Comparing Indices of Responsiveness for the Coma/Near-Coma Scale

PURPOSE: Occupational therapy practitioners must monitor the recovery of consciousness for patients with severe brain injury using validated measures. Indices of responsiveness (ie., conditional minimal detectable change (cMDC), MDC, and the distribution-based minimally clinically important difference (MCID)) classify patients as having measured a change (or not). The 10-item Coma Near-Coma Scale (CNC) was examined and found unidimensional after removing two pain items. The purpose of this study is to examine indices of responsiveness for the 10-item and 8-item CNC.

DESIGN: A secondary analysis of data including 32 adults with disordered consciousness for at least 28 consecutive days. Participant’s CNC scores at time 1 and 2 (12-16 days apart) were used to calculate indices of responsiveness.

METHOD: Participants were classified as improvers (CNC change > 0) or as non-improvers (CNC change < 0). The pooled standard deviation (SDpooled) was calculated using MedCalc. We calculated the MDC using a 95% confidence interval and the cMDC using the Rasch measure and standard error for each pair of measures.

RESULTS: Using the 8-item CNC, 20 participants were improvers and 12 were non-improvers. 8-item CNC Improvers: MCID (0.50SD)= 0.67, and MDC=1.33. 8-item CNC Non-improvers: MCID (0.50SD)=0.43, and MDC = 0.86. Using the 10-item CNC, 21 participants were improvers and 11 were non-improvers. 10-item CNC Improvers: MCID (0.50SD)=0.59, and MDC =1.77. 10-item CNC Non-improvers: MCID (0.50SD)=0.34, and MDC=0.61. 8-item and 10-item cMDC identified three and four patients, respectively, that made a change beyond measurement error.

CONCLUSION: The cMDC appears more precise for a pair of measures and should be used when making decisions for an individual.

IMPACT STATEMENT: Practitioners can use the cMDC to identify effective treatments and advocate for therapy services for patients with disorders of consciousness.

References

Giacino, J. T., Katz, D. I., Schiff, N. D., Whyte, J., Ashman, E. J., Ashwal, S., . . . Armstrong, M. J. (2018). Practice Guideline Update Recommendations Summary: Disorders of Consciousness: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology; the American Congress of Rehabilitation Medicine; and the National Institute on Disability, Independent Living, and Rehabilitation Research. Arch Phys Med Rehabil, 99(9). https://doi.org

Giacino, J. T., Whyte, J., Nakase-Richardson, R., Katz, D. I., Arciniegas, D. B., Blum, S., . . . Zasler, N. (2020). Minimum Competency Recommendations for Programs That Provide Rehabilitation Services for Persons With Disorders of Consciousness: A Position Statement of the American Congress of Rehabilitation Medicine and the National Institute on Disability, Independent Living and Rehabilitation Research Traumatic Brain Injury Model Systems. Arch Phys Med Rehabil, 101(6), 1072-1089. https://doi

Weaver, J., Liu, J., Guernon, A., Bender Pape, T., & Mallinson, T. (2020). Psychometric Properties of the Coma Near-Coma Scale for Adults in Disordered States of Consciousness: A Rasch Analysis. Arch Phys Med Rehabil. https://doi.org/10.1016/j.apmr.2020.10.119

Weaver, J., Cogan, A., Davidson, L., Schlumpf, K., & Mallinson, T. (2020). When is Change Meaningful?: A Comparison of the MCID, MDC, and cMDC. Arch Phys Med Rehabil, 101(11), e57. https://doi.org/https://doi.org/10.1016/j.apmr.2020.09.169