Tuesday, March 17, 2009

Our little club is getting bigger

After writing so much about the increased incidence of autoimmune diseases, and also about potential triggers for Psoriatic Arthritis, I wanted to make sure I wasn't barking up a non-existent tree. Are Psoriatic Arthritis incidence rates really on the rise?

The answer is... most probably yes.

In this opinion article from the Feb 2009 issue of the Journal of Rheumatology, Dr. Vinod Chandran from Toronto Western Hospital discusses a current study (in the same issue) that demonstrates that PsA rates are in the rise. He also devotes a bunch of page space to the diagnostic challenges of PsA, which profoundly affect how well we can measure incidence rates.

Here's a summary quote from the article, but I recommend going in and reading the whole piece:
...the prevalence of both psoriasis and PsA is increasing, and environmental rather than genetic factors are probably responsible.
So, why do I state above that the rates are "probably" rising? Because of the nature of research and available data. The quoted study was done only on people in one smallish area in Minnesota - so while we can assume this increase is true across the country, we can't be sure. Maybe there is something in Minnesota that is causing an increase - something not present elsewhere. The author also refers to our inability to truly understand why these rates are rising:
Genetic or ethnicity related factors are unlikely to be responsible for the observed change since there has not been any significant immigration or emigration from this “captive” population. It would be interesting to study how environmental factors have changed over the years to give us an explanation. However, such studies are best done prospectively.
(prospectively meaning: not after-the-fact)

I admire Dr. Chandran's analysis of the frustrations preventing true understanding of the prevalence rates of PsA. He cites weaknesses in diagnostics or "classification criteria", which is a reflection of how recently scientists have begun studying Psoriatic Arthritis. Until doctors and scientists nationwide agree on what PsA signs and symptoms really are, it is hard to compare epidemiological studies from different regions. And, of course, it's financially challenging to develop a nation-wide study.

Once again, I'm struck with how much PsA remains the "ugly stepsister" to Psoriasis and Rheumatoid Arthritis. I wish the science behind this disease wasn't still so hit-and-miss. I admire, and appreciate, those scientists and doctors dedicated to this disease, but I wish there were more of them. It may take more and more of us being diagnosed to generate more PsA researchers.

And unfortunately or fortunately, my wishes may be coming true.


  1. Hi I've just come upon your blog and not been reading it for too long, but love the way you question what your disease is all about - I am hooked already. I've always been fascinated by the science/biology behind my condition (mainly because it's not text book in it's nature).
    I've had PsA for over 15 years now, I was originally diagnosed with RA, and completely agree with what you say about PsA being the forgotten ugly sister of RA - drives me mad.
    I've also got IgA Nephropathy (usually linked to Lupus), and recently been told I have inflammatory disease of my pleura - at the end of the day it's all auto-immune (and probably overlapping) so should be equally prioritised regardless of it's name.
    Rant over. keep up the blogging.

  2. Hey - Thank so much for your kind words! I talked to my rheumatologist on Friday, tried to get more clarity from her on the difference between RA and PsA - (and why she is sure I have one, not the other) Apparently I have PsA, Rheumatoid type. (?) I bet in 20 years science will reclassify all of these diseases as symptoms of the same unified disease. And, yes, I do think that the human tendency to put things in neat categories has ended up pushing PsA to the background. We just gotta keep asking questions!

    I'm so glad you're reading - please let me know if you ever have something you're curious about - I'm always happy to go on a data-hunt!


  3. Hi JennyS just logged on to read a little further. I think your right that not so long ago lots of people with PsA where just diagnosed with RA and the increased incidence is as much to do with better diagnosis technique as anything else.
    When I was first referred to a Rheumatologist I was seen by Prof V Wright (? Vernon), who first identified the link between Psoriasis and inflammatory arthritis (in the early 1960 - if my memory serves me right).Probably explains why my diagnosis was changed, even though my GP had told me I had RA (based on RA factor and inflammatory markers at onset of disease).
    I had to laugh when the American PsA drug trial (Adalimumab - phase 2 and then phase 3) I was on ended after 3 years, and my now Consultant Prof Paul Emery (Prof Wright retired and is sadly dead now) said I might need to change your diagnosis to RA to get funding for you to continue getting weekly Adalimumab on the NHS, because it's not licensed to use weekly for PsA but is for RA (in the UK). Some almost 3years after the trial ended I am still getting it weekly so not sure how he manages it (but don't ask as to how so not to draw attention to it and risk being reduced to fortnightly injections!!). It's definitely been my miracle drug, I had aggressive progressive disease which was in permanent flare (for over 10yrs) despite every treatment I was put on, I now have a level of quality of life that prior to the trial I never even dreamed of again.
    I am a very questioning patient and always ask or research for myself to try and make sense of what I am experiencing.
    I noticed you have a list of Genes to watch out for, HLA B27 is not amongst them, have you not come across it in your research? Another thing I can remember reading a few years ago now was a link between the Hepatitis B vaccination and inflammatory disease - being a retired (due to my disease) Nurse had had several of them and always failed to become immune - makes you think.
    I will waffle on no longer................. although 15+ years later I have many a tale I could share, but will not bore you any longer.