David,
I was diagnosed with PsA about 22 years ago here in the US. Later I would also be diagnosed with sero-negative Rheumatoid Arthritis and Ankylosing Spondylitis.
The standard first line treatment back then was Methotrexate [DMARD]. They started me at 5 mg [pills] and graduated the dose over the next month until I was on 10 mg. Over the years the dose was increased gradually. It halted the progress of the disease.
Back in the early days we didn't know about taking folic acid, but that was added eventually.
By year 15 on MTX it seemed to not be as effective. I was at the 25mg dose, which is typically as high as they'll go. The body builds up a tolerance over time to drugs so the effectiveness goes down.
By this time biologics had been out for a number of years, but due to other medical issues, biologics like Enbrel and Humira were contraindicated for me.
I struggled with increasing joint pain and inflammation and turned to getting Kenalog [steroid] injections in the joints, which was a lifesaver for me. But still, it never really eradicated all the pain and inflammation.
I should mention that I never took systemic Prednisone pills. I did, and still do, take NSAIDS; I'm a huge fan of Celebrex. Over the counter pills like Tylenol, Aleve, Ibuprofen are a waste of money in this disease.
Finally, three years ago, I decided to gamble and try the Humira. It was a gamechanger. I feel better now than I have in over 20 years.
I'm a member of other RA and PsA forums and many people who go on the biologics have the same experience I do - excellent quality of life comes back.
Then there are those who can't seem to catch a break and rotate drugs just to find the right one.
I want to bring home one point: so many people do so well on biologics and even DMARDS such as Methotrexate that they don't bother posting on forums. So what you see are forums filled with members who are desperating seeking relief, which pretty much gives the impression that ALL people with the disease are doomed [because the successful patients are nowhere to be found on these forums].
I make it a point to post my successes with the drugs here so that people newly diagnosed can see that the drugs DO WORK in the vast majority of people.
I have to tell you that since I started the drugs over 20 years ago, I've had no further joint damage. The drugs are responsible for that.
No one knows yet what the very long term effects are, since the biologics have only been out about 10+ years. I have heard of people who enjoyed great success on a biologic for several years and then it stopped working. Most of those people switch to another biologic and most have success repeated. But at this point I don't know that anyone can say with accuracy exactly what the very long term remission probability is.