JMIR Publications

ABSTRACT

Background:

Developing new clinical measures for degenerative cervical myelopathy (DCM) is an AO Spine RECODE-DCM Research priority. Difficulties detecting DCM, and change in DCM, cause diagnostic and treatment delays in clinical settings and heightened costs in clinical trials due to elevated recruitment targets. Digital outcome measures can tackle these challenges due to their ability to measure disease remotely, repeatedly, and more economically.

Objective:

To assess the reliability of the MoveMed battery of performance outcome measures.

Methods:

Design: Prospective observational study. Setting: Decentralised secondary care in England, United Kingdom. Participants: Seven adults aged 59.5 (SD 12.4) who live with degenerative cervical myelopathy (DCM) and possess an approved smartphone. Primary and secondary outcome measures: The primary outcome was to determine the test-retest reliability of the MoveMed performance outcomes using the intra-class correlation of agreement (ICCagreement). The secondary outcome was to determine the measurement error of the MoveMed performance outcomes using both the standard error of agreement of the mean (SEMagreement) and the smallest detectable change of agreement (SDCagreement). Criteria from the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) manual were used to determine adequate reliability (i.e., ICCagreement ≥ 0.7) and risk of bias. Disease stability was controlled for using two minimum clinically important difference (MCID) thresholds obtained from the literature on the patient-derived modified Japanese Orthopaedic Association (P-mJOA): namely, MCID ≤1 point and MCID ≤2 points.

Results:

All tests demonstrated moderate-to-excellent test-retest coefficients and low measurement errors. In the MCID ≤1 group, ICCagreement values ranged from: 0.84–0.94 in the Fast Tap Test, 0.89–0.95 in the Hold Test, 0.95 in the Typing Test, and 0.98 in the Stand and Walk Test. SEMagreement values ranged from ±1 tap, ±1–3% stability score points, ±0.06 keys per second, and ±10 steps per inute, respectively. SDCagreement values were ±3 taps, ±4–7% stability score points, ±0.2 keys per second, and ±27 steps per minute. In the MCID ≤2 group, ICCagreement values ranged from: 0.61–0.91, 0.75–0.77, 0.98, and 0.62, respectively; SEMagreement values from: ±1 tap, ±2–4% stability score points, ±0.06 keys per second, and ±10 steps per minute; and SDCagreement values from: ±3–7 taps, ±7–10% stability score points, ±0.2 keys per second, and ±27 steps per minute. Furthermore, the Fast Tap, Hold, and Typing Tests obtained sufficient ratings (ICCagreement ≥ 0.7) in both MCID≤1 and MCID≤2 groups. No risk of bias factors from the COSMIN Risk of Bias checklist were recorded. Overall, ‘very good’ quality evidence of sufficient reliability was found for the MoveMed battery in DCM.

Conclusions:

Criteria from COSMIN provide ‘very good’ quality evidence of the reliability of the MoveMed tests in an adult population living with DCM.