Sot. Sri. & Med. Vol. 16. pp. 85 to 90. 1982
Printed in Great Britam. All rights reserved
‘kwlght
0277-9536/82/010085-06803.00,0
0 1982 Pergamon Press Ltd
MEASURING POTENTIAL PHYSICAL ACCESSIBILITY
TO GENERAL PRACTITIONERS
IN RURAL AREAS:
A METHOD AND CASE STUDY
ALUN E. JOSEPH and PETER R. BANTOCK
Department
of Geography, University of Guelph. Guelph, Ontario, Canada
Abstract-The
general practitioner is the key element within most rural health care delivery systems,
virtually controlling referral to higher levels of care as well as providing basic care. In consequence of
the progressive urban-based centralization of health care facilities and specialized personnel encouraged
by the desire to take advantage of economies of scale in supply, the role of the general practitioner
within rural health care delivery has become increasingly crucial. However, the supply of general
practitioners in rural areas has not kept pace with demands, and accessibility to physicians has become a
pressing issue in many rural areas. Although ‘accessibility’ is not taken to be synonymous with physical
or geographical accessibility, the dispersed settlement characteristic of most rural areas elevates the
latter to a position of primary importance. Following a discussion of the merits of measures of accessibility based upon utilization versus measures based upon the relative location of population and physicians, a measure on potential physical accessibility is presented and applied to a Canadian data set. The
results Suggest that although considerable differences in potential accessibility exist between rural areas
near and far from urban centres, the smaller catchment populations of most rural general practitioners
may partly compensate for isolation from major, urban concentrations of physicians.
INTRODUCTION
The importance
of the general practitioner
within
advanced health care delivery systems is widely recognized [l]. The general practitioner
provides not only
basic care but also acts as a referral agent or filter to
higher levels of care [Z]. Thus, accessibility to general
practitioners is an issue of considerable importance
within any consideration of the effectiveness of health
care delivery. Although accessibility has been shown
to be a function of aspatial factors (e.g. intake policy,
perceived status of facility, etc.) [3] as well as of
spatial ones (namely, distance of potential client from
source of treatment), the enduring importance of the
latter is reflected in the persistence of distance decay
effects in the utilization patterns of most health care
facilities [4]. The focus here is upon physical accessibility to general practitioners in rural areas, or, to be
more precise, upon its measurement.
It would be naive to suggest that the physical
accessibility or nearness of general practitioners to
potential clients is the sole issue of importance in
rural health care delivery. There exist serious problems, too, in terms of the quality of rural facilities [S]
and the availability of emergency treatment [6].
Nevertheless, the general question of physical accessibility has always been a pressing one in the rural
context because the low density and- high dispersion
of most rural populations means that greater average
separation between potential client and source of
treatment in rural areas compared to urban areas is
inevitable if supply thresholds are similar. Moreover,
this problem of intrinsically inferior physical accessibility to health care services in rural areas stemming
from settlement conditions has been made more
acute by recent developments in health care delivery
systems.
In the early decades of this century medical care in
advanced societies was provided almost entirely by
the general practitioner and, given the relatively
limited sophistication
of treatment, most of the
resources needed for the administration of care could
be carried with the individual physician. With the
passage of time the practice of medicine has advanced
to levels at which treatment often involves swift and
frequent access by the general practitioner to a wellequipped office, clinic or hospital, as well as to a host
of ancillary or specialized medical personnel [7].
Health care delivery has evolved from being homebased to being facility-based, with the hospital
becoming an increasingly vital element within health
care systems. Thus, in the United States, the annual
rate of admission to hospitals, which stood at 59 per
loo0 in 1935, had risen to 130 per 1000 during the
1960s [S].
Through increasing the need for sophisticated and
costly equipment, advances in medical technology
have pushed considerations of economies of scale to
the forefront of health care planning [9]. Increasingly
large catchment populations are required to ensure
maximum return on investment in equipment and
personnel. In geographic terms, this translates into a
need to progressively centralize services into larger
facilities. Such tendencies toward centralization
at
best aggravate existing problems of physical accessibility to services in rural areas, at worst they can
mean the disappearance of certain types of services
from areas with populations below critical thresholds.
