Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Background

Although hip and knee arthroplasties are considered to be common elective cost-effective operations, up to one-quarter of patients are not satisfied with the operation. A number of risk factors for implant failure are known, but little is known about the predictors of patient-reported outcomes.

Objectives

(1) Describe current and future needs for lower limb arthroplasties in the UK; (2) describe important risk factors for poor surgery outcomes and combine them to produce predictive tools (for hip and knee separately) for poor outcomes; (3) produce a Markov model to enable a detailed health economic analysis of hip/knee arthroplasty, and for implementing the predictive tool; and (4) test the practicality of the prediction tools in a pragmatic prospective cohort of lower limb arthroplasty.

Design

The programme was arranged into four work packages. The first three work packages used the data from large existing data sets such as Clinical Practice Research Datalink, Hospital Episode Statistics and the National Joint Registry. Work package 4 established a pragmatic cohort of lower limb arthroplasty to test the practicality of the predictive tools developed within the programme.

Results

The estimated number of total knee replacements (TKRs) and total hip replacements (THRs) performed in the UK in 2015 was 85,019 and 72,418, respectively. Between 1991 and 2006, the estimated age-standardised rates (per 100,000 person-years) for a THR increased from 60.3 to 144.6 for women and from 35.8 to 88.6 for men. The rates for TKR increased from 42.5 to 138.7 for women and from 28.7 to 99.4 for men. The strongest predictors for poor outcomes were preoperative pain/function scores, deprivation, age, mental health score and radiographic variable pattern of joint space narrowing. We found a weak association between body mass index (BMI) and outcomes; however, increased BMI did increase the risk of revision surgery (a 5-kg/m2rise in BMI increased THR revision risk by 10.4% and TKR revision risk by 7.7%). We also confirmed that osteoarthritis (OA) severity and migration pattern of the hip predicted patient-reported outcome measures. The hip predictive tool that we developed performed well, with a correctedR2of 23.1% and had good calibration, with only slight overestimation of Oxford Hip Score in the lowest decile of outcome. The knee tool developed performed less well, with a correctedR2of 20.2%; however, it had good calibration. The analysis was restricted by the relatively limited number of variables available in the extant data sets, something that could be addressed in future studies. We found that the use of bisphosphonates reduced the risk of revision knee and hip surgery by 46%. Hormone replacement therapy reduced the risk by 38%, if used for at least 6 months postoperatively. We found that an increased risk of postoperative fracture was prevented by bisphosphonate use. This result, being observational in nature, will require confirmation in a randomised controlled trial. The Markov model distinguished between outcome categories following primary and revision procedures. The resulting outcome prediction tool for THR and TKR reduced the number and proportion of unsatisfactory outcomes after the operation, saving NHS resources in the process. The highest savings per quality-adjusted life-year (QALY) forgone were reported from the oldest patient subgroups (men and women aged ≥ 80 years), with a reported incremental cost-effectiveness ratio of around £1200 saved per QALY forgone for THRs. In the prospective cohort of arthroplasty, the performance of the knee model was modest (R2 = 0.14) and that of the hip model poor (R2 = 0.04). However, the addition of the radiographic OA variable improved the performance of the hip model (R2 = 0.125 vs. 0.110) and high-sensitivity C-reactive protein improved the performance of the knee model (R2 = 0.230 vs. 0.216). These data will ideally need replication in an external cohort of a similar design. The data are not necessarily applicable to other health systems or countries.

Conclusion

The number of total hip and knee replacements will increase in the next decade. High BMI, although clinically insignificant, is associated with an increased risk of revision surgery and postoperative complications. Preoperative pain/function, the pattern of joint space narrowing, deprivation index and level of education were found to be the strongest predictors for THR. Bisphosphonates and hormone therapy proved to be beneficial for patients undergoing lower limb replacement. The addition of new predictors collected from the prospective cohort of arthroplasty slightly improved the performance of the predictive tools, suggesting that the potential improvements in both tools can be achieved using the plethora of extra variables from the validation cohort. Although currently it would not be cost-effective to implement the predictive tools in a health-care setting, we feel that the addition of extensive risk factors will improve the performances of the predictive tools as well as the Markov model, and will prove to be beneficial in terms of cost-effectiveness. Future analyses are under way and awaiting more promising provisional results.

