Aghayev E, Munting E, Röder C,

on behalf of the SWISSspine and Spine Tango registry groups

Institute for Evaluative Research in Medicine

University of Bern

IEFM

Benchmarking of low back pain alleviation after TDA by surgeon and its

comparison to pain alleviation after ALIF

Background

In 2010 the Obama administration provided 1.1 billion USD for so-called “comparative effectiveness research”.

On what level of the healthcare system can comparative effectiveness be analyzed? Therapies, implants or healthcare providers are examples.

What should be measured?! „Treatment success“ (Outcome).

The “treatment success” may be influenced by a multitude of factors and is rarely clearly defined.

Examples: achievement of minimum clinically relevant improvement, achievement of an average improvement in an implant or surgeon group - the so-called benchmark.

Total disc arthroplasty

- 534 patients (15 surgeons>10 cases)

- only monosegmental

- 59% females

- Ø age 42y (19-65ys)

ALIFdegenerative disease+ no previous surgery at the same level+ retroperitoneal or transperitoneal anterior approach+ anterior fusion between adjacent levels + rigid stabilization using a cage via anterior approach

- 50 patients (3 surgeons)

- only monosegmental

-78% females

- Ø age 46y (21-69ys)

Governmentally mandated national HTA registry

Voluntary Eurospine registry

Comparison of TDA and ALIF patients

The sole factor with an influence on back/leg pain and on quality of life improvement in the SWISSspine registry is its preoperative level.No significant influence: surgeon, implant, age, gender, FU time-point, depression, length of stay.

Back pain Leg pain Quality of life

Group N Ø Age (ys) Age range (ys) % female preop postop Δ preop postop Δ preop postop Δ

TDA 534 42 19-65 59% 69 31 38 54 23 31 0.342 0.738 0.396

ALIF 50 46 21-69 78% 67 29 38 49 22 27 n.v. n.v. n.v

Comparison (p-value) n.v. 0.003* n.v. 0.007* 0.20 0.54 0.85 0.19 0.87 0.36 n.v. n.v. n.v

The following box plots show average pain alleviation or improvement of quality of life for each individual implants and surgeons. Not adjusted and adjusted probabilities (by preoperative level) for achievement of minimum clinically relevant change were calculated. There were surgeons who had good patient selection, indicated by lower adjusted probabilities which mean worsening of their outcomes if they had treated an average patient sample. The opposite situation was with surgeons having higher adjusted probabilities indicative of lower preop pain values in their patient sample compared with an average patient sample.

Influence of disc prosthesis on back pain alleviation

Probability for the achievement of minimum clinically relevant pain alleviation of 18 VAS points

‘green‘ – TDA prostheses, ‘blue‘ - ALIF

Probability for the achievement of minimum clinically relevant pain alleviation of 18 VAS points

Influence of disc prosthesis on leg pain alleviation

‘green‘ – TDA prostheses, ‘blue‘ - ALIF

Probability for the achievement of minimum clinically relevant improvement of 0.25 EQ-5D points

Influence of disc prosthesis on quality of life improvement

TDA prostheses

Influence of surgeon on back pain alleviation

Probability for the achievement of minimum clinically relevant pain alleviation of 18 VAS points

‘green‘ – TDA prostheses, ‘blue‘ - ALIF

Influence of surgeon on leg pain alleviation

Probability for the achievement of minimum clinically relevant pain alleviation of 18 VAS points

‘green‘ – TDA prostheses, ‘blue‘ - ALIF

Influence of surgeon on quality of life improvement

Probability for the achievement of minimum clinically relevant improvement of 0.25 EQ-5D points

TDA surgeons

Study limitations

- we studied three influential factors (surgeon, implant, procedure), thereby adjusting for those co-variates that were available in the registry dataset. Other co-variates with an influence may exist.

- a clear domination of both types of pain may often not be given. Some patients may be treated for high preoperative back pain levels with low or no preoperative leg pain, which may have led to good probabilities for back pain MCRPI but low ones for leg pain.

Conclusions

- the influence of disc prosthesis and surgeon is not significant (the only significant co-variates are preoperative pain levels and quality of life)

- despite insignificance, there are visible (clinically relevant?!) variations in pain alleviation and in improvement of quality of life between different surgeons

- the analysis confirms that selection/indication criteria may be at least one of the causes of the different outcomes

- surgeons with the best outcome may help to improve the quality of indications by presenting their selection criteria to their peers.

Acknowledgment: We would like to thank the SWISSspine and Spine Tango registry groups who made this research possible by populating the database with their valuable and much appreciated entries. The analysed data were recorded by (in alphabetic order): Aebi M, Bärlocher C, Baur M, Berlemann U, Binggeli R, Boos N, Cathrein P, Etter C, Faundez A, Favre J, Forster T, Grob D, Hasdemir M, Hausmann O, Heilbronner Raoul, Heini P, Huber J, Jeanneret B, Kast E, Kleinstueck F, Kroeber M, Lattig F, Lutz T, Maestretti G, Marchesi D, Markwalder T, Martinez R, Min K, Morard M, Otten P, Porchet F, Ramadan A, Renella R, Richter H, Rischke B, Schaeren S, Schizas C, Schwarzenbach O, Seidel U, Selz T, Sgier F, Stoll TM, Tessitore E, Van Domelen K, Vernet O, Wernli FO, Waelchli B.

None of the authors has any potential conflict of interest.