Effects of competition and bundled payment on the performance of hip replacement surgery in Stockholm, Sweden: results from a quasi-experimental study

OBJECTIVE

To evaluate the effects of competition and a bundled payment model on the performance of hip replacement surgery.

DESIGN

A quasi-experimental study where a difference-in-differences analytical framework is applied to analyse routinely collected patient-level data from multiple registers.

SETTING

Hospitals providing hip replacement surgery in Sweden.

PARTICIPANTS

The study included patients who underwent elective primary total hip replacement due to osteoarthritis from 2005 to 2012. The final study sample consisted of 85 275 hip replacement surgeries, where the exposure group consisted of 14 570 surgeries (n=6380 prereform and n=8190 postreform) and the control group consisted of 70 705 surgeries (n=32 799 prereform and n=37 906 postreform).

INTERVENTION

A reform involving patient choice, free entry of new providers and a bundled payment model for hip replacement surgery, which came into force in 2009 in Region Stockholm, Sweden.

OUTCOME MEASURES

Performance is measured as length of stay of the surgical admission, adverse event rate within 90 days following surgery and patient satisfaction 1 year postsurgery.

RESULTS

The reform successfully improved the adverse event rate (1.6 percentage reduction, p<0.05). Length of stay decreased less in the more competitive market than in the control group (0.7 days lower, p<0.01). These effects were mainly driven by university and central hospitals. No effects of the reform on patient satisfaction were found (no significance).

CONCLUSIONS

The study concludes that the incentives of the reform focusing on avoidance of adverse events have a predictable impact. Since the payment for providers is fixed per case, the impact on resource use is limited. Our findings contribute to the general knowledge about the effects of financial incentives and market-oriented reforms.

The productivity development of total hip arthroplasty in Sweden: a multiple registry-based longitudinal study using the Malmquist Productivity Index

OBJECTIVE

The increasing demand for total hip arthroplasty (THA) combined with limited resources in healthcare puts pressure on decision-makers in orthopaedics to provide the procedure at minimum costs and with good outcomes while maintaining or increasing access. The objective of this study was to analyse the development in productivity between 2005 and 2012 in the provision of THA.

DESIGN

The study was a multiple registry-based longitudinal study.

SETTING AND PARTICIPANTS

The study was conducted among 65 orthopaedic departments providing THA in Sweden from 2005 to 2012.

OUTCOME MEASURES

The development in productivity was measured by Malmquist Productivity Index by relating department level total costs of THA to the number of non-cemented, hybrid and cemented THAs. We also break down the productivity change into changes in efficiency and technology.

RESULTS

Productivity increased significantly in three periods (between 1.6% and 27.0%) and declined significantly in four periods (between 0.8% and 12.1%). Technology improved significantly in three periods (between 3.2% and 16.9%) and deteriorated significantly in two periods (between 10.2% and 12.6%). Significant progress in efficiency was achieved in two periods (ranging from 2.6% to 8.7%), whereas a significant regress was attained in one period (3.9%). For the time span as a whole, an average increase in productivity of 1.4% per year was found, where changes in efficiency contributed more to the improvement (1.1%) than did technical change (0.2%).

CONCLUSIONS

We found a slight improvement of productivity over time in the provision of THA, which was mainly driven by changes in efficiency. Further research is, however, needed where differences in quality of care and patient case mix between departments are taken into account.

Geographical variations in patient-reported outcomes after total hip arthroplasty between 2008 - 2012

Background

Health care on equal terms is a cornerstone of the Swedish health care system. Total hip arthroplasty (THA) is considered a success story in Sweden with low frequency of reoperations and restored health-related quality of life (HRQoL). Administratively, health care in Sweden is locally self-governed by 21 counties. In this longitudinal nation-wide observational study we assessed the possible geographical variations in 1-year follow-up patient-reported outcomes (PROs): EQ-5D index, EQ VAS, Pain VAS and Satisfaction VAS.

Methods

Study population consisted of 36,235 Swedish THA patients, operated during 2008 to 2012 due to hip osteoarthritis. Individual data came from Swedish Hip Arthroplasty Register, Statistics Sweden and National Board of Health and Welfare. We used descriptive statistics together with multivariable regression analysis to analyse the data.

Results

We observed county level differences in both preoperative and postoperative PROs. The results showed that the differences observed in preoperative PROs could not fully explain the differences observed in postoperative PROs, even after adjustment for patient demographics (age, sex, BMI, Elixhauser comorbidity index, marital status, educational level and disposable income). This indicates that other factors might influence the outcome after THA.

Conclusion

Likely, structural and process differences such as indication for surgery have an influence on PROs after surgery. Standardization of care at hospital levels may decrease geographical variations in postoperative HRQoL. Remaining differences will then possibly be associated to patient demographics.

Electronic supplementary material

The online version of this article (10.1186/s12913-019-4171-5) contains supplementary material, which is available to authorized users.

Incidence and demographics of 1751 surgically treated periprosthetic femoral fractures around a primary hip prosthesis

INTRODUCTION

Periprosthetic femoral fractures (PPFF), treated surgically, have been recorded in the Swedish Hip Arthroplasty Register (SHAR) since 1979. It is postulated that fractures treated with other methods other than stem revision have a lower registration rate, which may lead to incomplete registry data and thus, inaccurate information. We collected all PPFFs surgically treated in Sweden between 2001 and 2011 with the purpose of studying the annual incidence, demographics and distribution of fracture types with regard to type of fixation.

METHODS

Data was linked between the SHAR and the National Patient Register (NPR) in order to detect even those PPFFs not reported to the SHAR. Fractures were classified according to the Vancouver classification system, based on information collected from the medical charts. This procedure was validated with observer variation analysis compared to fracture classification based on radiographs. In total 1751 first-time PPFFs around primary conventional stems were included.

RESULTS

The incidence of PPFF increased from about 1.0 per 1000 primary THRs to 1.4. Vancouver type C fractures (37% of all fractures) were more common than previously reported, and more common in cemented than in uncemented stems. The 3 most common stem designs involved were Exeter polished, Lubinus SPII, and Charnley (66.3% of all stems), partly reflecting their occurrence in the Swedish THR population.

DISCUSSION

The incidence of PPFFs has increased in Sweden during the period 2001 to 2011. The improved reporting of type C fractures, after data-linking, revealed an almost 4 times higher incidence compared to previous register studies in Sweden.

Aseptic loosening after total hip arthroplasty and the risk of cardiovascular disease: A nested case-control study

Background

Patients with surgically treated osteoarthritis of the hip have an increased risk of cardiovascular morbidity and mortality many years after the operation compared with controls. Our hypothesis is that this increased risk after total hip arthroplasty (THA) is mediated by development of periprosthetic osteolysis leading to aseptic loosening of the implant.

Methods

We conducted a nation-wide, nested, case-control study consisting of patients receiving a cemented THA due to osteoarthritis between the years 1992 and 2005. Our study population included a total of 14,430 subjects identified in the Swedish hip arthroplasty register and linked to the Swedish National Patient Register. The case group consisted of patients (n = 2,886) who underwent reoperation of the treated hip due to osteolysis or aseptic loosening at any time within five years after the index surgery. Each case was matched with four controls (n = 11,544) who had not undergone reoperation. The main outcomes were cardiovascular events i.e. myocardial infarction, heart failure and cerebral infarction according to ICD-codes and time to the first cardiovascular event during the exposure period. Outcomes were subgrouped into cardiac and cerebral events. We used regression models to calculate the incidence rates and adjusted our results for confounders.

Findings

Overall, 5.1% of patients had cardiac events, with slightly more overall cardiovascular events occurring in the control group (8.1% vs. 6.7%, odds ratio 0.8, 95% confidence interval (CI) 0.7 to 1.0). After adjusting for confounders, the case group had an increased relative risk of 1.3 (95% confidence interval (CI) 1.1 to 1.3) for total number of cardiovascular events. Similar effect sizes were observed for time to first event.

Interpretation

Patients with osteoarthritis who received THA and subsequently underwent a revision operation due to loosening had a higher relative risk of developing cardiovascular events than controls. Thus there is an association which could be explained by a common inflammatory disease pathway that requires further experimental research.

