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The National Ambulatory Medical Care Survey

PAs and NPs in outpatient surgery

Salibian, Ara A. MD; Mahboubi, Hossein MD, MPH; Patel, Madhukar S. MD, MBA, ScM; Kuan, Edward C. MD, MBA; Malinoski, Darren J. MD, FACS; Vagefi, Parsia A. MD; Djalilian, Hamid R. MD

Journal of the American Academy of PAs: May 2016 - Volume 29 - Issue 5 - p 47–53
doi: 10.1097/01.JAA.0000482302.40692.20
Original Research

Background: This study aimed to determine the prevalence and occupational characteristics of physician assistants (PAs) and nurse practitioners (NPs) in outpatient surgical subspecialty clinics.

Methods: The 2007 and 2008 National Ambulatory Medical Care Survey (NAMCS) databases were queried for the number and characteristics of office visits seen by different provider types (PAs or NPs, physicians, or both) in various surgical subspecialties.

Results: More than 250 million weighted sample visits were analyzed. PAs or NPs were involved in 5.9% of visits, though the percentage of patients seen by them alone (1.1%) was significantly lower (P<0.0001). PAs and NPs were more likely to be involved in pre- or postoperative visits, and often saw the same diagnoses alone as physicians only. The most common procedures performed by PAs and NPs varied according to subspecialty.

Conclusions: PAs and NPs have a minor prevalence in the ambulatory surgical workforce during the time period studied. Further integration of these providers into the outpatient setting may help optimize efficiency in ambulatory surgical care.

At the time this article was written, Ara A. Salibian was a medical student at the University of California at Irvine. He now is a resident in the Department of Plastic Surgery at New York (N.Y.) University. Hossein Mahboubi is a resident in the Department of Otolaryngology–Head and Neck Surgery at the University of California at Irvine. Madhukar S. Patel is a resident in the Department of Surgery at Massachusetts General Hospital in Boston, Mass. Edward C. Kuan is a resident in the Department of Head and Neck Surgery at the University of California at Los Angeles. Darren J. Malinoski is section chief in Surgical Critical Care at the Portland (Ore.) Veterans Affairs Medical Center and an associate professor of surgery at Oregon Health and Science University. Parsia A. Vagefi is associate surgical director of liver transplantation at Massachusetts General Hospital. Hamid R. Djalilian is director of the Division of Neurotology and Skull Base Surgery in the Department of Otolaryngology-Head and Neck Surgery at the University of California at Irvine. The authors have disclosed no potential conflicts of interest, financial or otherwise.

The roles of physician assistants (PAs) and nurse practitioners (NPs) in outpatient and inpatient clinical settings have received much attention because of concerns about access to care and rising costs of healthcare. Policymakers have considered expanding the roles of PAs and NPs to improve the quality of care, reduce the workforce demand for physicians, and lower costs by providing services that previously only physicians could deliver.1-5

Few studies in the surgical literature have examined the prevalence and evolving role of these providers in the ambulatory care setting.2,6,7 Assessing the workforce prevalence of PAs and NPs in surgical practice is important because the rate of surgeons entering the healthcare workforce is insufficient compared with the projected rate of increase of patients who may require surgery.8,9

This study aimed to examine the prevalence of PAs and NPs in the ambulatory setting of various surgical subspecialties, and to determine the occupational characteristics of these providers in each surgical subspecialty. Insight into PA and NP workforce patterns and resource use within the healthcare industry may provide improved understanding of how they can be integrated into the changing landscape of medical practice.

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The National Ambulatory Medical Care Survey (NAMCS) is an ongoing probability sample survey performed by the CDC's National Center for Health Statistics. The survey is designed to provide objective, quantifiable, and representative information on patterns of ambulatory medical care services use in the United States. Data from NAMCS are collected from direct outpatient visits to nonfederally employed, office-based physicians and community health centers. Data collected from visits include patient demographics; patient history specific to the visit, including providers seen; patient workup; patient management and interventions; and practice characteristics including physician specialty.

