Predicting multiple sclerosis is like forecasting the British weather. If you've spent much time on these islands you'll understand how fickle the weather here can be. Weathermen can only give the vaguest of indications of how things may turn out and, even then, only for the next few days. MS is similar - you can say that a number of factors are correlated with a poorer disease outcome but not with a great degree of certainty. Long-term benign disease courses can suddenly become progressive just as malignant courses can suddenly reach plateaux. With MS, nothing is certain.