Abstract
Background No population-based studies have investigated how the impact of hip and knee joint disease may vary with increasing severity.
Objective The purpose of this study was to evaluate health-related quality of life (HRQoL), work status, and health service utilization and costs according to severity of hip and knee joint disease.
Design A national cross-sectional survey was conducted.
Methods Five thousand individuals were randomly selected from the Australian electoral roll and invited to complete a questionnaire to screen for doctor-diagnosed hip arthritis, hip osteoarthritis (OA), knee arthritis, and knee OA. Severity was classified by means of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (range=0–100): <7=asymptomatic, 7–38=mild-moderate, and ≥39=severe. Health-related quality of life was evaluated by means of the Assessment of Quality of Life (AQoL) instrument (range=−0.04 to 1.00; scored worst-best). Self-reported data on work status and health service utilization were collected, with health care costs estimated with the use of government data.
Results Data were available for 1,157 participants, with 237 (20%) reporting hip or knee joint disease. Of these, 16% (n=37) were classified as asymptomatic, 51% (n=120) as mild-moderate, and 27% (n=64) as severe. The severe group reported very low HRQoL (adjusted mean AQoL=0.43, 95% confidence interval [95% CI]=0.38–0.47) compared with the mild-moderate group (adjusted mean AQoL=0.72, 95% CI=0.69–0.75) and the asymptomatic group (adjusted mean AQoL=0.80, 95% CI=0.74–0.86). Compared with the asymptomatic group, the severe group was >3 times less likely to undertake paid work (adjusted odds ratio=0.28, 95% CI=0.09–0.88) and >4 times less likely to undertake unpaid work (adjusted odds ratio=0.24, 95% CI=0.10–0.62). Although physical therapy services were used infrequently, primary and specialist care utilization and costs were highest for the severe group.
Limitations Other costs (including physical therapy consultations) were unavailable.
Conclusions A clear pattern of worsening HRQoL, reduced work participation, and higher medical care utilization was seen with increasing severity of joint disease.
Severe hip and knee joint disease is associated with significant pain1 and reduced function1,2 and is a growing burden on health services for many countries.3–5 This problem is best evidenced by rising rates of hip and knee replacement in Australia and internationally3,6,7 and projected future demand.8,9 The magnitude of the problem is further highlighted by recent research that estimated that 20% of adults aged 60 to 64 years in the United States will have advanced knee osteoarthritis (OA) in the next decade.5
The personal and economic burden of severe hip and knee joint disease is not well understood. Our research has shown that people with severe hip or knee arthritis waiting for joint replacement surgery had very poor health-related quality of life (HRQoL) and greater psychological distress compared with Australian population norms.2,10 Conducted at a single teaching hospital, this study provided important preliminary information about the impact of severe arthritis, which we planned to further evaluate (in terms of HRQoL, participation in paid and unpaid work, and health service utilization) in a national survey. Although clinical studies11,12 have investigated well-being and health service utilization among people with end-stage hip or knee joint disease (severe joint disease requiring joint replacement surgery), it is not known whether these data are generalizable beyond surgical waiting list settings. Importantly, how the impact of hip and knee joint disease might vary with increasing disease severity remains unclear, given the absence of comparison groups in these settings.
To improve understanding of the broader burden of severe hip and knee joint disease, this national study aimed to compare the following factors according to disease severity: (1) HRQoL, (2) paid and unpaid work status, and (3) health care utilization and prevalent costs.
Method
Study Design
A cross-sectional, population-based survey was undertaken to estimate the national burden of severe hip and knee OA in Australia, in terms of HRQoL, paid and unpaid work participation, and health care utilization.
Population and Recruitment
This research was approved by The University of Melbourne Human Research Ethics Committee (HREC). Following approval from the Australian Electoral Commission (AEC), an extract of the Australian electoral roll was obtained containing name, age group, sex, and address details for a random sample of 10,000 individuals drawn from all electoral divisions. This extract was used to randomly select a sample of the Australian population age ≥39 years from all states and territories (N=5,000), stratified by age group (Fig. 1). The 2 lowest age groups (39–43 years and 44–48 years) were over-sampled to increase precision, on the basis of an anticipated lower prevalence of joint disease among younger people.13,14
Study flowchart.
