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The United Nations General Assembly designated 1999 as the
International Year of Older Persons. Population ageing is a major
focus of social and economic planners and policymakers in Australia.
One particular concern is to provide equitable, affordable and
appropriate health care services to older people.1
In 1998, in Australia, there were 2.3 million people aged 65 years and
over, including 976 500 who were
aged 75 years and over. The proportion of the population aged 65 and
over is projected to increase from 12% to 21% between now and
2031.2
Osteoarthritis, of which the principal symptoms are pain and
restricted joint movement, affects about 25% of people over 65 years
and contributes to restricted mobility, the most common form of
disability among older men and women.3
North American studies have shown that
total hip replacement and total knee replacement effectively reduce
pain and improve function in patients with advanced
osteoarthritis.4,5 Such
surgery is associated with significant improvements in health
status and quality of life. However, surprisingly little is known
about the epidemiology and outcomes of joint replacement surgery for
osteoarthritis in Australia.
To define the national practice and outcomes of joint replacement
surgery, the Australian Orthopaedic Association established the
National Joint Replacement Registry in 1998. The Registry has
received significant federal funding, is supported by industry and
has been defined as a Federal Quality Assurance Activity.
Data collected by the Registry from State and Territory health
departments indicated that, in 1997-1998, 13
545 primary total hip replacements and 15 599 primary total knee replacements were
performed in Australia. Data from a Registry pilot study of 260
patients undergoing these procedures indicated that about 90% were
performed for osteoarthritis and about 80% were in people aged 60
years and over (Dr S Graves, Project Director, Australian
Orthopaedic Association National Joint Replacement Registry,
personal communication).
In this issue of the Journal, March and colleagues6 have investigated whether hip and knee replacement restore
health-related quality of life (as measured with the Medical
Outcomes Study Short-Form 36 [SF-36]) to that of the age-matched
general population.
They found that total hip replacement reduced pain and improved
physical function in those undergoing surgery to that of the
age-matched population. Social function and overall vitality were
also restored. Although total knee replacement reduced pain and
improved physical function somewhat, postoperative scores,
particularly among younger patients, were still significantly less
than the population norm or scores for patients undergoing total hip
replacement. Similar findings have been reported
elsewhere7-9 March and colleagues have
suggested that these findings might be related to factors such as
unrealistic expectations or the presence of comorbidities. Others
have been unable to explain the apparent difference in outcome
between hip replacement and knee replacement as measured by the
SF-36.
Although it is possible that knee replacement is less effective than
hip replacement in improving quality of life, it is also possible that
the SF-36 is less responsive to change following knee replacement.
Perhaps restoration of hip function allows patients to perform the
activities defined on the SF-36 better than restoration of knee
function.
March et al noted that the general health of the younger patients
undergoing knee replacement declined in the year after surgery. It is
not clear to what extent the decline in health status was a contributor
to or a consequence of the poorer functional outcomes of surgery in
this age group. The effect of comorbidities on long-term outcomes
after joint replacement surgery requires further investigation.
Debate continues over the best way to assess the outcomes of joint
replacement surgery. Currently, radiological, functional, health
status, quality-of-life and global satisfaction instruments are
being used to provide comprehensive assessment. Yet, it appears that
the more generic the instrument, the less responsive it is to change
following joint replacement surgery.4 There is no clear
correlation between improvements in health status and health
perceptions after joint replacement surgery.10
Should we use disease-specific or more global quality-of-life
measures when trying to assess the value of therapy, particularly in
the elderly?
Disease-specific measures may provide more relevant information to
patients and clinicians than global measures. Patients can be told
that, after hip replacement, it is likely they will have less pain and
be able to better perform activities of daily living such as dressing,
sitting, walking or climbing stairs. The patient can then weigh these
benefits against the risks and complications of surgery and make an
informed decision. Patients may have more difficulty in making such
decisions if outcomes are expressed in terms of improved vitality or
sense of well-being, particularly if it is known that such outcomes
can be influenced by comorbidities.
On the other hand, global measures allow comparisons between hip
replacement surgery and treatments of other conditions, which might
help a patient to determine treatment priorities.
The best instrument is the one that measures the outcome of greatest
relevance. Our challenge, in the International Year of Older
Persons, must be to define the outcomes of greatest relevance to the
elderly.
Owen D Williamson
Orthopaedic Surgeon
Alfred Hospital, Melbourne VIC
email: owen.williamsonATbigpond.com
- Commonwealth Department of Health and Family Services Conference
for Older Australians Interim Report. Canberra: The Department,
1998 (Publication No. 2325).
-
Australian Bureau of Statistics. Australian Social Trends 1999.
Catalogue No. 4102.1, 1999.
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Australian Bureau of Statistics. National Health Survey: Summary
of Results. Canberra, ABS: 1995 (Catalogue No. 4364.0).
-
Kreibich DN, Vaz M, Bourne RB, et al. What is the best way of assessing
outcome after total knee replacement? Clin Orthop 1996; 331:
221-225.
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Laupacis A, Bourne R, Rorabeck C, et al. The effect of elective total
hip replacement on health-related quality of life. J Bone Joint
Surg [Am] 1993; 75-A: 1619-1626.
-
March LM, Cross MJ, Lapsley H, et al. Outcomes after hip or knee
replacement surgery for osteoarthritis. Med J Aust 1999;
171: 235-238.
-
Hozack WJ, Rothman RH, Albert TJ, et al. Relationship of total hip
arthroplasty outcomes to other orthopaedic procedures. Clin
Orthop 1997; 344: 88-93.
-
Van Essen GL, Chipchase LS, O'Connor D, Krishnan J. Primary total
knee replacement: short-term outcomes in an Australian population.
J Qual Clin Practice 1998; 18: 135-142.
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Birdsall PD, Hayes JH, Cleary R, et al. Health outcome after total
knee replacement in the very elderly. J Bone Joint Surgery
[Br] 1999; 81-B: 660-662.
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McGuigan FX, Hozack WJ, Moriarty L, et al. Predicting
quality-of-life outcomes following total joint arthroplasty.
Limitations of the SF-36 health status questionnaire. J
Arthroplasty 1995; 10: 742-747.
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