A physician assistant in the United States, Canada and other select countries or physician associate in the United Kingdom (PA) is an Advanced Practice Provider (APP). PAs are medical professionals who diagnose illness, develop and manage treatment plans, prescribe medications, and often serve as a patient's principal healthcare provider. With thousands of hours of medical training, PAs are versatile and collaborative. PAs practice in every state and in every medical setting and specialty, improving healthcare access and quality. 
In the United States and Canada physician assistants are nationally certified by their respective certifying body. Physician assistants complete their qualifications for certification in less time than a traditional medical degree by following an educational model based on the fast-tracked training of physicians during the shortage of providers during World War II. 
The occupational title of physician assistant and physician associate originated in the United States in 1967 at Duke University in North Carolina.
Physician assistants or physician associates may:
Physician assistants train to work in settings such as hospitals, clinics and other types of health facilities or virtually via telemedicine services. Physician assistants are commonly found working in academics, teaching and research as well as hospital administration and other clinical environments. Physician assistants may practice in primary care or medical specialties, including emergency medicine, surgery, cardiology, etc. Extensive clinical training precedes obtaining a certification to practice as a physician assistant. Physician assistant education is similar to physician training but shorter in duration. Renewal of certification is usually necessary every few years, varying by jurisdiction. Physician assistants may also complete residency training, similar to physicians' residencies but most are generally shorter, in fields such as: OB/GYN, emergency medicine, critical care, orthopaedics, neurology, surgery, and other medical disciplines.
A compelling 2015 Netherland study of PAs in four different models of care examined tasks performed and showed that direct and indirect patient care on a hospital ward does differ. The researchers determined that PAs in PA-only models spend more time on direct patient care and had the highest provider continuity. Another Dutch cross-sectional study on general skill levels showed that PA students and physicians score about equal on history-taking, physical examinations, and communication. 
In 1961, Charles Hudson recommended to the American Medical Association, the creation of new medical providers. Eugene A. Stead of the Duke University Medical Center in North Carolina assembled the first class of physician assistants in 1965, composed of four former US Navy Hospital Corpsmen. He based the curriculum of the PA program on his first-hand knowledge of the fast-track training of medical doctors during World War II. Two other physicians, Richard Smith at the University of Washington in Seattle, and Hu Myers at Alderson-Broaddus College in Philippi, West Virginia, also launched their own programs in the mid and late 1960s. And Dr. J. Willis Hurst started the Emory University Physician Assistant Program in 1967.
Beginning in January 1971, the US Army produced eight classes of physician assistants, at 30 students per class, through the Academy of Health Sciences, Brooke Medical Center, Fort Sam Houston, Texas (academically accredited by Baylor University, Texas).
In 2017, approximately 68% of physician assistants in the United States identified as women and approximately 32% identified as male. 
The profession has expanded globally. It can now be found in Afghanistan, Australia, Canada, Germany, Ghana, India, Israel, Liberia, the Netherlands, New Zealand, Saudi Arabia, and the United Kingdom. Many countries do not use the term but do have people that are employed to do similar types of work, such as clinical officers in Africa, clinical associates in South Africa,assistant medical officers in Malaysia, assistant doctors in China,Health extension officers in Papua New Guinea, and feldshers in countries formerly comprising the Soviet Union. As a profession physician assistants have greatly influenced the theory and conceptualization of socially accountable health professional education.
The position of physician associate was established in the United Kingdom in 2005. It evolved from that of physician assistant, developed in the US in the 1960s. In 2012, the profession voted to change the name to physician associate to distinguish it from another with the same name within the NHS. Hillingdon Hospitals NHS Foundation Trust was asked to manage the recruitment of 200 physician associates who are expected to come from the US for 40 NHS trusts in September 2015.
The Faculty of Physician Associates is the professional body for Physician Associates working in the United Kingdom. A joint venture between the Royal College of Physicians of London and the previous professional body, the United Kingdom Associate of Physician Associates, the Faculty officially launched in July 2015, taking over all professional body rights from then on. The Faculty oversee the managed voluntary register, to which all practising associates are encouraged to become a member of, as well as setting and running the National Assessment Examination and National Recertification Examination.