Patients with a previous total hip replacement experience less reduction of back pain following lumbar back surgery

The coexistence of degenerative disorders from the hip joint and the lumbar spine, known as "the hip-spine syndrome," is a common encounter in clinical practice. These degenerative conditions may cause similar symptoms which often entail diagnostic challenges in determining the origin of pain. Lumbar back surgery (LBS) with fusion and/or decompression, and total hip replacement (THR) are both often successful interventions. However, the knowledge is limited about the post-operative patient-reported outcome (PRO) following LBS in the presence of a prior THR. The aims of this study were to compare 1-year post-operative patient-reported outcome measures (PROMs) following lumbar back surgery (LBS) in patients with and without a prior total hip replacement (THR). Data from Swespine and the Swedish Hip Arthroplasty Register were linked in order to identify the study group of patients with THR prior to LBS. The study group (n = 220) and a matched control group (n = 220) with isolated LBS was defined by using a step-wise selection process. Linear- and logistic regression analyses adjusted for age, sex and pre-operative PROMs demonstrated that THR prior to LBS was associated with worse back-pain (VAS) at 1-year follow-up (B = 5.3, 95%CI: 0.3;10.3). However, previous THR did not influence the EQ-5D index (B = 0.01, 95%CI: -0.05;0.06), EQ VAS (B = -3.0, 95%CI: -6.9;1.0), leg pain (B = 1.5, 95%CI: -4.0;7.0), Oswestry Disability Index (B = 2.6, 95%CI: -0.5;5.6) or satisfaction (OR = 1.1, 97.5%CI 0.7;1.6). This knowledge is important to communicate prior to LBS in order to set proper expectations on surgical outcomes. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2484-2490, 2018.

Arthroplasty implant registries over the past five decades: Development, current, and future impact

Local, regional, and national registries have played an important role in the development of hip and knee arthroplasty and the treatment of patients with various maladies of these joints. Four arthroplasty registries stand out as leading forces behind the drive to popularize the use of registries and pursue the concept of evidence based medicine. The Mayo registry, started by Mark Coventry, is recognized as the oldest continuing registry for arthroplasty. The Harris Registry at Massachusetts General Hospital, along with the Mayo Registry, has greatly contributed to the advancement of arthroplasty surgery and have served an important role of identifying poorly performing implants and techniques in the United States. The Swedish Knee Arthroplasty Registry is the oldest national registry dedicated to joint arthroplasty and along with the Swedish Hip Arthroplasty Registry have established the infrastructure, analysis and reporting mechanisms, and leadership that has enabled other countries to subsequently develop national registries around the world. As more countries have adopted the concept of national registries, a new area of research is possible by pooling the resources of large registries as is now occurring with the Nordic countries. Several international organizations have been formed to promote future collaboration and develop international standards. The process of globalization of registries is a result of continued efforts over the past 50 years in improving and disseminating the knowledge gained from the early registries. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2319-2330, 2018.

Do Patients Live Longer After THA and Is the Relative Survival Diagnosis-specific?

BACKGROUND

Hip replacements are successful in restoring mobility, reducing pain, and improving quality of life. However, the association between THA and the potential for increased life expectancy (as expressed by mortality rate) is less clear, and any such association could well be influenced by diagnosis and patient-related, socioeconomic, and surgical factors, which have not been well studied.

QUESTIONS/PURPOSES

(1) After controlling for birth year and sex, are Swedish patients who underwent THA likely to survive longer than individuals in the general population? (2) After controlling for relevant patient-related, socioeconomic/demographic factors and surgical factors, does relative survival differ across the various diagnoses for which THAs were performed in Sweden?

METHODS

Data from the Swedish Hip Arthroplasty Register, linked to administrative health databases, were used for this study. We identified 131,808 patients who underwent THA between January 1, 1999, and December 31, 2012. Of these, 21,755 had died by the end of followup. Patient- and surgery-specific data in combination with socioeconomic data were available for analysis. We compared patient survival (relative survival) with age- and sex-matched survival data in the entire Swedish population according to Statistics Sweden. We used multivariable modeling proceeded with a Cox proportional hazards model in transformed time.

RESULTS

Patients undergoing elective THA had a slightly improved survival rate compared with the general population for approximately 10 years after surgery. At 1 year after surgery, the survival in patients undergoing THA was 1% better than the expected survival (r = 1.01; 95% confidence interval [CI], 1.01-1.02; p < 0.001); at 5 years, this increased to 3% (r = 1.03; 95% CI, 1.03-1.03; p < 0.001); at 10 years, the difference was 2% (r = 1.02; 95% CI, 1.02-1.03; p < 0.001); and by 12 years, there was no difference between patients undergoing THA and the general population (r = 1.01; 95% CI, 0.99-1.02; p = 0.13). Using the diagnosis of primary osteoarthritis as a reference, hip arthroplasties performed for sequelae of childhood hip diseases had a similar survival rate (hazard ratio [HR], 1.02; 95% CI, 0.88-1.18; p = 0.77). Patients undergoing surgery for osteonecrosis of the femoral head (HR, 1.69; 95% CI, 1.60-1.79; p < 0.001), inflammatory arthritis (HR, 1.49; 95% CI, 1.38-1.61; p < 0.001), and secondary osteoarthritis (HR, 2.46; 95% CI, 2.03-2.99; p < 0.001) all had poorer relative survival. Comorbidities and the Elixhauser comorbidity index had a negative association with relative survival. Level of achieved education (middle level of education: HR, 0.90, 95% CI, 0.87-0.93, p < 0.001; high level: 0.76, 95% CI, 0.73-0.80, p < 0.001) and marital status (single status: HR, 1.33; 95% CI, 1.28-1.38; p < 0.001) were also negatively associated with survival.

CONCLUSIONS

Whereas it has been known that in most patients, THA improves quality of life, this study demonstrates that it also is associated with a slightly increased life expectancy that lasts for approximately 10 years after surgery, especially among patients whose diagnosis was primary osteoarthritis. This adds further proof of a health-economic value for this surgical intervention. The reasons for the increase in relative survival are unknown but are probably multifactorial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Does surgeon experience affect patient-reported outcomes 1 year after primary total hip arthroplasty?

Background and purpose - Several studies have reported on the influence of various factors on patient-reported outcomes (PROs) after total hip arthroplasty (THA), but very few have focused on the experience of the surgeon. We investigated any association between surgeons' experience and PROs 1 year after primary THA. Patients and methods - Patient characteristics and surgical data at 10 hospitals in western Sweden were linked with PROs (EQ-5D-3L, Satisfaction Visual Analogue Scale (VAS), Pain VAS). These data were retrieved from the Swedish Hip Arthroplasty Register (SHAR). The surgeon's level of experience was divided into 4 subgroups related to experience: < 8 years, 8-15 years, and >15 years of clinical practice after specialist certificate. If no specialist certificate was obtained the surgery was classified as a trainee surgery. Surgeons with >15 years' experience as an orthopedic specialist were used as reference group in the analyses. Results - 8,158 primary THAs due to osteoarthritis were identified. We identified the surgeons' level of experience in 8,116 THAs. Data from SHAR on pre- and postoperative PROs and satisfaction at 1 year were available for 6,713 THAs. We observed a statistically significant difference among the 4 groups of surgeons regarding mean patient age, ASA classification, Charnley classification, diagnosis, and fixation technique. At 1-year follow-up, there were no statistically significant differences in Pain VAS, EQ-5D index, or EQ VAS among the subgroups of orthopedic specialists. Patients operated on by orthopedic trainees reported less satisfaction with the result of the surgery compared with the reference group. Interpretation - These findings indicate that patients can expect similar health improvements, pain reduction, and satisfaction 1 year after a primary THA operation irrespective of years in practice after specialty certification as an orthopedic surgeon.

Development and validation of a shared decision-making instrument for health-related quality of life one year after total hip replacement based on quality registries data

RATIONALE, AIMS AND OBJECTIVES

Clinicians considering improvements in health-related quality of life (HRQoL) after total hip replacement (THR) must account for multiple pieces of information. Evidence-based decisions are important to best assess the effect of THR on HRQoL. This work aims at constructing a shared decision-making tool that helps clinicians assessing the future benefits of THR by offering predictions of 1-year postoperative HRQoL of THR patients.

