t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
Available online at www.sciencedirect.com
ScienceDirect The Surgeon, Journal of the Royal Colleges of Surgeons of Edinburgh and Ireland www.thesurgeon.net
Audit
Thirty-Day mortality after elective hip and knee arthroplasty E.J. Smith*, M. Maru, A. Siegmeth Department of Orthopaedics, Golden Jubilee National Hospital, Agamemnon Street, Clydebank G81 4DY, UK
article info
abstract
Article history:
Background: Hip and knee arthroplasties are very common operations in the UK with over
Received 30 July 2013
150,000 hip and knee arthroplasties taking place in England and Wales in 2011. Fortunately
Received in revised form
mortality following these operations is rare. This study aimed to evaluate the incidence
26 September 2013
and causes of death within 30 days after undergoing hip or knee arthroplasty in our unit
Accepted 22 December 2013
and to highlight possible risk factors.
Available online xxx
Methods: We looked at 30-day mortality in all patients undergoing hip or knee arthroplasty in our institution between 2005 and 2011. Data on post-operative deaths was requested
Keywords:
from the Information Services Division (ISD) and correlated with procedural and de-
Hip arthroplasty
mographic data from our hospital Patient Administration System (PAS). The notes of all
Knee arthroplasty
patients who died within 30 days were reviewed to collect data on co-morbid conditions,
30-Day mortality
pre-operative investigations, post-operative thromboprophylaxis and cause of death. All primary and revision knee and hip arthroplasties including bilateral procedures were included. Arthroplasty for trauma was excluded. Results: 12,243 patients underwent hip or knee arthroplasty within the study period. The male:female ratio was 2:3. The mean age was 68 with a range of 21e91. Ten patients died giving a 30-day mortality rate of 0.08%. The most common cause of death was myocardial infarction (7/10 patients). Conclusions: Our finding of a mortality rate of 0.08% is similar or lower to those found in previous studies. To our knowledge this is the first series of this size looking at mortality from hip and knee arthroplasty within a single centre in the UK. ª 2014 Published by Elsevier Ltd on behalf of Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland.
Background Hip and knee arthroplasties are extremely common operations in the UK. The Scottish Hip Arthroplasty Project reported that almost 7000 primary hip replacements and over 6500 primary
knee replacements were carried out in Scotland in 2011.1 In England and Wales, 71,672 primary hip arthroplasties and 84,653 primary knee arthroplasties were undertaken in 2011.2 Mortality is very rare following hip and knee arthroplasty. However it is important to understand the incidence and risk
* Corresponding author. Tel.: þ44 141 951 5000; fax: þ44 141 951 5419. E-mail address: [email protected] (E.J. Smith). 1479-666X/$ e see front matter ª 2014 Published by Elsevier Ltd on behalf of Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. http://dx.doi.org/10.1016/j.surge.2013.12.004
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
2
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
factors for mortality associated with hip and knee arthroplasty especially given the elective nature of this surgery and the large numbers of patients involved. Published 30-day and in-hospital mortality rates vary from 0.1 to 0.5%.3e6 A systematic review by Singh et al.6 looked at 80 studies of early postoperative mortality following hip or knee arthroplasty. Twenty-eight studies provided 30-day mortality rates and the overall 30-day mortality rate was 0.3%. The National Joint Registry has reported a 30-day mortality rate of around 0.2% for both primary hip and primary knee replacement.2 Although several authors have published 30-day mortality rates following hip and knee arthroplasty these tend to be either relatively small single centre cohorts or using registry data. As a large dedicated elective arthroplasty unit we have had the opportunity to evaluate early post-operative mortality in a large group of patients within a single centre. This audit aims to measure the incidence and assess the causes of mortality within 30 days after undergoing elective hip or knee arthroplasty in our unit. We also wished to highlight any possible risk factors.
Methods We looked at 30-day mortality in all patients undergoing hip or knee arthroplasty in our institution between 1st January 2005 and 31st December 2011. Details of patients who had died within 30 days of arthroplasty were requested from the Information Services Division (ISD) via the Scottish Arthroplasty Project. This was correlated with procedural and demographic data from our hospital Patient Administration System (PAS). The notes of all patients who had died within a period of 30 days post-operatively were reviewed to collect data on comorbid conditions, pre-operative investigations, postoperative thromboprophylaxis and cause of death. All primary and revision knee and hip arthroplasties including bilateral procedures were included. Arthroplasty for trauma was excluded.
