To the Editor: Cases of unnecessary disease or disability and unnecessary untimely deaths are sentinel health events that, like maternal and infant mortality, can serve as negative indexes of the quality of medical care. In an earlier article on measuring the quality of medical care,* 91 conditions (ICDA 8) were identified in Tables A (single case indexes) and B (indexes based on rates) as measures of the quality of medical care in individual hospitals or other medical-care units or as measures of health status in national or local areas. The tables of sentinel health events were brought up to . . .