Use of locum tenens specialists has accelerated, according to a survey by physician staffing firm Staff Care, a division of AMN Healthcare Services Inc. (NYSE: AMN).

One example: The survey found that 21% of healthcare facilities reported using locum tenens surgeons in 2019, up from 11% in 2016.

Other examples include locum tenens internal medicine subspecialists and anesthesiologists. Use of internal medicine subspecialists rose to 17% of healthcare facilities in 2019, up from 9% in 2016. Looking at locum tenens anesthesiologists, 22% reported using them, up from 11% in 2016.

The need for specialists is being driven by an aging population and by an aging physician workforce, according to Staff Care.

Primary care doctors are the most in-demand locum tenens doctors, the survey said. However, their use fell to 30% of healthcare facilities in 2019 from 44% in 2016, the last time Staff Care conducted this survey.

Overall, 85% of hospitals, medical groups and other healthcare facilities used locum tenens doctors in 2019. About 52,000 physicians worked as a locum tenens in 2019, about 6% of the active physician workforce.