Future work

Further research should focus on defining and predicting the most important outcome to the patient.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

The lifetime risk of total hip and knee arthroplasty: results from the UK general practice research database

OBJECTIVE

To estimate the lifetime risk of undergoing primary total hip (THR) or knee (TKR) replacement in the UK.

METHOD

A Population-based cohort study of 25,845 patients who had undergone a THR and 23,260 patients who had undergone a TKR between 1991 and 2006, using data from the UK General Practice Research Database.

RESULTS

The estimated mortality-adjusted lifetime risk of THR at age 50 for the year 2005 was 11.6% (95% CI: 11.1, 12.1) for women and 7.1% (95% CI: 6.7, 7.5) for men. For TKR the risks were 10.8% (95% CI: 10.3, 11.3) for women and 8.1% (95% CI: 7.6, 8.5) for men. Between 1991 and 2006, the lifetime risk of THR at age 50 rose from 4.0% (95% CI: 3.5, 4.4) to 11.1% (95% CI: 10.6, 11.6) for women and for men from 2.2% (95% CI: 1.8, 2.5) to 6.6% (95% CI: 6.2, 7.0). Over the same period, for TKR the risk for women increased from 2.9% (95% CI: 2.6, 3.3) to 10.6% (95% CI: 10.1, 11.1) and for men from 1.8% (95% CI: 1.5, 2.2) to 7.7% (95% CI: 7.3, 8.2).

CONCLUSION

The lifetime risk of undergoing THR or TKR is estimated to be substantially less than the risk of developing symptomatic hip or knee osteoarthritis. For the knee, the difference between these risk estimates is particularly wide. The reasons for the size of these differences are not clear, and further work is needed to quantify the extent of latent demand for these cost-effective and established interventions among the population with symptomatic osteoarthritis of the hip or knee.

Clinical effectiveness of knee rehabilitation techniques and implications for a self-care treatment model

BACKGROUND

Physiotherapy is a complex intervention frequently recommended for knee conditions. The International Classification of Functioning and Disability (ICF) can be used as a framework to evaluate evidence to develop care models and clinical guidelines.

OBJECTIVE

To evaluate the clinical effectiveness of knee rehabilitation modalities categorised according to the ICF domains.

DATA SOURCES

A keyword search of Medline, Cinahl, Amed, Embase and Cochrane databases from 1996 to 2010 using terms related to the knee joint and physiotherapeutic interventions.

STUDY SELECTION

Reviewer assessment using inclusion/exclusion criteria and a quality assessment tool compiled from the Critical Appraisal Skills Programme Tool, Consort and Cochrane Bone Joint and Muscle Trauma Groups.

DATA EXTRACTION

Information about the research design, intervention and subjects was extracted. Outcome measures and findings were categorised according to ICF domains.

DATA SYNTHESIS

The majority of studies evaluated exercise. Findings were supportive but specific recommendations were limited due to variations in content and application. There was limited quality research to support the theory that manual therapy, electrotherapy or taping in isolation contributes to recovery. Multimodality physiotherapy programmes were found to be beneficial and to reflect clinical practice, but the effectiveness of each component is unknown. Outcome measures from the participation domain of the ICF were used least frequently and were not generally true measures of participation.

CONCLUSION

Development of participation outcome measures is required to evaluate the long-term benefits of interventions. Rehabilitation should be based around delivery of effective exercise programmes incorporating participation outcomes to provide feedback and complement self-care for knee conditions.

Who should have knee joint replacement surgery for osteoarthritis?

Knee joint replacement is an effective and cost-effective intervention for severe symptomatic osteoarthritis of the knee joint. However, utilisation rates vary hugely, there are no indications, it is difficult to know when (in the course of arthritis) it is best to operate, and some 10-20% of people who have this surgery are unhappy with the outcome, and have persistent pain. In this article we briefly discuss the variations in utilization of knee joint replacement, and then outline four different approaches to the selection and prioritisation of patients for this procedure. Consensus criteria, including appropriateness criteria are available, but if produced by professionals alone, they may conflict with the views of patients and the public. Databases and cohort studies can be used to attempt relating outcomes to baseline characteristics, but at present we can only account for a small percentage of the variance with this technique. Finally, we propose use of the 'capacity to benefit framework' to attempt providing guidance to both patients and healthcare professionals.