In June 2009, an introductory letter, plain language statement, and study questionnaire were mailed to the selected sample with reply-paid envelopes to maximize response rates. To minimize participant burden, return of a completed questionnaire was deemed to constitute consent. This procedure was approved by the HREC. Limited follow-up with repeat administration of the study questionnaire was undertaken for a random sample of nonparticipants (stratified by state and territory, n=300). All questionnaires marked “return to sender” were re-sent where an alternative address could be located.
Because individual knowledge of arthritis type can be limited,15,16 the questionnaire was designed to screen for doctor-diagnosed hip arthritis, hip OA, knee arthritis, and knee OA. Screening was performed with the use of self-reported measures, similar to the methods used previously.16,17 The following questions were used:
“Have you ever been told by a doctor or other health professional that you have hip arthritis?”
“Have you ever been told by a doctor or other health professional that you have hip osteoarthritis?”
“Have you ever been told by a doctor or other health professional that you have knee arthritis?” and
“Have you ever been told by a doctor or other health professional that you have knee osteoarthritis?”
Questionnaires
Self-reported measures were used to classify the severity of hip and knee joint disease and evaluate HRQoL. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a disease-specific measure of health status commonly used in OA research18 and has demonstrated validity, reliability, and responsiveness.19 The WOMAC score is commonly transformed to a 0 (best health) to 100 (worst health) scale. Among participants with hip or knee arthritis or OA, this score was used to classify joint disease severity, similar to methods used previously.20 A WOMAC score of <7 was considered to be asymptomatic joint disease, a score of 7 to 38 was considered to be mild-moderate disease, and a score of ≥39 was considered to be severe joint disease. In their Canadian population-based study, Hawker et al21 used a score of ≥39 to classify severe arthritis potentially requiring joint replacement. This cutoff score equated to the 25th percentile of WOMAC scores for individuals undergoing hip or knee replacement surgery and approximately 90% of those with a score ≥39 had evidence of arthritis on radiographic and clinical examination. The Assessment of Quality of Life (AQoL) instrument is an Australian generic measure of HRQoL with robust psychometric properties.22 It has been used previously to evaluate HRQoL in arthritis2,23 and produces a utility score ranging from −0.04 (worst HRQoL) to 1.00 (full HRQoL).
Self-reported demographic, employment, and health service utilization information also was collected. Demographic data included date and country of birth, height, weight, marital status, and highest level of education completed. Employment information covered paid and unpaid work status, premature exit from the workforce because of hip or knee arthritis or OA, and changes to work because of hip or knee arthritis or OA. Health service utilization (specifically for hip or knee arthritis or OA) included number of visits to general practitioners (GPs), orthopedic surgeons, rheumatologists, physical therapists, and other health professionals in the previous month and previous hip or knee surgery.
Estimation of Health Care Costs
We assumed that all treatment was provided in public health care settings and costs were estimated from the perspective of the Commonwealth and State governments, which fund the majority of public health care in Australia. The direct costs included in these analyses relate specifically to hip arthritis, hip OA, knee arthritis, knee OA, or all. All costs are reported in Australian dollars (A$1.00=US$1.04).
Primary and specialist care costs were estimated by means of 2012 Medicare Benefits Schedule (MBS) data.24 The MBS is a list of health services subsidized by the Australian government. The unit cost associated with a GP consultation was A$35.60 (item 23, level B consultation of <20 minutes), and the cost associated with an orthopedic surgeon, rheumatologist, or other medical specialist or surgeon consultation was A$31.65 (item 105, subsequent specialist attendance). Physical therapy and other allied health care costs could not be estimated because these costs are not covered under the MBS scheme.
Previous hip and knee surgery was categorized through the use of Australian-Refined Diagnosis Related Groups (AR-DRG).25,26 The AR-DRG classification provides the foundation for case mix funding in Australia and is based on resource homogeneity (every patient within the same AR-DRG is assumed to consume the same amount of resources). The average total cost per AR-DRG was extracted from the National Hospital Cost Data Collection Cost Report Round 13 version 5.2 (2008–2009), except for tibial osteotomy and revision knee replacement procedures (for which costs were extracted from Round 13 version 6.0).27 By use of a conservative approach, these estimates excluded costs associated with perioperative or postoperative complications.
