‘Worse than death’ and waiting for a joint arthroplasty

Listen to Mr Andrew Duckworth interviewing Prof. Colin Howie and Miss Chloe Scott about their paper "‘Worse than death’ and waiting for a joint arthroplasty", published in the August 2019 issue of The Bone and Joint Journal.

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Transcript

[00:00:00] Welcome everyone to this month's BJJ Podcast. I'm Andrew Duckworth and a warm welcome to one of two podcasts we're doing for the month of August, from your team here at The Bone & Joint Journal. I would like to thank all our readers and listeners for the comments and support we've received so far for our podcast series, as well as to our authors and guest interviewers who have taken part so far. We really do appreciate all their efforts.

So far this year, we have covered a range of topics, including the management of open fractures with Professor Matt Costa. We had a great dialogue between Ian Murray and Dr. Scott Rodeo on cell therapies and orthopaedic surgery, and more recently a series of podcasts to accompany our supplements from the American Hip and Knee Society closed meetings. 

We do hope these podcasts are improving the accessibility and visibility for studies we publish here at the journal, both for you as our readers, as well as for our many authors.

As you know, we hope that during the next 15 to 20 minutes or so we'll cover a range of aspects of the chosen study, emphasizing theimportant parts of how the work has been designed as well as the key findings from the study and how these potentially fits into each of your day-to-day clinical [00:01:00] practices.

We also hope to give you a behind the scenes insight into how the authors have developed the study and give them an opportunity to put forward key findings of their work. So today I have the pleasure of being joined by two of my colleagues here at Edinburgh, Ms. Chloe Scott and Prof. Colin Howie  to discuss their study entitled Worse than death and waiting for joint replacement, which we published in the August edition of the BJJ. Welcome Chloe and Prof, and a big thank you to both of you for taking the time to join us today. 

So the aim of your study was to look at patients awaiting hip and knee arthroplasty and categorize their health state in particular category known as a state, worse than death. As you say, in your paper, there's an increasing demand for healthcare interventions to be economically viable and cost-effective. To assess this the quality adjusted life years is often calculated based on the EQ-5D score, as well as population demographics, demographics, such as life expectancy.

So Prof, if I could start with you, can you give us a brief background to the paper, specifically the concept of QOLS, the EQ-5D  score and how this is used to define the term a [00:02:00] state worse than death?

Over many years orthopaedics has looked carefully at the outcome treatments that it has undertaken. We've moved from the surgeon's opinion to the patient's opinion. And we've developed very sophisticated scores, such as the Oxford Score or some of the other Knee and Hip scores so that we can detect differences in the way that we operate. 

More recently in, across the country, and particularly in our department, we noticed that more and more patients were complaining about the time that we kept waiting for surgery. And I thought it'd be interesting to see if the waiting time had made any difference to their state and if there was any problem. 

The EQ-5D is a general score and it's used across all specialties in medicine, general medicine, orthopaedics, and all sub-specialties of medicine. It was developed in the latter half of the last century in a very scientific waylooking at questions and it covers five domains. That's the 5D. And those [00:03:00] 5Ds are mobility, self-care, ability to perform unusual tasks, pain and anxiety and depression.

In orthopaedics we've largely ignored it because there was only, there is only three scores that you can give each of those five domains. And it seemed that it perhaps didn't give us enough granularity to make decisions.

However, like many people, we discovered that this was actually much more informative than we had thought in the past. What happens in the EQ-5D is you don't just add up the score for each domain. Each domain is given a number one to three, and each of those states, each state for each individual patient is allocated one of 243 states.

The difference between the EQ-5D and other scores is that those 242 states were given to members of the public. And it was different members of the public in each country in Europe, to assess how long would they like to live when in that [00:04:00] particular state. And so one of the states, for example, would be allocated a number and the numbers go from minus one to one with zero being a state on the borderline between what the public would regard as acceptable or unacceptable and anything less zero is a state worse than death. 

Since then they've taken these numbers and they've looked at the cost utility. We've looked to see how much healthcare improvement you give the patient over time by your treatment. And you allocate the costs of giving the treatment and the cost to society of not giving the treatment.

