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Number of Patient Visits Made to Physician Assistants
and Number of Medications Prescribed or Recommended by Physician Assistants in 2002

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Overview

The AAPA estimates that in 2002, approximately 183 million patient visits were made to physician assistants (PAs) and approximately 223 million medications were prescribed or recommended by PAs. The procedures and assumptions used to estimate the number of patient visits made to PAs and the number of medications prescribed or recommended by PAs are presented

Methodology

To estimate the total number of patient visits made to PAs and the total number of medications prescribed by PAs in 2002, we analyzed information from:

• The 2002 AAPA Market Research Survey (conducted at AAPA's annual conference in Boston, Massachusetts in May)
• The 2002 AAPA Physician Assistant Census Survey

The estimation process involved the following seven stages, which are discussed in greater detail below.

1. Estimating the mean number of medications prescribed per patient visit by PAs working in an exhaustive set of specialty categories during 2002
2. Estimating the number of PAs in clinical practice in each specialty during 2002
3. Estimating the mean number of patient visits per week made to a PA practicing each specialty
4. Estimating the total number of patient visits per week made to PAs practicing each specialty
5. Estimating the total number of visits made to PAs practicing each specialty during 2002
6. Estimating the total number of medications prescribed per week by the PAs practicing each specialty
7. Estimating the total number of medications prescribed by the PAs practicing each specialty during 2002

The estimates produced in each stage for the PAs practicing each specialty and the total population of clinically practicing PAs are presented in the attached table.

Stage 1: Estimating the Mean Number of Medications per Visit
As part of the 2002 AAPA Market Research Survey, AAPA collected data about:

• The primary specialty practiced by each PA (categories represented an exhaustive set of 14 mutually exclusive specialties)
• The numbers of visits made to each PA in a typical week
• The number of medications prescribed or recommended by each PA in a typical week

We used these data to estimate the mean number of medications prescribed or recommended per patient visit to a PA practicing each specialty. However, because the sample was relatively small (relevant data were available for 2524 PAs), self-selected, and limited to conference attendees who are disproportionately AAPA members and from geographic areas more proximate to the site of the conference, we did not use these data to estimate the total number of patient visits made to PAs or the number of medications PAs prescribed.

Our specific procedures involved the following two steps.

• We divided the number of medications prescribed by the number of visits to calculate the mean number of medications prescribed per visit.
• We summed the mean numbers of medications prescribed per visit for all of the PAs practicing each specialty and divided the resulting sum by the number of PAs practicing that specialty. The results of those calculations represent the mean numbers of medications prescribed per visit to a PA practicing each specialty in 2002. These estimates are presented in column B of the attached table.

Stage 2: Estimating the Number of PAs in Clinical Practice
As part of the 2002 AAPA Physician Assistant Census Survey, we collected data about clinical practice status and the specialty practiced most frequently in the primary job (defined as the one in which the most time was spent providing clinical services). Since we believe that the 2002 AAPA Physician Assistant Census Survey respondents adequately represented the population of clinically practicing PAs during 2002, we used this information to estimate the number of PAs practicing each specialty in 2002. Specifically, we calculated the number of PAs practicing each specialty separately for AAPA fellow members, potential fellow members, and new PA program graduates because we have consistently found in our surveys that members of these groups have had significantly different practice status and specialty distributions.

Finally, to estimate the total number of PAs practicing each specialty, we summed the estimates produced for the three groups. The estimated numbers of clinically practicing PAs in each specialty are presented in column C of the attached table. For more details about our methodology for projecting the number of people in clinical practice as PAs, please refer to Information Update: Projected Number of PAs in Clinical Practice as of January 1, 2003: AAPA, 11/1/2002.

Stage 3: Estimating the Mean Number of Visits per Week
As part of the 2002 AAPA Physician Assistant Census Survey, we also collected data about:

• The number of visits made per week to each PA in the primary job
• The number of hours worked per week by each PA in the primary job
• The number of hours worked per week by each PA in all clinical PA jobs

As a first step in this stage, we prepared for each specialty a separate estimate for AAPA fellow members, potential fellow members, and 2002 graduates. Next, we calculated the weighted average of these estimates to reflect the proportion of the total number of PAs practicing the specialty who were members of each group.

To estimate the total number of visits made per week to each PA at all of his/her clinical PA jobs, we multiplied the number of visits made to the PA per hour of work at the primary job by the total number of hours worked at all clinical PA jobs. Please note that these figures needed to be estimated because no information was collected on the number of visits made per week to the PAs at their secondary jobs. In addition, since no information was collected on the specialty practiced at secondary jobs or the nature of the secondary employers, this estimation procedure required us to assume that PAs with multiple jobs practiced the same specialty and were responsible for the same number of visits per hour at all their jobs. Our estimates of the mean numbers of patient visits made per week to a PA in each specialty and overall are presented in column A of the attached table.