Data Analysis
Body mass index (BMI) was calculated by means of self-reported height and weight and classified into underweight/normal weight (BMI ≤24.99 kg/m2), overweight (BMI 25–29.99 kg/m2), and obese (BMI ≥30 kg/m2) categories.28 Residential location was classified as metropolitan or provincial/rural on the basis of AEC ratings.29 Socioeconomic status was approximated by means of post codes to link to the Australian Socio-Economic Indexes for Areas (SEIFA) 2006 Index of Relative Socio-Economic Advantage and Disadvantage.30
Preliminary analyses revealed considerable overlap between diagnoses of arthritis and OA. For example, of those participants who reported hip arthritis (n=83), 47 (57%) also reported hip OA. Given these findings, the decision was made to pool the diagnosis data for analysis. Participants, therefore, were considered to have “hip or knee joint disease” if they had been diagnosed with at least 1 of: hip arthritis, hip OA, knee arthritis, or knee OA. Demographic characteristics were compared by means of Mann-Whitney and chi-square tests. Among those with hip or knee joint disease, the proportion with asymptomatic, mild-moderate, or severe joint disease was calculated. Multiple binary logistic regression was used to generate adjusted odds ratios for the risk of severe hip or knee joint disease, with sex, age tertile, BMI category, and highest level of education entered simultaneously. Reference categories included male sex, age <57.5 years, BMI ≤24.99 kg/m2 (underweight/normal weight), and primary school or less level of education.
Health-related quality of life was compared across severity categories by means of analysis of covariance, with adjustment for age and sex. Chi-square tests were used to compare paid and unpaid work status and changes to work. Multiple binary logistic regression was used to estimate the likelihood of being in paid employment or undertaking unpaid work according to disease severity. Sex, age tertile, and severity category were entered simultaneously; reference categories included male sex, age <57.5 years, and asymptomatic joint disease (WOMAC score <7). Chi-square tests were used to compare the proportion of participants who had consulted a GP, orthopedic surgeon, rheumatologist, or physical therapist in the previous month across categories of severity. The total cost for primary and specialist care for hip and knee joint disease was estimated by summing MBS items for visits to GPs and medical specialists in the previous month. Because medical or surgical care was not used by all participants, these data were asymmetrically distributed, which did not improve after log transformation. Although Kruskal-Wallis tests were used to compare medical costs and surgical costs across categories of severity, both median and mean costs are presented to portray the data more clearly.
Sensitivity analyses (which excluded individuals with previous hip or knee replacement surgery) also were performed, as were additional analyses that included previous hip or knee replacement surgery as a potential covariate. However, these analyses produced similar findings and are not presented in this report.
Results
Participants
Questionnaires were returned by 1,158 participants (23% response rate). Only limited information was available regarding nonparticipation in the study: questionnaires were returned for 91 individuals (2%) because of incorrect address details, 45 individuals (1%) declined to participate, and 1 had died. Additionally, 1 participant was <39 years of age (having been incorrectly listed in the 69- to 73-year age category in the federal electoral roll extract) and was subsequently excluded from the analyses. Age data for all analyses were based on self-reported date of birth from the study questionnaire.
Demographics
Comparison of demographic characteristics indicated that the overall sample (n=1,157) was broadly representative of the Australian population. In particular, average HRQoL was comparable to Australian population norms, with a mean (95% confidence interval [95% CI]) AQoL score of 0.81 (0.80–0.82) for the sample versus the population norm of 0.83 (0.82–0.84).31 The BMI distribution for the sample also closely reflected Australian government data,32 and 67% resided in a metropolitan area compared with 58% of all Australian electoral enrollees.33 Although there were more people from the highest socioeconomic status areas in the study sample (21% and 17% living in the 9th and 10th SEIFA deciles, respectively), higher education status (completion of trade/technical or university education) was similar to recent government data on educational attainment.34
Of the overall sample, 20% of participants (n=237) reported hip or knee joint disease (diagnosis of hip arthritis, hip OA, knee arthritis, knee OA, or all). Seventy-nine percent (n=917) did not have hip or knee joint disease, and complete diagnosis information was not available for the remaining 3 participants (<1%). As shown in Table 1, those with hip or knee joint disease were older (P<.01) and had a higher BMI (P<.01) compared with those who did not have joint disease. A lower proportion of participants with hip or knee joint disease were married or living with a partner (P<.01), and a university education was less common among those with hip or knee joint disease (P<.01).
