From: French recommendations for the management of systemic necrotizing vasculitides (polyarteritis nodosa and ANCA-associated vasculitides)
The FFS prognostic score in its 1996 version studied the factors impacting overall survival during PAN and EGPA, but not of other necrotizing vasculitides. However, the distinction between PAN and MPA was not straightforward at that time, and the two diseases were sometimes confused.
The items found to have a negative impact on survival are proteinuria > 1 g/24 h, serum creatinine > 140 µmol/L, specific cardiomyopathy, severe gastrointestinal impairment, and central nervous system impairment. The score is zero when all of these factors are absent. The FFS is 1 when only one of the prognostic criteria is present; the FFS is 2 when two criteria are present.
The FFS prognostic score was revised in 2009 to include other SNVs, namely GPA and MPA. The items having a negative impact on survival are age > 65 years, serum creatinine > 150 μmol/L, specific cardiomyopathy, severe gastrointestinal impairment, and the absence of any ENT impairment (only for GPA and EGPA).