And that's how a QALY is worked out. The difference in EQ-5D, including the costs of not treating the patient versus the costs of treating the patient measured out over the period of time. 

That's fantastic. That's a really good  overview of the EQ-5D and [00:05:00] obviously the QALY and how that's  related.

So Chloe if I come to you next, in relation to hip and knee arthroplasty, what do we already know about cost-effectiveness in terms of the QALY in particular? 

Thanks Andrew. And thanks for inviting us to participate in this podcast. So for a treatment to be considered cost-effective, NICE has determined that it should cost less than £20,000 per QALY gained. And for cancer therapies this figure is increased to less than £100,000 per QALY gained. 

In addition to being highly clinically effective, both total hip and total knee replacements are known to be highly cost-effective too. And in front work from our centre, by Paul  Jenkins and colleagues  published in The Bone & Joint Journal in 2013, shows that for total hip replacement, the cost of the QALY is £1,371. And for total knee replacement, it's £2,101. So both interventions, therefore highly [00:06:00] cost-effective. 

To give some comparison, Panjeer et al published a cost-effectiveness model for a statin use in the primary prevention of cardiovascular disease in adults in JAMA, back in 2015. They found that to reduce the ten-year risk of cardiovascular disease to 7.5%, half of 40 75 year old adults would need treatment. And this would come at a cost of $37,000 per QALY. 

So compared to these other medical interventions that are well accepted joint replacement is certainly proven to be cost-effective. 

That's really interesting Chloe. I think it really puts it into context in terms of the wider medical community.

So if we move on to your study in particular, looking at the methods, it is obviously a cross-sectional study using data from January 2014 to September [00:07:00] 2017. There was a source from our arthoplasty database here in Edinburgh, and it was once patients who'd had a second arthroplasty *inaudible* were excluded. There were 2,073 hip replacements and 2,168 knee replacements. 

So Chloe, just to give the listeners some background to joint replacement in our centre, initially. Can you describe the type of prosthesis we use in our standard sort of postoperative protocol? 

Of course. So our centres are a university teaching hospital, and we perform about 800 total hips and 800 total knees per year in addition to revision arthroplasty. Our standard is to use cemented implants for both procedures. For a total hip replacement we use cemented Exeter stem with a cemented contemporary cup, normally implanted by a posterior approach. For a total knee  replacement we use the triathlon Krisha retaining to me , uh, inserted using a measured resection technique.

So postoperatively , um, both total hips and total knees are allowed to wait there [00:08:00] as a or from the first post-operative morning. They start initially with a frame and progressed to specs and they normally go home on day two to four when they can do stairs independently with their steps. They receive daily physiotherapy while in hospital.

Um, in addition to occupational therapy and foot, and after discharge, they're reviewed at six to eight weeks, our team of arthroplasty practitioners and , um, patient reported outcome measures are routinely collected and at a year post-operatively. Great. And that sort of brings on to minus sort of next question.

So you're describing in the paper when the patients got the questionnaires and what these entails. So it just gives a bit more detail regarding that and also how, how the waiting list and the time data was obtained and calculated. So, um , um, patient reported outcome questionnaires include the ITI five D as we've already mentioned as a measure of general health and health related quality of life.

They include the appropriate Oxford score, either hip or me, and a series of detailed co-morbidity [00:09:00] questions, which cover 12 specific conditions, including heart failure, NMI stroke, performance, aerial disease, CAPD diabetes, connected tissue disorders and inflammatory arthropathies kidney and liver disease.

Um, and other muscular skeletal diseases, giving back pain or pain and other joints. Whilst I knew that our listeners are well versed in the joint specific Oxford scores. Um, the  is, is less well understood. Uh, professor Howie has obviously gone through it in more detail , um, using the UK scoring system at the impossible scores for your age, you find the index , um, range from minus 0.6 to one , uh, one defined as full health.

Zero is death and negative scores, therefore worse than death though, this terminology is provocative sounding. Um, it's part of the score that has been used by a number of authors previously. And as we've already [00:10:00] mentioned, the score is widely validated and used throughout in Europe to determine cost effectiveness.