Inequalities in primary care management of knee pain and disability in older adults: an observational cohort study

OBJECTIVES

To describe primary care management of knee pain, in relation to National Institute for Health and Clinical Excellence (NICE) OA guidelines, and examine variation in management by patient characteristics.

METHODS

Subjects were 755 adults aged ≥50 years who responded to baseline and 3-year surveys and had consulted primary care for knee pain. Medical records (1997-2006) were searched. Associations of having interventions from the outer circle (adjunctive treatments or Step 3) of the NICE guidelines with self-reported socio-demographic and knee-specific factors were determined.

RESULTS

Eighty per cent had received a Step 3 intervention. Thirty-eight per cent had been referred to secondary care, and 10% had received a knee replacement. Forty-three per cent had been prescribed an opioid and 41% an NSAID. Severe knee pain or disability at baseline and follow-up was the main association with receiving a Step 3 intervention [adjusted odds ratio (OR) 2.26; 95% CI 1.38, 3.70] and with referral (OR 2.57; 95% CI 1.72, 3.83). Older patients were less likely to be referred. Although non-significant, those of higher social class, in more affluent areas, older age or overweight or obese, appeared more likely to receive a knee replacement. Fifty per cent of those reporting severe knee pain or disability in both surveys had not been referred to secondary care.

CONCLUSION

Most of the older adults who consult primary care with knee pain receive at least one Step 3 intervention from the OA guidelines. Inequalities in the management and referral of knee problems in primary care were generally not observed, although there were some trends towards differences in likelihood of total knee replacement.

Equity in access to total joint replacement of the hip and knee in England: cross sectional study

OBJECTIVE

To explore geographical and sociodemographic factors associated with variation in equity in access to total hip and knee replacement surgery.

DESIGN

Combining small area estimates of need and provision to explore equity in access to care.

SETTING

English census wards.

SUBJECTS

Patients throughout England who needed total hip or knee replacement and numbers who received surgery.

MAIN OUTCOME MEASURES

Predicted rates of need (derived from the Somerset and Avon Survey of Health and English Longitudinal Study of Ageing) and provision (derived from the hospital episode statistics database). Equity rate ratios comparing rates of provision relative to need by sociodemographic, hospital, and distance variables.

RESULTS

For both operations there was an "n" shaped curve by age. Compared with people aged 50-59, those aged 60-84 got more provision relative to need, while those aged >or=85 received less total hip replacement (adjusted rate ratio 0.68, 95% confidence interval 0.65 to 0.72) and less total knee replacement (0.87, 0.82 to 0.93). Compared with women, men received more provision relative to need for total hip replacement (1.08, 1.05 to 1.10) and total knee replacement (1.31, 1.28 to 1.34). Compared with the least deprived, residents in the most deprived areas got less provision relative to need for total hip replacement (0.31, 0.30 to 0.33) and total knee replacement (0.33, 0.31 to 0.34). For total knee replacement, those in urban areas got higher provision relative to need, but for total hip replacement it was highest in villages/isolated areas. For total knee replacement, patients living in non-white areas received more provision relative to need (1.04, 1.00 to 1.07) than those in predominantly white areas, but for total hip replacement there was no effect. Adjustment for hospital characteristics did not attenuate the effects.

CONCLUSIONS

There is evidence of inequity in access to total hip and total knee replacement surgery by age, sex, deprivation, rurality, and ethnicity. Adjustment for hospital and distance did not attenuate these effects. Policy makers should examine factors at the level of patients or primary care to understand the determinants of inequitable provision.

Patient-reported outcomes one year after primary hip replacement in a European Collaborative Cohort

OBJECTIVE

To identify whether patients have symptomatic improvement 12 months following total hip replacement (THR) surgery.

