Primary care physician
A primary care physician, or PCP, is a physician who provides both the first contact for a person with an undiagnosed health concern as well as continuing care of varied medical conditions, not limited by cause, organ system, or diagnosis. A PCP generally does not specialize in the treatment of specific organ systems, such as neurology, cardiology, or pulmonology, nor perform surgery. The term "PCP" is most commonly used in the United States. A primary care physician can be described by training, skill and scope of practice, role in the health care system, and the usual setting in which care is delivered. Primary care physicians are declining in numbers in many developed countries.

# Defining primary care physicians
Certain clinicians, most commonly those trained in family practice, general practice, pediatrics and internal medicine are referred to as primary care physicians.  Some HMOs consider gynecologists as PCPs for the care of women, and have allowed certain subspecialists to assume PCP responsibilities for selected patient types, such as allergists caring for people with asthma and nephrologists acting as PCPs for patients on kidney dialysis. Some experts and groups have included nurse practitioners and physician assistants by broadening the term to primary care practitioners.

## Scope of practice
A set of skills and scope of practice may define a primary care physician, generally including basic diagnosis and non-surgical treatment of common illnesses and medical conditions.  Diagnostic techniques include interviewing the patient to collect information on the present symptoms, prior medical history and other health details, followed by a physical examination. Many PCPs are trained in basic medical testing, such as interpreting results of blood or other patient samples, electrocardiograms, or x-rays. More complex and time-intensive diagnostic procedures are usually obtained by referral to specialists, due to either special training with a technology, or increased experience and patient volume that renders a risky procedure safer for the patient.  After collecting data, the PCP arrives at a differential diagnosis and, with the participation of the patient, formulates a plan including (if appropriate) components of further testing, specialist referral, medication, therapy, diet or life-style changes, patient education, and follow up results of treatment. Primary care physicians also counsel and educate patients on safe health behaviors, self-care skills and treatment options, and provide screening tests and immunizations.

## Role in the health care system
A primary care physician is usually the first medical practitioner contacted by a patient, due to factors such as ease of communication, accessible location, familiarity, and increasingly issues of cost and managed care requirements. Many health maintenance organizations position PCPs as "gatekeepers", who regulate access to more costly procedures or specialists. Ideally, the primary care physician acts on behalf of the patient to collaborate with referral specialists, coordinate the care given by varied organizations such as hospitals or rehabilitation clinics, act as a comprehensive repository for the patients records, and provide long-term management of chronic conditions. Continuous care is particularly important for patients with medical conditions that encompass multiple organ systems and require prolonged treatment and monitoring, such as diabetes and hypertension.

## Health care setting
PCPs provide the majority of services at the primary level of care, an entry point to a system that includes secondary care (by community hospitals) and tertiary care (by medical centers and teaching hospitals), also referred to an ambulatory care setting versus inpatient care. Many primary care physicians follow their patients in a variety of health care settings, such as offices, hospitals, critical care units, long-term facilities, and at home. A PCP may supervise a non-physician health professional, such as a nurse practitioner or physician assistant.

# Studies of the quality of care provided by primary care physicians
Studies that compare the knowledge base and quality of care provided by generalists versus specialists usually find that the specialists are more knowledgeable and provide better care . However, these studies examine the quality of care in the domain of the specialists. In addition, these studies need to account for clustering of patients and physicians .
Studies of the quality of preventive health care find the opposite results - primary care physicians perform best. 
An analysis of elderly patients found that patients seeing generalists, as compared to patients seeing specialists, were more likely to receive influenza vaccination. In health promotion counseling, a studies of self-reported behavior found that generalists were more likely than internal medicine specialists to counsel patients  and to screen for breast cancer .
Exceptions may be diseases that are so common that primary care physicians develop their own expertise. A study of patients with acute low back pain found the primary care physicians provided equivalent quality of care, but at lower costs that orthopedic specialists .
Low value care may be more common in settings with low numbers of primary care physicians.
Factors associated with quality of care by primary care physicians include:
- The more experience the primary care physician has with a specific disease..
- Physician group affiliation with networks of multiple groups.