Results During the 6-year period studied 12,243 patients underwent an elective hip or knee arthroplasty. There were 5278 primary hip replacements, 6419 primary knees, 289 revision hip procedures and 257 revision knee procedures. Overall the male:female ratio was 2:3. The mean age was 68 with a range of 21e91. There were ten deaths which occurred within 30 days of surgery. This gives a 30-day mortality rate of 0.08%. The mean age of patients who died was 76 (range 65e90) and the male:female ratio was 4:1. Two of the patients died after primary hip replacement, 7 after primary knee arthroplasty and one after a revision knee procedure.
Cause and time of death The cause of death was ascertained from documentation in the medical notes. One patient had a post mortem. In one
other case a post mortem was requested but the patient’s family declined. The most common cause of death was myocardial infarction which was the cause in 7 out of 10 cases. One patient died of pulmonary embolism and one from a cerebrovascular accident. In one case the medical records were not available for review therefore we were not able to find the cause of death. The mean time from operation to death was 7.3 days with a range of 1e13 days. 60% of deaths occurred in-hospital, 40% after discharge.
Pre-operative evaluation and post-op thromboprophylaxis All patients underwent a standardised multi-disciplinary preoperative assessment which includes nurse-led health questionnaire, examination by a junior doctor, routine blood tests and electrocardiogram. Patients with significant medical history were then reviewed by an anaesthetist and further investigations such as echocardiogram or pulmonary function tests carried out. Eight out of 10 patients who died had at least one pre-operative risk factor, such as hypertension, diabetes or a history of ischaemic heart disease. One patient (who died of pulmonary embolism) had no significant past medical history except benign prostatic hypertrophy. For one patient this information was not available. During the time period of this audit the standard protocol in our unit was to use aspirin 150 mg for 6 weeks as thromboprophylaxis. Seven of the 10 patients received aspirin and 2 dalteparin (one patient’s notes not available).
Discussion We have shown a 30-day mortality rate of 0.08% in 12,243 patients undergoing elective lower limb arthroplasty. The most common cause of death was myocardial infarction (MI) and all patients who died of MI had previously identified cardiac risk factors. The rate of fatal pulmonary embolism (PE) was extremely low, with at most 2 fatal PEs in over 12,000 patients. When comparing the group of patients who died to the cohort as a whole there was a higher percentage of male patients and the mean age was higher. Our finding of a 30-day mortality rate of 0.08% is lower than in several other previously published papers.2e6 Although several authors have published mortality rates following hip and knee replacement arthroplasty these tend to be either small cohorts from single centres or data from national databases. We have not found any other papers demonstrating such a large patient population from a single centre in the UK. Given the low rate of post-operative mortality in elective lower limb arthroplasty it may be considered that this simply reflects the background mortality rate in this population. However, several studies have shown that mortality is raised in the early post-operative period.4,7,8 A recent study from the UK by Parry et al.4 found a 30-day mortality rate of 0.37% in 2695 patients undergoing primary knee arthroplasty in comparison to 0.07% in a control group of 5857 patients added to the waiting list for knee arthroplasty, suggesting an increased risk of mortality associated with surgery. In our study the most common cause of death was myocardial infarction. This is consistent with the published
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
literature. Reported causes of death in early post-op period include cardiovascular causes, pulmonary embolism, cerebrovascular incidents, sepsis and bleeding with cardiovascular causes being the most frequent.3,9e11 In the series of over 7000 hip arthroplasties reported by Aynardi3 et al. the most common cause of death was found to be cardiovascular related (23 of 41). Within this group the most common cause was acute coronary syndrome (8 patients). Due to the small numbers of deaths we did not attempt a multivariate analysis to try to establish a link between any particular risk factors and increased mortality. However we did note that both the mean age and the proportion of male patients were higher in the group of patients who died than in the cohort as a whole. Identification of male sex and increasing age as risk factors for post-operative mortality is consistent with the published literature.4,6,12,13 Several authors have studied the risk factors for mortality after joint replacement surgery. The review article by Singh et al.6 reported that the 30-day mortality rates were higher in men and in patients undergoing bilateral procedures while the series reported by Parry et al.4 identified increasing age as a risk factor for post-operative