POS0516 REDEFINING THE CLINICAL AND LABORATORY FEATURES OF RHEUMATIC PLEURAL EFFUSION: A 30-CASE SERIES

Abstract

Background:Rheumatoid pleural effusion (RPE) is a common extra-articular complication in patients with rheumatoid arthritis (RA). Previous studies have shown that RPE usually occurs in middle-aged men with rheumatoid factor (RF)-positive RA. RPE usually has features of pleural fluid acidosis, high lactate dehydrogenase (LDH) levels, and very low glucose levels(1). However, to the best of our knowledge, these findings were based on very few case series and reports, and most of these reports were published by the early 2000s(1, 2).Objectives:To investigate the clinical and laboratory characteristics and typical clinical courses of patients with RPE in a single centre of Japan since the beginning of the 21st century.Methods:Medical records of RPE patients were retrospectively reviewed between May 2006 and September 2020. RPE was identified by fulfilling these five conditions: (1) confirmation of the RA diagnosis; (2) having an exudative pleural effusion according to Light’s criteria; (3) negative results of pleural fluid culture; (4) negative results of pleural fluid cytology; and (5) exclusion of a parapneumonic effusion or empyema defined as no antibiotic use or ineffectiveness of antibiotics during the clinical course. Patients were divided into two groups according to their age at diagnosis: <60 years (Group A) and ≥60 years (Group B).Results:A total of 30 cases of RPE were included in the study. The median age was 71 years (interquartile range [IQR], 66–78 years). Of these patients, 16 (53%) were women. The median disease duration of RA was 98 months (IQR, 8–162 months). The two groups comprised six patients aged <60 years old and 24 patients ≥60 years. The median age was 54 years (IQR, 49–56 years) in Group A and 74 years (IQR, 69–78 years) in Group B. The median disease duration of RA was longer in Group B than that in Group A (132 vs. 3 months, p=0.008). Compared with Group A, Group B had fewer patients with fever (14% vs. 83%, p=0.003), and had lower serum C-reactive protein levels (3.3 vs. 11.1 mg/dL, p=0.03). Moreover, Group B was more likely to show mild inflammatory pleural fluids with higher pH (7.5 vs. 7.2, p=0.005) and lower LDH levels (155 vs. 1810 IU/L, p=0.046). Corticosteroids were started or increased in five (83%) and nine (38%) patients, and biologic disease-modifying anti-rheumatic drugs were started in one (17%) and two (8%) patients in groups A and B, respectively. One patient (16%) died within 5-years in Group A, and seven patients (29%) died in Group B.Conclusion:In contrast to previous studies, RPE was seen in older patients as well as middle-aged adults, and the pleural fluid analysis in older patients with RPE showed milder inflammation than the middle-aged patients.References:[1]Balbir-Gurman A, et al. Semin Arthritis Rheum. 2006 Jun; 35(6): 368-78.[2]Faurschou P, et al. Thorax. 1985 May; 40(5): 371-5.Table 1.Comparison of clinical and laboratory findings between Group A and Group B.Group A (n=6)Group B (n=24)P valueAge (years)54 [49-56]74 [69-78]Female2 (n=6, 33.3)14 (n=24, 58.3)0.38Disease duration of RA (months)3 [1-9]132 [44-199]0.008Fever ≥37.0°C5 (n=6, 83.3)3 (n=22, 13.6)0.003SerumCRP (mg/dL)11.1 [5.6-1.4]3.3 [0.9-10.5]0.03  RF (IU/mL)100 [19-816]63 [23-193]0.95  Anti-CCP ab positive5 (n=6, 83.3)12 (n=15, 80)1.00Pleural fluid analysispH7.2 [7.2-7.2]7.5 [7.4-7.5]0.005LDH (IU/L)1810 [594-2932]155 [123-346]0.046Glu (mg/dL)59 [10-123]105 [91-122]0.42Tp (g/dL)5.1 [4.9-5.6]4.6 [3.6-5.2]0.21Number of cells (/μL)5235 [3353-9300]3300 [1490-5008]0.27 Glu/serum Glu0.41 [0.09-0.99]1.05 [0.85-1.15]0.71Started or increased CS5 (n=6, 83.3)9 (n=24, 37.5)0.18Started bDMARDs1 (n=6, 16.6)2 (n=24, 8.3)0.50Died within 5 years1 (n=6, 16.6)7 (n=24, 29.1)1.00Data are median [interquartile range], or number (total number, percent).Abbreviations: RA, rheumatoid arthritis; CRP, C-reactive protein; RF, rheumatoid factor; Anti-CCP ab, anti-cyclic citrullinated peptide antibodies; LDH, lactate dehydrogenase; Glu, glucose; Tp, total protein; CS, corticosteroid; bDMARDs, biologic disease-modifying anti-rheumatic drugsDisclosure of Interests:None declared