Letter to the editor on “new algorithmic approach for easier and faster extended disability status scale calculation”

Dear Editor,

We would like to thank Dr Cohen and his colleagues for their meticulous work in the field of EDSS scoring. We would also like to provide some clarifications.

As we mentioned in our article, many electronic applications were introduced to facilitate daily practice, including the Easy EDSS application developed by Dr Cohen and his colleagues, which was introduced in 2015 and cited in our article (Reference 8) as a reference website (www.mikeiosapps.com) ¹ which is still operational, and one can still purchase and rate the application from it.

We stated that “Most of them provide little information about the specific rules used to estimate the FS scores and EDSS steps” and “None of these tools give a clear way to calculate the FS based on a complete neurological assessment.” ² In fact, we were not the first to make such observations, D'Souza and colleagues made the same observations regarding these electronic applications in a study they published in 2017. ³

In their recent publication in 2021, Dr Cohen and his colleagues show some details about the basis behind the automated calculation of the eight smart functional parameters (sFP). However, no data or algorithms are available regarding the final EDSS step; the smart EDSS (sEDSS) and the basis of its automated calculation based on the sFP. The authors state that “The EDSS score is automatically derived from the ambulatory function and the combination of FP scores according to the original definitions.” ⁴

Our article on the other hand provides a novel method for calculating the final EDSS score by interpreting the results of the seven functional scores and ambulation (Figures 6–8), ² which is unique and distinguishes our method from previous ones.

As mentioned by Dr Cohen and his colleagues, a significant difference between the two studies is that Easy EDSS is based on the original EDSS definitions, whereas our algorithm is based on the Neurostatus. Dr Cohen and his colleagues state that Neurostatus is restricted to clinical trials, and in their recent publication, Cohen et al. mention the reason behind this: “In clinical trials, patients are generally evaluated by a unique assessor, using the Neurostatus scale, derived from the EDSS. The Neurostatus definitions are less subjective than usual EDSS functional parameters. However, it is a little bit more time-consuming and more complex as it requires a regularly renewed certification to ensure that the evaluator can handle the scale properly.” ⁴

Our new algorithmic approach could overcome this problem by introducing the Neurostatus in a way that is simpler and more time-efficient (reducing the time needed by approximately half), thus it can enhance not only clinical trials, but it also makes the less subjective Neurostatus more accessible to everyday practice.

We are grateful for the positive feedback we had been receiving since our article was published, and we hope that our work along with the work of Cohen et al. and the work of other colleagues who have been working on EDSS and its scoring helps in making the EDSS simpler, more time-efficient and thus more accessible to all healthcare professionals working with MS patients.

Thank you for considering my reply.

Amr M Fouad