The Diffusion of Physicians
Thomas C. Ricketts, Ph.D.
Randy Randolph, M.R.P.
University of North Carolina at Chapel Hill
The “diffusion” of physicians
 Economists argue that there is marketresponsive diffusion from urban (more
dense) to rural (less dense) places.
(Newhouse, Rosenthal, Zaslavsky)
 The number of rural (and Urban)
physicians has increased overall.
 There is a mixed pattern of gains and
losses.
Change in Primary Care Physicians
to Population Ratio, 1995-2001
Alaska
and Hawaii
Not to Scale
*See Note
Change in PC Physician to Population Ratio
(# of Counties)
1.67 to 17.1
0.79 to 1.66
0.01 to 0.78
No Change
-0.01 to -0.41
-0.42 to -1.24
-1.25 to -15.6
(713)
(713)
(698)
(200)
(301)
(258)
(258)
*Alaska's state total is 2.47. County data were not available.
Sources: AMA Masterfile as reported in : HRSA, BHPr. Area Resource File, 2002.
Produced By: North Carolina Rural Health Research and Policy Analysis Center, Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill.
Question
What are the factors that predict
migration of physicians?
Economic
Personal
Ecological
How we did this?
 We linked the AMA Masterfiles from 1981,
1986, 1991, 1996, 2001, (2003) by
individual physician records
 Practice locations were linked to ARF data
for counties
Income, employment, race, education
Physician supply, hospitals
 We looked at physicians who moved from
one county to another (MOVERS) between
1981 and 1991 and 1991 and 2001
Specific Questions
Did doctors who moved move to
places with fewer docs (less
demand)?
Who were the MOVERS and who
were stayers?
Were there other factors that
influenced where MOVERS went?
Movers/Stayers, 1981-2001
1981-1991
Total active both years
297,466
Moved
Stayed
95,923 (32%)
201,541
To different state
58,709 (61%)
Female
15,632 (43%)
New to practice
19,418 (72%)
Primary care
27,064 (26%)
Total female
36,297
Total new to pract.
25,596
Total primary care
92,145
1991-2001
Total active both years
424,154
Moved
Stayed
152,829 (36% )
271,325
To different
state
93,989 (61%)
Female
Total female
38,535 (43%)
88,239
New to practice Total new to pract.
61,240 (76%)
85,512
Primary care
Total primary care
41,624 (27%)
152,829
Movement by Physician
Density Deciles 1991-2001
Low
TO
1
2
3
4
5
6
7
8
9
10
Total
1
2,809
1,946
1,432
923
1,101
1,142
1,055
1,162
919
517
13,007
2
2,145
1,627
1,582
1,181
1,048
1,071
795
1,026
797
654
11,928
3
1,979
1,646
1,373
844
929
1,180
943
1,039
1,257
629
11,822
4
1,874
1,894
2,082
1,553
1,353
1,391
1,221
1,284
1,101
1,904
15,661
FROM
5
1,202
1,601
1,352
1,337
1,743
929
897
767
755
700
11,288
1991
6
2,741
2,305
2,218
1,632
1,926
2,055
1,696
2,746
1,816
1,852
20,993
High
7
1,252
1,178
1,358
1,026
903
1,037
1,013
931
1,092
989
10,786
To Higher Ratio Class
Same Ratio Class
To Lower Ratio Class
8
2,273
2,149
1,897
1,668
1,566
1,773
1,467
1,864
1,627
1,099
17,391
9
1,414
1,688
1,775
1,512
1,902
1,976
1,353
2,326
2,401
2,576
18,932
10
1,386
1,829
2,237
1,714
1,616
2,165
2,150
2,343
2,555
3,071
21,076
35.2%
12.8%
52.0%
total
19,076
17,865
17,309
13,394
14,092
14,725
12,597
15,496
14,329
14,001
152,829
Long Term and Regional Flows
 83,383 Of 254,226 physicians (1981-2003)
were in primary care in both years.
59.3% remained in or returned to the same county
27.4 moved within region and type of county
13.2% moved to another rural-urban type of county or
different region
Flow from the Northeast and the Midwest to
South and West
Net flow from central metro counties (-2,512) to
small metro and adjacent counties, +1,837
Small net gain to nonmetro, nonadjacent, +675
Multivariate analysis
Two models predicting MOVE, one
for each 10-year period
County variables for Departure
county relate to initial year: 19811991
County variables for Destination
county relate to later year, 1991-2001
Regression results
Odds Ratios (Change of Sign, Significant Both Years)
Variables
1981-1991
FROM
TO
1991-2001
FROM
TO
Female
1.189
1.359
1.074
1.187
Age
0.903
0.900
0.907
0.901
Prim Care
0.974
0.750
0.990
0.733
Population
1.000
1.000
1.000
1.000
Ratio
1.053
0.955
1.010
0.991
Highsch %
1.000
0.998
0.998
0.999
Unempl
1.005
0.998
1.024
0.985
Nonwh ite
1.011
0.996
1.013
0.996
Income
0.956
1.014
0.986
1.005
Hosp
0.984
1.006
0.964
0.993
Conclusions
 Physician supply is dynamic, 33% in 5 yr
period
 Physicians go to places with fewer other
MDs but higher per capita income, fewer
non-whites, and lower unemployment
 Policies should recognize the dynamic
nature of the supply when considering:
Evaluation of programs (e.g.: retention rates in
context of normal flows)
Placement (prepare physicians for inevitable
geographic change)
The economic argument that diffusion meets
needs is confirmed but conditioned