Stage 4: Estimating the Number of Visits Made to PAs per Week
To estimate the number of visits made per week to all PAs practicing each specialty, we multiplied our estimate of the total number of PAs in the specialty by the estimated mean number of patient visits made per week to a PA practicing the specialty. These estimates are presented in column D of the attached table.

Stage 5: Estimating the Number of Visits Made to PAs per Year
For these estimates, we multiplied the estimated total number of patient visits made per week to all PAs in each specialty group by 50 weeks for the PAs who graduated before 2002. For PAs who graduated in 2002, we multiplied the weekly total by 25 weeks to accommodate our belief that most new graduates would have been in practice for only about half of 2002. These estimates are presented in column F of the attached table.

Stage 6: Estimating Total Medications Prescribed or Recommended per Week
To estimate the number of medications prescribed per week by the PAs practicing each specialty, we multiplied the estimated number of patient visits made per week to all PAs practicing the specialty by the estimated mean number of medications prescribed or recommended per visit by a PA in that specialty. These estimates are presented in column E of the attached table.

Stage 7: Estimating Total Medications Prescribed or Recommended per Year
For these estimates, we multiplied the estimated total number of medications prescribed per week by all PAs in each specialty group by 50 weeks for the PAs who graduated before 2002. For PAs who graduated in 2002, we multiplied the weekly total by 25 weeks to accommodate our belief that most new graduates would have been in practice for only about half of 2002. These estimates are presented in column G of the attached table.

Findings

The following represent some of the more interesting estimates produced through these analyses.

• PAs practicing general pediatrics, family practice medicine, and emergency medicine accounted for more patient visits per week (95, 95, and 93 visits, respectively) than did PAs practicing other specialties.
• PAs practicing general internal medicine wrote many more prescriptions per visit (1.5) than did PAs practicing other specialties.
• During 2002, more PAs (35%) practiced family medicine than any other specialty. These PAs accounted for approximately 40 percent of the patient visits made to PAs during 2002 and approximately 46 percent of the total number of medications prescribed or recommended by PAs during 2002.

Estimated Number of Patient Visits and Medications Prescribed or Recommended by Physician Assistants in 2002

	A Mean Visits to Each PA per Week (a)	B Mean Prescriptions per Visit	C Number of PAs in Practice	D Total Visits to PAs per Week	E Total Prescriptions by PAs per week	F Total Visits to PAs in 2002 (b)	G Total Prescriptions by PAs in 2002 (b)
Family Practice	95.29	1.41	15,996	1,524,248	2,145,993	73,527,051	103,518,907
General Internal Medicine	76.24	1.5	4,319	329,247	494,280	15,822,794	23,753,927
Internal Medicine: Cardiology	62.96	1.08	1,237	77,886	83,968	3,703,732	3,992,980
Other IM Subspecialty	62.22	1.17	2,862	178,108	208,237	8,471,114	9,904,135
Obstetrics/gynecology	73.62	0.86	1,307	96,184	82,907	4,585,074	3,952,129
Emergency Medicine	93.04	1.19	5,286	491,771	587,573	23,738,012	28,362,426
General Pediatrics	95.44	0.86	1,373	131,083	113,372	6,287,087	5,437,622
Pediatric Subspecialty	52.82	1.12	777	41,026	45,891	1,972,932	2,206,863
General Surgery	63.96	0.69	896	57,300	39,592	2,708,896	1,871,763
Cardiovascular Surgery	50.25	1.06	1,304	65,549	69,792	3,139,068	3,342,300
Orthopedic Surgery	75.42	0.73	2,770	208,908	153,527	9,858,110	7,244,756
Other Surgical Subspecialty	63.80	0.87	2,276	145,210	125,740	6,905,131	5,979,301
Occupational Medicine	87.41	0.65	1,442	126,080	82,159	6,213,625	4,049,029
Other	82.13	1.23	4,157	341,443	420,350	16,164,392	19,899,955
Total	82.91	1.22	46,002	3,814,043	4,653,383	183,097,016	223,516,092

1. The mean numbers of visits and prescriptions per week are rounded to 2 decimal points; therefore, the totals presented cannot be accurately reproduced from the figures presented.
2. The annual totals project output of a 50-week work year for PAs graduating before 2002 and a 25-week work year for PAs graduating in 2002.

Data sources: 2002 AAPA Market Research Survey, 2002 AAPA Physician Assistant Census Survey, and AAPA Masterfile, 10/31/2002.

 

 

Last Revised: 11/7/02