The “diffusion”
diffusion” of physicians
The Diffusion of Physicians
Thomas C. Ricketts, Ph.D.
Randy Randolph, M.R.P.
University of North Carolina at Chapel Hill
z Economists argue that there is marketmarketresponsive diffusion from urban (more
dense) to rural (less dense) places.
(Newhouse,
Newhouse, Rosenthal, Zaslavsky)
Zaslavsky)
z The number of rural (and Urban)
physicians has increased overall.
z There is a mixed pattern of gains and
losses.
Change in Primary Care Physicians
to Population Ratio, 1995-2001
Question
z What are the factors that predict
migration of physicians?
VEconomic
VPersonal
VEcological
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.
How we did this?
z We linked the AMA Masterfiles from 1981,
1986, 1991, 1996, 2001, (2003) by
individual physician records
z Practice locations were linked to ARF data
for counties
VIncome, employment, race, education
VPhysician supply, hospitals
z We looked at physicians who moved from
one county to another (MOVERS) between
1981 and 1991 and 1991 and 2001
Specific Questions
z Did doctors who moved move to
places with fewer docs (less
demand)?
z Who were the MOVERS and who
were stayers?
stayers?
z Were there other factors that
influenced where MOVERS went?
1
Movement by Physician
Density Deciles 19911991-2001
Movers/Stayers,
Movers/Stayers, 19811981-2001
Low
TO
1981-1991
1991-2001
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
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
Long Term and Regional Flows
z 83,383 Of 254,226 physicians (1981(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 ruralrural-urban type of county or
different region
VFlow from the Northeast and the Midwest to
South and West
VNet flow from central metro counties (-2,512) to
small metro and adjacent counties, +1,837
VSmall net gain to nonmetro, nonadjacent, +675
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
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
Nonwhite
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
1.187
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
7
1,252
1,178
1,358
1,026
903
1,037
1,013
931
1,092
989
10,786
8
2,273
2,149
1,897
1,668
1,566
1,773
1,467
1,864
1,627
1,099
17,391
To Higher Ratio Class
Same Ratio Class
To Lower Ratio Class
9
1,414
1,688
1,775
1,512
1,902
1,976
1,353
2,326
2,401
2,576
18,932
High
10
1,386
1,829
2,237
1,714
1,616
2,165
2,150
2,343
2,555
3,071
21,076
total
19,076
17,865
17,309
13,394
14,092
14,725
12,597
15,496
14,329
14,001
152,829
35.2%
12.8%
52.0%
Multivariate analysis
z Two models predicting MOVE, one
for each 1010-year period
z County variables for Departure
county relate to initial year: 198119811991
z County variables for Destination
county relate to later year, 19911991-2001
Conclusions
z Physician supply is dynamic, 33% in 5 yr
period
z Physicians go to places with fewer other
MDs but higher per capita income, fewer
nonnon-whites, and lower unemployment
z Policies should recognize the dynamic
nature of the supply when considering:
VEvaluation of programs (e.g.: retention rates in
context of normal flows)
VPlacement (prepare physicians for inevitable
geographic change)
VThe economic argument that diffusion meets
needs is confirmed but conditioned
2