Vari M Drennan et al. has produced a research briefing of the evidence thus far collected regarding physician associates working in England. This briefing can be used as an aid to help those seeking answers as to if these new practitioners are safe, effective, efficient and acceptable. Here we have collected extracts from a few of the abstracts of the studies included in this briefing. Please see the briefing for a full breakdown of the evidence. This can be found at here.
In 2011 Vari Drennan et al  performed a qualitative study of the view points of employers of physician assistants (now known as physician associates) with the study concluding that..
“General practice employers view PAs as a positive addition to a mixed skill team for meeting patient demand within a practice's finances. There is a need to develop stronger governance and regulatory frameworks for this emerging profession.” 
In 2014 Vari Drennan et al.  used a mixed methods study to investigate the contribution physician assistants (now known as physician associates) provide to primary care. In this study physician associates were found to be...
"...acceptable, effective and efficient in complementing the work of GPs. PAs can provide a flexible addition to the primary care workforce.” 
In 2015 Vari Drennan et al.  studied the comparisons between physician associates and general practitioners which concluded...
"The processes and outcomes of PA and GP consultations for same-day appointment patients are similar at a lower consultation cost. PAs offer a potentially acceptable and efficient addition to the general practice workforce.” 
This was followed by a comparative video observations study  in 2016 which concluded that physician associates were...
"...judged as competent and safe, although general practitioner consultations, unsurprisingly, were rated as more competent. Physician associates offer a complementary addition to the medical workforce in general practice.”