnesses such as liver disease and AIDS, not found in the general population. So, these controls would need to be put into place to make a true judgment about the adequacy of health care.
As a former prison physician, I can say that there certainly were deficiencies. However, the care afforded to inmates, even at its worst, always greatly exceeded that available to indigent people without insurance.