Population aging and the use of office-based physician services.

KEY FINDINGS From 1998 to 2008, the proportion of physician office-based visits in the United States became increasingly concentrated on those aged 45 and over. The intensity of physician office visits, as measured by medications prescribed or continued, imaging tests ordered or provided, and time spent with physicians, also became increasingly concentrated on those aged 45 and over. Although most physicians accept Medicare patients, acceptance of Medicare was higher among ophthalmologists and general surgeons than among general or family practitioners, internists, and psychiatrists. Over the past 30 years, the specialty concentration of visits has shifted significantly. In 1978, 62 percent of visits by patients aged 65 and over were to primary care physicians compared with 45 percent in 2008. The percentage of visits to physicians with a medical or surgical specialty increased from 37 percent to 55 percent.