METHODS

We used data from the Swedish Hip Arthroplasty Register. Data from 2008 were used as training set and data from 2009 to 2012 as validation set. We adopted two approaches. First, we assumed a continuous distribution for the EQ-5D index and modelled the postoperative EQ-5D index with regression models. Second, we modelled the five dimensions of the EQ-5D and weighted together the predictions using the UK Time Trade-Off value set. As predictors, we used preoperative EQ-5D dimensions and the EQ-5D index, EQ visual analogue scale, visual analogue scale pain, Charnley classification, age, gender, body mass index, American Society of Anesthesiologists, surgical approach and prosthesis type. Additionally, the tested algorithms were combined in a single predictive tool by stacking.

RESULTS

Best predictive power was obtained by the multivariate adaptive regression splines (R²  = 0.158). However, this was not significantly better than the predictive power of linear regressions (R²  = 0.157). The stacked model had a predictive power of 17%.

CONCLUSIONS

Successful implementation of a shared decision-making tool that can aid clinicians and patients in understanding expected improvement in HRQoL following THR would require higher predictive power than we achieved. For a shared decision-making tool to succeed, further variables, such as socioeconomics, need to be considered.

Trends in hip replacements between 1999 and 2012 in Sweden

National Registers document changes in the circumstance, practice, and outcome of surgery with the passage of time. In the context of total hip replacement (THR), registers can help elucidate the relevant factors that affect the clinical outcome. We evaluated the evolution of factors related to patient, surgical procedure, socio-economy, and various outcome parameters after merging databases of the Swedish Hip Arthroplasty Register, Statistics Sweden and the National Board of Health and Welfare. Data on 193,253 THRs (164,113 patients) operated between 1999 and 2012 were merged. We studied the evolution of surgical volume, patient demographics, socio-economic factors, surgical factors, length-of-stay, mortality rate, adverse events, re-operation and revision rates, and Patient Reported Outcome Measures (PROMs). Throughout this time period the majority of patients were operated on with a diagnosis of primary osteoarthritis. Comorbidity indices increased each year observed. The share of all-cemented implants has dropped from 92% to 68%. More than 88% of the bearings were metal-on-polyethylene. Length-of-stay decreased by 50%. There was a reduction in 30- and 90-day mortality. Re-operation and revision rates at 2 years are decreasing. The post-operative PROMs improved despite the observation of worse pre-operative pain scores getting over time. The demographics of patients receiving a THR, their comorbidities, and their primary diagnosis are changing. Notwithstanding these changes, outcomes like mortality, re-operations, revisions, and PROMs have improved. The practice of hip arthroplasty has evolved, even in a country such as Sweden that is considered to be conservative with regard taking on new surgical practices. © 2017 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 36:432-442, 2018.

Consistency in patient-reported outcomes after total hip replacement

Purpose - The primary objective in this study was to describe the patient-reported outcome measures (PROMs) of total hip replacement (THR) patients 6 years after index surgery. Second, we sought to analyze how the preoperative, 1- and 6-year outcomes were associated. Patients and methods - By assessing the Swedish Hip Arthroplasty Register (SHAR), 15,755 patients with complete follow-up were included in the study group. 1-year and 6-year response rates were 93% and 87%. PROMs used by the SHAR include the EQ-5D instrument, and 2 modified visual analogue scales, 1 for pain and 1 for satisfaction. We used a multivariable linear regression model to examine the relationship between preoperative, 1-year, and 6-year outcome. Results - On average, patient-reported outcomes 6 years after THR were satisfactory. Though there was some deterioration in all mean 6-year PROMs, the patient-reported outcome after 6 years strongly resembled that of the 1-year results. The 1-year follow-up was the strongest factor associated with the 6-year results. Interpretation - There is little deterioration in patient-reported outcomes 6 years after THR compared with the 1-year results. Although the 1-year follow-up was the strongest predictor of the 6-year results it could not alone explain the results, thus supporting the utility of the 6-year follow-up in THR patients.

Comorbidity does not predict long-term mortality after total hip arthroplasty

Background and purpose - In-hospital death following total hip arthroplasty (THA) is related to comorbidity. The long-term effect of comorbidity on all-cause mortality is, however, unknown for this group of patients and it was investigated in this study. Patients and methods - We used data from the Swedish Hip Arthroplasty Register, linked to the National Patient Register from the National Board of Health and Welfare, for patients operated on with THA in 1999-2012. We identified 120,836 THAs that could be included in the study. We evaluated the predictive power of the Charlson and Elixhauser comorbidity indices on mortality, using concordance indices calculated after 5, 8, and 14 years after THA. Results - All comorbidity indices performed poorly as predictors, in fact worse than a base model with age and sex only. Elixhauser was, however, the least bad choice and it predicted mortality with concordance indices 0.59, 0.58, and 0.56 for 5, 8, and 14 years after THA. Interpretation - Comorbidity indices are poor predictors of long-term mortality after THA.

Outcome in design-specific comparisons between highly crosslinked and conventional polyethylene in total hip arthroplasty

Background and purpose - Most registry studies regarding highly crosslinked polyethylene (XLPE) have focused on the overall revision risk. We compared the risk of cup and/or liner revision for specific cup and liner designs made of either XLPE or conventional polyethylene (CPE), regarding revision for any reason and revision due to aseptic loosening and/or osteolysis. Patients and methods - Using the Nordic Arthroplasty Register Association (NARA) database, we identified cup and liner designs where either XLPE or CPE had been used in more than 500 THAs performed for primary hip osteoarthritis. We assessed risk of revision for any reason and for aseptic loosening using Cox regression adjusted for age, sex, femoral head material and size, surgical approach, stem fixation, and presence of hydroxyapatite coating (uncemented cups). Results - The CPE version of the ZCA cup had a risk of revision for any reason similar to that of the XLPE version (p = 0.09), but showed a 6-fold higher risk of revision for aseptic loosening (p < 0.001). The CPE version of the Reflection All Poly cup had an 8-fold elevated risk of revision for any reason (p < 0.001) and a 5-fold increased risk of revision for aseptic loosening (p < 0.001). The Charnley Elite Ogee/Marathon cup and the Trilogy cup did not show such differences. Interpretation - Whether XLPE has any advantage over CPE regarding revision risk may depend on the properties of the polyethylene materials being compared, as well as the respective cup designs, fixation type, and follow-up times. Further research is needed to elucidate how cup design factors interact with polyethylene type to affect the risk of revision.

Reverse hybrid total hip arthroplasty

Background and purpose - The use of a cemented cup together with an uncemented stem in total hip arthroplasty (THA) has become popular in Norway and Sweden during the last decade. The results of this prosthetic concept, reverse hybrid THA, have been sparsely described. The Nordic Arthroplasty Register Association (NARA) has already published 2 papers describing results of reverse hybrid THAs in different age groups. Based on data collected over 2 additional years, we wanted to perform in depth analyses of not only the reverse hybrid concept but also of the different cup/stem combinations used. Patients and methods - From the NARA, we extracted data on reverse hybrid THAs from January 1, 2000 until December 31, 2013. 38,415 such hips were studied and compared with cemented THAs. The Kaplan-Meier method and Cox regression analyses were used to estimate the prosthesis survival and the relative risk of revision. The main endpoint was revision for any reason. We also performed specific analyses regarding the different reasons for revision and analyses regarding the cup/stem combinations used in more than 500 cases. Results - We found a higher rate of revision for reverse hybrids than for cemented THAs, with an adjusted relative risk of revision (RR) of 1.4 (95% CI: 1.3-1.5). At 10 years, the survival rate was 94% (CI: 94-95) for cemented THAs and 92% (95% CI: 92-93) for reverse hybrids. The results for the reverse hybrid THAs were inferior to those for cemented THAs in patients aged 55 years or more (RR =1.1, CI: 1.0-1.3; p < 0.05). We found a higher rate of early revision due to periprosthetic femoral fracture for reverse hybrids than for cemented THAs in patients aged 55 years or more (RR =3.1, CI: 2.2-4.5; p < 0.001). Interpretation - Reverse hybrid THAs had a slightly higher rate of revision than cemented THAs in patients aged 55 or more. The difference in survival was mainly caused by a higher incidence of early revision due to periprosthetic femoral fracture in the reversed hybrid THAs.

