Table 2

Relative frequency of positive answers for the entry criteria

Cohort
CriteriaScreening (n=950)Referral (n=670)Validation (n=334)
C1: Morning stiffness >30 min22.0%30.8%32.9%
C2: Improvement by movement not by rest60.4%72.4%65.6%
C3: Waking up in the second half of the night because of back pain38.9%54.9%46.4%
C4a: Improvement with NSAIDs within 48 h (in the whole cohort)44.6%57.0%55.4%
C4b: Improvement with NSAIDs within 48 h (if taken)73.6%80.9%76.4%
  • NSAID, non-steroidal anti-inflammatory drug.