Invariably, the centralization of services puts the general practitioner into a crucial position within the
rural health care delivery picture, not only as the
main provider of care in the growing absence of alternative sources such as clinics and hospitals, but also
as the access point to an increasingly complex health
care system. However, the supply of general practitioners in rural areas may not always be sufficient for
these functions to be performed properly.
Spatial inequality in the supply of general practi85
ALUN E. JOSEPHand PETER R. BANTOCK
86
tioners has long been regarded as an important health
care delivery problem [lo], particularly in rural areas
[I I]. Historically, the shortfall in rural physicians has
developed in parallel with, and as a Primary consequence of, the overall developments in health care
delivery discussed above. In the United States, for
instance, rural areas with 53% of the total national
population had 41% of all physicians in 1906 but, by
1926, the corresponding percentages were 48 and 31.
indicating a marked decline in the availability of rural
physicians [ 121.
Broadly speaking, the rural-urban
imbalance in
physician supply reflects the increasing urban-orientation of medical education and the attractiveness of
practices located within easy reach of a wide range of
support facilities and personnel [13]. It has been suggested that inequalities in supply would be reduced if
the overall supply of doctors was increased [14];
underserviced areas, rural or otherwise, would gradually see an increase in their supply of doctors as the
absolute number of physicians increased [lS]. However, this has not always occurred [16]. Indeed,
increases in the supply of physicians has often exacerbated problems of maldistribution. This was particularly evident in Ontario, Canada during the 1960s.
Physician supply increased by 45% during the decade,
while the province’s population increased by only
25%. Although most areas increased their number of
doctors, distribution disparities actually increased,
with rural areas being the most negatively affected
c171.
Given the importance of physical accessibility to
general practitioners within the functioning of rural
health care systems, there is a clear need to be able to
measure accessibility conditions in a simple and unambiguous manner. In this way ‘black spots’ could be
identified and steps taken to ameliorate adverse conditions. The remainder of this paper is devoted to the
presentation of a simple measure on physical accessibility and the consideration of results from a trial
application.
relative importance of which will be time and space
specific.
The second approach to the measurement
of
accessibility to general practitioners focuses upon the
physical or geographical accessibility of the population to general practitioners and is thus much more
specific than the measure based upon utilization. Such
a measure is best termed ‘potential’ physical accessibility because no actual interaction between the two
sides of the demand-supply equation is implied. Although examples of potential accessibility measures
are common in other areas of geography. most notably in economic geography, applications in medical
geography are rare. Indeed. the only one we are
familiar with in the general practitioner context is
that reported on by Barnett [23], who examined
potential accessibility to general practitioners in two
New Zealand urban areas. Unfortunately the measure
used by Barnett has several shortcomings. which have
been discussed by Joseph [24], so a different measure
is used here.
A measure on potential physical accessibility to general
practitioners
Given a maximum range for the service offered by a
general practitioner and assuming that each and every
member of the population is a potential user of general practitioner services. the pattern over space of
physical accessibility will depend only upon the relative location of population and physicians.
Research on the utilization of health care services
suggests a continuous but progressive impact of distance from facility or personnel on the probability of
utilization [25]. Thus a simple measure on potential
physical accessibility would be
Aj =
c
GP,Id$
(1)
where:
Ai = potential physical accessibility of area i to
general practitioners;
MEASURING
ACCESSIBILITY TO GENERAL
PRA~ITIONERS
There are two basic approaches to measuring
accessibility to general practitioners: the first involves
the measuring of actual or revealed accessibility
through analysis of utilization data; and, the second,
the measurement of potential physical accessibility
based upon the location of population relative to that
of physicians.
Geographical analyses of health care utilization
PatternS are numerous
[lf?]. Examples with an
emphasis on the utilization of genera1 practitioner
services are presented by Phillips [19] and by Girt
1201. Although work such as this is critical in demonstrating basic regularities, both spatial and aspatial. in
utilization patterns, post facto measures of accessibility based upon utilization are constrained in their
usefulness by the complexity of utilization behaviour.
Such behaviour. although strongly influenced by sup
ply-demand locational relationships [21], is a function also of other. less well-understood factors such as
territoriality, action space and intake policy [22]. the
GPj = general practitioner
at j within the range of
area i;
dij = distance between i and j: and
b = exponent on distance.