Demographic Characteristics of Study Participantsa
Classification of Severity
Of those participants with hip or knee joint disease, 37 (16%) were classified as asymptomatic, 120 (51%) as mild-moderate, and 64 (27%) as severe. The remaining 16 individuals (7%) could not be classified because of missing WOMAC data. Participants who were obese were more likely to be classified as severe compared with those classified as underweight or normal weight (adjusted odds ratio [AOR]=2.53, 95% CI=1.10–5.86). Risk of severe arthritis or OA was considerably lower for those who had completed a university education compared with those who had completed primary school or less (AOR=0.12, 95% CI=0.03–0.51). Neither age nor sex was associated with severity (P>.05 for each variable).
HRQoL According to Severity of Joint Disease
Figure 2 shows a clear deterioration in HRQoL with increasing severity of hip or knee joint disease (P<.01). After adjusting for age and sex, participants in the severe group had extremely low HRQoL (adjusted mean AQoL=0.43, 95% CI=0.38–0.47) compared with those in the mild-moderate group (adjusted mean AQoL=0.72, 95% CI=0.69–0.75) and the asymptomatic group (adjusted mean AQoL=0.80, 95% CI=0.74–0.86). The HRQoL of participants without hip or knee joint disease (adjusted mean AQoL=0.85, 95% CI=0.84–0.86) was similar to Australian population norms.31
Health-related quality of life by severity of hip and knee joint disease. Lower Assessment of Quality of Life (AQoL) instrument score indicates lower health-related quality of life (range=−0.04 to 1.00). Classification of severity: asymptomatic=Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score <7, mild-moderate=WOMAC score 7–38, severe=WOMAC score ≥39. Asterisk indicates analysis of covariance with adjustment for age and sex. CI=confidence interval, OA=osteoarthritis. AQoL scores were missing for 2 participants from the mild-moderate group.
Paid and Unpaid Work Status According to Severity of Joint Disease
Participants classified as having severe joint disease were less frequently in paid employment compared with those classified as asymptomatic or mild-moderate (Tab. 2). This difference remained after adjustment for age and sex; people with severe hip or knee joint disease were >3 times less likely to be in paid employment compared with those classified as asymptomatic (AOR=0.28, 95% CI=0.09–0.88). Mild to moderate joint disease was not associated with a reduced likelihood of being in paid employment (AOR=0.57, 95% CI=0.21–1.54).
Paid and Unpaid Work Status According to Severity
Nine percent (n=6) of the severe group reported stopping work because of their hip or knee arthritis or OA, whereas no participant from the asymptomatic or mild-moderate groups had stopped work for this reason. Of those who had stopped work, 1 participant had concurrent rheumatoid arthritis and OA and had stopped working at 19 years of age. For the remainder, the median age at the time of ceasing employment was 50 years (range=33–54).
Table 2 also shows that a lower proportion of the severe group reported undertaking unpaid work compared with the asymptomatic and mild-moderate groups (P<.01). Thirty-three percent of the severe group (n=21) were unable to undertake unpaid work because of their hip or knee compared with 4% of the mild-moderate group and 3% of the asymptomatic group. After adjustment for age and sex, people with severe hip or knee joint disease were >4 times less likely to undertake unpaid work compared with those classified as asymptomatic (AOR=0.24, 95% CI=0.10–0.62). Mild to moderate joint disease was not associated with a lower likelihood of undertaking unpaid work (AOR=0.51, 95% CI=0.23–1.13).
A greater proportion of the severe group reported having to change the way they performed their paid or unpaid work because of their hip or knee (Tab. 2, P<.01). Examples of changes included adapting tools, having to work in a seated position, performing light duties or sedentary work, and avoidance of kneeling and prolonged standing. Having to change the number of hours of paid or unpaid work because of their hip or knee condition also was more common among the severe group (P<.01). Examples included changing from full-time to part-time roles, limiting the number of hours worked, undertaking fewer chores, incorporating rest periods, and only working for short periods of time.
Health Service Utilization According to Severity of Joint Disease
A clear pattern of higher primary health care use was evident with increasing severity. As shown in Table 3, a greater proportion of the severe group had consulted a GP for their hip or knee arthritis or OA in the previous month compared with the mild-moderate and asymptomatic groups (P<.01). Additionally, the severe group reported more visits to GPs (total=69 visits) compared with the mild-moderate group (35 visits) and asymptomatic group (9 visits). A similar pattern was seen for orthopedic consultations; the severe group was more likely to have seen an orthopedic surgeon in the previous month (P=.01) and reported more visits to orthopedic surgeons (total=17 visits versus 4 visits for the mild-moderate group and 1 visit for the asymptomatic group). There was no difference in the proportion of participants who had seen a rheumatologist (P=.24) or physical therapist (P=.33). Physical therapy services were used infrequently by those with hip and knee joint disease; only 10% and 11% of the mild-moderate and severe groups, respectively, reported seeing a physical therapist in the previous month. Very few participants reported visits to other types of health professionals, precluding further analysis of these data (Tab. 3).
