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.

Choice of Prosthetic Implant Combinations in Total Hip Replacement: Cost-Effectiveness Analysis Using UK and Swedish Hip Joint Registries Data.

BACKGROUND: Prosthetic implants used in total hip replacements (THR) have a range of bearing surface combinations (metal-on-polyethylene, ceramic-on-polyethylene, ceramic-on-ceramic, and metal-on-metal), head sizes (small [<36 mm in diameter] and large [≥36 mm in diameter]), and fixation techniques (cemented, uncemented, hybrid, and reverse hybrid). These can influence prosthesis survival, patients' quality of life, and healthcare costs. OBJECTIVES: To compare the lifetime cost-effectiveness of implants for patients of different age and sex profiles. METHODS: We developed a Markov model to compare the cost-effectiveness of various implants against small-head cemented metal-on-polyethylene implants. The probability that patients required 1 or more revision surgeries was estimated from analyses of more than 1 million patients in the UK and Swedish hip joint registries, for men and women younger than 55, 55 to 64, 65 to 74, 75 to 84, and 85 years and older. Implant and healthcare costs were estimated from local procurement prices, national tariffs, and the literature. Quality-adjusted life-years were calculated using published utility estimates for patients undergoing THR in the United Kingdom. RESULTS: Small-head cemented metal-on-polyethylene implants were the most cost-effective for men and women older than 65 years. These findings were robust to sensitivity analyses. Small-head cemented ceramic-on-polyethylene implants were most cost-effective in men and women younger than 65 years, but these results were more uncertain. CONCLUSIONS: The older the patient group, the more likely that the cheapest implants, small-head cemented metal-on-polyethylene implants, were cost-effective. We found no evidence that uncemented, hybrid, or reverse hybrid implants were the most cost-effective option for any patient group. Our findings can influence clinical practice and procurement decisions for healthcare payers worldwide.

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.

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.

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.

Is Preoperative Patient-Reported Health Status Associated with Mortality after Total Hip Replacement?

The influence of comorbidities and worse physical status on mortality following total hip replacement (THR) leads to the idea that patient-reported health status may also be a predictor of mortality. The aim of this study was to investigate the relationship between patient-reported health status before THR and the risk of dying up to 5 years post-operatively. For these analyses, we used register data on 42,862 THR patients with primary hip osteoarthritis operated between 2008 and 2012. The relative survival ratio was calculated by dividing the observed survival in the patient group by age- and sex-adjusted expected survival of the general population. Pre-operative responses to the five EQ-5D-3L (EuroQol Group) dimensions along with age, sex, education status, year of surgery, and hospital type were used as independent variables. Results shown that, as a group, THR patients had a better survival than the general population. Broken down by the five EQ-5D-3L dimensions we observed differentiated survival patters. For all dimensions, those reporting extreme problems had higher mortality than those reporting moderate or no problems. In conclusion, worse health status according to the EQ-5-3L before THR is associated with higher mortality up to five years after surgery. EQ-5D-3L responses may be useful in a multifactorial individualized risk assessment before THR.

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.

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.

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.

Lifetime Risk of Primary Total Hip Replacement Surgery for Osteoarthritis From 2003 to 2013: A Multinational Analysis Using National Registry Data.

OBJECTIVE: To compare the lifetime risk of total hip replacement (THR) surgery for osteoarthritis (OA) between countries, and over time. METHODS: Data on primary THR 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 THR was calculated for 2003 and 2013 using registry, life table, and population data. RESULTS: In 2003, lifetime risk of THR ranged from 8.7% (Denmark) to 15.9% (Norway) for females, and from 6.3% (Denmark) to 8.6% (Finland) for males. With the exception of females in Norway (where lifetime risk started and remained high), lifetime risk of THR increased significantly for both sexes in all countries from 2003 to 2013. In 2013, lifetime risk of THR was as high as 1 in 7 women in Norway, and 1 in 10 men in Finland. Females consistently demonstrated the highest lifetime risk of THR at both time points. Notably, lifetime risk for females in Norway was approximately double the risk for males in 2003 (females 15.9% [95% confidence interval (95% CI) 15.6-16.1], males 6.9% [95% CI 6.7-7.1]), and 2013 (females 16.0% [95% CI 15.8-16.3], males 8.3% [95% CI 8.1-8.5]). CONCLUSION: Using representative, population-based data, this study found statistically significant increases in the lifetime risk of THR in 5 countries over a 10-year period, and substantial between-sex differences. These multinational risk estimates can inform resource planning for OA service delivery.

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.

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.