Minimal clinically important differences in 6-minute walking distance in patients with severe and mild lumbar spinal stenosis

Tomoyoshi Sakaguchi, Kazuhiko Takamatsu, Yosuke Yasuda, Masato Tanaka
Purpose:

This study aims to calculate the MCID of 6MWD for patients with severe and mild LSS.

Methods:

A total of 107 patients (male: 62 age at surgery: 72.6 ± 8.4 years) who underwent surgery for LSS from April 2022 to June 2023 were included. Assessment measures included preoperative and 12-month postoperative 6MWD and physical function scores on the Zurich claudication questionnaire (ZCQ). The subjects were classified into mild group (MG) and severe group (SG) using the median pre-operative 6MWD of 300m.  Wilcoxon signed-rank test was used to compare pre-and postoperative 6MWD and ZCQ. Spearman's rank correlation coefficient evaluated the changes in 6MWD and ZCQ. MCID and area under the curve (AUC) of 6MWD were calculated using a Receiver Operating Characteristic (ROC) curve with ZCQ as an anchor. The calculated MCID was internally validated by the bootstrap method. A value of p0.05 was considered statistically significant. This study was conducted according to the guidelines of the Declaration of Helsinki and approved by the institutional review boards at Okayama Rosai Hospital (approval No. 348-3).

Results:

Pre- and post-operative comparison of 6MWD showed a significant improvement from 377m to 419m in MG (p0.01). SG significantly improved from 197m to 340m (p0.01). Pre- and post-operative comparison of ZCQ showed a significant improvement from 2.6 to 1.8 points in MG (p0.01). SG significantly improved from 2.9 to 1.8 points (p0.01). The correlation between 6MWD and change in ZCQ was significant for SG but not for MG (SG: r=-0.55, p0.01), (MG: r=-0.25, p=0.153). MCID for SG calculated by ROC curve was 130m (sensitivity: 89%, specificity: 71%, AUC: 84%). The 95% confidence interval for SG in internal validation was 60-135 m for MCID and 74-93% for AUC.

Conclusion(s):

The MG did not correlate with 6MWD, so an evaluation index other than 6MWD is needed. The MCID calculated by SG was 130 m, which was robust to internal validation. Therefore, 6MWD should be evaluated according to the preoperative severity of LSS.


Implications:

MCID at 6MWD for LSS patients with severe intermittent claudication was 130m. This MCID can be used to interpret postoperative changes in 6MWD.

Funding acknowledgements:
The work was not funded.
Keywords:
Lumbar spinal stenosis
Six minutes walk distance
Minimal clinically important difference
Primary topic:
Musculoskeletal: spine
Second topic:
Orthopaedics
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
Okayama Rosai Hospital
Provide the ethics approval number:
348-3
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

Back to the listing