So our questionnaire has included , uh,  Oxford knee score co-morbidity scores. And these were, um , uh, client to patients two to three weeks prior to their surgery in a pre-assessment clinic where they were completed independently. Um, and again, the same scores were posted out to patients as a year. Um, in addition to these problems , uh, demographic data, including the Scottish index of multiple deprivation and BMI were collected all the patients.

Okay. And with regards to the waiting list and time data, how was that collected? So I think it's important to highlight that. The paper isn't primarily about waiting lists, but we thought , uh, including this as a variable was important in the analysis, because we wondered whether waiting on German, lots of time for joint replacement, which affect your list and death status.

So for the time spent [00:11:00] on the actual waiting list for surgery. So the length of time from the decision to operate to the actual surgery , um, that was provided by our waiting list office. However it was more complicated and determine the weight from the primary care referral to the actual review. Um, in orthopedic, in orthopedic outpatients, this was made more complicated.

Um, as not all patients listed for surgery are listed at their first orthopedic out-patient review. And some patients may be seen on a number of occasions over a couple of years. There's four. They actually reached the point of, of, of bunting , um, ask plasty. So for this reason patients who haven't been placed on the waiting list at their first orthopedic outpatient review , um, were excluded from the waiting time evaluation.

Um, as we didn't know what the basis for the delay to surgery was. Yeah. That makes a lot of sense. And obviously you just briefly mentioned the nurse that is obsolete. And things you, the papers, [00:12:00] obviously over us, some details on that analysis that have been performed. So can you just for our listeners, give us a brief overview of the rationale ancestor forms and how the ROC Kev analysis was used to identify the professionalism, both the Hawks and hip and knee scores associated with the state worth and death category.

Um, sure. So for total hip and total knee patients, there were separately. Um, analyze using univer univariate analysis to identify significant associations with their preoperative worse than death status. So as our sample sizes were large with 2073 hips. In 2,168. Nice. Um, a number of variables, whereas associated as being , um, statistically significant at the 10% level less, and therefore a multivariate analysis was performed of all of these variable significant , um, at the 10% level or less.

So this was a multi-variate binary, logistic regression analysis performed using SPSS [00:13:00] , um, to identify it. Specifically which variables were independently associated with a worst than death status. Um, as Oxford scores, as we'll go on to find , uh, to hear about , uh, were found to be independently associated with worse than death status for both hips and knees, this was further investigated using receiver operator curve analysis.

So, this is a method you use to determine the sensitivity and specificity of a test and can be used, therefore, to determine a threshold value or a cut point of a continuous variable. Like the Oxford hip score, Oxford knees for that is associated with a dichotomous outcome, like worse than death status.

That's it. That's a very good overview there. Thank you. So if we move on to the findings of the study, and if we, obviously, as you were doing your paper, start with hip replacement and these sort of raw forgets, how many patients prior to joint replacement were defined as having a worse than that status.

[00:14:00] So prior to total hip replacement, fringe and 91 patients, which was 19% , um, were defined as being in a health state, worse than death, with a negative eating fighting score and 99% of these patients, worse than death reported, extreme levels of pain. Um,  score following  the median age, the index for the whole cohort , um, improved from 0.36 to 0.79.

Um, and the number of patients worse than death reduced from 19% to 2%. And I think it's important to note that these patients. Would same patients, the ones that were worse than death uh post-operatively um, weren't necessarily preoperatively, so it doesn't seem to be a function of personal. Sure. Sure.

And in terms of, when you then went onto the predictors of, of, of worse and death status on the multi-varied analysis, what did you find and what were the thresholds for the opposite hip school you're identifying? So [00:15:00] the multivariate analysis determined that for hips and having a poor joint specific hip function.

Um, measured using the Oxford hip score , uh, was an independent predictor of worse than death status in addition to the presence of CAPD. Um, so none of the other demographic variables and none of the other co-morbidities , um, were significant , uh, in the multivariate analysis. So the rock analysis was then associated with a highly significant area under the curve.

Uh, an identified a threshold Oxford hip school value of 14 and a half , um, as being associated with worse than death status with fairly high sensitivity of 80% and a specificity of 75%. So I think the key message here is that worse than death status was. Significantly determined by the hip specific function rather than other co-morbidities general health.