Health Service Utilization in the Previous Month According to Severity
Overall, primary and specialist care (specifically for hip and knee joint disease) was used by 14%, 27%, and 67% of the asymptomatic, mild-moderate, and severe groups, respectively (P<.01). The estimated costs of this care increased significantly with joint disease severity (P<.01), and the severe group reported the highest costs for the previous month (median=A$35.60, interquartile range=A$0–$71.20, mean=A$53.22, SD=A$72.13).
Previous Surgery and Estimated Costs
There was no difference between groups in the proportion who had received hip or knee surgery (P=.80) or in estimated surgery costs (P=.71), as shown in Table 4. Forty-seven percent (n=30) of the severe group had undergone at least 1 surgical procedure compared with 42% each for the mild-moderate and asymptomatic groups.
Previous Hip and Knee Surgery and Estimated Costs According to Severitya
Discussion
This study is the first to explore the broader burden of severe hip and knee joint disease in a contemporary Australian population. A clear pattern was evident with increasing severity of joint disease, which included worsening HRQoL, a lower likelihood of undertaking both paid and unpaid work, greater difficulty in undertaking paid and unpaid work, and higher utilization of medical services. Although these findings may seem intuitive, this study has quantified the reduction in HRQoL and the reduced work participation associated with severe joint disease. The HRQoL of this group was almost 50% lower than for those without joint disease, and these individuals were >3 times less likely to be in paid employment and >4 times less likely to undertake unpaid work compared with people classified as asymptomatic. Building on our previous research involving people waiting for joint replacement surgery,2,10 these findings deepen our understanding of the substantial personal and economic burden of severe joint disease and provide useful information for health care planners and clinicians caring for people with joint disease.
To date, few studies have looked at the impact of hip or knee joint disease severity on well-being, and none have involved population-based sampling. With the use of a convenience sample of people with hip or knee OA from Hong Kong medical clinics, Woo et al35 reported lower health status among those with severe OA compared with the mild disease group. Sadosky et al36 analyzed data from >700 individuals with OA affecting any joint, extracted from multinational studies of chronic disease. On the basis of a self-rated classification of overall OA severity, people with severe OA had higher pain and greater functional impairment compared with the mild and moderate groups. HRQoL was not evaluated in either study. In the present study, individuals with mild-moderate joint disease had reduced HRQoL (compared with participants without joint disease); however, the severe group reported the poorest HRQoL which was substantially lower than population norms.31 To put these findings into a clinical context, average AQoL scores for people with severe joint disease were lower than for patients with lung cancer37 and comparable to those reported by patients with recent stroke.38
Severe hip and knee joint disease affects many people of working age. More than one third of primary total hip and knee replacements in Australia are performed for people <65 years of age, and this group constitutes approximately 90% of those undergoing hip resurfacing surgery.39 Understanding work participation among people with severe hip or knee joint disease, therefore, is an important direction for research. Although this idea seems intuitive, our data provide clear evidence that people with severe OA are less likely to undertake both paid and unpaid work. Maximizing work participation by providing advice about task modification and management of symptoms should therefore be an important focus for physical therapists caring for these individuals. The inclusion of questions in the present study relating to unpaid work was novel, with participants defining unpaid work broadly to include activities such as volunteer work, carer roles, and household duties. The severe group also was more likely to have changed the way they worked and the number of hours worked because of their condition. Other studies have shown that people with severe hip or knee OA had more days off work and were less likely to be in paid employment (although these analyses were not adjusted for age)40 and that severe OA was associated with greater losses in work productivity, although this finding was not specific to the hip and knee joints.36
This research has generated new information about health service utilization and costs for severe hip and knee joint disease, which is important for understanding the economic impact of these conditions. Recent data from the Australian Institute of Health and Welfare indicate that more than A$1.2 billion of direct health expenditure in 2004 to 2005 was linked to OA.41 Of this total, almost A$900 million was spent on hospital admissions including joint replacement surgery, and A$189 million was related to out-of-hospital medical services. However, these data are not specific to the hip and knee joints, and beyond joint replacement provision, data relating to disease severity are not available. Although the estimated prevalent costs of medical services in the previous month seem low (median=A$35.60 per participant for the severe group), when applied to increasing numbers of people living for ≥30 years with severe joint disease, they are likely to represent a significant financial burden. Use of physical therapy services by both the mild-moderate and severe groups was low in this study (10% and 11%, respectively). This finding suggests that promotion of the potential benefits of physical therapy in hip and knee joint disease to patients, GPs, and specialists may be required (in terms of pain management, improving muscle strength, and maximizing physical function).