Physician Associates/Assistants are trained under the medical model, similarly to physicians, to deliver medical care in both primary and secondary care settings. Upon graduation, they can specialize in many different areas of medicine, including acute medicine, primary care, emergency medicine, surgery, and psychiatry. The role has developed to provide medical services similar to those provided by house officers or senior house officers. They are trained to perform a variety of tasks including diagnosis, treatment, complex medical procedures and taking medical histories.
The title of physician associate is not a protected medical profession. Hence, even if a PA has been trained in pharmacology and IRMER (ability to request radiology imaging - X-rays), they are not able to prescribe or request imaging. At present, there is no regulatory body for PAs, such as the General Medical Council for doctors. Since June 2010, physician associates have been able to obtain membership of the Managed Voluntary Register for physician associates. This database, run by PAs for PAs, aims to identify all qualified PAs who are able to practise in the United Kingdom. It is intended to maintain high standards in the UK. To remain on the register, physician associates in the United Kingdom are required to re-certify every 5-6 years and maintain up-to-date practice through attendance of training accumulating CPD hours (continuous professional development), which need to be completed on an annual basis.
In 2018 Matt Hancock announced the plan for the regulation of associates, details of which are currently being discussed by the government, the relevant options for the regulatory body, Health Education England and the Faculty of Physician Associates.
Training in the UK is through a two-year accelerated medical training (MSc or Postgraduate Diploma) in Physician Associate Studies. As of 2017there are at least 32 universities offering these programs:
Barts and the London School of Medicine and Dentistry, Queen Mary University of London requires candidates to hold a minimum of 2:2 or above in a Life Science, Biomedical Science, or Healthcare subject. Due to the competitive nature of this course, a ranking system will be used to shortlist for interview.
Aberdeen requires a science-based degree with a minimum 2:1 grade achieved and St George's requires a science-based degree with a minimum 2:2 grade achieved. This includes sport science, biology, psychology and biomedical degrees. Applicants should preferably have experience in the healthcare industry. Applications from other professionals such as nurses, radiographers and paramedics will also be considered.
University of Bradford requires a 2:1 (or above) undergraduate degree in a Life Science, Biomedical Science, or Healthcare subject. Under exceptional circumstances, extensive experience in healthcare practice may contribute and compensate if the above requirements have not been fully met.
The average starting salary of a Physician Associate (PA-R) in the United Kingdom is Band 7 (£37,000), and can vary based on locations. In London, the average salary is around £43,000 and goes up to 50k with experience, particularly with lead PAs. PAs are also able to do locum shifts on top of their full-time job. Compensation of physician associates in the United Kingdom remains lower in comparison to the United States and Canada. However, compensation of physician associates in the United Kingdom is on the same pay band as other advanced care providers such as nurse practitioners.
In the United States, the profession is represented by the American Academy of Physician Assistants, and all PAs must graduate from a nationally accredited ARC-PA program as well as passing the national certification exam. It was not until 1970 that the AMA passed a resolution to develop educational guidelines and certification procedures for PAs. The Duke University Medical Center Archives had established the Physician Assistant History Center, dedicated to the study, preservation, and presentation of the history of the profession. The PA History Center became its own institution in 2011, was renamed the PA History Society, and is now located in Johns Creek, Georgia.
As of May 2019 Most educational programs are graduate programs leading to the award of master's degrees in either Physician Assistant Studies, Health Science (Master of Health Science), or Medical Science (MMSc), and require a bachelor's degree and Graduate Record Examination or Medical College Admission Test scores for entry. The majority of PA programs in the United States utilize the CASPA application for selecting students. Professional licensure is regulated by the medical boards of the individual states. Physician assistant students train at medical schools and academic medical centers across the country., there were 243 accredited PA programs in the United States, and dozens more in development, represented by the Physician Assistant Education Association.
Physician assistant education is based on medical education although unlike medical school which lasts four years plus a specialty-specific residency, PA training is usually 2 to 3 years of full-time graduate study like most master's degrees. The training of PA education consists of classroom and laboratory instruction in medical and behavioral sciences, such as anatomy, microbiology, immunology, pharmacology, pathophysiology, hematology, pathology, genetics, clinical medicine, and physical diagnosis, followed by clinical rotations in internal medicine, family medicine, surgery, pediatrics, obstetrics and gynecology, emergency medicine, and geriatric medicine, as well as elective rotations. Unlike physicians, who must complete a minimum of three years of residency after completion of medical school, PAs are not required to complete such residencies after they complete their schooling. There are residency programs in certain specialties for PAs who choose to continue formal education in such a format.
