Bone health

Vertebroplasty evidence aired by MSAC ahead of MBS re-listing decision

An eight-year long battle to have the spinal fracture treatment vertebroplasty relisted on the MBS has seen experts meet with the Medical Services Advisory Committee (MSAC) in a final bid to iron out ‘polarised views’ about the controversial procedure’s benefits ahead of a highly anticipated November decision.

Advocates for the intervention say they now have good evidence of efficacy with early intervention for new fractures. But some clinicians have questioned whether key trials were adequately blinded, while others have suggested multidisciplinary collaborative decision making for vertebroplasty

But a decision on the 2017 application by the Interventional Radiological Society of Australia (IRSA) to secure Medicare subsidies for the procedure has been plagued by delays amid persistent debate around optimal patient selection and efficacy compared to placebo.

In 2011, a systematic evidence review of the treatment – which involves injecting polymethylmethacrylate (PMMA) into the fractured vertebral body – undertaken by MSAC revealed it was no more effective than placebo in reducing pain, which lead to it being scrapped from the MBS.

But at the latest meeting vertebroplasty proponents argued against the decision,  claiming that two trials in particular that were critical to the decision (see here and here) did not reflect the patient group being treated in Australia, nor the technical approach that practitioner’s here use.

IRSA has applied to MSAC for an MBS item for vertebroplasty in patients aged over the age of 60 with osteoporotic spinal fractures less than six weeks duration based on positive findings in that group from the anticipated Australian VAPOUR trial published in 2016.

MSAC considered the application at both its November 2018 and March 2019 meetings but deferred its advice instead convening a second stakeholder meeting in July this year stating it needed ‘broader clinical consultation’.

Lead VAPOUR investigator, Sydney-based interventional radiologist Dr William Clark has spearheaded the push for reinstating public funding for the treatment since its 2011 removal.

He says elderly hospitalised patients with ‘the worst pain in their life’ are required to fund vertebroplasty themselves, even despite private health insurance, which he says is ‘incredibly unfair’.

“The MSAC has granted equal weighting to three negative trials in a different patient group with older fractures and less severe symptoms which are irrelevant to this application,” Dr Clark told the limbic.

Records from the most recent vertebroplasty meeting obtained by the limbic reveal the application for vertebroplasty MBS listing has now been limited to fracture durations of three weeks or less based on a VAPOUR subgroup analysis in which 79% of patients had fractures of this duration.

Dr Clark said evidence for treatment efficacy is strongest in this subgroup group and while he maintains that patients will show improvement up to 6 weeks he concedes that a decision will ultimately rely on what is demonstrated by evidence.

“One of the things we did agree to at the last meeting was that we would now further restrict our application to people with only thoracolumbar fractures of not more than three weeks duration.

We did two sub group analyses in the VAPOUR trial one of them was in this thoracolumbar group who did much better than the rest of the fractures. Those four bones (t-11 t-12 L-1 and L-2) account for about 85% of hospitalised fractures and it’s been my experience too that vertebroplasty works best in those bones.”

Dr Clark said he had provided MSAC with additional analyses of pain results limited to this subgroup of VAPOUR trial patients (n = 95), which also show that significantly more patients in the vertebroplasty arm achieved an NRS pain score of ≤4/10 after 14 days than in the sham arm, and the difference between the groups for this outcome was maintained out to at least 6 months.

“These patients have had stunningly good results – they were functional, independent and home five days earlier compared to placebo. These aren’t small results in terms of outcomes so we’re hopeful that MSAC might agree to funding for that highly targeted sub group of patients,” said Dr Clark.

The procedure would only be offered to patients whose pain does not improve with appropriate pain management including opiates and other analgesics  – a response that would indicate an unstable fracture. Patients must also have severe, or at least established, osteoporosis, he added.

But, according to the July meeting minutes MSAC remains unconvinced about the size of the treatment effect as well as its durability, proposing that an individual patient data (IPD) meta-analysis be undertaken to give it more confidence about the treatment’s benefit.

“Considering that the available randomised trials show a small variation in effect size, and the totality of evidence shows a small effect favouring vertebroplasty, would such a meta-analysis be able to give more clarity and confidence about the clinical meaningfulness of the effect and which patients would most benefit?” the Committee asked experts in July.

Dr Clarke told the limbic such an analysis would be a ‘waste of time’ lambasting the proposal as a ‘delay tactic’.

He and other vertebroplasty supporters strongly maintain that ‘there is no rationale for combining data from the VAPOUR trial for patients in the acute phase with data from other trials in patients with chronic fractures’, according to the meeting minutes.

“IPDs are good if you’ve got similar trials but in the case of vertebroplasty you’ve got totally different patient groups – 60% of ours were hospitalised versus none in the others. You’re comparing trials using different filling techniques on patients with different fracture duration and different degrees of osteoporosis and pain scores,” explained Dr Clark separately to the limbic.

Minutes from the July meeting also revealed that the Committee would consider whether patient eligibility should be a combined decision between a spinal surgeon and an interventional radiologist.

While many clinicians agreed that collaboration between specialists, including geriatricians, pain specialists and endocrinologists, should be part of best practice, they argued it would not be appropriate for an MBS listing to specify who can and cannot collaborate.

What’s more, requiring specialty-specific referrals could lead to problems with under-referral, said one clinician who noted inherent conflict of interest in referral patterns pointing out that providers are ‘financially incentivised to keep patients’.

Dr Clark says his main concern with this proposal is delay.

Clinical success requires early intervention while the bone is still soft and not completely collapsed, says Dr Clark. He fears a process that requires a multidisciplinary meeting to approve eligibility for the procedure could add up to a week or more onto the time from first presentation to treatment.

“Interventional radiology has developed and those of us doing vertebroplasty are quite good at sorting out who is going to benefit from it. Furthermore, all of those requirements are going to be listed in the proposed MBS item number, which is that patients must have established osteoporosis, their age is greater than 60 they have a pain score of at least seven out of ten despite the fact that they are using adequate analgesic.”

MSAC also asked IRSA to address criticism raised in a widely publicised Cochrane review and commentary in BMJ Evidence Based Medicine that raised concerns of potential unblinding of patients in the VAPOUR trial.

According to the commentary co-authored by rheumatologist Professor Rachelle Buchbinder, an MSAC member, the benefits of vertebroplasty might have been overestimated because of a number of issues, including the differential blinding of participants.

“Patients undergoing vertebroplasty recall the cement odour and the tapping of vertebra. Clark et al used odourless cement and only injected local anaesthetic into the subcutaneous tissues.

“Problems with blinding may have led to a significant difference in the proportion of participants who correctly guessed their treatment allocation at 14 days (80% in the vertebroplasty group vs 54% in the placebo group),” they wrote.

But Dr Clark said the cement used in the trial was mixed in a closed system – so there would be no detectable smell in either procedure. Patients were also under conscious sedation and so would be very unlikely at the time to be aware of which procedure they had, he added.

And while patients were asked in a questionnaire to guess whether they had undergone the vertebroplasty or sham procedure, a reduction in pain had been the only reason patients gave for their response, he noted.

A final recommendation on vertebroplasty MBS listing is expected to be announced by MSAC in November.

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