Trend data on medical encounters: tracking a moving target.

The National Health Care Survey (NHCS), conducted by the National Center for Health Statistics, consists of separate data collection activities that can be used to track the number and content of health care encounters in the United States. Tracking even something as simple as the number of encounters, however, is complicated by the fact that the content of these encounters changes over time. Results from the NHCS indicate that the U.S. population has been receiving more drugs, more cardiac procedures, more ambulatory surgery, more therapies in nursing homes, and more home health care over time. Policymakers and researchers who examine health care trends should be wary about judging whether the number of length of encounters is positive or negative without also examining the content of these encounters.