mortality. A population based study of over 6million patient discharges identified several preoperative risk factors for inpatient mortality: revision hip arthroplasty, advanced age, presence of cardiovascular disease, dementia or renal disease.13 There is currently strong political emphasis on trying to reduce mortality from pulmonary embolism. Current national guidelines recommend routine prescribing of low molecular weight heparin, rivaroxaban, dabigatran or fondaparinux for post-operative lower limb arthroplasty patients.14,15 At the time of this patient sample our standard protocol was to use aspirin but despite this we have found an extremely low rate of fatal pulmonary embolism of less than 0.02%. Other authors have reported similar findings.16e18 Some recent publications have shown evidence that routine use of potent anticoagulants does not have any beneficial effect on post-op mortality following lower limb arthroplasty. A meta-analysis published in January 2012 which analysed mortality rate and cause of death in groups of patients with differing thromboprophylaxis regimens (including a group with no routine chemoprophylaxis) found no significant difference in the overall mortality or proportion of deaths caused by pulmonary embolism.9 A previous metaanalysis showed no difference between low molecular weight heparin (LMWH) and placebo in risk of fatal PE, other deaths or all cause mortality.19 Interestingly, a study analysing the impact of the introduction of the national guidelines recommending routine prescription of LMWH found no change in rates of thromboembolism events.20 Return to theatre also showed no change but there was a significant increase in the number of patients diagnosed with thrombocytopaenia. There is also some limited evidence that all cause mortality may be reduced by using aspirin.18 This paper is an observational study with only 1549 patients in a single centre, therefore the results must be interpreted with caution. However given that our data has shown myocardial infarction to be the commonest cause of death in post-operative arthroplasty patients, and that aspirin is widely used in prevention of cardiovascular disease, it seems plausible that aspirin may
3
reduce mortality post-operatively and this is an area worthy of further investigation. We recognise a number of limitations in this study. This was a retrospective audit which, as with any retrospective study, relies on the accuracy of documentation. However the data on the number of deaths came from official national statistics. The cause of death was recorded from the cause of death documented in the case notes and correlated with the results of any relevant investigations prior to death. This clearly relies on the accuracy of the diagnosis made by the team treating the patient at the time. It could be argued that more accurate data on cause of death could be found if postmortems had been carried out. Only one of the patients in this study underwent a post mortem. However to carry out post mortems for all early post-op deaths would require a significant change of culture in our practice and population. A further limitation of this study was that with data from a single centre the numbers of deaths within 30 days are too small to allow any further analysis with regards risk factors or trends over time. We also did not collect data on the comorbidities of the cohort of patients who had surgery and survived therefore we were unable to compare this to the comorbidity profile of the deceased patients. We believe that any further effort to reduce mortality in elective lower limb arthroplasty should focus on managing cardiac risk, particularly in older male patients. Possible avenues for future research may include evaluating the effect of routine prescription of aspirin on all-cause post-operative mortality; or investigating the usefulness of pre-operative cardio-pulmonary exercise testing in selected high risk patients.
Conclusion and recommendations We present a review of mortality in 12,243 patients undergoing lower limb arthroplasty at a single centre over a 6-year period. We believe that the data presented in this audit can help inform the consent process. Patients and surgeons should be aware of the small but real risk of mortality with elective arthroplasty surgery. The mortality rate was low at 0.08% with the commonest cause of death being myocardial infarction. Further efforts to reduce post-operative mortality in elective joint replacement should focus on the assessment and management of cardiovascular risk.
references
1. Scottish Arthroplasty Project. Biennial report [accessed 26.07.13], http://www.arthro.scot.nhs.uk/Reports/sap_ national_report_2012.pdf; 2012. 2. National Joint Registry. 9th Annual report [accessed 26.07.13], http://www.njrcentre.org.uk/NjrCentre/Portals/0/ Documents/England/Reports/9th_annual_report/NJR%209th% 20Annual%20Report%202012.pdf; 2011. 3. Aynardi M, Pulido L, Parvizi J, Sharkey PF, Rothman RH. Early mortality after modern total hip arthroplasty. Clin Orthop Relat Res 2009;467(1):213e8. 4. Parry MC, Smith AJ, Blom AW. Early death following primary total knee arthroplasty. J Bone Jt Surg Am 2011;93(10):948e53.
