Physician extenders like nurse practitioners and physician assistants originally had fairly constrained scope of practice. Access, cost and even quality considerations have led to greater independence from physician oversight. Assuming even equal quality, these non-physician but independently practicing providers are generally much cheaper on a unit cost basis and therefore can help control spending growth. A study published in the Journal of Health Economics analyzes the link between nurse practitioner independence and certain outcomes. (JHE Article) Nurse practitioners probably represent over 20% of primary care providers at this point. But the services which these nurse practitioners actually deliver is governed by state scope of practice laws, which vary widely (which in itself is stupid, there is no reason not to have a national standard). The authors sought to see if these variations in state law could be tied to differences in utilization and cost outcomes. They used MEPS data and looked over a long-period of time before and after changes allowing greater nurse practitioner independence. Allowing nurse practitioners more independence can have beneficial capacity impacts on both doctors and the NPs, as they spend less time on supervision or being supervised.
The general findings were that in states with more independent scope of practice there was greater use of primary care, specifically more likelihood of an annual preventive checkup. Patients also had higher self-reported satisfaction, apparently partly due to longer visits and a perception of greater responsiveness. There was a reduction in ER use for conditions that are ambulatory care sensitive. The effects appear to widespread across the population without respect to geographic area, sex, age or other factors. There was some suggestion that areas which were underserved with respect to primary care resources had a greater improvement. This isn’t necessarily the strongest design, or the best data sources, but it seems intuitively accurate to me. It is just another bad effect of our political system that nurse practitioners have their scope of practice limited in many states. Greater use would not compromise quality and like would reduce overall spending.