## Dissemination of information to generalists compared to specialists
The dissemination of information to generalists compared to specialists is complicated . Two studies found specialists were more likely to adopt COX-2 drugs before the drugs were recalled by the FDA . One of the studies went on to state "using COX-2s as a model for physician adoption of new therapeutic agents, specialists were more likely to use these new medications for patients likely to benefit but were also significantly more likely to use them for patients without a clear indication". Similarly, a separate study found that specialists were less discriminating in their choice of journal reading. 

## Financial incentives
FInancial incentives to primary care physicians are not clearly effective.

## Summary
In summary, each type of physician has strengths, especially when practicing in areas of their expertise and experience. Accordingly, one study found the best care after myocardial infarctions was when both a specialist and a generalist cared for a patient .

# Challenges for primary care

## Professional satisfaction
Primary care physicians are less satisfied when employeded and salaried in a large medical group with more physicians.  Other the other hand, primary care physicians in micropractices have higher satisfaction.

## Declining numbers
Shortages of primary care physicians are an increasing problem in many developed countries. In the United States, the number of medical students entering family practice training dropped by 50% between 1997 and 2005.  In 1998, half of internal medicine residents chose primary care, but by 2006, over 80% became specialists or hospitalists.  Causes parallel the evolutionary changes occurring in the US medical system: payment based on quantity of services delivered, not quality; aging of the population increases the prevalence and complexity of chronic health conditions, most of which are handled in primary care settings; and increasing emphasis on life-style changes and preventative measures, often poorly covered by health insurance or not at all.  In 2004, the median income of specialists in the US was twice that of PCPs, and the gap is widening.  Primary care practices in the United States increasingly depend on foreign medical graduates to fill depleted ranks. 

## Insufficient time for tasks
Primary care physicians have insufficient time to manage chronic disease.

## Replacement by non-physicians
Non-physicians may replace much of the work of primary care physicians. This disruption has been predicted by Clayton Christensen in his book, The Innovators Prescription: A Disruptive Solution for Healthcare

## Maldistribution
Developing countries face an even more critical disparity in primary care practitioners. The Pan American Health Organization reported in 2005 that "...the Americas region has made important progress in health, but significant challenges and disparities remain. Among the most important is the need to extend quality health care to all sectors of the population...Experience over the last 27 years shows that health systems that adhere to the principles of primary health care produce greater efficiency and better health outcomes in terms of both individual and public health..."  The World Health Organization (WHO) has identified worsening trends in access to PCPs and other primary care workers, both in the developed and the developing nations: 
- "Worker numbers and quality are positively associated with immunization coverage, outreach of primary care, and infant, child and maternal survival"
- "The quality of doctors and the density of their distribution have been shown to correlate with positive outcomes in cardiovascular diseases"
- "In health systems, (primary care) workers function as gatekeepers and navigators for the effective, or wasteful, application of all other resources such as drugs, vaccines and supplies"
- "there are currently 57 countries with critical shortages equivalent to a global deficit of 2.4 million doctors, nurses and midwives"
- "In many countries, the skills of limited yet expensive professionals are not well matched to the local profile of health needs"
- "...all countries suffer from maldistribution characterized by urban concentration and rural deficits"
- "Richer countries face a future of low fertility and large populations of elderly people, which will cause a shift towards chronic and degenerative diseases with high care demands"
- "Growing gaps will exert even greater pressure on the outflow of health workers from poorer regions"

## Lagging quality of care measures
A survey of 6,000 primary care physicians in seven countries revealed disparities in several areas that affect quality of care. Differences did not follow trends of the cost of care; primary care physicians in the United States lagged behind their counterparts in other countries, despite the fact that the US spends two to three times as much per capita. Arrangements for after-hours care were almost twice as common in the Netherlands, Germany and New Zealand as in Canada and the United States, where patients must rely on emergency facilities. Other major disparities include automated systems to remind patients about follow-up care, give patients test results or warn of harmful drug interactions. There were differences as well among primary care doctors, regarding financial incentives to improve the quality of care.