Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Background/Purpose: ILD is a frequent and potentially severe complication of CTDs. The course of ILD can be difficult to predict in this setting. The term IPAF (Interstitial Pneumonia with Auto-immune Features) has been recently created to design patients not fulfilling the diagnostic criteria for defined CTD. KL-6 (Krebs von den Lungen-6) biomarker, also known as Mucin1, is a glycoprotein produced by type II pneumocytes. Levels of serum KL-6 are well recognized to be correlated to the clinical outcome of idiopathic ILDs. However, its prognostic relevance in CTDs and IPAF-ILDs needs to be better determined.
Methods: The levels of KL-6 of the sera of 129 patients (66 males; age 61 ± 13 years; smokers or ex-smokers: n = 56(43%) have been retrospectively analyzed using the FUJIREBIO Lumipulse Chemiluminescent enzyme immunoassay at the time of ILD diagnosis. Cut-off for normal values has been set to 500 U/mL according to previous published studies. Among the 128 patients, 61 had CTDs-ILD, 21 had IPAF-ILD, 34 had idiopathic pulmonary fibrosis (IPF), and 13 had nonspecific interstitial pneumonia (NSIP). KL-6 levels were correlated with baseline forced vital capacity (FVC) and diffusion capacity for carbon monoxide (DLCO) using the Spearman non parametric correlation test. Correlation of KL-6 levels with the clinical outcome (improvement/stabilization of ILD or worsening, as defined by a decrease of 10% in FVC or 15% in DLCO/death) at one year were studied using a U Mann-Whitney test.
Results: The mean levels of KL-6 for CTDs, IPAF, IPF, and NSIP were 2204 ± 2285, 2393 ± 2172, 1802 ± 1584, and 1839 ± 1328 U/mL, respectively. KL-6 levels were over the normal value in 87 % (53/61), 90 % (19/21), 91 % (31/34) and 100 % (13/13) in CTDs, IPAF, IPF, and NSIP, respectively. Overall, KL-6 levels were negatively correlated with FVC (r=-0.2, p=0.035) and DLCO (r=-0.28, p=0.004). As regards the clinical outcome of ILD, higher levels of KL-6 were observed in patients with poor outcome (progression/death) when compared to those with better outcome (stabilization or improvement) in CTDs (2855 ± 2490 vs 1932 ± 2166 U/mL, p=0.05). Similar trends were observed in IPF (2351 ± 1908 vs 1107 ± 561, p=0.04) and in NSIP (2628 ± 1667 vs 1360 ± 543.7, p=0.18), while no difference was observed in IPAF (2418 ± 1583 vs 2388 ± 2679, p=0.33).
Conclusion: High levels of KL-6 measured at early time points in the clinical history of CTDs-associated may be predictive of poorer outcomes. Similar trends were observed in IPF and NSIP. Further prospective studies are required to confirm these results.
To cite this abstract in AMA style:Moreer L, Nunes H, Bondeelle L, Uzunhan Y, Ghillani-Dalbin P, Valeyre D, Musset L, Miyara M. Serum KL-6 Levels in Interstitial Lung Diseases (ILDs) Associated to Connective Tissue Diseases (CTDs) [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/serum-kl-6-levels-in-interstitial-lung-diseases-ilds-associated-to-connective-tissue-diseases-ctds/. Accessed October 19, 2021.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-kl-6-levels-in-interstitial-lung-diseases-ilds-associated-to-connective-tissue-diseases-ctds/