How PAs improve access to care for the underserved

Study variables and statistical analyses for the current study In our study, we analyzed data provided in the NAMCS. Payer mix is recorded on the NAMCS survey under primary expected source of payment for this visit; we examined this variable from 1997 to 2003. Choices for source of payment on the NAMCS survey included private insurance, Medicaid, Medicare, workers' compensation, self-pay, no charge/charity, not known. For our analysis, we combined several of these original variables and identified them using the following terms: private insurance, source of payment Medicaid only, source of payment Medicare only, workers' compensation, self (outof-pocket) payment, and no charge/charity. The category not known was not included in our analysis.

We also used NAMCS variables indicating the provider seen from 1997 to 2003. We grouped the choices into physician only, PA only, physician and PA, and other professional. Additional sociodemographic information utilized included gender, race, age, whether the visit was conducted in an urban or a rural area, geographical region, and year. We first examined the relationships between payer mix, metropolitan status, and other covariates with provider type and tested them separately using a Rao-Scott corrected Pearson statistic to account for the survey design. A weighted logistic regression was conducted next, where the log-odds of provider type was treated as the function of payer mix and the other variables. The regression was performed using the SVYLOGIT procedure available in the STATA Statistical Analysis System version 9.1. Visits to both physicians and PAs or to other types of professionals were not included in the logistic regression model.

RESULTS

An estimated 5.87 billion visits were made to nonfederally-employed office-based physicians in the United States from 1997 to 2003 (see Table 1). Approximately 55% of the overall visits involved patients who were younger than 49 years; 60% of the visits involved female patients; and 87% of the visits were made by white patients. In 56% of the total visits, the primary source of payment was private insurance; Medicaid and Medicare covered 31% of the visits. Patient visits occurred most often in the South (34%) and in metropolitan areas (84%). A large number of visits were to physicians only (94%). Visits to PAs only were made by 32.5 million people, as much as 0.56% of the study population. The remaining 5% of visits were either to both physicians and PAs or to other types of health care providers.

Provider category was significantly associated with patients' source of payment and physicians' urban status (ie, whether or not the physician's practice was in a metropolitan statistical area) (P < .0001) (see Table 2). The statistically significant relationship between urban status and provider type suggests that proportionally more visits were to PAs (4.59%) in rural areas rather than urban areas (4.02%).

The logistic regression model suggested that patients who paid out-of-pocket (self-pay) had higher odds of visiting PAs than did patients with private insurance (odds ratio [OR]: 1.37; 95% confidence interval [CI]: 1.18-1.77). Patients who had only Medicare insurance were less likely to visit PAs than were patients who had private insurance (OR: 0.48; CI: 0.29-0.81). Patients in rural areas (as identified by physician practice area) were 102% more likely to visit PAs than were patients in urban areas (OR: 2.02; CI: 1.31-3.14). Nonwhite patients were more likely to visit PAs than were white patients (OR: 2.21; CI: 1.32-3.68). Further, visits made by patients in the Midwest were more likely to be to PAs than were visits made by patients in the West (OR: 1.79; CI: 1.40- 2.84) (see Table 3).

DISCUSSION

Historically, PAs were one potential solution to the inaccessibility of health care, particularly in rural areas. Today, PAs not only provide access to care in these areas but also allow the health care team to function as a more cost-effective and efficient unit. Exploring patient-related and physician-related determinants of the type of provider visited is important to further understanding of the role PAs play.



Compared to urban visits, rural visits are relatively more likely to be made to PAs than to physicians. Thus, PAs still tend to fill the rural gap where physician shortages are more prevalent. Assuming that people in rural areas have less access to health care than do people in metropolitan or urban areas, these results support the hypothesis that PAs are indeed providing care to more underserved populations. One plausible explanation for why PAs tend to care for a more rural population is that physicians are making a practice of shunting their lower income patients to PAs, either to improve the cost-effectiveness of their clinics or to direct their own time and resources towards a higher-income population.

Our analysis suggests that despite the evolving role of nonphysician clinicians, many of these practitioners continue to fulfill the role of providing access to care where it is most needed, often in lower-income rural areas. Our analysis also found a significant relationship between the type of provider seen and the patient's insurance type. Patients who paid out-of-pocket were more likely to visit a PA than were patients who paid using private insurance. Generally, patients who pay out-of-pocket might be thought to have a lower socioeconomic status than those who have private insurance. Although correlating source of payment with patient income level in a study such as ours is complicated, it is clear that visits made by patients who have any type of insurance are more likely to be paid for in full than are visits that are paid for out-of-pocket. Thus, the tendency of self-pay visits to be to PAs could be attributed to uncertainty within the practice that full payment for visits paid outof- pocket will be received.

Furthermore, in this population, patients with public insurance, such as Medicare, were less likely to visit PAs than were patients with private insurance. Patient race was also found to be an important predictor of PA visits. Nonwhite patients were more likely to visit PAs than were white patients. The comparatively lowersocioeconomic status of nonwhites in the United States further supports our hypothesis that poorer patients tend to be cared by PAs.

Our study does have some limitations. First, the data analyzed were collected from 1997 to 2003, and the role and distribution of PAs have evolved since then, with many PAs today practicing in specialties rather than in primary care and choosing to work in more metropolitan areas rather than in rural areas. In addition, we did not limit our analysis only to those physicians that employed PAs. Thus, the tendency for physicians to shunt lower-income patients to PAs could not be accurately assessed. Finally, our conclusions make assumptions about patient income level based on patient source of payment and metropolitan status of visit, which may be subject to bias in interpretations. Despite these limitations, the results of our study help us to understand the determinants of health care visits to PAs in the national population. The study lays a background for the future research that will be required to better understand the role of physician assistants in today's health care system. JAAPA

Forrest Staton is a student in the PA program; Fabian Camacho is a statistician in the Department of Public Health Sciences; and Steven Feldman is Professor of Dermatology, Pathology, and Public Health Sciences, all at Wake Forest University School of Medicine, Winston-Salem, North Carolina. Monali Bhosle is a graduate research associate in the Department of Pharmacy Practice and Administration; and Rajesh Balkrishnan is Merrell Dow Professor, College of Pharmacy and School of Public Health, both at Ohio State University, Columbus. 

REFERENCES

1. Grumbach K, Hart LG, Mertz E, et al. Who is caring for the underserved? A comparison of primary care physicians and nonphysician clinicians in California and Washington. Ann Fam Med. 2003;1(2):97-104.

2. Hoffman C. Medicaid payment for nonphysician practitioners: an access issue. Health Aff. 1994;13(4):140-152.

3. Hooker RS, Berlin LE. Trends in the supply of physician assistants and nurse practitioners in the United States. Health Aff. 2002;21(5):174-181.

4. Lin SX, Gebbie K, Fullilove R, Arons R. Characteristics of patient visits to nurse practitioners in hospital outpatient departments. J Prof Nurs. 2003;19(4):211-215.

5. Martin KE. A rural-urban comparison of patterns of physician assistant practice. JAAPA. 2000;13(7):49-50.

6. Roblin DW, Howard DH, Becker ER, et al. Use of midlevel practitioners to achieve labor cost savings in the primary care practice of an MCO. Health Serv Res. 2004;(39):607-626.