Time might tell if TDR or fusion is more cost-effective


TDR is used as an alternative to fusion in selected patients with degenerative disc disease (DDD). A randomised controlled trial was conducted in Sweden to determine whether the concept of TDR was more cost-effective than instrumented fusion (FUS) after two years, assessing all direct and indirect costs in TDR (Charité/Prodisc/Maverick) and FUS (PLF/PLIF).

Inclusion/exclusion criteria: 20–55 years of age, LBP with or without leg pain for more than one year, MRI “positive”, ODI ≥ 30 or VAS back > 50/100 the week before inclusion. Patients should have failed conservative treatment undertaken for more than three months and have an open mind about either of the two treatment options. Patients excluded had relevant comorbidity, spinal stenosis requiring decompression, moderate or worse facet joint degeneration at three or more painful levels on clinical examination, spondylolysis/olisthesis or degenerative olisthesis >3mm, major deformity, compromised vertebral body or osteoporosis, previous surgery, other than discectomy.


One hundred and fifty two patients (TDR n=80, and FUS n=72) were included in the study from 2003–2005 with no cross-over after randomisation. Clinical data was collected after 12, 24 months, and cost data was collected after one, three, six,12,18 and 24 months. Follow up clinical data was 100% and follow up cost data was 99%.


Before surgery, approximately 70% of patients were on sick leave (part- or full-time) and after two years approximately 70% in both groups were working part or full time. Workers (full- or part-time) at the 2-year follow up, had been on sick leave (days with standard deviation in brackets). In the TDR group: 185 (146), and in the FUS group: 252 (189) (p=0.129).


Using the EQ-5D instrument to measure quality of life, the quality adjusted life years gained by using TDR instead of FUS, was only 0.01 effect units on a 1 scale (ns). Two year costs for the healthcare sector in the TDR group was (Swedish kronor) SEK 147 750 (SD 73 408) and in the FUS group 170 746 (58 290), the difference was 22 996 (43 055 to 1 202). For the society, the corresponding costs were: TDR SEK 599 560 (400 272), and for FUS: SEK 685 919 (422 903), the difference was 86 359 (214 332 to – 45 605). 


As was illustrated on the cost-effectiveness plane, TDR could not be shown to be cost-effective compared with instrumented FUS, mostly due to the low effect difference and the high uncertainty (assessed using bootstrapping). Net benefit analyses confirmed the conclusion


Reoperation in the FUS group was performed often (mostly due to implant removal), 36% compared with 10% in the TDR group, reflecting the surgeon’s preference, which increased costs in this group. However, excluding re-operation costs in a sensitivity analysis did not alter the conclusions from a societal perspective, while from a healthcare perspective the significant cost difference between the study groups was eliminated, illustrating the impact of re-operation cost.


“In the TDR group you strive to preserve motion and what this does for example to the facet joints we do not really know. In the FUS group, there are those who argue for an increased risk of adjacent level degeneration, although I personally believe that this is mostly caused by genetic predisposition. This is why you have to follow these patients for five, 10, 15, 20, 25 years,” said Fritzell when asked whether he thought there will be a change in cost-effectiveness over time. (Note: Peter Fritzell performed the health-economic evaluation and was not attached to the study clinic and was not involved in the treatment of any patient)



“We cannot live only in a world of treatment effects”


Peter Fritzell, associate professor, Centre for Clinical Research, Falun, Sweden told Spinal News International that physicians have to adapt to a new reality and that future studies would have to analyse cost-effectiveness.


“This is inevitable. We have to discuss cost-effectiveness, we cannot live only in a world of treatment effects. We have to compare it with how much an additional effect unit gained by using one treatment instead of another, will cost the society, because it is not only the patient who is paying for this effect, it is also society as a whole. We have to adapt to this new reality, that we are asked to deliver these comparisons of cost-effectiveness. For example, in the pharmaceutical industry no new drug will get reimbursed in Sweden if the company cannot argue that this is cost-effective. At the moment, this is not the situation for the implant industry, where you can do approximately what you want (sic), without discussing cost-effectiveness. But the situation will ultimately be the same as in the drug industry. It will be positive for our profession, if we take the lead in this question and evaluate these cost effectiveness questions before we are told to present them.”


He highlighted that it was better for spine specialists to self-regulate because “It is much better for the credibility of the profession, as this means that we take our responsibility in society seriously and that we are concerned with the gravity of the economic situation. We do not have unlimited money at the moment. This is why cost effectiveness is important.”


Fritzell added: “I think all studies today; and certainly all clinical studies should seriously consider adding a cost-effectiveness branch to the clinical trial, it is very easy to do methodology wise now that the knowledge is there. However, in general, it takes both time and effort to understand the specifics of implementing such studies. When it comes to understanding results, and presenting them, they may not be easy to understand at first glance.


“It took me ‘two years’ to grasp the underlying meaning and nuances of for example the cost-effectiveness curve— it is like learning music. If you do not like rock and roll you have to listen for some time to learn the nuances. It is the same with this as most of us physicians are not really interested in health economy, that is why we are physicians; otherwise we would have probably been health economists. But we have to learn this specific trait because those in charge, those who have access to the money they speak this “language” of health economics. And they can never learn to speak our language but we can learn to speak theirs, as this is easier than the other way round.