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
4
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
5. Seah VW, Singh G, Yang KY, Yeo SJ, Lo NN, Seow KH. Thirtyday mortality and morbidity after total knee arthoplasty. Ann Acad Med Singap 2007;36(12):1010e2. 6. Singh JA, Kundukulam J, Riddle DL, Strand V, Tugwell P. Early postoperative mortality following joint arthroplasty: a systematic review. J Rheumatol 2011;38(7):1507e13. 7. Lie SA, Engesæter LB, Havelin LI, Furnes O, Vollset E. Early postoperative mortality after 67,548 total hip replacements: causes of death and thromboprophylaxis in 68 hospitals in Norway from 1987 to 1999. Acta Orthop Scand 2002;73(4):392e9. 8. Lie SA, Pratt N, Ryan P, Engesaeter LB, Havelin LI, Furnes O, et al. Duration of the increase in early post-operative mortality after elective hip and knee replacement. J Bone Jt Surg Am 2010;92(1):58e63. 9. Poultsides LA, Gonzalez Della Valle A, Memtsoudis SG, Ma Y, Roberts T, Sharrock N, et al. Meta-analysis of cause of death following total joint replacement using different thromboprophylaxis regimens. J Bone Jt Surg Br 2012;94(1):113e21. 10. Gill GS, Mills D, Joshi AB. Mortality following primary total knee arthroplasty. J Bone Jt Surg Am 2003;85-A:432e5. 11. Nunley RM, Lachiewicz PF. Mortality after total hip and knee arthroplasty in a medium-volume university practice. J Arthroplasty 2003;18:278e85. 12. Singh JA, Jensen MR, Harmsen WS, Gabriel SE, Lewallen DG. Cardiac and thromboembolic complications and mortality in patients undergoing total hip and total knee arthroplasty. Ann Rheum Dis 2011;70(12):2082e8. 13. Memtsoudis SG, Della Valle AG, Besculides MC, Esposito M, Koulouvaris P, Salvati EA. Risk factors for perioperative mortality after lower extremity arthroplasty: a population based study of 6,901,324 patient discharges. J Arthroplasty 2010;25(1):19e26.
14. Scottish Intercollegiate Guidelines Network. Prevention and management of venous thromboembolism. A National Clinical Guideline. http://www.sign.ac.uk/pdf/sign122.pdf [accessed 26.07.13]. 15. National Institute for Clinical Excellence. Venous thromboembolism: reducing the risk of venous thromboembolism (deep venous thrombosis and pulmonary embolism) in patients admitted to hospital. http://www.nice. org.uk/nicemedia/live/12695/47920/47920.pdf [accessed 26.07.13]. 16. Blom A, Pattison G, Whitehouse S, Taylor A, Bannister G. Early death following primary total hip arthroplasty: 1,727 procedures with mechanical thrombo-prophylaxis. Acta Orthop 2006;77(3):347e50. 17. Cusick LA, Beverland DE. The incidence of fatal pulmonary embolism after primary hip and knee replacement in a consecutive series of 4253 patients. J Bone Jt Surg Br 2009;91(5):645e8. 18. Parry M, Wylde V, Blom AW. Ninety- day mortality after elective total hip replacement: 1549 patients using aspirin as a thromboprophylactic agent. J Bone Jt Surg Br 2008;90(3):306e7. 19. Tasker A, Harbord R, Bannister GC. Meta-anlysis of low molecular weight heparin versus placebo in patients undergoing total hip replacement and post-operative morbidity and mortality since their introduction. Hip Int 2010;20(1):64e74. 20. Jameson SS, Bottle A, Malviya A, Muller SD, Reed MR. The impact of national guidelines for the prophylaxis of venous thromboembolism on the complications of arthroplasty of the lower limb. J Bone Jt Surg Br 2010;92(1):123e219.
