Background: Coping in MS refers to cognitive and behavioural efforts to manage stresses imposed by the illness. Existing generic and disease-specific coping scales do not meet modern guidelines for scale development, and/or cannot produce interval-level metrics to allow for change scores.
Objective: To develop a brief patient-reported outcome measure for coping in MS, capable of interval-level measurement.
Methods: Qualitative work in 43 people with MS lead to a draft scale which was administered to 5,747 participants, with longitudinal collection in 2,290. A calibration sample of 1,000 subjects split into development and validation sets was used to generate three scales consistent with Rasch model expectations.
Results: The total Coping Index-MS (CI-MS-T), CI-MS-Internal (CI-MS-I) and CI-MS-External (CI-MS-E) cover total, internal and externally-focused coping. All three scales are capable of interval-level measurement.
Trajectory analysis of 9,000 questionnaires showed two trajectories in CI-MS-T: Group 1 showed a low level of coping with slight decline over 40 months while Group 2 had a better and stable level of coping due to improving CI-MS-Internal which compensated for the deteriorating CI-MS-External over time. CI-MS-Total<30 identified group membership at baseline.
Conclusion: The CI-MS-Total, CI-MS-Internal and CI-MS-External, comprising 20 items, provide interval-level measurement and are free-for-use in not-for-profit settings.