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The NAMCS databases from 2007 to 2008 were merged. Only the visits provided by general surgery, obstetrics and gynecology, ophthalmology, orthopedic surgery, otolaryngology, and urology were included. All other specialties (71%) were excluded as they were either not surgical specialties or were not surveyed as individual groups by the NAMCS. PAs and NPs were defined in the study using the healthcare providers included in the variable “other providers seen,” which includes PAs and NPs grouped together. Mental health providers as well as registered nurses (RNs) and licensed practical nurses (LPNs) were excluded from analyses. Providers were recoded into the following categories:

  • PA or NP only
  • PA or NP plus physician (for patients seen by both during the same visit)
  • physician only.

Geographic location in the dataset was encoded according to US census categories (West, South, Midwest, Northeast). Where available, the major reason of visit (new problem of less than 3 months of onset, routine chronic problem, flare-up of chronic problem, pre/postsurgery, or preventive care) was extracted and analyzed. Patient diagnoses were encoded using the ICD-9-CM. The most common ICD-9-CM diagnosis and procedure codes were identified for each type of provider. Visits with incomplete data or those that did not code for provider type were excluded from analysis (0.5%). A small number of patients were seen by only RNs or LPNs; these visits were included in calculating the total number of visits, but were excluded from further analysis.

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Statistical analysis

The NAMCS uses a multistage estimation procedure to generate unbiased national estimates from its basic sampling unit, which is the physician-patient encounter or visit. The survey reports an adjusted sample weight for each visit based on the probabilities of a visit being selected for the survey. Using this patient visit weight, national estimates from sample data were produced. All results from this study are reported using these national estimates.

The estimated numbers and 95% confidence interval were calculated for different types of PAs and NPs, surgical specialties, provider types, geographic distribution, major reason for visit, and the most common diagnoses (by ICD-9 coding convention) for each provider type within each specialty. The Pearson chi-square test was used to compare differences in practice patterns among provider types. A significance level of 0.05 was used for all tests, and statistical analyses were performed using SAS 9.3.

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After combining data from the 2007 and 2008 NAMCS datasets and applying exclusion criteria, a weighted sample of 250,428,405 office visits (extrapolated from 17,680 visits) was evaluated. Across all of the surgical subspecialties, 1.1% of outpatient office visits involved PAs or NPs only, 92.9% involved physicians only, and 4.8% included physicians plus a PA or NP (Table 1). A comparison of provider-specific office visits per specialty revealed significant variability in the proportion of PA or NP use across the different surgical subspecialties (P<0.0001) (Table 1), with urology and orthopedic surgery having the highest percentage of PA or NP use. In terms of geographic distribution, the Northeast had the highest use of PAs and NPs (Table 2).





The proportion of cases seen by a PA or NP, either alone or in combination with a physician, also varied with regard to the major reason for the visit (Table 3). Pre- or postsurgery visits were most likely to involve a PA or NP (7.5%); those involving flare-ups of chronic problems were the least likely (4.9%). To better understand the different types of cases being seen by provider type, the most common diagnosis seen by each provider group was also identified for each surgical specialty (Table 4). This diagnosis often overlapped among different provider groups, with the same diagnosis being seen by all three provider types for both urology and ophthalmology.





Similarly, the top procedure for each provider group was also identified for each surgical specialty (Table 5). In both obstetrics and gynecology and orthopedics, the most common procedure performed by PAs or NPs alone was an injection. On the other hand, the most common procedure performed by these providers in ambulatory urology and ophthalmology offices involved more complex interventions, such as circumcisions and “other operations on the eyeball,” respectively. General surgery was unique in reporting no procedures that PAs or NPs performed alone.



