Let's talk about
On average if a person has UC then the chance of a flare in a one year period is 0.5. This is a broad sweeping generilisation but lets work with it for the time being. On average if you take only a 5ASA over a one year period the chance of a flare reduces to 0.33. Thus a 5ASA drug offers you 0.1667 or 1 divided by 6 chance of extra protection per year on average.
Now 1/6 looks a pretty good gamble for someone with maybe mild symptoms but if someone suffers from UC pretty badly I cant see them take comfort from merely 16.67% extra protection.
Plus i'm sure this 1/6 is boosted up by the market surveys carried out by companies. It would be noble but highly unrealistic to think that the numbers quoted are as good as that. The actual extra protection offered by 5ASA could be nearer 10% per annum.
The source of my figures above come from literature produced by Asacol distributors.
PS: I think that some people above need to look at forum rule 3 including the moderators.