Presenter: Mr T Partridge MBBS, MRCS SIMULTANEOUS OR STAGED BILATERAL TOTAL HIP REPLACEMENT? AN ANALYSIS OF COMPLICATIONS IN 12,110 PATIENTS USING NATIONAL DATA Presenter: Mr T Partridge MBBS, MRCS Co-authors: M Wyatt, J Charity, P Baker, M Reed, S Jameson. AAOS ANNUAL CONGRESS 2016 1-4 March, Orlando

DISCLOSURES Presenting Author: T Partridge - Disclosures: Research support from Zimmer P Baker - Disclosures: Speakers bureau for Stryker; Research support from Stryker M Reed - Disclosures: Speakers bureau for Heraeus, Zimmer. Paid Consultant for Zimmer. Research support from Convatec, Heraeus, Stryker. Other financial support or material support from Zimmer. S Jameson, M Wyatt and J Charity - No disclosures Here are our disclosures for which I am not aware of any conflicts of interest.

BACKGROUND Simultaneous bilateral total hip replacement performed in younger, fitter patients cost effective reduced anaesthetic time, length of stay If not suitable for simultaneous procedures, staged replacements are often performed between 3 and 6 months apart Simultaneous bilateral total hip replacement is often performed in younger, fitter patients with bilateral hip disease. It is arguably more cost-effective; reducing overall anaesthetic time, length of stay, rehabilitation, and therefore potentially the impact on a patients working life. It is historically associated with a higher risk of medical complications and so If deemed not suitable for simultaneous procedures, staged replacements are often performed between 3 and 6 months apart, to minimize morbidity.

AIM SIMULTANEOUS STAGED To compare versus bilateral hip replacement in order to determine any differences in morbidity and mortality So we aimed to compare simultaneous versus staged bilateral hip replacement on a national scale in order to determine any differences in morbidity and mortality.

METHODOLOGY Hospital Episode Statistics (HES) data Unique resource Improved reliability since PbR in 2004 Retrospective cohort study using HES bilateral THRs April 2005 to July 2014 grouped into - simultaneous (same day) - staged (3 to 6 months) Comparison of medical and surgical complications Exclusion criteria Low complication rates make it difficult to determine risk factors from case series reports. Hospital Episode Statistics or HES, codes every hospital patient encounter and is an internationally unique resource, the accuracy of which is perceived to be improving. Payment by results means this is billed data, each trust is externally audited to ensure accuracy. Hospital Episode statistics data for all patients who underwent bilateral hip replacements in the English NHS between April 2005 and July 2014 were obtained from CHKS and used in accordance with their permissions. Patients were grouped into simultaneous bilaterals (i.e. same day) or staged, with the time period determined as 3 to 6 months between operations. Medical and surgical complications were compared and total length of stay was assessed. Exclusion criteria was under 18s, and those units identified to have done fewer than 5 simultaneous procedures.

UNITS PERFORMING SIMULTANEOUS BILATERAL THR, BY VOLUME This graph shows the simultaneous hips by volume and we feel analyzing those who perform simultaneous procedure more routinely has more relevance and probably removes those which were incorrectly recorded.

POPULATION Planned simulataneous bilateral Failure after first hip Successful Simultaneous When someone is planned for simultaneous or indeed staged procedures, if they develop a complication during or after the first hip this may very well significantly delay or even prevent the second procedure. Given this is retrospective data we cannot tell who was planned for what and therefore we unfortunately lose these subgroups of patients. Failure after first operation Planned staged bilateral Successful Staged

RESULTS SIMULTANEOUS STAGED P-VALUE NUMBER 2818 9292 MEAN AGE (IQR) 60.6 years (53-69) 66.0 years (60-74) P<0.001 SEX 46.3% MALE (1162) 39.6% MALE (3912) CHARLSON SCORE MEDIAN (RANGE) MEAN (0-9) 0.29 0.32 P<0.05 So overall 2818 underwent a simultaneous procedure and 9292 had staged procedures. Patients who had the simultaneous procedure were significantly younger, were more male, and has less co-morbidities although the median score was the same.

ADJUSTED ODDS RISK RATIO COMPLICATION SIMULTAN ABSOLUTE RISK STAGED ADJUSTED ODDS RISK RATIO P-VALUE PULMONARY EMBOLISM 1.4% 0.3% 5.4 (3.2-8.9) P<0.00 1 MYOCARDIAL INFARCTION 0.6% 0.1% 6.0 (2.7-13.3) RENAL FAILURE 1.0% 4.0 (2.3-6.8) CHEST INFECTION 1.2% 4.8 (2.8-8.0) READMISSION 2.2% 1.9 (1.4-2.7) WOUND INFECTION 0.7% 2.0 (1.3-3.0) IN-HOSPITAL DEATH 0.4% 6.3 (2.6-15.3) DISLOCATION 0.8% 1.5 (0.9-2.6) P=0.10 1 HOSPITAL STAY 7 DAYS 10 DAYS Despite being younger and fitter the absolute risk of developing a PE, heart attack, renal failure, chest infection, readmission, wound infection and inhospital death was higher in the simultaneous group than the staged. Using regression modelling to adjust for age, sex and co-morbidities the odds risk ratios demonstrate significantly more risk of complications in the simultaneous group notably inhospital death with an odds ratio of 6.3, myocardial infarction and PE. Dislocation rates were similar. As expected the overall average length of stay was significantly longer in the staged group.