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As healthcare reform progresses, clinicians and policymakers must understand the prevalence and role that different providers play in delivering care to patients. In this study, we evaluated a descriptive analysis of the division of patient care between physicians and PAs or NPs in surgical specialty offices. Analyzing the prevalence and responsibilities of PAs and NPs in these clinics provides a better understanding of the integration of these providers in the outpatient surgical setting. Such information may be particularly important when considering changes in healthcare delivery, as previous studies have reported that PAs or NPs may be able to improve the quality of care while reducing costs.1-5

By using a national probability sample survey of the outpatient practices of six surgical subspecialties, we were able to compare trends in the use of different providers across specialties and across geographic regions. Although overall PAs and NPs appeared to be used minimally in the surgical outpatient setting, the proportion of PAs or NPs used across specialty types varied widely. Furthermore, the number of patients seen by only PAs or NPs varied considerably. Many of these observations can be rationalized by the different scopes of practice among the various specialists. The noted variations, as well as the fact that nearly 93% of all cases are seen by physicians only, suggest that there may be room for further defining and optimizing the use of PAs and NPs in surgical outpatient settings.

Despite a thorough search of the literature, we were unable to find similar studies that encompassed several different surgical specialties; however, singular specialty investigations have allowed for comparisons. For example, our results showed that 0.7% of visits for otolaryngology involved PAs or NPs, significantly lower than a recent study analyzing NAMCS data for similar providers in ambulatory otolaryngology practices (31.4%).6 However, most of the providers who saw patients in the latter study were RNs or LPNs. In our study, visits conducted by RNs or LPNs were excluded from the groups, as visits involving these providers may be due to checking in or obtaining vital signs, subsequently confounding the roles of PAs and NPs in providing a more advanced level of care.

The type of patients seen by PAs and NPs also must be considered. A better understanding of these patient populations may provide important information on how PAs and NPs can apply their training and skill sets to provide efficient care in the office setting. A 2008 study that examined patterns of use of PAs and NPs in dermatology clinics found that they were most likely to see established patients with stable existing problems.10 Our study revealed that PAs and NPs manage patients for a range of reasons (Table 3), albeit often collaboratively with a physician. This may favor the recruitment of PAs and NPs in the ambulatory surgical setting, as they can be involved in the care of a broad spectrum of patients.

In this study, PAs and NPs were involved in only 5.2% of visits related to new problems. This is in contrast to a survey of rheumatology PAs in different office-based practices (private, university, and government service) over the period of a year, in which most rheumatology PAs provided the initial consultation for new patients.11 Such differences may be due to the wide variety of diseases and patient complaints encountered in different medical and surgical specialties, which can characterize the various types of patient visits as well as how they involve PAs or NPs. Furthermore, our results showed variation in the major reasons for visits within each specialty with regards to provider type. This may point to a lack of standardization of what types of cases (new problem, chronic problem, etc.) are triaged to be seen by a particular provider. Interestingly, PAs and NPs alone saw the same diagnosis as the physicians-only group in almost half of the specialties. This finding suggests that PAs and NPs are capable of assuming certain responsibilities of physicians in these specialty groups.

Four out of the six specialty groups displayed similar trends with regards to the most common procedure performed. To better understand this observation, we would need to see if the amount of time the physician-only group took to see the same diagnosis or perform the same procedure differed from the time taken by the physician plus PA or NP group. Further analysis of these data demonstrated that procedures (whether performed alone or as an assistant to a physician) accounted for a minority of visits seen by PAs or NPs. A similar finding was seen in a 2011 study on the use of PAs and NPs in dermatologic surgery. Tierney and colleagues reported that 75% or more of PAs' and NPs' time in surgical dermatology practices was dedicated to treating medical dermatology patients.7 This may be intended to free up the physician's time to perform more procedures, or could be due to a deficiency in procedural training for PAs or NPs.

As PA and NP use continues to increase in the healthcare workforce, one must consider how they bring value to a physician's practice. The value of PAs and NPs can be interpreted in many ways: actual revenue generated for a physician's practice, or by more qualitative measures such as their ability to improve the efficiency and quality of patient care.1,3 PAs and NPs also may free physicians to perform other procedures or conduct other patient visits. This is particularly important for certain subspecialties such as otolaryngology, in which the top diagnosis seen by the PA- or NP-only group is the same as the top diagnosis seen by the physician-only group (Table 4). Dividing the workload with PAs and NPs will not only permit physicians to support a larger patient population, but also enhance the efficiency of their work by allowing them to dedicate more time to complex or more time-consuming cases. Overall, these series of simple considerations appear to support the increasing role that PAs and NPs have in surgical specialty offices, on the basis of their ability to add value to physicians' practices. However, more robust modeling is needed to carry out comprehensive estimations and calculations.