Yeah, absolutely. And so with regards to the one year outcomes that she faced and how did this correlate with the , uh, the worst in desk status? [00:16:00] So I think the second key message is that those patients who will worse than death, preoperatively achieved significantly worse outcomes of one year with Oxford hip scores, which were a mean of 7.7 points worse than those who weren't worse than death preoperatively.

And this is important because this value exceeds the , um, minimal clinically important difference for this score, which is five. Um, it was also associated with worse patient satisfaction rates. So patients worse than death, preoperatively , um, achieved. Was satisfied 85% of the time versus 92% , uh, when not worse than better.

Okay. So that's obviously the hips. And then if we now move on to the knee replacements, what did you find in regards to these outcomes we've just discussed and how did that compare to the total hip replacements? So the picture was very similar for knees and the long coins is bad. So 12% of patients were worse than death preoperatively.

Um, all of whom again, reported extreme levels pain. [00:17:00] So following the replacement, the median age, you find the index improved from 0.59 to 0.76. And the number of patients worse than death produced , uh, from 12% to 3%. Again, the multivariate analysis determined the Oxford knee score was an independent association with worse than death status.

This time though, peripheral arterial disease was the co-morbidity or the only co-morbidity associated with this status. Again, the ROC analysis provided adequate sensitivity and specificity and suggested a cut-point of 17 and a half. So an Oxford Knee Score of 17.5 was the cut-point for worse than death status.

In terms of the outcomes at a year, the pattern was similar. So patients worse than death preoperatively achieved worse one year outcomes with a [00:18:00] mean Oxford Knee Score, which was 8.2 points less than those not worse than death and satisfaction rates of 73% versus 84. 

And again, that exceeds the MCID. 

Absolutely.

So Prof if I come back to you, with regards to the waiting list status both as, what did you find?

 The waiting list data, because it was over a relatively short period of time in the recent history, doesn't fully achieve statistical significance, but there's absolutely no doubt that the patients who wait longer have a higher worse than death score. And if we had this new trend towards that.

 The interesting thing is that the patients who were in a state of worse than death were often seen earlier, perhaps  because the GPs are good at picking out patients who are suffering. And also because we do have a degree of humanity and like to see them quickly.

So I think that the waiting, although that is a little bit of evidence to show that the longer you wait, the worse you [00:19:00] become, there's no doubt that there's also evidence to show that the system of prioritization by people contacting you makes a difference. 

So that's obviously very reassuring that, like you say, that we potentially do pick up the patients who are suffering the most. So great, great overview of the key findings of the paper. And if we move on to sort of, what does it mean? What are the implications of the study? You know, it's obviously found that once the waiting lets just repeat those numbers for our listeners - 19% of patients with joint disease of the hip and 12% within the knee and defined as having a state worse than death using the EQ-5D score. The strengths of this study are without doubt. There's a large number of patients from that, a robust prospective database, and obviously excellent and robust announces have been performed throughout. 

So Prof again, if I could ask you, what do you feel are the key findings of the study and the work and considering any potential limitations of the data?

 First of all, we have to accept that the state worse than death is a state that was given by members of the public who didn't have any [00:20:00] diseases concerned whatsoever, but it was allocated by the general public over 3500 of them, in an independent review, which had nothing to do with arthritis of the hip.

And so it has strengths, but it also has a weakness that actually, if you ask the people who aren't in a state worse than death, only 15% of them would actually like to be dead. However, they do see their life as miserable and, as Chloe suggested, it's loss of function and pain that are the two predictors of it. And these are the key predictors.

The other major different thing here at this point is the difference between the preoperative score and the postoperative score. Almost everybody gets better and loses the pain within two days of surgery, which is a huge difference. Certainly compared with us, as Chloe suggested, the treatment of statins, where you take it for many, many years and you don't know if they work or not even when you [00:21:00] *inaudible*.

Absolutely. So Chloe you emphasize nicely in discussion in relation to the importance of interpretting results in view of how the EQ-5D score is calculated. We sort of discussed, and I touched on that briefly, but can you expand on that in a little bit more detail? 

