Background The SPARCC-score of the SI joints is often used in clinical trials to detect changes over time1. Therefore, it is important to know if the SPARCC-scores spontaneously change over time in patients on non-biological treatment.
Objectives To investigate how much change in the SPARCC-score of the SI joints can be detected over a 3-month period in patients on non-biological treatment.
Methods Ninety patients with chronic back pain (≥3 months, ≤2 years, onset <45 years) in the SPondyloArthritis Caught Early (SPACE)-cohort in the outpatient clinic in the LUMC in Leiden underwent a baseline and 3-month follow-up MRI of the SI-joints (MRI-SIJ). All MRI-SIJs were scored according to the SPARCC-score by 2 independent readers, blinded for time sequence. The mean SPARCC of the readers was used in this analysis. Delta scores in SPARCC between both time points were calculated. Patients were treated by their rheumatologist, who was unaware of the MRI scores; treatment was recorded.
Results Forty-five out of 90 patients had a SPARCC score of 0 at both time points. In 49 (54.4%) patients (45 patient with a SPARCC-score of 0; 2 with a SPARCC-score of 1; 2 with a SPARCC-score ≥2), the SPARCC-score did not change over the period of 3 months. In 17 (18.8%) patients, the SPARCC-score changed 1 point (increased in 8 patients and decreased in 9 patients). In 24 (26.6%) patients the SPARCC-score changed 2 or more points (10 patients showed an increase and 14 patients a decrease). In the patients that showed a change, the mean (SD) change in score was -0.7 (6.0), the median (range; IQR) change was -1 (-17 to 16; -3 to 1.3).
In the 49 patients without a change in SPARCC-score, 12 (24.5%) patients did not use any medication, 16 (32.7%) patients were on stable non-biological treatment, and 21 (42.9%) changed treatment (10 patients switched NSAID, 6 started NSAID treatment, 4 stopped treatment with NSAID, 1 patient started NSAIDs and stopped after 2 months during the follow-up period).
Of all patients (n=41) with change in SPARCC-score over time, 8 (19.5%) patients did not use any medication, 22 (53.7%) patients were on stable non-biological treatment, and 11 (26.8%) patients changed treatment during that period. Six of them switched to another NSAID (SPARCC-score decreased 1 point in 3 patients, 5 points in 1 patient and 6 points in another patient, and increased 2 points in the remaining patient). One patient switched NSAID and started sulphasalazine at the same time, and showed an increase in SPARCC-score of 1 point. Three patients started treatment with NSAIDs, and SPARCC-score decreased in all of them (3 points in 2 patients and 13 points in 1 patient). One patient stopped NSAID treatment and SPARCC-score increased 1 point in this patient.
Conclusions Over a short period of 3 months, the SPARCC-score changed without the start of a TNF-blocker in 41 patients (45.6%) on non-biological treatment, with a range from -17 to 16 points. While analyzing results of clinical trials, it is important to keep in mind that a change in SPARCC-score in patients on non-biological treatment is possible. This is important information for the power calculation of a trial.
Maksymowych W. A&R 2005;53:703-9
Disclosure of Interest None Declared