The Guy’s Neurological Disability scale (GNDS) and the Multiple Sclerosis Impact Scale (MSIS-29) are patient reported outcome measures (PROMs) which can serve as a proxy for measuring disability and impact in patients with diagnosed multiple sclerosis (pwMS). In times of increased interest for telemedicine such measures are important.
The aim of this study was to investigate correlations between two multi-domain PROMs and often used clinical outcome measures.
248 MS patients were assessed using the GNDS, the physical part of the MSIS-29 (MSIS-phys), the Expanded Disability Status Scale (EDSS), the 9-hole peg test (9-HPT) and the Timed 25-foot walk test (T25WT) at baseline (BSL) and follow-up (FU) with a mean of 6.4 years. Cross-sectional and longitudinal correlations were studied between the overall scores and specific subcategories of the PROMs and clinical outcome measures. Additionally, the relationship between clinically significant changes in the PROMs and clinical outcomes were studied. We defined a clinically significant change of three or more points on the GDNS, eight or more points on the MSIS-phys and one point or more on an EDSS score <5.5 and one-half point or more on an EDSS score ≥5.
Strong cross-sectional correlations were found between the “legs” domain of the GNDS and the pyramidal functional system (p-FS) of the EDSS (Rbsl(247)=.55, p<0.001; RFU(238)=.77, p<0.001) and the T25WT (RBSL(247)=.56, p=0.000; RFU(233)=.77, p<0.001) especially in progressive patients (PPMSbsl R(34)=.76, p<0.001; PPMSFU R(26)=.86, p<0.001, SPMSBSL R(21)=.61, P=0.003; SPMSFUR(34)=.82, p<0.001). The MSIS-phys also showed strong correlations compared to the p-FS of the EDSS RBSL(162)=.59, p<0.001; RFU(236)=.70, p<0.001) and T25WT RBSL(162)=.61, p<0.001; RFU(231)=.61, p<0.001). Only good correlations were found between the MSIS-phys and T25WT in RRMS patients (RBSL(114)=.45, p<0.001; RFU(172)=.54, p<0.001).
Longitudinal correlations for the global GNDS/MSIS-phys and EDSS/MSFC were relatively poor except for changes on the leg domain of the GNDS in relation to changes on the T25WT (R(231)=.58, p<0.001), especially in PPMS patients (R(25)=.68, p<0.001). In the majority of cases a clinically significant deterioration on the EDSS also resulted in a clinically significant worsening of the GDNS and MSIS-phys.
The GNDS and MSIS-phys correlate well with clinical outcome measures for physical disability. The GNDS in particular, for the lower limb function in progressive patients. PROMs are easy to apply, less-time consuming and are a more cost-effective way of capturing patients’ disability.