Diagnosis of AS is delayed for many years and these criteria can be used to make an earlier diagnosis.
Calin's criteria have been advocated to define Inflammatory Back Pain. These require the presence of four of the following five criteria:
Calin's criteria have been advocated to define Inflammatory Back Pain. These require the presence of four of the following five criteria:
- age at onset <40>
- duration of back pain >3 months,
- insidious onset,
- morning stiffness
- improvement with exercise
The specificity of Calin's screening criteria is ~75% but the sensitivity is low (23-38%).
Rudwaleit criteria proposed a new candidate set of criteria for IBP, which consisted of
Rudwaleit criteria proposed a new candidate set of criteria for IBP, which consisted of
- morning stiffness of >30 min duration,
- improvement in back pain with exercise but not with rest,
- nocturnal awakening (second half of the night only)
- alternating buttock pain.
The sensitivity was about 70%, specificity 81% and likelihood ratio (LR) for disease presence was 3.7 if two of the four criteria were fulfilled. The LR further increased to 12.4 if three of the four criteria were fulfilled.