However, this formulation does not take into account
the differential availability of physicians, in that those
with heavily populated catchment areas will, in all
likelihood, be effectively less available than those with
less heavily populated ones. This differential availability can be estimated as follows:
Dj = 1 Pi/dTi.
i
That is. the potential demand on a doctor at j, Dj is a
function of the magnitude of the population within
the range of the service offered (i.e. within the doctor’s
catchment area), modified by their distance away. By
combining equations (1) and (2), we arrive at a dimensionless but internally consistent measure on potential
physical accessibility to general practitioners, At. that
combines a realistic assumption of utilization behav-
Physical accessibilityto general practitionersin rural areas
iour with a weighted estimate of physician availability.
The merit of this measure on physical accessibility
lies not only in its uniimbiguous focus on the poten-
tial impact of locational relationships on the functioning of the general practitioner component of the rural
health care delivery system, but also in its conservative data requirements. As opposed to measures on
revealed accessibility based upon utilization,
which
demand reliable and detailed information
over
reasonably long time periods [26], the potential
physical accessibility measure can be calculated with
data on population distribution and physician location only, which are usually available in published
form.
A CASE STUDY
The case study was carried out in Wellington
County in Southern Ontario (Fig. 1). Population data
were obtained at the enumeration area level from the
1976 census [27], while the location of general practitioners (Fig. 1) was taken from a survey carried out in
1978 by the local District Health Council 1281. It
should be noted that several general practitioners
located
. _- -outside the county boundary are known to
serve the population of the study area-[29]. These
physicians are included in the calculation of potential
physical accessibility and their availability is estimated in the normal fashion (equation (2)). Distances
are measured between enumeration area centroids.
Before applying the measure of potential physical
accessibility to the Wellington County data, values for
the exponent on distance, b, and for the range of the
service offered by general practitioners were set. The
former was set always ai 2.0 in light of empirical work
on various types of interaction [30], while three
values, 5, 10 and 15 miles, were used in turn for the
latter. The reluctance to set a single value for one
constant but not the other reflects the degree to which
their roles in this sort of .measurement are understood. The impact of varying the exponent on distance has been investigated elsewhere [31]; in short,
an increase in the exponent reduces the measured
accessibility of distant places, whereas a reduction in
its value will increase the measured accessibility of
those same places. Conversely, the impact of altering
the range of service limit has not been investigated
empirically.
RtWh
Calculated values for the potential physical accessibility measure with the service range set, in turn, at 5,
10 and 15 miles are mapped in Figs 2a, 2b and 2c
respectively. Note that scores have been raised by a
constant of 10’ to help interpretation. Although the
dimensionless nature of the measure makes it impossible to compare absolute enumeration area scores
produced with different range of service values.
changes in the relative pattern of potential physical
accessibility are noticeable.
With a service range of 5 miles, a stark contrast
87
exists between the potential physical accessibility of
rural areas near to urban centres, the location of genera1 practitioners, and those less so (Fig. 2a). Indeed,
Se%%ralenumeration areas are beyond the range of the
nearest general practitioner and have a score of 0.0.
When the service range is extended to 10 miles
(Fig. 2b), only one enumeration area has a potential
physical atissibiTiiy score of 0.0 and, as would be
expected, the overall pattern displays a systematic,
though minor, reduction of the disparity between
rural areas near and far from urban centres. Extension of the service range to 15 miles has only a minor
impact on the pattern of potential physical accessibility (Fig. 24. Indeed, it appears that the measure is
not very sensitive to change in the service range
beyond that distance at which most or all areas are
within the range of the service. This limited sensitivity
stems of course from the progressive impact of the
exponent on distance in equation (3), which exponentially reduces the contribution to potential accessibility of physicians at increasing distances away.
