Validity of a smartphone app to objectively monitor performance outcomes in degenerative cervical myelopathy: an observational study

ObjectivesTo assess the validity of MoveMed, a battery of performance outcome measures performed using a mobile phone application, in the measurement of degenerative cervical myelopathy (DCM). DesignProspective observational study. SettingDecentralised secondary care in England, United Kingdom. Participants27 adults aged 60 (SD: 11) who live with DCM and possess an approved smartphone. Primary and secondary outcome measuresCriteria from the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) manual were used to assess validity and risk of bias. Briefly, each MoveMed outcome was compared to two patient-reported comparators, and a priori hypotheses of convergence/divergence were tested against consensus thresholds. The primary outcome was the correlation coefficient between the MoveMed outcome and the patient-reported comparators. The secondary outcome was the percent of correlations in correspondence with a priori hypotheses. The comparators were the patient-derived modified Japanese Orthopaedic Association (P-mJOA) score and the World Health Organization Quality of Life Brief Version (WHOQOL-Bref) questionnaire. Thresholds for convergence/divergence were [&ge;]0.3/<0.3, and >0/<0 for directionality. ResultsAs expected, MoveMeds tests of neuromuscular function correlated most with questionnaires of neuromuscular function ([&ge;]0.3) and least with questionnaires of quality of life (<0.3). Furthermore, directly related constructs correlated positively to each other (>0), while inversely related constructs correlated negatively (<0). Over 70% and 50% of correlations (unidimensional and multidimensional, respectively) were in accordance with hypotheses. No risk of bias factors from the COSMIN Risk of Bias checklist were recorded. Overall, this was equivalent to very good quality evidence of sufficient construct validity in DCM. ConclusionsCriteria from COSMIN provide very good quality evidence of the validity of the MoveMed tests in an adult population living with DCM.