PA clinical postgraduate programs are clinical training programs which differ from training on the job in their inclusion of education and supervised clinical experience to meet learning objectives which are clearly defined. The Montefiore Medical Center Postgraduate Surgical Physician Assistant Program was established in 1971 as the first clinical postgraduate PA program to be recognized. Currently, there are known to be 49 programs in various specialties such as Neurology, Trauma/Critical Care and Oncology. The Association of Postgraduate Physician Assistant Programs was formed in 1988 as an instrument in the establishment of educational standards for postgraduate PA programs and currently includes 50 member programs.
A physician assistant may use the post-nominal initials "PA", "PA-C", "APA-C", "RPA" or "RPA-C", where the "-C" indicates "Certified" and the "R" indicates "Registered". The "R" designation is unique to a few states, mainly in the Northeast. APA stands for aeromedical physician assistant and indicates that a physician assistant successfully completed the US Army Flight Surgeon Primary Course. During training, PA students are designated PA-S. The use of "PA-C" is limited only to those PAs currently certified and in compliance with the regulations of the national certifying organization, the National Commission on Certification of Physician Assistants and who have passed the PANCE.
In the United States, a graduate from an accredited PA program must pass the NCCPA-administered Physician Assistant National Certifying Exam (PANCE) before becoming a PA-C; this certification is required for licensure in all states. The content of the exam is covered in the PANCE BLUEPRINT. In addition, a PA must log 100 Continuing Medical Education hours and reregister his or her certificate with the NCCPA every two years. Every ten years (formerly six years), a PA must also recertify by successfully completing the Physician Assistant National Recertifying Exam (PANRE) There is a growing number of doctoral programs for certified PAs leading to a Doctor of Medical Science (DMSc) but there is no requirement for one to have a doctorate in order to practice. "National Physician Assistant Week" is celebrated annually in the US from October 6 through October 12. This week was chosen to commemorate the anniversary of the first graduating physician assistant class at Duke University on October 6, 1967. October 6 is also the birthday of the profession's founder, Eugene A. Stead, Jr., MD.
Physician assistants have their own licenses with distinct scope of practice. Each of the 50 states has different laws regarding the prescription of medications by PAs and the licensing authority granted to each category within that particular state through the Drug Enforcement Administration (DEA). PAs although trained to prescribe, in Kentucky, Puerto Rico and the US Virgin Islands are not allowed to prescribe any controlled substances. Several other states place a limit on the type of controlled substance or the quantity that can be prescribed, dispensed, or administered by a PA. Depending upon the specific laws of any given state board of medicine, the PA must have a formal relationship on file with a collaborative physician. The collaborating physician must also be licensed in the state in which the PA is working, although he or she may physically be located elsewhere. Physician collaboration can be in person, by telecommunication systems or by other reliable means (for example, availability for consultation). In emergency departments the laws governing PA practice differ by state, generally allowing a broad scope of practice and limited direct supervision.
The COVID-19 Pandemic forced local, state & federal governments to relax regulations around scope of practice, in an effort to maximize the healthcare workforce and allow PAs & NPs to better assist in the crisis. New bills are being passed as a result, which pave the way for physician assistant independence:
The first employer of PAs was the then-Veterans Administration, known today as the Department of Veterans Affairs. Today it is the largest single employer of PAs, employing nearly 2,000.
According to the AAPA, there are more than 108,500 certified PAs in the United States as of 2016.
In the 2008 AAPA census, 56 percent of responding PAs worked in physicians' offices or clinics and 24 percent were employed by hospitals. The remainder were employed in public health clinics, nursing homes, schools, prisons, home health care agencies, and the United States Department of Veterans Affairs Fifteen percent of responding PAs work in counties classified as non-metropolitan by Economic Research Service of the United States Department of Agriculture; approximately 17% of the US population resides in these counties.
The US Department of Labor Bureau of Labor Statistics report on PAs states, "... Employment of physician assistants is projected to grow 37 percent from 2016 to 2026, much faster than the average for all occupations ..." This is due to several factors, including an expanding health care industry, an aging baby-boomer population, concerns for cost containment, and newly implemented restrictions to shorten physician resident work hours.