METHODS

The European Collaborative Database of Cost and Practice Patterns of Total Hip Replacement study consists of 1,327 patients receiving primary THR for osteoarthritis (OA) across 20 European orthopedic centers. The primary outcome was the difference in Western Ontario and McMaster Universities OA Index (WOMAC) score between preoperative and 12-month postoperative measurements. To classify whether patients responded to THR at 12 months, we used return to normal, Outcome Measures in Rheumatology Clinical Trials (OMERACT)-OA Research Society International (OARSI) criteria, minimum important difference (MID), and minimum clinically important difference. Exposures were age, sex, obesity, employment, educational attainment, American Society of Anesthesiologists status, and radiographs.

RESULTS

On average, there was a large improvement in WOMAC scores 12 months after surgery, but whereas some patients improved, others got worse. The OMERACT-OARSI method classified 85.7% of patients as responders, MID 70.1%, and return to normal 64.1%. In general, each approach classified the same groups of patients as responding to THR. Based on total WOMAC score, patients who were younger, morbidly obese, employed, and better educated were more likely to respond to THR, but the effects were attenuated after adjustment for confounding, with only the effect of education remaining important.

CONCLUSION

The overall average response to THR was good, but approximately 14-36% of patients did not improve, or were worse, 12 months postsurgery. Although the OMERACT-OARSI criteria were originally designed for use in clinical drug trials, they performed well in classifying patient response 12 months post-THR. Further research is required to understand the determinants of patient outcomes following THR.

Variations in the pre-operative status of patients coming to primary hip replacement for osteoarthritis in European orthopaedic centres

Background

Total hip joint replacement (THR) is a high volume, effective intervention for hip osteoarthritis (OA). However, indications and determinants of outcome remain unclear. The 'EUROHIP consortium' has undertaken a cohort study to investigate these questions. This paper describes the variations in disease severity in this cohort and the relationships between clinical and radiographic severity, and explores some of the determinants of variation.

Methods

A minimum of 50 consecutive, consenting patients coming to primary THR for primary hip OA in each of the 20 participating orthopaedic centres entered the study. Pre-operative data included demographics, employment and educational attainment, drug utilisation, and involvement of other joints. Each subject completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC – Likert version 3.1). Other data collected at the time of surgery included the prosthesis used and American Society of Anaesthesiologists (ASA) status. Pre-operative radiographs were read by the same three readers for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Regression analyses were carried out.

Results

Data from 1327 subjects has been analysed. The mean age of the group was 65.7 years, and there were more women (53.4%) than men. Most (79%) were ASA status 1 or 2. Reported disease duration was 5 years or less in 69.2%. Disease in other joint sites was common.

Radiographs were available in 1051 subjects and the K&L grade was 3 or 4 in 95.8%. There was much more variation in clinical severity (WOMAC score); the mean total WOMAC score was 59.2 (SD 16.1). The radiographic severity showed no correlation with WOMAC scores.

Significantly higher WOMAC scores (worse disease) were seen in older people, women, those with obesity, those with worse general health, and those with lower educational attainment.

Conclusion

1. Clinical disease severity varies widely at the time of THR for OA.

2. In advanced hip OA clinical severity shows no correlation with radiographic severity.

3. Simple scores of pain and disability do not reflect the complexity of decision-making about who should have a THR.

Consumer involvement in setting the health services research agenda: persistent questions of value

Interest in consumer involvement in health services research started to gain momentum at around the same time that the MRC Health Services Research Collaboration (HSRC) was established. Consumer involvement was not the focus of a formal research programme within the HSRC, but HSRC members took opportunities to conduct three projects relating to consumer involvement in research agenda-setting activities. These were: (1) a comparison of the focus of published research relating to the management of osteoarthritis of the knee with clinicians' and patients' ideas about research priorities; (2) a survey that examined the consumer involvement policies of public- and voluntary-sector organizations that fund health services research in the UK; and (3) a citizens' jury that was convened to develop priorities for research relating to primary health and social care in the Bristol area. This paper reviews the findings of these projects and highlights the continued need for attention to underlying values in the development and evaluation of future efforts to involve consumers in research agenda setting.