FURTHER WORK HES Data Multi-site validation project We will conduct multi-site validation projects to assess the accuracy of the HES data.

SINGLE CENTRE VALIDATION Exeter Hip Unit database (high volume bilateral unit) Anonymised dataset comparison based on age, sex, date of operation 92.3% accurate for identifying simultaneous bilateral THRs Complications were 100% accurate 2 pulmonary embolis 1 myocardial infarction No deaths No DVT, renal failure, chest infection, stroke The first of which we compared HES data with Exeters own hip unit database, Exeter being a high volume simulataneous bilateral unit). It was found to be 92.3% accurate for identifying true simultaneous bilaterals and the complications were 100% accurate. Notably over 10 years there were just 2 PEs, 1 myocardial infarction and no deaths.

FURTHER WORK HES Data Multi-site validation project Analyse data at high volume simultaneous bilateral centres We have then used a cut off of at least 5 simultaneous procedures per year to identify 10 high volume centres to compare to low volume centres. 5 per year

HIGH VOLUME VS LOW VOLUME P-VALUE NUMBER 831 (5-30 per year) 1676 (<5 per year) MEAN AGE (IQR) 59.3 years 61.2 years P<0.001 SEX 49.3% MALE 45.8% MALE P=0.116 CHARLSON SCORE MEAN 0.21 0.32 There were 831 hips in the high volume group, the most being 30 simultaneous bilaterals a year. The high volume group were significantly younger and less co-morbid than the low volume group.

ADJUSTED ODDS RISK RATIO COMPLICATION HIGH VOL ABSOLUTE RISK LOW VOL ADJUSTED ODDS RISK RATIO P-VALUE PULMONARY EMBOLISM   1.1% 1.6% 1.4 (0.6-3.0) p=0.41 MYOCARDIAL INFARCTION 0.4% 0.7% 1.5(0.4-5.7) p=0.59 RENAL FAILURE 0.8% 1.0 (0.4-2.5) p=0.96 CHEST INFECTION 0.5% 1.5% 2.6 (0.9-7.6) p=0.09 READMISSION 1.7% 2.4% 1.4 (0.8-2.6) p=0.27 WOUND INFECTION 1.7 (0.7-4.1) p=0.20 IN-HOSPITAL DEATH 0% NA DISLOCATION 0.9 (0.4-2.3) p=0.88 There were no deaths in the high volume group with the absolute risk of 0.7% in low volume centres being significantly higher than the national average. Otherwise after adjustment for age sex and co-morbidities each complication risk was higher in the low volume group but no significantly so.

FURTHER WORK HES Data Multi-site validation project Analyse data at high volume simultaneous bilateral centres Analysing effect of time between stages Local work with QoL measures in Exeter We also plan to assess the effect of time between stages broadening out our 3-6 month cut off and evaluate differences in Quality of life outcomes.

LIMITATIONS HES Data 7% error rate Department of Health. Payment by Results: The quality of clinical coding in the NHS. October 2014. 7% error rate Staged patients with complication potentially delay second procedure No QoL measures The limitations of this study include the accuracy of HES data however a recent publication found just a 7% error rate amongst 50 trusts. And as previously mentioned we have lost the group of patients who had a complication during their first hip. We plan to construct a number of models adding in average risk of a primary total hip to attempt to account for this.

CONCLUSIONS Complication and mortality rate key concerns for patient, anaesthetist and surgeon Whilst risks are low, these findings highlight the greater risks of bilateral simultaneous hip replacement Patient selection and risk tool Enhance the informed consent process and provides evidence to guide surgical practice In conclusion complications and mortality are key concerns for patient, anaesthetist and patient - whilst the risks are low these findings highlight the greater risks of bilateral simultaneous hip replacement. Whilst there may be benefits of cost and length of rehabilitation this serves to emphasize the importance of patient selection and potentially the use of risk tools. It provides up with up to date evidence which can enhance the informed consenting process.

ACKNOWLEDGEMENTS Phillip James (CHKS) Sarah Whitehouse (Statistician RD&E PEOC) and the Exeter Hip Unit CHKS provided data and advice on clinical coding to support this study (free of charge) in order to assist in furthering the understanding of outcomes in English NHS hospitals HES data was re-used with permission of the Health and Social Care Information Centre.  Copyright (c) 2015. All rights reserved

Thank you