Lumbar surgery prior to total hip arthroplasty is associated with worse patient-reported outcomes

Aims

The aims of this study were to describe the prevalence of previous lumbar surgery in patients who undergo total hip arthroplasty (THA) and to investigate their patient-reported outcomes (PROMs) one year post-operatively.

Patients and Methods

Data from the Swedish Hip Arthroplasty Register and the Swedish Spine Register gathered from 2002 to 2013 were merged to identify a group of patients who had undergone lumbar surgery before THA (n = 997) and a carefully matched one-to-one control group. We investigated differences in the one-year post-operative PROMs between the groups. Linear regression analyses were used to explore the associations between previous lumbar surgery and these PROMs following THA. The prevalence of prior lumbar surgery was calculated as the ratio of patients identified with previous lumbar surgery between 2002 and 2012, and divided by the total number of patients who underwent a THA in 2012.

Results

The prevalence of lumbar surgery prior to THA in 2012 was 3.5% (351 of 10 082). Linear regression analyses showed an association with more pain (B = 4.35, 95% confidence interval (CI) 2.57 to 6.12), worse EuroQol (EQ)-5D index, (B = -0.089, 95% CI -0.112 to -0.066), worse EQ VAS (B = -6.75, 95% CI -8.58 to -4.92), and less satisfaction (B = 6.04, 95% CI 4.05 to 8.02).

Conclusion

Lumbar spinal surgery prior to THA is associated with less reduction of pain, worse health-related quality of life, and less satisfaction one year after THA. This is useful information to share in the decision-making process and may help establish realistic expectations of the outcomes of THA in patients who also have previously undergone lumbar spinal surgery. Cite this article: Bone Joint J 2017;99-B:759–65.

Substantial rise in the lifetime risk of primary total knee replacement surgery for osteoarthritis from 2003 to 2013: an international, population-level analysis

OBJECTIVE

To estimate and compare the lifetime risk of total knee replacement surgery (TKR) for osteoarthritis (OA) between countries, and over time.

METHOD

Data on primary TKR procedures performed for OA in 2003 and 2013 were extracted from national arthroplasty registries in Australia, Denmark, Finland, Norway and Sweden. Life tables and population data were also obtained for each country. Lifetime risk of TKR was calculated for 2003 and 2013 using registry, life table and population data.

RESULTS

Marked international variation in lifetime risk of TKR was evident, with females consistently demonstrating the greatest risk. In 2013, Finland had the highest lifetime risk for females (22.8%, 95%CI 22.5-23.1%) and Australia had the highest risk for males (15.4%, 95%CI 15.1-15.6%). Norway had the lowest lifetime risk for females (9.7%, 95%CI 9.5-9.9%) and males (5.8%, 95%CI 5.6-5.9%) in 2013. All countries showed a significant rise in lifetime risk of TKR for both sexes over the 10-year study period, with the largest increases observed in Australia (females: from 13.6% to 21.1%; males: from 9.8% to 15.4%).

CONCLUSIONS

Using population-based data, this study identified significant increases in the lifetime risk of TKR in all five countries from 2003 to 2013. Lifetime risk of TKR was as high as 1 in 5 women in Finland, and 1 in 7 males in Australia. These risk estimates quantify the healthcare resource burden of knee OA at the population level, providing an important resource for public health policy development and healthcare planning.

Risk of early mortality after cemented compared with cementless total hip arthroplasty

Aims

It has been suggested that cemented fixation of total hip arthroplasty (THA) is associated with an increased peri-operative mortality compared with cementless THA. Our aim was to investigate this through a nationwide matched cohort study adjusting for age, comorbidity, and socioeconomic background.

Patients and Methods

A total of 178 784 patients with osteoarthritis who underwent either cemented or cementless THA from the Swedish Hip Arthroplasty Register were matched with 862 294 controls from the general population. Information about the causes of death, comorbidities, and socioeconomic background was obtained. Mortality within the first 90 days after the operation was the primary outcome measure.

Results

Patients who underwent cemented THA had an increased risk of death during the first 14 days compared with the controls (hazard ratio (HR) 1.3, confidence interval (CI) 1.11 to 1.44), corresponding to an absolute increase in risk of five deaths per 10 000 observations. No such early increase of risk was seen in those who underwent cementless THA. Between days 15 and 29 the risk of mortality was decreased for those with cemented THA (HR 0.7, CI 0.62 to 0.87). Between days 30 and 90 all patients undergoing THA, irrespective of the mode of fixation, had a lower risk of death than controls. Patients selected for cementless fixation were younger, healthier and had a higher level of education and income than those selected for cemented THA. A supplementary analysis of 16 556 hybrid THAs indicated that cementation of the femoral component was associated with a slight increase in mortality up to 15 days, whereas no such increase in mortality was seen in those with a cemented acetabular component combined with a cementless femoral component.

Conclusion

This nationwide matched cohort study indicates that patients receiving cemented THA have a minimally increased relative risk of early mortality that is reversed from day 15 and thereafter. The absolute increase in risk is very small. Our findings lend support to the idea that cementation of the femoral component is more dangerous than cementation of the acetabular component. Cite this article: Bone Joint J 2017;99-B:37–43.

Implant survival of the most common cemented total hip devices from the Nordic Arthroplasty Register Association database

Background and purpose - According to previous Nordic Arthroplasty Register Association (NARA) data, the 10-year implant survival of cemented total hip arthroplasties (THAs) is 94% in patients aged 65-74 and 96% in patients aged 75 or more. Here we report a brand-level comparison of cemented THA based on the NARA database, which has not been done previously. Patients and methods - We determined the rate of implant survival of the 9 most common cemented THAs in the NARA database. We used Kaplan-Meier analysis with 95% CI to study implant survival at 10 and 15 years, and Cox multiple regression to assess survival and hazard ratios (HRs), with revision for any reason as endpoint and with adjustment for age, sex, diagnosis, and femoral head material. Results - Spectron EF THA (89.9% (CI: 89.3-90.5)) and Elite THA (89.8% (CI: 89.0-90.6)) had the lowest 10-year survivorship. Lubinus (95.7% survival, CI: 95.5-95.9), MS 30 (96.6%, CI: 95.8-97.4), and C-stem THA (95.8%, CI: 94.8-96.8) had a 10-year survivorship of at least 95%. Lubinus (revision risk (RR) = 0.77, CI: 0.73-0.81), Müller (RR =0.83, CI: 0.70-0.99), MS-30 (RR =0.73, CI: 0.63-0.86), C-stem (RR =0.70, CI: 0.55-0.90), and Exeter Duration THA (RR =0.84, CI: 0.77-0.90) had a lower risk of revision than Charnley THA, the reference implant. Interpretation - The Spectron EF THA and the Elite THA had a lower implant survival than the Charnley, Exeter, and Lubinus THAs. Implant survival of the Müller, MS 30, CPT, and C-stem THAs was above the acceptable limit for 10-year survival.

Early mortality and morbidity after total hip arthroplasty in patients with femoral neck fracture

Background and purpose - Early postoperative mortality is relatively high after total hip arthroplasty (THA) that has been performed due to femoral neck fracture. However, this has rarely been investigated after adjustment for medical comorbidity and comparison with the mortality in an age-matched population. We therefore assessed early mortality in hip fracture patients treated with a THA, in the setting of a nationwide matched cohort study. Patients and methods - 24,699 patients who underwent THA due to a femoral neck fracture between 1992 and 2012 were matched with 118,518 controls. Kaplan-Meier survival analysis was used to calculate cumulative unadjusted survival, and Cox regression models were fitted to compute hazard ratios (HRs) and 95% confidence intervals (CIs), with adjustment for age, sex, comorbidity, and socioeconomic background. Results - 90-day survival was 96.3% (95% CI: 96.0-96.5) for THA cases and 98.7% (95% CI: 98.6-98.8) for control individuals, giving an adjusted HR of 2.2 (95% CI: 2.0-2.4) for THA cases compared to control individuals. Comorbidity burden increased in THA cases over time, but the adjusted risk of death within 90 days did not differ statistically significantly between the time periods investigated (1992-1998, 1999-2005, and 2006-2012). A Charlson comorbidity index of 3 or more, an American Society of Anesthesiologists (ASA) grade of 3 and above, male sex, an age of 80 years and above, an income below the first quartile, and a lower level of education were all associated with an increased risk of 90-day mortality. Interpretation - The adjusted early mortality in femoral neck fracture patients who underwent THA was about double that in a matched control population. Patients with femoral neck fracture but with no substantial comorbidity and an age of less than 80 years appear to have a low risk of early death. Patients older than 80 years and those with a Charlson comorbidity index of more than 2 have a high risk of early death, and such patients would perhaps benefit from treatment strategies other than THA, but this should be investigated further.

