Fampridine helps you walk faster but it doesn’t work for everyone.
Your baseline walking speed may predict if it will work for you.
Fampridine is a potassium channel modulator, which helps your nerves fire faster, allowing to walk faster.
Filli L, Werner J, Beyer G, Reuter K, Petersen JA, Weller M, Zörner B, Linnebank M. Predicting responsiveness to fampridine in gait-impaired patients with multiple sclerosis.
Eur J Neurol. 2018 Sep 1. doi: 10.1111/ene.13805. [Epub ahead of print]
Fampridine leads to significant walking improvements in many persons with multiple sclerosis (PwMS). However, a relevant proportion of PwMS does not respond to fampridine and predictors of initial drug responsiveness are unknown.
Drug response to prolonged-release (PR)-fampridine was assessed in 55 PwMS using the timed 25-foot walk (T25FW), the 6-minute walk test (6MWT) and the 12-item multiple sclerosis walking scale (MSWS-12) as outcome parameters. Patients were treated with PR-fampridine and placebo each for 6 weeks in a randomised, double-blind, placebo-controlled trial with cross-over design (NCT01576354). Possible predictors of drug responsiveness were investigated by multiple correlation analysis and binary logistic regression models. An additional longitudinal analysis followed drug responses of 32 patients treated with PR-fampridine over 3 years to identify potential predictors of long-term drug responsiveness.
Severity of walking disability was positively correlated with enhanced responses to PR-fampridine. The strongest single predictor of drug responsiveness was poor 6MWT performance at baseline, which was positively correlated with enhanced drug response in the 6MWT (R=-0.541; P<0.001). A model including 6MWT and T25FW baseline performances predicted PR-fampridine responder status with an accuracy of 85.5% (specificity: 90.0%; sensitivity: 73.3%), with a threshold of 211m in the 6MWT best separating responders from non-responders. Enhanced drug responsiveness after 3 years correlated with decline in walking endurance during this period (R=-0.634; P=0.001).
Initial walking impairment is a good predictor of therapeutic responsiveness to PR-fampridine. Valid predictors of patients’ responsiveness to PR-fampridine are essential for patient stratification and optimisation of MS treatment.
So it says that if you can walk over 211m in 6 minutes it is more likely that you will respond to fampridine. However, this data is based on an R (regression) value of 0.6 meaning that it is good enough for a clinical scientist to get excited and write a paper and a clinical referee to say “Alright Yeah” but bad enough when viewed by a basic scientist to say that it has very little predictive value for the individual so some people will respond well if they casn walk 211m in 10 minute and some people won’t respond well. Maybe it may help you decide whether you are willing to give it a trial run to see if it works for you.
If we said R= 0.0.5 to 0.6 or R = -0.5 to -0.6 didn’t really tell the individual much about their prognosis then many of our MRI papers wouldn’t see the light of day as a way of explaining pathology in MS.