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
Available online at www.sciencedirect.com
ScienceDirect The Surgeon, Journal of the Royal Colleges of Surgeons of Edinburgh and Ireland www.thesurgeon.net
Audit
Thirty-Day mortality after elective hip and knee arthroplasty E.J. Smith*, M. Maru, A. Siegmeth Department of Orthopaedics, Golden Jubilee National Hospital, Agamemnon Street, Clydebank G81 4DY, UK
article info
abstract
Article history:
Background: Hip and knee arthroplasties are very common operations in the UK with over
Received 30 July 2013
150,000 hip and knee arthroplasties taking place in England and Wales in 2011. Fortunately
Received in revised form
mortality following these operations is rare. This study aimed to evaluate the incidence
26 September 2013
and causes of death within 30 days after undergoing hip or knee arthroplasty in our unit
Accepted 22 December 2013
and to highlight possible risk factors.
Available online xxx
Methods: We looked at 30-day mortality in all patients undergoing hip or knee arthroplasty in our institution between 2005 and 2011. Data on post-operative deaths was requested
Keywords:
from the Information Services Division (ISD) and correlated with procedural and de-
Hip arthroplasty
mographic data from our hospital Patient Administration System (PAS). The notes of all
Knee arthroplasty
patients who died within 30 days were reviewed to collect data on co-morbid conditions,
30-Day mortality
pre-operative investigations, post-operative thromboprophylaxis and cause of death. All primary and revision knee and hip arthroplasties including bilateral procedures were included. Arthroplasty for trauma was excluded. Results: 12,243 patients underwent hip or knee arthroplasty within the study period. The male:female ratio was 2:3. The mean age was 68 with a range of 21e91. Ten patients died giving a 30-day mortality rate of 0.08%. The most common cause of death was myocardial infarction (7/10 patients). Conclusions: Our finding of a mortality rate of 0.08% is similar or lower to those found in previous studies. To our knowledge this is the first series of this size looking at mortality from hip and knee arthroplasty within a single centre in the UK. ª 2014 Published by Elsevier Ltd on behalf of Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland.
Background Hip and knee arthroplasties are extremely common operations in the UK. The Scottish Hip Arthroplasty Project reported that almost 7000 primary hip replacements and over 6500 primary
knee replacements were carried out in Scotland in 2011.1 In England and Wales, 71,672 primary hip arthroplasties and 84,653 primary knee arthroplasties were undertaken in 2011.2 Mortality is very rare following hip and knee arthroplasty. However it is important to understand the incidence and risk
* Corresponding author. Tel.: þ44 141 951 5000; fax: þ44 141 951 5419. E-mail address: [email protected] (E.J. Smith). 1479-666X/$ e see front matter ª 2014 Published by Elsevier Ltd on behalf of Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. http://dx.doi.org/10.1016/j.surge.2013.12.004
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
2
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
factors for mortality associated with hip and knee arthroplasty especially given the elective nature of this surgery and the large numbers of patients involved. Published 30-day and in-hospital mortality rates vary from 0.1 to 0.5%.3e6 A systematic review by Singh et al.6 looked at 80 studies of early postoperative mortality following hip or knee arthroplasty. Twenty-eight studies provided 30-day mortality rates and the overall 30-day mortality rate was 0.3%. The National Joint Registry has reported a 30-day mortality rate of around 0.2% for both primary hip and primary knee replacement.2 Although several authors have published 30-day mortality rates following hip and knee arthroplasty these tend to be either relatively small single centre cohorts or using registry data. As a large dedicated elective arthroplasty unit we have had the opportunity to evaluate early post-operative mortality in a large group of patients within a single centre. This audit aims to measure the incidence and assess the causes of mortality within 30 days after undergoing elective hip or knee arthroplasty in our unit. We also wished to highlight any possible risk factors.
Methods We looked at 30-day mortality in all patients undergoing hip or knee arthroplasty in our institution between 1st January 2005 and 31st December 2011. Details of patients who had died within 30 days of arthroplasty were requested from the Information Services Division (ISD) via the Scottish Arthroplasty Project. This was correlated with procedural and demographic data from our hospital Patient Administration System (PAS). The notes of all patients who had died within a period of 30 days post-operatively were reviewed to collect data on comorbid conditions, pre-operative investigations, postoperative thromboprophylaxis and cause of death. All primary and revision knee and hip arthroplasties including bilateral procedures were included. Arthroplasty for trauma was excluded.