Linking Swedish health data registers to establish a research database and a shared decision-making tool in hip replacement

BACKGROUND

Sweden offers a unique opportunity to researchers to construct comprehensive databases that encompass a wide variety of healthcare related data. Statistics Sweden and the National Board of Health and Welfare collect individual level data for all Swedish residents that ranges from medical diagnoses to socioeconomic information. In addition to the information collected by governmental agencies the medical profession has initiated nationwide Quality Registers that collect data on specific diagnoses and interventions. The Quality Registers analyze activity within healthcare institutions, with the aims of improving clinical care and fostering clinical research.

MAIN BODY

The Swedish Hip Arthroplasty Register (SHAR) has been collecting data since 1979. Joint replacement in general and hip replacement in particular is considered a success story with low mortality and complication rate. It is credited to the pioneering work of the SHAR that the revision rate following hip replacement surgery in Sweden is amongst the lowest in the world. This has been accomplished by the diligent follow-up of patients with feedback of outcomes to the providers of the healthcare along with post market surveillance of individual implant performance. During its existence SHAR has experienced a constant organic growth. One major development was the introduction of the Patient Reported Outcome Measures program, giving a voice to the patients in healthcare performance evaluation. The next aim for SHAR is to integrate patients' wishes and expectations with the surgeons' expertise in the form of a Shared Decision-Making (SDM) instrument. The first step in building such an instrument is to assemble the necessary data. This involves linking the SHARs database with the two aforementioned governmental agencies. The linkage is done by the 10-digit personal identity number assigned at birth (or immigration) for every Swedish resident. The anonymized data is stored on encrypted serves and can only be accessed after double identification.

CONCLUSION

This data will serve as starting point for several research projects and clinical improvement work.

Is the use of antidepressants associated with patient-reported outcomes following total hip replacement surgery?

Background and purpose - Patients with anxiety and/or depression tend to report less pain reduction and less satisfaction with surgical treatment. We hypothesized that the use of antidepressants would be correlated to patient-reported outcomes (PROs) 1 year after total hip replacement (THR), where increased dosage or discontinuation would be associated with worse outcomes. Patients and methods - THR cases with pre- and postoperative patient-reported outcome measures (PROMs) were selected from the Swedish Hip Arthroplasty Register (n = 9,092; women: n = 5,106). The PROMs were EQ-5D, visual analog scale (VAS) for pain, Charnley class, and VAS for satisfaction after surgery. These cases were merged with a national database of prescription purchases to determine the prevalence of antidepressant purchases. Regression analyses were performed where PROs were dependent variables and sex, age, Charnley class, preoperative pain, preoperative health-related quality of life (HRQoL), patient-reported anxiety/depression, and antidepressant use were independent variables. Results - Antidepressants were used by 10% of the cases (n = 943). Patients using antidepressants had poorer HRQoL and higher levels of pain before and after surgery and they experienced less satisfaction. Preoperative antidepressant use was independently associated with PROs 1 year after THR regardless of patient-reported anxiety/depression. Interpretation - Antidepressant usage before surgery was associated with reduced PROs after THR. Cases at risk of poorer outcomes may be identified through review of the patient's medical record. Clinicians are encouraged to screen for antidepressant use preoperatively, because their use may be associated with PROs after THR.

Patient-reported outcome measures in arthroplasty registries

The International Society of Arthroplasty Registries (ISAR) Steering Committee established the Patient-Reported Outcome Measures (PROMs) Working Group to convene, evaluate, and advise on best practices in the selection, administration, and interpretation of PROMs and to support the adoption and use of PROMs for hip and knee arthroplasty in registries worldwide. The 2 main types of PROMs include generic (general health) PROMs, which provide a measure of general health for any health state, and specific PROMs, which focus on specific symptoms, diseases, organs, body regions, or body functions. The establishment of a PROM instrument requires the fulfillment of methodological standards and rigorous testing to ensure that it is valid, reliable, responsive, and acceptable to the intended population. A survey of the 41 ISAR member registries showed that 8 registries administered a PROMs program that covered all elective hip or knee arthroplasty patients and 6 registries collected PROMs for sample populations; 1 other registry had planned but had not started collection of PROMs. The most common generic instruments used were the EuroQol 5 dimension health outcome survey (EQ-5D) and the Short Form 12 health survey (SF-12) or the similar Veterans RAND 12-item health survey (VR-12). The most common specific PROMs were the Hip disability and Osteoarthritis Outcome Score (HOOS), the Knee injury and Osteoarthritis Outcome Score (KOOS), the Oxford Hip Score (OHS), the Oxford Knee Score (OKS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC), and the University of California at Los Angeles Activity Score (UCLA).

Patient-reported outcome measures in arthroplasty registries Report of the Patient-Reported Outcome Measures Working Group of the International Society of Arthroplasty Registries Part II. Recommendations for selection, administration, and analysis

- The International Society of Arthroplasty Registries (ISAR) Patient-Reported Outcome Measures (PROMs) Working Group have evaluated and recommended best practices in the selection, administration, and interpretation of PROMs for hip and knee arthroplasty registries. The 2 generic PROMs in common use are the Short Form health surveys (SF-36 or SF-12) and EuroQol 5-dimension (EQ-5D). The Working Group recommends that registries should choose specific PROMs that have been appropriately developed with good measurement properties for arthroplasty patients. The Working Group recommend the use of a 1-item pain question ("During the past 4 weeks, how would you describe the pain you usually have in your [right/left] [hip/knee]?"; response: none, very mild, mild, moderate, or severe) and a single-item satisfaction outcome ("How satisfied are you with your [right/left] [hip/knee] replacement?"; response: very unsatisfied, dissatisfied, neutral, satisfied, or very satisfied). Survey logistics include patient instructions, paper- and electronic-based data collection, reminders for follow-up, centralized as opposed to hospital-based follow-up, sample size, patient- or joint-specific evaluation, collection intervals, frequency of response, missing values, and factors in establishing a PROMs registry program. The Working Group recommends including age, sex, diagnosis at joint, general health status preoperatively, and joint pain and function score in case-mix adjustment models. Interpretation and statistical analysis should consider the absolute level of pain, function, and general health status as well as improvement, missing data, approaches to analysis and case-mix adjustment, minimal clinically important difference, and minimal detectable change. The Working Group recommends data collection immediately before and 1 year after surgery, a threshold of 60% for acceptable frequency of response, documentation of non-responders, and documentation of incomplete or missing data.

Total Hip Arthroplasty in 6690 Patients with Inflammatory Arthritis: Effect of Medical Comorbidities and Age on Early Mortality

Objective.

We analyzed early mortality after total hip arthroplasty (THA) in patients with inflammatory arthritis (IA), adjusting for medical comorbidities and socioeconomic background.

Methods.

Data on 6690 patients with IA who underwent THA during 1992–2012 were extracted from the Swedish Hip Arthroplasty Register. Data on comorbidity, measured using the Charlson Comorbidity Index (CCI), and socioeconomic data were gathered from the Swedish National Inpatient Register and Statistics Sweden. The CCI was divided into low (0), moderate (1–2), and high (> 2). Cox proportional hazards models were fitted to calculate adjusted HR of early mortality, with 95% CI.

Results.

Twenty-five patients (0.4%) died within 0–90 days, giving a 90-day unadjusted survival rate of 99.6% (CI 99.5–99.8). Comorbidity was associated with an increased risk of death within 90 days postoperatively [high vs low CCI: adjusted HR 9.0 (CI 1.6–49.9)]. There was a trend toward lower risk of death during the period 1999–2005, although patients operated on during this period had more comorbidities than those operated on from 1992 to 1998. A large proportion of patients was re-admitted to hospital within 90 days after the index procedure (30.2%), but rarely for cardiovascular reasons.

Conclusion.

Medical comorbidity and an age above 75 years are associated with a substantial increase in the risk of early death after THA in patients with IA. Awareness of potential risk factors may alert clinicians and thus improve perioperative care.

