Causes of Sleep Disturbance in Early ASAS Spondyloarthritis: A Retrospective Long-Term Experience.

Introduction: Sleep disturbance (SD) in the second half of the night due to inflammatory pain was included in the 2009 ASAS classification criteria of Spondyloarthritis (SpA), even though its definition is uncertain. Aim: We aimed to investigate SD in early-SpA (e-SpA) patients at T1 (2010-2013), comparing them to long-term SpA (l-SpA) patients at T2 (2023-2024) after at least 10 years of follow-up. Methods: At T1, in e-SpA and l-SpA cases, SD, classified as "difficulty in initiating sleep" (DIS), "difficulty in maintaining sleep" (DMS) and "early awakening" (EA), was compared to clinical parameters (ASDAS-CRP, BASDAI, m-HAQ-S, BASMI, MASES, 68/66 joint count, tenderness of sacroiliac joints, fatigue [FACIT] and HADS for anxiety [A] and depression [D]). At T2, e-SpA patients were re-evaluated using the Pittsburgh Sleep Quality Index (PSQI). Results: At T1, 45% of 166 SpA patients had SD; in e-SpA patients (60), SD correlated with sacroiliac pain (DMS) BASDAI, FACIT and HADS-D (EA); in l-SpA patients (106), it correlated with HADS-A (DIS), BASDAI and FACIT (DMS). At T2, e-SpA patients showed a high PSQI in 51.5% of cases, correlated with T2-ASDAS-CRP and T2-BASDAI. Moreover, T1-ASDAS-CRP was predictive of T2-PSQI. Conclusions: SD is more specific for inflammatory pain in e-SpA and might be influenced by disease activity also in long-term disease.