Results During the 6-year period studied 12,243 patients underwent an elective hip or knee arthroplasty. There were 5278 primary hip replacements, 6419 primary knees, 289 revision hip procedures and 257 revision knee procedures. Overall the male:female ratio was 2:3. The mean age was 68 with a range of 21e91. There were ten deaths which occurred within 30 days of surgery. This gives a 30-day mortality rate of 0.08%. The mean age of patients who died was 76 (range 65e90) and the male:female ratio was 4:1. Two of the patients died after primary hip replacement, 7 after primary knee arthroplasty and one after a revision knee procedure.
Cause and time of death The cause of death was ascertained from documentation in the medical notes. One patient had a post mortem. In one
other case a post mortem was requested but the patient’s family declined. The most common cause of death was myocardial infarction which was the cause in 7 out of 10 cases. One patient died of pulmonary embolism and one from a cerebrovascular accident. In one case the medical records were not available for review therefore we were not able to find the cause of death. The mean time from operation to death was 7.3 days with a range of 1e13 days. 60% of deaths occurred in-hospital, 40% after discharge.
Pre-operative evaluation and post-op thromboprophylaxis All patients underwent a standardised multi-disciplinary preoperative assessment which includes nurse-led health questionnaire, examination by a junior doctor, routine blood tests and electrocardiogram. Patients with significant medical history were then reviewed by an anaesthetist and further investigations such as echocardiogram or pulmonary function tests carried out. Eight out of 10 patients who died had at least one pre-operative risk factor, such as hypertension, diabetes or a history of ischaemic heart disease. One patient (who died of pulmonary embolism) had no significant past medical history except benign prostatic hypertrophy. For one patient this information was not available. During the time period of this audit the standard protocol in our unit was to use aspirin 150 mg for 6 weeks as thromboprophylaxis. Seven of the 10 patients received aspirin and 2 dalteparin (one patient’s notes not available).
Discussion We have shown a 30-day mortality rate of 0.08% in 12,243 patients undergoing elective lower limb arthroplasty. The most common cause of death was myocardial infarction (MI) and all patients who died of MI had previously identified cardiac risk factors. The rate of fatal pulmonary embolism (PE) was extremely low, with at most 2 fatal PEs in over 12,000 patients. When comparing the group of patients who died to the cohort as a whole there was a higher percentage of male patients and the mean age was higher. Our finding of a 30-day mortality rate of 0.08% is lower than in several other previously published papers.2e6 Although several authors have published mortality rates following hip and knee replacement arthroplasty these tend to be either small cohorts from single centres or data from national databases. We have not found any other papers demonstrating such a large patient population from a single centre in the UK. Given the low rate of post-operative mortality in elective lower limb arthroplasty it may be considered that this simply reflects the background mortality rate in this population. However, several studies have shown that mortality is raised in the early post-operative period.4,7,8 A recent study from the UK by Parry et al.4 found a 30-day mortality rate of 0.37% in 2695 patients undergoing primary knee arthroplasty in comparison to 0.07% in a control group of 5857 patients added to the waiting list for knee arthroplasty, suggesting an increased risk of mortality associated with surgery. In our study the most common cause of death was myocardial infarction. This is consistent with the published
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
literature. Reported causes of death in early post-op period include cardiovascular causes, pulmonary embolism, cerebrovascular incidents, sepsis and bleeding with cardiovascular causes being the most frequent.3,9e11 In the series of over 7000 hip arthroplasties reported by Aynardi3 et al. the most common cause of death was found to be cardiovascular related (23 of 41). Within this group the most common cause was acute coronary syndrome (8 patients). Due to the small numbers of deaths we did not attempt a multivariate analysis to try to establish a link between any particular risk factors and increased mortality. However we did note that both the mean age and the proportion of male patients were higher in the group of patients who died than in the cohort as a whole. Identification of male sex and increasing age as risk factors for post-operative mortality is consistent with the published literature.4,6,12,13 Several authors have studied the risk factors for mortality after joint replacement surgery. The review article by Singh et al.6 reported that the 30-day mortality rates were higher in men and in patients undergoing bilateral procedures while the series reported by Parry et al.4 identified increasing age as a risk factor for post-operative mortality. A population based study of over 6million patient discharges identified several preoperative risk factors for inpatient mortality: revision hip arthroplasty, advanced