Association between hospital procedure volume and risk of revision after total hip arthroplasty: a population-based study within the Nordic Arthroplasty Register Association database

OBJECTIVE

Outcome after total hip arthroplasty (THA) depends on several factors related to the patient, the surgeon and the implant. It has been suggested that the annual number of procedures per hospital affects the prognosis. We aimed to examine if hospital procedure volume was associated with the risk of revision after primary THA in the Nordic countries from 1995 to 2011.

DESIGN

The Nordic Arthroplasty Register Association database provided information about primary THA, revision and annual hospital volume. Hospitals were divided into five volume groups (1-50, 51-100, 101-200, 201-300, >300). The outcome of interest was risk of revision 1, 2, 5, 10 and 15 years after primary THA. Multivariable regression was used to assess the relative risk (RR) of revision.

RESULTS

417,687 THAs were included. For the 263,176 cemented THAs no differences were seen 1 year after primary procedure. At 2, 5, 10 and 15 years the four largest hospital volume groups had a reduced risk of revision compared to group 1-50. After 10 years RR was for volume group 51-100 0.79 (CI 0.65-0.95), group 101-200 0.76 (CI 0.61-0.95), group 201-300 0.74 (CI 0.57-0.96) and group >300 0.57 (CI 0.46-0.71). For the uncemented THAs an association between hospital volume and risk of revision were only present for hospitals producing 201-300 THAs per year, beginning at years 2 through 5 and in all subsequent time intervals to 15 years.

CONCLUSION

Hospital procedure volume was associated with a long term risk of revision after primary cemented THA. Hospitals operating 50 procedures or less per year had an increased risk of revision after 2, 5, 10 and 15 years follow up.

Increased Long-Term Cardiovascular Risk After Total Hip Arthroplasty: A Nationwide Cohort Study

Total hip arthroplasty is a common and important treatment for osteoarthritis patients. Long-term cardiovascular effects elicited by osteoarthritis or the implant itself remain unknown. The purpose of the present study was to determine if there is an increased risk of late cardiovascular mortality and morbidity after total hip arthroplasty surgery.A nationwide matched cohort study with data on 91,527 osteoarthritis patients operated on, obtained from the Swedish Hip Arthroplasty Register. A control cohort (n = 270,688) from the general Swedish population was matched 1:3 to each case by sex, age, and residence. Mean follow-up time was 10 years (range, 7-21).The exposure was presence of a hip replacement for more than 5 years. The primary outcome was cardiovascular mortality after 5 years. Secondary outcomes were total mortality and re-admissions due to cardiovascular events.During the first 5 to 9 years, the arthroplasty cohort had a lower cardiovascular mortality risk compared with the control cohort. However, the risk in the arthroplasty cohort increased over time and was higher than in controls after 8.8 years (95% confidence interval [CI] 7.0-10.5). Between 9 and 13 years postoperatively, the hazard ratio was 1.11 (95% CI 1.05-1.17). Arthroplasty patients were also more frequently admitted to hospital for cardiovascular reasons compared with controls, with a rate ratio of 1.08 (95% CI 1.06-1.11).Patients with surgically treated osteoarthritis of the hip have an increased risk of cardiovascular morbidity and mortality many years after the operation when compared with controls.

The EQ-5D-5L Improves on the EQ-5D-3L for Health-related Quality-of-life Assessment in Patients Undergoing Total Hip Arthroplasty

BACKGROUND

The EQ-5D is a generic health survey that can be used to compare improvement across different interventions, measure changes in health-related quality of life over time, or to explore cost-effectiveness among treatments, hospitals, or providers. The original EQ-5D survey has three response options for each of five health dimensions; however, with so few response options, ceiling and floor effects are problematic in some populations. A new version, called the EQ-5D-5L, was developed, which gives respondents five answer options (the "5L" refers to five response levels, which is in contrast to the original survey's three levels). However, the validity of this version has not, to our knowledge, been evaluated in patients undergoing total hip arthroplasty (THA).

QUESTIONS/PURPOSES

The purposes of this study were (1) to characterize the redistribution of responses using the new version; (2) to describe the ceiling and floor effects in the current three-level version and identify whether the new EQ-5D-5L survey diminished these effects; and (3) to understand the convergent validity of the new version with the old and the EQ visual analog scale.

METHODS

Both versions of the survey were administered either preoperatively or 1 to 6 years after THA, allowing at least 2 weeks between administrations. Responses to the two versions were compared to determine response redistribution properties, ceiling and floor effects, and convergent validity. Sample sizes were determined so that the study would have 90% power to detect a Spearman correlation over 0.7 when comparing the responses of the three-level survey with the five-level survey and allowing for a rate of 25% loss to followup.

RESULTS

Most patients before surgery used the new responses in the majority of dimensions, whereas the patients taking the test after surgery used the new responses predominantly for the pain dimension. The five-level diminished ceiling effects in both groups by up to 30% and diminished floor effects in the pain dimension for patients taking the assessment before surgery by 14%, which was the only dimension in either patient group that had high rates of floor effects. The correlation between the surveys' visual analog scale and response patterns was not different for the two versions of the survey in these populations.

CONCLUSIONS

The EQ-5D five-level survey appears able to discriminate new health states indistinguishable in the original, which may allow more sensitive measurements of change in patients undergoing THA. The five-level survey should be considered for implementation in local and national registry monitoring of health-related quality of life in patients undergoing THA.

Historical view and future demand for knee arthroplasty in Sweden

BACKGROUND AND PURPOSE

The incidence of knee osteoarthritis will most likely increase. We analyzed historical trends in the incidence of knee arthroplasty in Sweden between 1975 and 2013, in order to be able to provide projections of future demand.

PATIENTS AND METHODS

We obtained information on all knee arthroplasties in Sweden in the period 1975-2013 from the Swedish Knee Arthroplasty Register, and used public domain data from Statistics Sweden on the evolution of and forecasts for the Swedish population. We forecast the incidence, presuming the existence of a maximum incidence.

RESULTS

We found that the incidence of knee arthroplasty will continue to increase until a projected upper incidence level of about 469 total knee replacements per 10(5) Swedish residents aged 40 years and older is reached around the year 2130. In 2020, the estimated incidence of total knee arthroplasties per 10(5) Swedish residents aged 40 years and older will be 334 (95% prediction interval (PI): 281-374) and in 2030 it will be 382 (PI: 308-441). Using officially forecast population growth data, around 17,500 operations would be expected to be performed in 2020 and around 21,700 would be expected to be performed in 2030.

INTERPRETATION

Today's levels of knee arthroplasty are well below the expected maximum incidence, and we expect a continued annual increase in the total number of knee arthroplasties performed.

Increased risk of revision for infection in rheumatoid arthritis patients with total hip replacements

BACKGROUND AND PURPOSE

Medical treatment of rheumatoid arthritis (RA) has changed dramatically over the last 15 years, including immune modulation. We investigated the risk of revision for infection after primary total hip replacement (THR) in patients with rheumatoid arthritis over a 16-year period, and compared it with that in THR patients with osteoarthritis (OA).

PATIENTS AND METHODS

We identified 13,384 THRs in RA patients and 377,287 THRs in OA patients from 1995 through 2010 in a dataset from the Nordic Arthroplasty Register Association (NARA). Kaplan-Meier survival curves, with revision for infection as the endpoint, were constructed. Cox regression analyses were performed to calculate the relative risk (RR) of revision for infection adjusted for age, sex, fixation technique, and year of primary surgery.

RESULTS

RA patients had a 1.3 times (95% CI 1.0-1.6) higher risk of revision for infection. After 2001, this risk increased more for RA patients than for OA patients. During the first 3 months and from 8 years postoperatively, the risk of revision for infection was higher in RA patients with THRs fixated with antibiotic-loaded cement than in corresponding OA patients.

INTERPRETATION

We found a slightly higher overall risk of revision for infection in RA patients than in OA patients, but this difference was only present after 2001. In THRs with antibiotic-loaded cement, the risk of very early and late infections leading to revision was higher in RA patients than in OA patients.

Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal bearings

BACKGROUND AND PURPOSE

Data from the national joint registries in Australia and England and Wales have revealed inferior medium-term survivorship for metal-on-metal (MoM) total hip arthroplasty (THA) than for metal-on-polyethylene (MoP) THA. Based on data from the Nordic Arthroplasty Register Association (NARA), we compared the revision risk of cementless stemmed THA with MoM and MoP bearings and we also compared MoM THA to each other.

PATIENTS AND METHODS

We identified 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM bearings (11,567 patients, 35%) or MoP bearings (21,111 patients, 65%). The patients were followed until revision, death, emigration, or the end of the study period (December 31, 2011), and median follow-up was 3.6 (interquartile range (IQR): 2.4-4.8) years for MoM bearings and 3.4 (IQR: 2.0-5.8) years for MoP bearings. Multivariable regression in the presence of competing risk of death was used to assess the relative risk (RR) of revision for any reason (with 95% confidence interval (CI)).

RESULTS

The cumulative incidence of revision at 8 years of follow-up was 7.0% (CI: 6.0-8.1) for MoM bearings and 5.1% (CI: 4.7-5.6) for MoP bearings. At 6 years of follow-up, the RR of revision for any reason was 1.5 (CI: 1.3-1.7) for MoM bearings compared to MoP bearings. The RR of revision for any reason was higher for the ASR (adjusted RR = 6.4, CI: 5.0-8.1), the Conserve Plus (adjusted RR = 1.7, CI: 1.1-2.5) and "other" acetabular components (adjusted RR = 2.4, CI: 1.5-3.9) than for MoP THA at 6 years of follow-up.

INTERPRETATION

At medium-term follow-up, the survivorship for cementless stemmed MoM THA was inferior to that for MoP THA, and metal-related problems may cause higher revision rates for MoM bearings with longer follow-up.

Residual effect after oral bisphosphonate treatment and healthy adherer effects--the Swedish Adherence Register Analysis (SARA)

Little is known of the effect of alendronate and risedronate on osteoporotic fractures after discontinuation of therapy. We found that time on treatment was significantly inversely associated with the incidence of hospitalized fractures during posttreatment follow-up. Our results will inform health economic analysis of osteoporosis interventions.

INTRODUCTION

Real-world persistence to treatment of osteoporosis is well-understood, but little is known of the posttreatment residual effect on fractures. The objective of this study was to investigate the residual effect of alendronate and risedronate on fractures and assess whether a healthy adherer effect confounds the association between persistence and residual anti-fracture effect.

METHODS

A treatment-naïve cohort from the Swedish Prescribed Drug Register was identified through prescriptions for alendronate or risedronate between 2005 and 2009. Persistence was estimated, and patients were stratified by time on treatment (<1 month, 1-6 months, 7-12 months, and >12 months). Survival analysis was used to study hospitalized fractures and mortality up to 18 months after treatment discontinuation.

RESULTS

The crude incidence proportion of fractures the first 6 months after treatment discontinuation ranged from 2.26% (<1 month of treatment) to 1.16% (>12 months). The corresponding estimates for month 7 to 12 after discontinuation was 3.18 to 1.96%, and for month 13 to 18 after discontinuation 2.69 to 1.95%. Adjusted regression results showed that patients persisting with therapy for >12 months had 60% lower fracture risk the first six months after treatment discontinuation (RR 0.40, p = 0.001). Patient characteristics, including prevalent fractures and co-morbidities, and posttreatment mortality were comparable across persistence durations, and we found no evidence of a healthy adherer effect.

CONCLUSIONS

Time on bisphosphonate treatment was significantly inversely associated with the incidence of hospitalized fractures during posttreatment follow-up. We found no evidence of a healthy adherer effect confounding the relationship between treatment persistence and fracture risk.

Validation of reoperations due to infection in the Swedish Hip Arthroplasty Register

Background

Complete or almost complete recording of reoperations is essential to enable a correct interpretation of data in arthroplasty registers. The completeness of recordings due to infection is unknown in the Swedish Hip Arthroplasty Register (SHAR). We therefore used a combination of data from the Swedish Prescribed Drug Register (SPDR) and studies of medical records to validate the data of reoperations due to infection in the SHAR.

Methods

All patients registered for a primary Total Hip Replacement (THR) in the SHAR between July 1, 2005 and December 31, 2008 were selected for the study (45,531 patients with 49,219 THRs) and were matched with the SPDR. All patients with a minimum of 4 weeks of continuous outpatient antibiotic treatment within 2 years after their primary THR (1,989 patients, with 2,219 THRs) were selected for a medical records review to find the THRs reoperated due to infection.

Results

599 (1.3%) of the THRs had been reoperated within 2 years after the index operation and in 47.4% of these the prosthesis had been revised or extracted. 400 of the THRs were registered for a reoperation in the SHAR resulting in a completeness of 67%.

Conclusions

The completeness of registration due to early infection after THR questions whether the SHAR reoperation data can be used in order to evaluate changes in postoperative infection rates.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-384) contains supplementary material, which is available to authorized users.

Deep infection after total hip replacement: a method for national incidence surveillance

OBJECTIVE

The purpose of this study was to estimate the incidence of deep periprosthetic joint infections (PJIs) after primary total hip replacement (THR) in Sweden prior to the introduction of a national initiative to reduce these infections.

DESIGN

Prospective open cohort study with 2 years follow-up of each subject.

SETTING

All THR-performing clinics in Sweden.

METHODS

All patients registered for a primary THR in the Swedish Hip Arthroplasty Register between July 1, 2005, and December 31, 2008, were selected for the study (45,531 patients with 49,219 THRs) and were matched with the Swedish Prescribed Drug Register. All patients with a minimum of 4 weeks of continuous outpatient antibiotic treatment within 2 years after their primary THR (1,989 patients with 2,219 THRs) were selected for a medical records review, and the number of cases with PJI was determined.

RESULTS

The cumulative incidence of PJI within 2 years after primary THR was 0.9% (95% confidence interval, 0.85-1.02; n = 443), and 405 of these had been reoperated. The incidence rate of PJI for the first 3 months was 5 per 10,000 THR-weeks and, thereafter, 0.3 per 10,000 THR-weeks. Staphylococcus aureus and coagulase-negative staphylococci were the most common bacteria isolated.

CONCLUSIONS

This study describes a new method of national postoperative infection surveillance. The incidence is similar to previous smaller reports and is useful for monitoring changes over time to evaluate the national initiative to reduce infections.

Better Management of Patients with Osteoarthritis: Development and Nationwide Implementation of an Evidence-Based Supported Osteoarthritis Self-Management Programme

BACKGROUND

Information and exercise are core treatments of osteoarthritis. Self-management and coping strategies with the disease are crucial to gain benefits. We developed a supported osteoarthritis self-management programme, delivered by trained physiotherapists, to facilitate patient and healthcare compliance. The programme combined peer- and healthcare professional-delivered information, and individually adapted exercise.

METHODS

Physiotherapists were trained to deliver and evaluate the programme. Patient-reported compliance and satisfaction with the programme was assessed at three- and 12-month follow-ups.

RESULTS

Data from 20,200 consecutive patients in 320 different care centres in Sweden showed that 97% attended the theory sessions and 83% volunteered for the optional individual exercise programme. The intervention was rated as good or very good by 94% of patients. After three months, 62% reported daily use of what they had learned during the course, and 91% reported weekly use. Corresponding numbers after 12 months were 37% and 72%.

CONCLUSIONS

The supported osteoarthritis self-management programme is feasible in clinical practice, and seems useful and acceptable to patients.

Periprosthetic femoral fracture within two years after total hip replacement: analysis of 437,629 operations in the nordic arthroplasty register association database

BACKGROUND

We used the Nordic Arthroplasty Register Association database to evaluate whether age, sex, preoperative diagnosis, fixation, and implant design influence the risk of revision arthroplasty due to periprosthetic fracture within two years from operation of a primary total hip replacement.

METHODS

Included in the study were 325,730 cemented femoral stems and 111,899 uncemented femoral stems inserted from 1995 to 2009. Seven frequently used stems (two cemented stems [Exeter and Lubinus SP II] and five uncemented stems [Bi-Metric, Corail, CLS Spotorno, ABG I, and ABG II]) were specifically studied.

