Background/Purpose:

To evaluate the impact of 18F-fluorodeoxyglucose PET-CT (FDG-PET/CT) score at baseline, on the therapeutic response to prednisone, in patients with polymyalgia rheumatica (PMR).

Methods:

This is a monocentric retrospective study realized at the university hospital of Besancon. We included patients with a diagnosis of PMR meeting the 2012 ACR/EULAR criteria, who had performed a FDG-PET/CT at baseline, between december 2012 and december 2017. Patients were treated with an initial prednisone dose of 0.3mg/kg a day, progressively decreased following a standardized tapering dose protocol (10% /month). We excluded patients who received corticosteroids before the FDG-PET/CT, or without baseline FDG-PET/CT. Seventeen specifics previously described hotspots were visually analyzed (1). We realized a semi-quantitative analysis of FDG uptake (4-point score from 0 to 3), following Goerres scoring system (2). Hotspot with 0 indicating no uptake (same as bone); 1, slight uptake; 2, moderate uptake (same as liver); and 3, uptake higher than the liver. It results in a score of 0 to 51. Then we defined two groups of patients according to their resistance to prednisone at 6 months, defined as the reoccurrence of symptoms and/or an increase of systemic inflammation twice during the prednisone tapering.

Results:

30 patients where included: 12 in the group “resistant “and 18 in the group “sensitive”. There were 60% of women, with a mean age of 67,57 ± 11,63 years. The mean CRP at baseline was 45,02 ± 39,59 mg/L. The mean FDG-PET/CT score at baseline was 18/51. The FDG-PET/CT score baseline was significantly lower in the resistant group (9 vs 23, p<0.009). Resistant patients were younger (60 years vs 74.5 years, p<0.008), and mostly men (66.5% vs 22%, p<0.02). ROC curve shows a predictive threshold of corticoresistance at 9/51 on the PET/CT score at baseline, with 66.67 % of sensibility and 83.37 of specificity [AUC: 0,78 ± 0,08] Patients with peripheral synovitis had higher PET/CT score baseline (p=0.02).

However, there was no statistically significantly difference of CRP at baseline between the two groups (13.75 vs 15, p<0.8), and no correlation between CRP and PET/CT score at baseline ( p=0.17). There was no difference concerning the presence of neoplasia (16.5% vs 11%, p<1.00) in the two groups.

Conclusion:

These data suggest that higher baseline FGD-PET/CT score is predictive of a better response to prednisone in patients with PMR, with a predictive threshold of corticoresistance lower than 9/51 on FDG-PET/CT score at baseline. Corticoresistant patients seemed to be mostly men and younger, with no significantly difference inCRP at baseline.

References:

1 Sondag.M et al. Utility of 18F-fluoro-dexoxyglucose positron emission tomography for the diagnosis of polymyalgia rheumatica: a controlled study. 2016 Aug;55(8):1452-7.

2 . Goerres GW, Forster A, Uebelhart D et al. F-18 FDG whole-body PET for the assessment of disease activity in patients with rheumatoid arthritis. Clin Nucl Med 2006;31:386_90.

« Back to 2018 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-18f-fluorodeoxyglucose-pet-ct-score-at-baseline-on-the-therapeutic-response-to-prednisone-in-polymyalgia-rheumatica-a-retrospective-study/