As a final step in the analysis, potential physical
accessibility scores were re-calculated for a service
range of 10 miles using equation (1) instead of equation (3) (Fig. 2d). Comparison of the two patterns
(Figs 2b and 2d) underlines the importance of weighting the availability of doctors, as represented by equation (2). The unweighted pattern is dominated by the
concentration of general practitioners in Guelph, 52
of the 89 in the study; thus, only one enumeration
area in the four most northerly townships away from
Guelph has a score above the lowest category. In contrast, the pattern produced by the weighted measure
is more complex; in the same four northern townships
six enumeration areas have scores above the lowest
category. By assuming each physician to be fully
available regardless of the size of his catchment area
population, the unweighted measure makes the disparity between rural areas near to urban centres and
those further away appear worse than it may actually
be. In all probability, although physicians in more
isolated rural areas may be at some distance from
potential clients, they are likely to be more available
to them, which serves to compensate in part for the
inherent disadvantage of isolation from major, urban
concentrations of general practitioners.
CONCLUSIONS
This paper has considered the nature and importance of physical accessibility to general practitioners
as a problem in rural health care delivery and has
presented and applied a method for measuring such
accessibility. Although the results produced in the
case study are in many ways specific to the conditions
prevalent in Wellington County, they suggest that in
areas where the settlement pattern and associated distribution of general practitioners is reasonably well
developed, the underservicing of more remote rural
areas may not be as pronounced as suggested by
gross locational
relationships.
namely
distance
between potential clients and major concentrations of
physicians. However. despite the relatively greater
‘availability’ of general practitioners in some rural
areas. considerable disparities do exist between areas
near and far from urban centres, and will continue to
AWN E. JOSEPHand PETERR. BANTOCK
88
SO"THERN“‘““I-
TOWN!JlilP BOUNDARY
_---
ENUMERATION AREA
BOUNDARY
!33lLEMENT
NUMBER Of GENERAL
PRACTlTlONERS
Fig. 1. The study area: administrative boundaries and location of general practitioners.
Physical accessibility to general practitioners
in rural areas
b) 10
a) 5 Miles
Miles
,
ban
Scwe
g
=
Mean Score--Z.52
2.04
0.00
r-J
0.00
0.01 - 1.02
m
0.01 - 156
m
137-2.52
1.03 -2.04
2.05 -3.07
2.53 - 3.70
>
>
3.07
Settlemenh
Sefflements
C) 15
3.78
d)
Miles
10
Miles
LJean score-2.57
m
0.01 -1.26
m
1.29 - 2.57
f-?j
0.01 - 0.56
2.56 -3.66
m
0.57 - 1.12
fggj
>
kss!
1.13 -1.66
3.66
> 1.66
SettlCWWltS
k
Fig, 2. Potential physical accessibility to general practitioners:
trial results.
89
ALUN
90
E. JOSEPHand PETERR.
do so as long as the centralization of health care services and personnel continues and distance still acts
as a deterrent to utilization.
The solution to major rural health care delivery
issues, amongst which physical accessibility to general
practitioners must rank as one of the most important,
lies with those who determine health care priorities
and strategies. The intention of this paper has been
the modest one of suggesting a method for measuring
disparities in potential physical accessibility to the
key element within the rural health care delivery system, the general practitioner. The measure developed
is simple yet realistic and uses data readily available
in most health care systems. Hopefully, it will prove
useful to others interested in rural health care delivery. perhaps in conjunction with detailed investigation of the role of the general practitioner.
7. Hassinger E. W. Pathways of rural people to health
services. In Hassinger and Whiting op. cit.. pp. 164-87.
8. Andersen 0. W. and Anderson R. M. Patterns of use
bf health services. In Handbook of Medical Sociology
(Edited by Freeman H. R.. Levine S. and Reader L.
G.), pp. 386-407). Prentice Hall. Englewood Cliffs. NJ.
1972.
9. Migue J. L. and Belanger G. The Price o/Health. Macmillan of Canada. Toronto. 1974.
10. Shannon and Dever, op. cit.
11. Garfield S. R. The delivery of medical care. Scienr. Am.
222, 15. 1970.
12. Shannon and Dever. op. cit.
13. Hassinger, op. cit.
14. Pyle G. F. Applied Medical Geography. Winston &
Sons, Washington DC., 1979.
15. Barnett J. R. and Sheerin I. G. Inefficiency and inequality: an evaluation of selected policy responses to
medical maldistribution
in New Zealand. Commun.
Hlth
are grateful to the Ontario Ministry of Agriculture and Food for financial support under
Program 40.
Acknowledgements-We
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26 Joseph A. E. and Boeckh J. L. Locational variation in
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