RESULTS

The incidence of revision at two years was low: 0.47% for uncemented stems and 0.07% for cemented stems. Uncemented stems were much more likely to have this complication (relative risk, 8.72 [95% confidence interval, 7.37 to 10.32]; p < 0.0005). Age had no consistent influence on the risk for revision of cemented stems, but revision in the uncemented group increased with increasing age. A cemented stem was associated with a higher risk in male patients compared with female patients (hazard ratio, 1.95 [95% confidence interval, 1.51 to 2.53]; p < 0.0005), whereas an uncemented stem was associated with a reduced risk in male patients compared with female patients (hazard ratio, 0.74 [95% confidence interval, 0.62 to 0.89]; p = 0.001). The risk for revision due to early periprosthetic fracture increased during the 2003 to 2009 period compared with the 1995 to 2002 period both before and after adjustment for demographic factors and fixation (relative risk, 1.44 [95% confidence interval, 1.18 to 1.69]; p < 0.0005). The hazard ratio for the Exeter stem was about five times higher than that for the Lubinus SP II stem (hazard ratio, 5.03 [95% confidence interval, 3.29 to 7.70]; p < 0.0005). Of the five uncemented stems, the ABG II stem showed an increased hazard ratio of 1.63 (95% confidence interval, 1.16 to 2.28) (p = 0.005), whereas the Corail stem showed a decreased hazard ratio of 0.47 (95% confidence interval, 0.34 to 0.65) (p < 0.0005) compared with the reference Bi-Metric design.

CONCLUSIONS

The shape and surface finish of the femoral stem and its fixation could be related to the increased risk of some prosthetic designs. Even if the incidence of early periprosthetic fracture in general is low and other reasons for revision must be considered, specific attention should be given to the choice of fixation and stem design in risk groups.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Women in Charnley class C fail to improve in mobility to a higher degree after total hip replacement

BACKGROUND

The Charnley comorbidity classification organizes patients into 3 classes: (A) 1 hip involved, (B) 2 hips involved, and (C) other severe comorbidities. Although this simple classification is a known predictor of health-related quality of life (HRQoL) after total hip replacement (THR), interactions between Charnley class, sex, and age have not been investigated and there is uncertainty regarding whether A and B should be grouped together.

METHODS

We selected a nationwide cohort of patients from the Swedish Hip Arthroplasty Register operated with THR due to primary osteoarthritis between 2008 and 2010. For estimation of HRQoL, we used the generic health outcome questionnaire EQ-5D of the EuroQol group. This consists of 2 parts: the EQ-5D index and the EQ VAS estimates. We modeled the EQ-5D index and the EQ VAS against the self-administered Charnley classification. Confounding was controlled for using preoperative HRQoL values, pain, and previous contralateral hip surgery.

RESULTS

We found that women in class C had a poorer EQ-5D outcome than men. This effect was mostly due to the fact that women failed to improve in the mobility dimension; only 40% improved, while about 50% of men improved. Age did not interact with Charnley class. We also found that the classification performed best without splitting or aggregating classes.

INTERPRETATION

Our results suggests that the self-administered Charnley classification should be used in its full capacity and that it may be interesting to devote special attention to women in Charnley class C.

Different patient-reported outcomes in immigrants and patients born in Sweden: 18,791 patients with 1 year follow-up in the Swedish Hip Arthroplasty Registry

BACKGROUND AND PURPOSE

Some patients have persistent symptoms after total hip arthroplsty (THA). We investigated whether the proportions of inferior clinical results after total hip arthroplasty-according to the 5 dimensions in the EQ-5D form, and pain and satisfaction according to a visual analog scale (VAS)-are the same in immigrants to Sweden as observed in those born in Sweden.

METHODS

Records of total hip arthroplasties performed between 1992 and 2007 were retrieved from the Swedish Hip Arthroplasty Register (SHAR) and cross-matched with data from the National Board of Health and Welfare and also Statistics, Sweden. 18,791 operations (1,451 in immigrants, 7.7%) were eligible for analysis. Logistic and linear regression models including age, sex, diagnosis, type of fixation, comorbidity, surgical approach, marital status, and education level were analyzed. Outcomes were the 5 dimensions in EQ-5D, EQ-VAS, VAS pain, and VAS satisfaction. Preoperative data and data from 1 year postoperatively were studied.

RESULTS

Preoperatively (and after inclusion of covariates in the regression models), all immigrant groups had more negative interference concerning self-care. Immigrants from the Nordic countries outside Sweden and Europe tended to have more problems with their usual activities and patients from Europe and outside Europe more often reported problems with anxiety/depression. Patients born abroad showed an overall tendency to report more pain on the VAS than patients born in Sweden. After the operation, the immigrant groups reported more problems in all the EQ-5D dimensions. After adjustment for covariates including the preoperative baseline value, most of these differences remained except for pain/discomfort and-concerning immigrants from the Nordic countries-also anxiety/depression. After the operation, pain according to VAS had decreased substantially in all groups. The immigrant groups indicated more pain than those born in Sweden, both before and after adjustment for covariates.

CONCLUSION

The frequency of patients who reported moderate to severe problems, both before and 1 year after the operation, differed for most of the dimensions in EQ-5D between patients born in Sweden and those born outside Sweden.

Age- and health-related quality of life after total hip replacement: decreasing gains in patients above 70 years of age

BACKGROUND

While age is a common confounder, its impact on health-related quality of life (HRQoL) after total hip replacement is uncertain. This could be due to improper statistical modeling of age in previous studies, such as treating age as a linear variable or by using age categories. We hypothesized that there is a non-linear association between age and HRQoL.

METHODS

We selected a nationwide cohort from the Swedish Hip Arthroplasty Register of patients operated with total hip replacements due to primary osteoarthritis between 2008 and 2010. For estimating HRQoL, we used the generic health outcome questionnaire EQ-5D of the EuroQol group that consits or 2 parts: the EQ-5D index and the EQ VAS estimates. Using linear regression, we modeled the EQ-5D index and the EQ VAS against age 1 year after surgery. Instead of using a straight line for age, we applied a method called restricted cubic splines that allows the line to bend in a controlled manner. Confounding was controlled by adjusting for preoperative HRQoL, sex, previous contralateral hip surgery, pain, and Charnley classification.

RESULTS

Complete data on 27,245 patients were available for analysis. Both the EQ-5D index and EQ VAS showed a non-linear relationship with age. They were fairly unaffected by age until the patients were in their late sixties, after which age had a negative effect.

INTERPRETATION

There is a non-linear relationship between age and HRQoL, with improvement decreasing in the elderly.

Education attainment is associated with patient-reported outcomes: findings from the Swedish Hip Arthroplasty Register

BACKGROUND

Age, sex, and medical comorbidities may be associated with differences in patient-reported outcome scores after THA. Highest level of education may be a surrogate for socioeconomic status, but the degree to which this is associated with patient-reported outcomes after THA is not known.

QUESTIONS/PURPOSES

We investigated the national Swedish Hip Arthroplasty Register for the association of education attainment on patient-reported outcomes 1 year after THA; specifically, we evaluated level of education attainment against health-related quality of life (HRQoL), pain reduction, and satisfaction with treatment 1 year after THA.

METHODS

All THAs for osteoarthritis performed from 2005 through 2007 with complete patient-reported outcome measures (representing 49% of the THAs performed for this diagnosis) were selected from the Swedish Hip Arthroplasty Register. These cases were merged with national databases containing education attainment, marital status, and comorbidities (n = 11,464; mean age of patients, 64 years). The patient-reported outcome measure protocol included the HRQoL measure EuroQol five-dimension scale (EQ-5D), a VAS for pain, the Charnley classification survey, and a VAS addressing THA satisfaction. Linear regression analyses determined the association of preoperative patient factors with patient-reported outcomes.

RESULTS

High education attainment was associated with higher HRQoL (EQ-5D index ß(high) = 0.03 ± 0.01; EQ VAS ß(high) = 2.6 ± 0.5) after THA, whereas those with low and medium education were at risk for lower HRQoL. High education was associated with less pain after treatment (ß(high) = -3.3 ± 0.05). Individuals with low or medium education were at risk for less satisfaction with THA (p < 0.001).

CONCLUSIONS

Our results suggest clinicians should support patients with low and medium education to a greater extent. Identification of patients who will benefit most from THA and educating those at risk for poorer outcomes, like patients with low and medium education, ultimately may improve patient satisfaction, HRQoL, pain, and the cost utility of THA.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.