AB1256 CORRELATION BETWEEN SERUM CALPROTECTIN LEVELS, RAPID3 AND DISEASE ACTIVITY MEASURES IN PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: M. Valls Roc, O. Codina Guinó, M. Sala Gomez, S. Castell Quiñones, C. Mora Maruny
Journal: Annals of the Rheumatic Diseases (2020)

Background: Tight control of rheumatoid arthritis (RA) is essential and we need a validated, objective and reproducible disease measure to achieve it. There is not gold standard in RA. There is a rising interest in evaluating disease activity on the patient’s point of view using patient-reported outcomes like RAPID3. Furthermore, some new biomarkers have appeared, like serum calprotectin, with promising results on its analyzing. Objectives: To evaluate correlation between disease activity measures usually used in patients with RA (DAS28 ESR/CRP, SDAI and CDAI) and other alternative tools (RAPID3 and calprotectin). To analyze correlation between RAPID3 and serum calprotectin levels. Methods: A cross-sectional study was performed. RA-patients (n=114) according to the ACR/EULAR 2010 classification criteria were consecutively enrolled from Rheumatology department at Hospital de Figueres during the period from February to June 2019. Disease activity, biomarkers and the assessment of the patient’s health status with RAPID3 data were collected. Modified RAPID3 (mRAPID3) was calculated by subtracting the questions about the mood included in the questionnaire (k,l,m questions) to the results of the RAPID3 as if it were a response of the HAQ test. Coefficient Spearman’s correlation (r) was used to assess the relationship between the variables, and coefficient of determination (r-squared=r 2 and adjusted r 2 ) was used to show the strength of correlation. Results: 114 patients were included: 71% women, mean (SD) age 60(11) years, median disease duration 13(8) years. 80% had positive RF and 70% positive ACCP antibodies. 52% had erosions. 89% patients had been receiving treatment with csDMARDs, 38% with bDMARDs o dsDMARS and 66% with glucocorticoids. Disease activity measures’ median values were DAS28ESR 3.07, DAS28CRP 2.76, SDAI 9.62 and CDAI 8.99 and showed low activity. The mean values of RAPID3 y mRAPID3 showed moderate activity (8.95 and 8.68 respectively). Median serum calprotectin level was 1.48μg/ml. All correlations between variables were statistically significant and directly proportional although with different values (table). Spearman’s correlation coefficient between mRAPID3, serum calprotectin, disease activity scores and laboratory parameters mRAPID3 C alprotectin CRP ESR DAS28ESR DAS28PCR SDAI CDAI mRAPID3 1 Calprotectin 0.23 1 CRP 0.33 0.59 1 ESR 0.23 0.39 0.54 1 DAS28-ESR 0.62 0.32 0.41 0.62 1 DAS28-CRP 0.69 0.32 0.42 0.28 0.83 1 SDAI 0.74 0.31 0.35 0.27 0.82 0.91 1 CDAI 0.73 0.25 0.24 0.21 0.80 0.89 0.99 1 DAS28: Disease Activity Score, SDAI: Simplified Disease Activity Index, CDAI: Clinical Disease Activity Index, RAPID3m: Routine Assessment of Patient Index Data 3 modificative with k,l,m questions. CRP: C-reactive protein. ESR: erythrocyte sedimentation rate Coefficient of determination found a weak association between RAPID3 and mRAPID3 with DAS28ESR (r 2 =0,38) and moderate with DAS28CRP, SDAI and CDAI (r 2 =0,47, 0,55 y 0,53). Determination serum calprotectin levels together with RAPID3 or mRAPID3 increased strength of correlation between DAS28ESR, DAS28CRP, SDAI and CDAI with RAPID3 (adjusted r 2 =0,40, 0,49, 0,56, 0,52) and with mRAPID3 (adjusted r 2 =0,41, 0,50, 0,56, 0,53). Correlation between RAPID3 and serum calprotectin levels was very weak (r 2 =0,05). Conclusion: Correlation between disease activity measures and mRAPID3 was strong, but it was weak with serum calprotectin levels. Correlation strength between RAPID3 and DAS28ESR was low and it was moderate with other composite indices, it maintained with RAPID3m and improved by adding serum calprotectin levels although modestly. There was a very weak correlation between RAPID3 and serum calprotectin levels suggesting that these two variables give us different information about the disease activity. Acknowledgments: Mrs. Dolors Ragolta. Mr. Carlos Sanchez Piedra and Mr. Fernando Sanchez Alonso Disclosure of Interests: None declared