This study had several strengths, including the population-based sampling frame, which meant that the sample included people with a range of joint disease severity, a distinct advantage over studies conducted in surgical waiting list settings. The recruitment strategy included every Australian state and territory, which should improve the external validity of our findings.
We acknowledge several limitations, including the low response rate (23%), which may relate to the use of a mailed introductory letter and questionnaire. Although we incorporated strategies to maximize response rates, only limited follow-up could be undertaken, given available resources. Despite this limitation, the analyses indicated that the sample was broadly representative of the Australian population across several key characteristics, including residential location, educational attainment, BMI, and HRQoL. Also, these analyses are based on pooled data from people with hip arthritis, hip OA, knee arthritis, and knee OA and provide an overall snapshot of “hip and knee joint disease.” Although we did not plan to combine diagnosis groups, this approach was adopted after considerable overlap was found between “arthritis” and “OA.” This overlap may be consistent with research suggesting limited individual knowledge of arthritis type,15,16 or it could reflect the different terms used to explain joint disease to patients. We also acknowledge the difficulty in identifying disease-specific health care utilization and that self-reported health service utilization data may be less accurate than administrative data, although we attempted to limit recall bias by focusing on visits in the previous month.
Additionally, we did not have information on comorbidities, individual costs of consultations, whether services were provided within public or private health systems, or whether participants were awaiting joint replacement. To conservatively estimate costs, it was assumed that all services were provided within the public health system and unit (average) costs were used for the analyses. Additionally, the costs of specialist consultations were estimated by means of MBS costs for “subsequent” consultations. Because these costs are lower than for initial consultations, this approach is likely to have underestimated these costs. This study has only estimated 1 aspect of economic burden (direct costs relating to use of medical services), and the analyses do not include the costs of physical therapy consultations, complementary therapies, or medications. Finally, out-of-pocket costs and indirect costs relating to lost productivity, time taken off work to attend appointments, and travel to appointments were not captured but could be included in future studies to evaluate the total economic burden of severe hip and knee joint disease. However, these data are more difficult to accurately collect, requiring cost diaries that can be associated with greater participant burden and recall bias. Data linkage could be used to obtain individual government data on use of medical services and medications but typically involves additional approval and patient consent processes.
In conclusion, the personal and economic burden of hip and knee joint disease is substantial, with evidence of a graded relationship according to disease severity. Compared with those who had milder disease, individuals with severe joint disease reported markedly lower HRQoL, reduced paid and unpaid work participation, and higher utilization of primary care and orthopedic services. These findings confirm the broad impact of severe joint disease and highlight the need for timely access to care to optimize well-being and facilitate work participation. Promotion of the benefits of physical therapy for individuals with mild-moderate and severe joint disease may be required to improve uptake of these services.
Footnotes
All authors provided concept/idea/research design and writing. Dr Ackerman provided data collection and project management. Dr Ackerman, Dr Ademi, and Dr Osborne provided data analysis. Dr Ackerman and Dr Osborne provided fund procurement. Dr Osborne and Professor Liew provided consultation (including review of manuscript before submission). The authors thank Professor Ian Wicks and the study participants for their support of this research.
This research was supported, in part, by a Physiotherapy Research Foundation and United Pacific Industries Thermoskin Research Grant (T09-THE003). Dr Ackerman was supported by an Australian National Health and Medical Research Council Public Health (Australia) Training Fellowship (520004).
This research was approved by the University of Melbourne Human Research Ethics Committee.
This work was presented, in part, at the American College of Rheumatology/Association of Rheumatology Health Professionals 75th Annual Scientific Meeting; November 4–9, 2011; Chicago, Illinois. This work also was presented, in part, at Melbourne Health Research Week; May 24–31, 2012; Parkville, Victoria, Australia, for which it was awarded an Allied Health Research Award.
- Received October 28, 2012.
- Accepted April 1, 2013.
- © 2013 American Physical Therapy Association
References
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