Money magazine, in conjunction with Salary.com, listed the PA profession as the "fifth best job in America" in May 2006, based both on salary and job prospects, and on an anticipated 10-year job growth of 49.65%. In 2010, CNN Money rated the physician assistant career as the number two best job in America. In 2012, Forbes rated the physician assistant degree as the number one master's degree for jobs. In 2015, Glassdoor rated physician assistant as the number one best job in America. According to Bureau of Labor Statistics, the median pay for physician assistants working full-time was $108,610 per year or $52.22 per hour, and the highest 10 percent earned more than $151,850. Physician assistants in emergency medicine, dermatology, and surgical subspecialties may earn up to $200,000 per year.
PAs are employed by the United States Department of State as foreign service health practitioners. PAs working in this capacity may be deployed anywhere in the world where there is a State Department facility. They provide primary care to US government employees and their families in American embassies and consulates around the world. An important part of their jobs is to get to know what resources are available locally that they can count on in an emergency. They have some other important roles, such as advising their ambassadors on the health situation in the country and provide health education to the diplomatic community. In order to be considered for the position these PAs must be licensed and have at least two years of recent experience in primary care.
Military PAs serve in the White House Medical Unit, where they provide care to the president and vice president and their families as well as White House staff.
They are employed by several organizations with the intelligence community, specifically the Central Intelligence Agency. While much of the job description is classified, they work under the Directorate of Support and are deployed to "austere environments" where they provide medical care, including trauma stabilization, and teach in the fields of survival, field medicine, and tactical combat casualty care.
United States Army PAs serve as Medical Specialist Corps officers, typically within Army combat or combat support battalions located in the continental United States, Alaska, Hawaii, and overseas. These include infantry, armor, cavalry, airborne, artillery, and (if the PA qualifies) special forces units. They serve as the "front line" of Army medicine and along with combat medics are responsible for the total health care of soldiers assigned to their unit, as well as of their family members.
PAs also serve in the Air Force and Navy as clinical practitioners and aviation medicine specialists, as well as in the Coast Guard and Public Health Service. The skills required for these PAs are similar to that of their civilian colleagues, but additional training is provided in advanced casualty care, medical management of chemical injuries, aviation medicine, and military medicine. In addition, military PAs are also required to meet the officer commissioning requirements, and maintain the professional and physical readiness standards of their respective services.
The marine physician assistant is a US Merchant Marine staff officer. A certificate of registry is granted through The United States Coast Guard National Maritime Center located in Martinsburg, West Virginia. Formal training programs for marine physician assistants began in September, 1966 at the Public Service Health Hospital located in Staten Island, N.Y.
As of October 2018 The first formally trained physician assistants graduated in 1984 from the Canadian Forces Medical Services School at Borden, Ontario. The Canadian Medical Association (CMA) recognized physician assistants as a health professional in 2003. Physician assistants are able to perform medical functions such as ordering tests, diagnosing diseases, prescribing medications, treating patients, educating patients and performing various medical and surgical procedures. Physician assistants are labeled under the federal government national occupational classification code 3124: allied primary health practitioners. , there are approximately 800 physician assistants working in healthcare settings in Canada.
The first civilian physician assistant education programs were launched in 2008 at the University of Manitoba and McMaster University. In 2010, a third civilian program was launched by the consortium of physician assistant education (University of Toronto, Northern Ontario School of Medicine, and The Michener Institute). Admission to the physician assistant program in all three of the university programs across Canada are highly competitive with grades, education, interviews, professional experience, credentials, personal statements and testing considered in the candidate selection process. Approximately 15 seats at the University of Manitoba are available yearly while the two other programs in Ontario respectively have approximately 30 seats at the University of Toronto and approximately 24 seats at McMaster University. In Canada, the education of a physician assistant generally consists of three years of professional post-graduate university education. The education is delivered over a two calendar year time-frame by completing fall, winter and summer semesters for both years of the program in either a master level university physician assistant program or post-graduate professional university bachelor level physician assistant program. Physician assistant graduates become eligible for the certification exam by being a graduate of a Canadian physician assistant program that is recognized by the Physician Assistant Certification Council of Canada (Canadian Armed Forces physician assistant program, University of Manitoba, McMaster University and the consortium of physician assistant education all of which are accredited by the Canadian Medical Association).
