Department of Rheumatology and Immunology, Medical University of Graz, Graz, Austria.
Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands.
RMD Open. 2024 Sep 30;10(3):e004584. doi: 10.1136/rmdopen-2024-004584.
To follow up four previously identified classes 'pure axial spondyloarthritis' (axSpA) ('axial'), 'axSpA with peripheral signs' ('inflammatory back pain+peripheral'), 'axSpA at risk' and 'no spondyloarthritis' ('no SpA'). They reflect the expert-opinion-free construct or 'Gestalt' of chronic back pain suspicious of axSpA. The aim was to assess participants' transitions between these classes over time.
Participants with chronic back pain of ≤2 years duration, suspicious of axSpA from the SPondyloArthritis Caught Early cohort were analysed. Latent class (LCA) and latent transition analysis (LTA) using clinical, laboratory and imaging data at baseline and 2 years were calculated. Conditional and marginal probabilities were obtained, reflecting the probability of a spondyloarthritis feature in a class and the probability of the participant's class membership, respectively. Transitional probabilities were extracted revealing potential switches across classes. The analyses were performed in all participants using imputations for missing data and in participants with full data at baseline and 2 years.
Baseline and 2 years LCA models were constructed for 702 participants, resulting in the same four-class model as previously described. LTA revealed only a 3% transition from the 'no SpA' to the 'at-risk' class from baseline to 2 years with all other participants remaining in their initially assigned class. Sensitivity analysis on 384 participants with complete data at both baseline and 2 years showed similar results, underlining the model's robustness.
Transitions between the four classes over 2 years were basically inexistent, highlighting the unlikelihood of developing new class-defining features of axSpA after an initial clinical workup.
随访之前确定的四个类别“单纯轴性脊柱关节炎”（axSpA）（“轴性”）、“伴有外周征象的 axSpA”（“炎性背痛+外周”）、“axSpA 风险”和“无脊柱关节炎”（“无 SpA”）。它们反映了慢性腰痛怀疑 axSpA 的专家意见免费构建或“整体”。目的是评估参与者在这段时间内这些类别的转移情况。
对来自 SPondyloArthritis Caught Early 队列的慢性腰痛持续时间≤2 年且怀疑 axSpA 的患者进行分析。使用基线和 2 年时的临床、实验室和影像学数据进行潜在类别（LCA）和潜在转移分析（LTA）。获得条件和边缘概率，分别反映类别中脊柱关节炎特征的概率和参与者类别的概率。提取过渡概率，揭示潜在的类别间转换。使用缺失数据的插补在所有参与者中以及在基线和 2 年时具有完整数据的参与者中进行分析。
对 702 名参与者进行了基线和 2 年的 LCA 模型构建，结果与之前描述的相同的四个类别模型。LTA 仅显示从基线到 2 年，“无 SpA”到“风险”类别的 3%的转移，所有其他参与者保持其最初分配的类别。对 384 名基线和 2 年时均有完整数据的参与者进行敏感性分析，结果相似，突出了该模型的稳健性。
在 2 年内，这四个类别的转移基本上不存在，突出了在初始临床评估后不太可能出现 axSpA 的新类别定义特征。
