Abstract
Background Context
The 6-minute walking test (6WT) has been previously shown to be a reliable and valid
outcome measure. It is unclear if the 6WT may further help to detect differences in
well performing patients that reach a ceiling effect in PROMs after surgery.
Purpose
To evaluate changes and timing of change in objective functional impairment (OFI)
as measured with the smartphone-based 6WT in relation to patient-reported outcome
measures (PROMs) after surgery for degenerative lumbar disorders (DLD).
Study design
Prospective observational cohort study.
Patient Sample
Fifty consecutive patients undergoing surgery for DLD.
Outcome Measures
Patients self-determined their OFI using the 6WT application (6WT-app) and completed
a set of paper-based PROMs before, 6 weeks and 3 months after surgery.
Methods
Fifty patients undergoing surgery for DLD were assessed preoperatively (baseline),
6 weeks (6W) and 3 months (3M) postoperatively. Paired sample t-tests were used to establish significant changes in raw 6-minute walking distance
(6WD) and standardized Z-scores, as well as PROMs. Pearson correlation coefficient
was used to define the relationship between 6WT and PROMs. Floor and ceiling effects
were assessed for each PROM (visual analogue scale [VAS], core outcome measure index
[COMI], Zurich claudication questionnaire [ZCQ]).
Results
Mean 6WT results improved from 377 m (standard deviation - SD 137; Z-score: 1.8, SD
1.8) to 490 m (SD 126; -0.7, SD 1.5) and 518 m (SD 112; -0.4, SD 1.41; all p<.05)
at 6W and 3M follow-up. No significant improvement was observed between 6W and 3M
for the ZCQ, VAS back and leg pain. While correlation between 6WT and all PROMs were
weak at baseline, correlation coefficient increased to moderate at 3M. A considerable
ceiling effect (best possible score) was observed, most notably for the ZCQ physical
performance, VAS back and leg pain in 24%, 20%, and 16% of patient at 6W and in 30%,
24%, and 28% at 3M.
ConclusionS
Objective functional tests can describe the continued change in the physical recovery
of a patient and may help to detect differences in well performing groups as well
as in cases where patients' PROM results cannot further improve because of a ceiling
effect.
Keywords
Abbreviations:
6WT (6-minute walking test), 6WD (6-minute walking distance), app (application), COMI (Core Outcome Measures Index), DLD (degenerative lumbar disorders), LDH (lumbar disc herniation), LSS (lumbar spinal stenosis), m (meters), PROMs (patient reported outcome measures), SRM (standardized responsive mean), VAS (visual analogue scale), ZCQ PF (Zurich Claudication Questionnaire Physical Function), ZCQ SS (Zurich Claudication Questionnaire Symptom Severity), COPD (chronic obstructive pulmonary disease), LBP (low back pain), SD (standard deviation)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: May 12, 2023
Accepted:
May 2,
2023
Received in revised form:
April 28,
2023
Received:
October 6,
2022
Publication stage
In Press Journal Pre-ProofFootnotes
FDA device/drug status: Not applicable.
Author disclosures: MZ: Nothing to disclose. MS: Nothing to disclose. AMZ: Nothing to disclose. LR: Nothing to disclose. OB: Nothing to disclose. AW: Nothing to disclose. JKR: Nothing to disclose. MNS: Nothing to disclose. NM: Grant: Forschungsförderung Kantonsspital St. Gallen, CTU 19/24 (D).
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