Physician assistants resemble and provide many of the functions of physicians in Canada and act as advanced-level medical provider. Physician assistants may be compared to the role of nurse practitioner by the general public and may be confused as the same profession. Nurse practitioners in Canada practice under an advanced nursing model.  Physician assistants practice under a medical model, similarly modeled after medical school (physician) education.  Nurse practitioners practice within their defined specific scope of practice autonomously and sometimes collaboratively. The defined scopes of a nurse practitioner include the areas of (family care, adults and paediatrics). Physician assistants are permitted to practice in all medical specialties by mirroring the practice of a physician with a full range of skills and scope by practicing both autonomously as a clinician and collaboratively with physicians when required. Some examples of practice areas for physician assistants include (emergency medicine, critical care medicine, cardiology, psychiatry, community and family medicine, neurology, surgery, orthopaedics, internal medicine, oncology, gastroenterology, military medicine, respirology, dermatology, women's health and many more specialities). Physician assistants may perform certain roles which have been traditionally only provided by physicians in clinical practice, making the PA's medical training over other providers unique in this regard.
Physician assistant salaries in civilian practice in Canada are relatively new and can range from approximately $80,000 CAD for entry level positions to $142,000 CAD a year for experienced providers which are not on call and up to $178,000 CAD for experienced providers which are on call.  As the physician assistant profession is newer to civilian practice in Canada, salaries have been improving to reflect physician assistant positions and their value to the health care system. Salaries in Canada currently remain lower, in comparison to the United States where a range from approximately $110,000 USD to $150,000 USD is common place and in some cases even up to $200,000 or more in specialized medical areas. Physician assistants in the province of Ontario must be paid at minimum $75,000 CAD annually, although organizations may find it challenging to recruit physician assistants at this salary. In provinces where physician assistants are not currently regulated, the title physician assistant may not be a protected title. Employers incorrectly may post job postings that make reference to the title physician assistant, with duties of assisting a physician, such as a clerk or medical assistant. The compensation report published in 2019 by the Canadian Association of Physician Assistants outlines the typical salaries across Canada being an entry median salary of approximately $80,000 CAD and an experienced median salary of approximately $105,000 CAD.  Generally, provinces which have regulated physician assistants for longer periods of time, or larger urban areas compensate significantly more that the listed median salaries at both the entry and experienced levels. Competitive hourly compensation rates for physician assistants vary between approximately $50.00 CAD for entry level providers to $70.00 CAD dollars an hour for experienced providers. This salary is in line with other allied primary health practitioners listed under the national occupational classification (NOC:3124).
Physician assistants are currently practicing across Canada in the Canadian Armed Forces as commissioned officers in domestic and international environments and have been in practice since the 1960s.  Physician assistants outside of the Canadian Armed Forces practice usually in the public health care system in the provinces of Manitoba, Ontario, New Brunswick, Nova Scotia and Alberta. Physician assistants have been regulated in Manitoba since 1999 and in New Brunswick since 2009  and are registrants of their respective provincial college of physicians and surgeons. In Ontario, Alberta and Nova Scotia the profession is not regulated at this time. Physician assistants in Ontario were introduced in 2007 to the public health system as a joint venture between the Ontario Ministry of Health and the Ontario Medical Association.  In Alberta, a registry has been established for physician assistants under the College of Physicians and Surgeons of Alberta with future regulation underway.  In Ontario, future regulation has been discussed by the Ontario Ministry of Health in which physician assistants would be members of the College of Physicians and Surgeons of Ontario. Physician assistants are represented by the Canadian Association of Physician Assistants, which originally was formed in October 1999 as the "Canadian Academy of Physician Assistants".
In February 2015, Health Workforce New Zealand completed a Phase-2 trial of PAs who worked for a period of two years (2013-2015) in four clinical settings. Specifically, the sites included one rural emergency department and three primary care settings (two rural and one urban) located on the North and South Islands of New Zealand. At conclusion of the trial, several clinics continued to employ PAs while the process of health regulation makes its way through the government bureaucracy.
In 2011, Health Workforce Australia began developing the role of physician assistant throughout the country culminating with registration and a PA Program based out of James Cook University. Despite all initial indicators showing that the new profession would be successfully integrated into the health care system, the progress has floundered resulting in the majority of PAs in Australia being unemployed.
The first PA program in India was established in 1992.