Medicare patients in areas with the highest levels of ambulatory primary care had lower mortality rates and fewer preventable hospitalizations than did those who lived in areas with less primary care, according to a report in the May 25 issue of JAMA.
But more primary care didn’t always mean more physician head count: The improvements came in areas with the most "primary care physician ambulatory care clinical effort," rather than simply the highest number of primary care physicians.
"Our findings suggest that a higher local workforce of primary care physicians has a generally positive benefit for [patient] populations, but that this association may not simply be the result of having more physicians trained in primary care in the area," said Chiang-Hua Chang, Ph.D., of the Dartmouth Institute for Health Policy and Clinical Practice in Hanover, N.H., and associates (JAMA 2011;305:2096-2105).
Most studies of the issue have found an association between a greater number of primary care physicians per population and better health outcomes, and almost all have based their conclusions on simple head counts of primary care physicians derived from the American Medical Association Masterfile.
However, such counts don’t accurately reflect the number of physicians trained in primary care who actually provide ambulatory primary care in their communities, the investigators noted.
Many physicians designate their specialty as "primary care" in the AMA Masterfile while they practice as hospitalists or physicians in emergency departments. Others are counted as being full-time primary care practitioners when, in fact, they are retired or work only part time. Still others are counted as primary care physicians when their specialty is not actually primary care, when they see no ambulatory patients, or when their patients do not reside in the community being counted as their "per-population" base.
To address those inaccuracies, Dr. Chang and colleagues assessed outcomes in a 20% national sample of fee-for-service Medicare beneficiaries (more than 5 million patients) using two strategies:
– A simple head count of 155,729 physicians listed as family physicians or general internists in the 2007 AMA Masterfile in several designated geographic service areas.
– An estimate of the ambulatory clinical full-time equivalents (FTEs) of primary care physicians derived from office- and clinic-based Medicare claims from the same designated geographic service areas.
As the researchers suspected, the use of a simple head count of primary care physicians yielded a "modest" association between the number of primary caregivers and improved patients outcomes, including lower mortality.
But using the more accurate estimate of FTEs of primary care physicians yielded a much stronger association, the investigators said.
Not only did patients residing in the highest quintile of primary care FTEs have 5% lower mortality rates, but they also had 9% fewer "highly preventable" hospitalizations for disorders such as pneumonia, asthma, hypertension, angina, diabetes, urinary infection, or dehydration.
The costs of care were slightly higher in areas with the highest level of primary care FTEs, but that was likely because the spending for primary physicians’ early detection, prevention, and coordination of care was slightly higher than the costs of acute hospitalization, Dr. Chang and associates said.
"Our study offers the cautionary note that having more physicians trained in primary care practicing in an area, by itself, does not ensure substantially lower mortality, fewer hospitalizations, or lower costs," the investigators noted. "Increasing the training capacity of family medicine and internal medicine may have disappointing [results] if the resulting physicians are primary care in name only."
The study findings also demonstrate that "research and health care planning that relies solely on the AMA Masterfile for primary physician counts will not accurately measure the primary care workforce," they said.
This study was supported in part by the Robert Wood Johnson Foundation and the National Institute on Aging. Dr. Chang’s associates reported ties to numerous health care entities.