Author Affiliations: Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, Mass.
Health care quality improvement experts often argue that "you can't
manage what you can't measure." Suitable yardsticks are essential to judge
the magnitude of potential quality problems and track whether interventions
improve care. However, this aphorism needs one critical addendum: "You can't
measure what you can't define."
Measurement and definitional issues loom large when discussing patient
safety. The bellwether 1999 Institute of Medicine report To Err Is Human provided compelling evidence that medical errors pose
daily risks throughout the US health care system but failed to quash controversy
about the magnitude of that risk.1 The best-known
estimates of the extent of medical error rely on extrapolations from medical
record review studies,2,3 although
these numbers have generated heated debate.4- 6
Weingart SN, Iezzoni LI. Looking for Medical Injuries Where the Light Is Bright. JAMA. 2003;290(14):1917-1919. doi:10.1001/jama.290.14.1917