Table 3

Predictive validity of the ASAS classification criteria, by testing the classification at baseline against the rheumatologist's diagnosis at follow-up (on average 4.4 years)

CriteriaPredictive valuesClassification at baselineRheumatologist's diagnosis at follow-up
PPV (%)NPV (%)SpANo-SpA
SpA*92.262.0Positive
Negative
309
87
26
142
335
229
396168564
pSpA89.558.7Positive
Negative
85
31
10
44
95
75
11654170
axSpA93.363.6Positive
Negative
224
56
16
98
240
154
280114394
axSpA:
imaging arm (with/without clinical arm)

94.7

51.0
Positive
Negative
180
100
10
104
190
204
280114394
axSpA:
clinical arm (with/without imaging arm)

96.0

48.9
Positive
Negative
168
112
7
107
175
219
280114394
axSpA:
imaging arm only
86.231.9Positive
Negative
56
224
9
105
65
329
280114394
axSpA:
clinical arm only
88.031.4Positive
Negative
44
236
6
108
50
344
280114394
  • *Combination of ASAS criteria for axSpA (in patients with predominant back pain with or without peripheral manifestations) and criteria for pSpA for patients with peripheral manifestations only.

  • ASAS, Assessment of SpondyloArthritis international Society; axSpA, axial spondyloarthritis; NPV, negative predictive value; PPV, positive predictive value; pSpA, peripheral spondyloarthritis.