"Given the rising costs of health care, policymakers are increasingly interested in identifying the inefficiencies in our health care system," the authors write as background. "The objective of this study was to determine whether the overuse and misuse of health care services in the ambulatory setting has decreased in the past decade."

Minal S. Kale, M.D., with Mt. Sinai School of Medicine, New York, and colleagues conducted an analysis using data from the 1998, 1999, 2008 and 2009 National Ambulatory Medical Care Survey (NAMCS) and the outpatient department component of the National Hospital Ambulatory Medical Care Survey (NHAMCS), both of which are nationally representative surveys conducted annually by the Centers for Disease Control and Prevention's National Center for Health Statistics.

The study sample included 79,083 and 102,980 unweighted visits by adult patients at least 18 years of age in 1998 to 1999, and 2008 to 2009, respectively. Compared with visits made in 1998-1999, visits in 2008-2009 were by slightly older patients (average age 54.2 years vs. 50.9 years), and more patients were insured by Medicare.

The authors found a statistically significant improvement in six of nine underuse quality indicators, including improvement in use of antithrombotic therapy for atrial fibrillation; use of aspirin, β-blockers, and statins in coronary artery disease; use of β-blockers in congestive heart failure; and the use of statins in diabetes mellitus.

The authors also observed improvement in two of 11 overuse quality indicators, which included a statistically significant decrease in cervical cancer screening among women older than 65 years, as well as a reduction in the overuse of antibiotics for asthma exacerbations. However, there was an increase in one overuse indicator, prostate cancer screening in men older than 74 years. The authors observed no changes in the other eight quality indicators during the study period.

"In our examination of ambulatory care in the United States, we found an improvement in most of the underuse measures but limited changes in the delivery of inappropriate care," the authors conclude. "Developing clinical practice guidelines that define when care should not be delivered and performance measures to address inappropriate care are critical steps to advance the mission of increasing the value and efficiency of health care delivery."