age, presence of cardiovascular disease, dementia or renal disease.13 There is currently strong political emphasis on trying to reduce mortality from pulmonary embolism. Current national guidelines recommend routine prescribing of low molecular weight heparin, rivaroxaban, dabigatran or fondaparinux for post-operative lower limb arthroplasty patients.14,15 At the time of this patient sample our standard protocol was to use aspirin but despite this we have found an extremely low rate of fatal pulmonary embolism of less than 0.02%. Other authors have reported similar findings.16e18 Some recent publications have shown evidence that routine use of potent anticoagulants does not have any beneficial effect on post-op mortality following lower limb arthroplasty. A meta-analysis published in January 2012 which analysed mortality rate and cause of death in groups of patients with differing thromboprophylaxis regimens (including a group with no routine chemoprophylaxis) found no significant difference in the overall mortality or proportion of deaths caused by pulmonary embolism.9 A previous metaanalysis showed no difference between low molecular weight heparin (LMWH) and placebo in risk of fatal PE, other deaths or all cause mortality.19 Interestingly, a study analysing the impact of the introduction of the national guidelines recommending routine prescription of LMWH found no change in rates of thromboembolism events.20 Return to theatre also showed no change but there was a significant increase in the number of patients diagnosed with thrombocytopaenia. There is also some limited evidence that all cause mortality may be reduced by using aspirin.18 This paper is an observational study with only 1549 patients in a single centre, therefore the results must be interpreted with caution. However given that our data has shown myocardial infarction to be the commonest cause of death in post-operative arthroplasty patients, and that aspirin is widely used in prevention of cardiovascular disease, it seems plausible that aspirin may
3
reduce mortality post-operatively and this is an area worthy of further investigation. We recognise a number of limitations in this study. This was a retrospective audit which, as with any retrospective study, relies on the accuracy of documentation. However the data on the number of deaths came from official national statistics. The cause of death was recorded from the cause of death documented in the case notes and correlated with the results of any relevant investigations prior to death. This clearly relies on the accuracy of the diagnosis made by the team treating the patient at the time. It could be argued that more accurate data on cause of death could be found if postmortems had been carried out. Only one of the patients in this study underwent a post mortem. However to carry out post mortems for all early post-op deaths would require a significant change of culture in our practice and population. A further limitation of this study was that with data from a single centre the numbers of deaths within 30 days are too small to allow any further analysis with regards risk factors or trends over time. We also did not collect data on the comorbidities of the cohort of patients who had surgery and survived therefore we were unable to compare this to the comorbidity profile of the deceased patients. We believe that any further effort to reduce mortality in elective lower limb arthroplasty should focus on managing cardiac risk, particularly in older male patients. Possible avenues for future research may include evaluating the effect of routine prescription of aspirin on all-cause post-operative mortality; or investigating the usefulness of pre-operative cardio-pulmonary exercise testing in selected high risk patients.
Conclusion and recommendations We present a review of mortality in 12,243 patients undergoing lower limb arthroplasty at a single centre over a 6-year period. We believe that the data presented in this audit can help inform the consent process. Patients and surgeons should be aware of the small but real risk of mortality with elective arthroplasty surgery. The mortality rate was low at 0.08% with the commonest cause of death being myocardial infarction. Further efforts to reduce post-operative mortality in elective joint replacement should focus on the assessment and management of cardiovascular risk.
references
1. Scottish Arthroplasty Project. Biennial report [accessed 26.07.13], http://www.arthro.scot.nhs.uk/Reports/sap_ national_report_2012.pdf; 2012. 2. National Joint Registry. 9th Annual report [accessed 26.07.13], http://www.njrcentre.org.uk/NjrCentre/Portals/0/ Documents/England/Reports/9th_annual_report/NJR%209th% 20Annual%20Report%202012.pdf; 2011. 3. Aynardi M, Pulido L, Parvizi J, Sharkey PF, Rothman RH. Early mortality after modern total hip arthroplasty. Clin Orthop Relat Res 2009;467(1):213e8. 4. Parry MC, Smith AJ, Blom AW. Early death following primary total knee arthroplasty. J Bone Jt Surg Am 2011;93(10):948e53.
Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
4
t h e s u r g e o n x x x ( 2 0 1 4 ) 1 e4
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Please cite this article in press as: Smith EJ, et al., Thirty-Day mortality after elective hip and knee arthroplasty, The Surgeon (2014), http://dx.doi.org/10.1016/j.surge.2013.12.004
