These days, when you visit your primary care doctor, a hospital emergency department or even some medical specialists, it’s more likely than ever before that a physician assistant (PA) or nurse practitioner (NP) will be caring for you. Who are these health-care providers—and when should they be relied upon?

For answers, Bottom Line/Health recently spoke with Robert L. Kane, MD, a renowned expert on medical care in the US.

A Growing Trend

There are currently more than 70,000 PAs and 140,000 NPs practicing in the US, and their numbers are expected to rise significantly over the next decade due, in part, to the increasing patient load from the aging baby-boomer population and soaring health-care costs.

Although these nonphysician providers are trained to diagnose and treat medical conditions on their own, all states require that PAs must be supervised by a physician either in person or by telephone or some other means of telecommunication. NPs are allowed to practice without direct physician supervision in 10 states, but most require collaboration with a physician as well.

In general, medical doctors have a more thorough and rigorous grounding in basic science and patient care than do nonphysician providers. Medical doctors attend four years of medical school after college and complete three to seven years of residency training.

In addition to college, PAs and NPs are required to complete a two-year master’s degree for their medical training. In the next few years, certification to become an NP will require a doctoral degree as well. While PAs often have previous health-care experience—as an emergency medical technician, for example—all NPs have previous nursing experience as registered nurses (RNs).

Because both PAs and NPs are state-licensed, their actual responsibilities vary somewhat from state to state, but in most states, they’re allowed to take medical histories, conduct diagnostic exams and tests, prescribe drugs and treatment plans, and administer care with a growing range of medical devices such as electrocardiograms.

Important: If nonphysician providers play a role in your doctor’s practice, you should be informed when you make your appointment whether you’re going to be seen by a physician or a nonphysician provider.

In your first meeting with the PA or NP, ask what the facility’s policy is regarding when patients are seen by a physician versus a nonphysician provider. If you have a complex condition, such as unstable heart failure or difficult-to-manage blood pressure or diabetes, you should also double-check that the physician will be reviewing your chart or electronic medical record on a regular basis. It is reasonable to see your physician about every third visit to ensure that your treatment is on track.

When to Use a PA or NP

When it is—and isn’t—appropriate to see a PA or NP in place of a physician…

Simple health problems. It’s OK to be treated by a PA or NP if you just need a checkup or treatment for a straightforward medical condition, such as a sore throat. In the US, more than one-third of all PAs and two-thirds of NPs work in primary care. Studies have repeatedly found that their patient outcomes and patient satisfaction levels in this area are as good as—or better than—those of physicians.

Interesting research finding: In one trial that I helped conduct at New York Presbyterian Hospital, more than 1,300 patients who had visited the emergency department or an urgent-care center were then randomly assigned for follow-up care to either a primary care physician or a primary care NP with full authority to treat and prescribe drugs. When tested six months later, patients who were treated by an NP were just as healthy, on average, as those treated by a physician. Patient satisfaction rates for the two groups were also equivalent after six months.

Ask for a physician consult if… your nonphysician provider appears uncertain about your condition’s diagnosis… your condition poses a challenging diagnostic dilemma (such as pain that does not improve or fatigue for no clear reason)… the treatment regimen being prescribed is complex and involves multiple medications or other interventions… or you are not confident that the provider’s diagnosis and/or treatment recommendations are appropriate.

Routine follow-up. It’s OK to be treated by a PA or NP if you’re making a routine follow-up visit for a chronic condition. Following initial diagnosis and treatment, managing chronic diseases, such as diabetes or hypertension, largely involves ongoing monitoring and preventive care, including medical intervention such as adjusting the dosage of a medication if a condition begins to worsen. This is done through routine follow-up visits or, increasingly, by patients checking in via phone or e-mail.

Important benefit: PAs and NPs are able to spend more time with each patient, so nonphysician providers typically excel at encouraging patients to adhere to their prescribed medical regimens, ensuring that treatment plans are working effectively and identifying problems with diet, sleep, drug side effects, psychological stress, pain and other areas that may impact the condition being treated.

Ask for a physician consult if… your chronic condition changes significantly in some other way that your PA or NP can’t account for.

Monitoring after seeing a specialist. It’s OK to be treated by a PA or NP if you need follow-up care after seeing a specialist. An increasing number of nonphysician providers now are working in specialty practices. For example, an NP might specialize in obstetrics/gynecology, while a PA might specialize in cardiology. If you are referred to a specialist who uses a PA or NP, the physician will typically evaluate you on your first visit.

But once a treatment plan has been established, it’s appropriate for a PA or NP to conduct follow-up exams to monitor your treatment and overall health. Similarly, with a specialist that you see regularly for preventive care—a pulmonologist or urologist, for example—it’s fine to see a PA or NP if you need to make an unscheduled visit for a straightforward complaint, such as a cough or urinary tract infection.

Ask for a physician consult if… you suspect that the PA or NP is not keeping your doctor sufficiently apprised of your ongoing treatment…you aren’t happy with how your preventive care or treatment is progressing… or you think that your current complaint is too complex for the PA or NP to handle or you suspect that it hasn’t been diagnosed properly by the non¬physician provider.

When you need a fast appointment. It’s OK to be treated by a PA or NP if you want to be seen quickly, but your doctor isn’t immediately available. In certain cases, you may be given the option of seeing the doctor in, say, two weeks or seeing a PA or NP tomorrow.

If you have a routine condition, such as the flu, that requires immediate attention, seeing a nonphysician provider right away may be your best option. This also holds true for visits to the emergency department, where PAs and NPs are increasingly the front-line providers who diagnose medical conditions.

Ask for a physician consult if… you believe that your condition is extremely serious or life-threatening… your illness involves an ongoing medical condition, such as cancer or hepatitis, that the PA or NP is inexperienced at treating or that requires the skills of a physician specialist.