Six-minute walk test is reliable and sensitive in detecting response to therapy in CIDP
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The current clinical measures (ONLS, R-ODS, mRS, and MRC) may not be so sensitive in capturing minimal variations or measuring fatigue in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Our aim was to assess if 6-min walk test (6MWT) is able to increase the sensitivity in detecting response to therapy and to capture fatigue in CIDP patients.
We tested 6MWT in 42 CIDP patients. Using both anchor-based and distribution-based approaches, we estimated the meaningful clinical change after therapy by calculating the minimum improvement cutoff (Minimal Clinically Important Difference Score—MCID) required for considering a patient as responder. We calculated the sensitivity of the 6MWT versus the other clinical outcomes. We analysed fatigue by comparing the velocities between first and sixth minutes of the 6MWT and the effect of treatment on fatigue using an ANOVA model for repeated measures.
MCID resulted equal to 20 m. The combination of 6MWT-MCID cutoff with the other clinical measures led to identify 74% of responders. The sensitivity of the 6MWT was 90% versus 77% of the other clinical measures. The 6MWT was also sensitive in capturing fatigue-related changes, even though fatigue was not influenced by treatment.
The combination of the 6MWT with the other clinical measures increased the chance to detect the quote of responders. We propose to include the 6MWT in the routine assessment of CIDP patients and the MCID cutoff at 20 m could be set for identifying the responders and properly guiding the therapy management.
KeywordsCIDP MCID 6MWT Fatigue
ES: study design, acquisition of data, analysis and interpretation of data, and drafting the manuscript, ES: statistical analysis was performed. AT: study design, acquisition of data, and interpretation of data, revising the manuscript. RI: acquisition and interpretation of data, revising the manuscript; ST: acquisition and interpretation of data, revising the manuscript; LR: acquisition and interpretation of data, revising the manuscript; RD: acquisition and interpretation of data, revising the manuscript; ME: acquisition and interpretation of data, revising the manuscript; PD: analysis and interpretation of data; LS: study conceptualization, interpretation of data, and revising the manuscript; FM: study design, acquisition and interpretation of data, and drafting and revising the manuscript.
No funding sources.
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Conflicts of interest
Dr. Spina reports no disclosures; Dr. Topa reports no disclosures; Dr. Iodice reports no disclosures; Dr. Tozza reports no disclosures; Dr. Ruggiero reports no disclosures; Dr. Dubbioso reports no disclosure; Dr. Esposito reports no disclosure; Dr. Dolce reports no disclosure; Dr. Santoro reports no disclosure; and Dr. Manganelli reports no disclosures. The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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