Background/Purpose: In order to follow subclinical inflammation and adjust the therapy for an optimal disease control, clinicians seek for readily accessible, affordable and reproducible markers. C reactive protein (CRP) is widely used for this purpose. Some suggest that CRP measures are not conclusive in all cases, especially in initial stages of inflammation. It is suggested that Serum Amyloid A (SAA) may be more reliable and sensitive in predicting an ongoing inflammation.

Methods: In order to evaluate and to compare the sensitivity of SAA and CRP, 148 measurements from 33 FMF patients with M694V homozygous mutation were obtained during a mean follow-up of 4 months.  For the analysis, the folds of normal CRP and SAA values were used for correlation.  Serum levels of the given markers were measured with nephelometric kits (normal CRP levels <5 mg/L and SAA levels <6,8 mg/L) .

Results:

All patients were on prophylactic colchicine. Among 33 patients 1 patient was being treated with tocilizumab, 2 patients with adalimumab, 19 patients with anti-IL-1 regimens. There were a total of 143 measurements of CRP and SAA from 33 patients.  Figure 1 demonstrates the correlation between CRP and SAA results. A similar significant correlation was found when we tested only the values obtained during 128 attack-free occasions (r=0.743, p<0.001). Both acute phase reactants were increased in 102 measurements, while in 9 CRP was high but SAA was normal and in 17 SAA was high however CRP was within normal limits. The mean increase in CRP of the population was 2,55 ± 5,26 fold, whereas mean increase in SAA was 6,78 ± 16,39 fold of the normal.

Conclusion: According to these results, serial testing of SAA does not provide any additional advantages over CRP.  Readily accessible and affordable bio-marker CRP seems to be sufficient for follow-up of patients with FMF