That's good information SJLC.
I searched around Google and gleaned that calprotectin correlates well with incidence and severity of RA.
But with AS an PsA it is not as good, that is, like ESR and CRP it is raised for only about half of these AS and PsA patients.
Kind of sounds like there could be a couple of distinct subpopulations getting the AS diagnosis, eh? My GP says that happens quite often during the stage where the diagnosis is based on symptoms without understanding the disease very well, and it can confuse study results a lot.