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The NAMCS database, when applied to this study, only allows descriptive analyses with no outcomes data, restricting the conclusions that can be drawn on the quality of healthcare delivered. In addition, although the number of cases from a national estimate standpoint is substantial, these statistics are derived from a raw number of sample surveys. This sample size, before applying weights to generate estimates, was relatively small (n<30) in particular categories, and is considered unreliable by National Center for Health Statistics guidelines when below this threshold. PAs and NPs may be inherently underrepresented in national health surveys, so changes in survey design and implementation may be needed to obtain a more accurate understanding of the prevalence of these providers in the clinical setting.12

“Incident to” billing is a policy that permits full reimbursement if a physician is part of the encounter. This policy financially encourages physicians to be part of the encounter, and may be a factor in why PA or NP plus surgeon encounters were so high in this study.

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Although the PA and NP workforce continues to expand, our study demonstrates that these providers have limited penetration into the ambulatory surgical setting. The ability of PAs and NPs to be involved in a wide variety of responsibilities warrants further efforts to integrate their roles in outpatient surgical practice. PAs and NPs also may generate value for surgical practices, though further studies are needed to investigate their effect on healthcare outcomes. As PAs and NPs will remain important providers to fill the gap between the current supply of healthcare providers and demand for patient care, policymakers should consider optimizing the use of these providers in the ambulatory surgical workforce.

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1. Clark AR, Monroe JR, Feldman SR, et al. The emerging role of physician assistants in the delivery of dermatologic health care. Dermatol Clin. 2000;18(2):297–302.
2. Druss BG, Marcus SC, Olfson M, et al. Trends in care by nonphysician clinicians in the United States. N Engl J Med. 2003;348(2):130–137.
3. Laurant M, Harmsen M, Wollersheim H, et al. The impact of nonphysician clinicians: do they improve the quality and cost-effectiveness of health care services. Med Care Res Rev. 2009;66(6 suppl):36S–89S.
4. US Department of Health and Human Services. Health Resources and Service Administration. Projecting the Supply of Non-Primary Care Specialty and Subspecialty Clinicians: 2010-2025. July 2014.
    5. Everett C, Thorpe C, Palta M, et al. Physician assistants and nurse practitioners perform effective roles on teams caring for Medicare patients with diabetes. Health Aff (Millwood). 2013;32(11):1942–1948.
    6. Bhattacharyya N. Involvement of physician extenders in ambulatory otolaryngology practice. Laryngoscope. 2012;122(5):1010–1013.
    7. Tierney EP, Hanke CW, Kimball AB. Practice models and roles of physician extenders in dermatologic surgery. Dermatol Surg. 2011;37(5):677–683.
    8. Sheldon GF. The evolving surgeon shortage in the health reform era. J Gastrointest Surg. 2011;15(7):1104–1111.
    9. Williams TE Jr, Ellison EC. Population analysis predicts a future critical shortage of general surgeons. Surgery. 2008;144(4):548–554.
    10. Resneck JS Jr, Kimball AB. Who else is providing care in dermatology practices? Trends in the use of nonphysician clinicians. J Am Acad Dermatol. 2008;58(2):211–216.
    11. Hooker RS, Rangan BV. Role delineation of rheumatology physician assistants. J Clin Rheumatol. 2008;14(4):202–205.
    12. Morgan PA, Strand J, Østbye T, Albanese MA. Missing in action: care by physician assistants and nurse practitioners in national health surveys. Health Serv Res. 2007;42(5):2022–2037.

    physician assistant; nurse practitioner; National Ambulatory Medical Care Survey; ambulatory surgical care; surgeons; workforce

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