Of course, so as we have already discussed although the EQ-5D is widely used, it's not necessarily widely understood. And we've talked now about that 243 potential health states that it defines. And the fact that this definition is based on nearly three and a half thousand members of the UK population valuing these states and deciding that they wouldn't be able to endure living in them. 

So I think a criticism of the paper and of the worst than death status is that it doesn't apply to the individual patients. You know, we haven't asked the individual patients do you feel that you're in a state worse than death? [00:22:00] I think it's significant that it's a value judgment that has been placed on these health things by the general population. The general population who often vote based on how they feel that the NHS has been funded and many of whom will ultimately go on to develop degenerative joint diseases. And I think, I don't think you can ignore the fact that the general public obviously consider these conditions to be serious and unpleasant to put up with. And in the context of having a treatment that works reliably and is highly cost-effective, I think it's difficult to argue that arthroplasty shouldn't be delivered. 

Yeah, no, absolutely. I mean that figure alone, one in five patients waiting for hip replacement are in that category. I mean, just going back to sort of you presented the health-related quality of life for patients undergoing [00:23:00] joint replacement obviously, but how does this, you know, you actually put it in a table in the actual paper, but how does this compare to other medical conditions? I think that's quite important to put it into context, really.

 Absolutely. So because QALYs are used to calculate the cost-effectiveness of all medical interventions EQ-5D indexes are available for a number of chronic health conditions. And so if we consider our mean preoperative EQ-5D index for end-stage degenerative joint disease of the hip, which was 0.30 and of the knee, which was 0.43, these are notably worse than those reported in the literature for a number of chronic health conditions, which include type two diabetes, which is 0.78, heart failure 0.64, COPD 0.52, asthma 0.42 and arthropathies, I mean, the list goes on. 

I think this is especially important to appreciate in the context of resource management in the health service, [00:24:00] where hip and knee arthroplasty are often some of the first procedures to be reduced or rationed in order to save money. And in fact, they'd been designated as procedures of limited clinical value by number of CCGs down South. And I think what this paper shows is that doing this isn't a benign act and leaving patients in pain with end-stage hip or knee degenerative joint disease has significant effects, both on their health-related quality of life and on the outcome that they can expect to achieve when they are treated for joint replacement surgery.

Yeah. No, absolutely. Yeah. That's very well put and Prof just to finish off with you I mean, obviously I think the implications of the study are obviously going to be large, but sort of moving forward, what do you feel is the next step particularly when considering that increasingly as Chloe has alluded to, but increasing referrals to secondary care for joint replacement are being monitored by various criteria, such as BMI and PROMs, what do you think the path forward is going to be?

[00:25:00] Well, first of all, I think that the point of Chloe made before that actually patients with degenerative joint disease have a worse health status than many of the conditions that are not limited to access to healthcare and where the cost benefit is very much poorer than that, the joint replacement is a major question for those commissioning healthcare.

And I think the other thing for orthopaedic surgeons is to realize that we do something which is hugely beneficial for our patients using a similar system, one of our colleagues published in last month's BJJ, the QALYs for subacromial rotator cuff repair and showed that it was highly cost-effective, the same has been done for surgery for hallux valgus. Again, usually cost effective so it is on other healthcare systems. 

It also shows that the outcome is almost universally successful. We take somebody who is ill [00:26:00] and we almost instantly make them better. They have to recover from the surgery. And I think that that's important. 

Personally I think that it's cruel to create a healthcare system, which claims to have universal access to key out the point of delivery free to limit access to the patients who would benefit most. For one of the commonest surgical procedures carried out, major surgical procedures carried out in health service at the moment. And I think that no matter how it's been done to reduce instant costs, but actually within a year, it increased cost to society. And more importantly, to the patient's, future voters. The sit in the community in a state  worse than death.

That's very well put Prof, and I think that's a good point at which we can wrap up. So Chloe and Prof thank you so much for joining us for our podcast and congratulations on a really excellent study that I'm sure will give our listeners [00:27:00] and readers alike, much food for thought.

 And to our listeners, we do hope you've enjoyed joining us here today. And we encourage you to share your thoughts and comments through Twitter, Facebook, and a like, and feel free to post or tweet about anything we've discussed here today. And thanks again for joining us.