Objectives

The existence of phenotypes has been hypothesized to explain the large heterogeneity characterizing the knee osteoarthritis. In a previous systematic review of the literature, six main phenotypes were identified: Minimal Joint Disease (MJD), Malaligned Biomechanical (MB), Chronic Pain (CP), Inflammatory (I), Metabolic Syndrome (MS) and Bone and Cartilage Metabolism (BCM). The purpose of this study was to classify a sample of individuals with knee osteoarthritis (KOA) into pre-defined groups characterized by specific variables that can be linked to different disease mechanisms, and compare these phenotypes for demographic and health outcomes.

Methods

599 patients were selected from the OAI database FNIH at 24 months’ time to conduct the study. For each phenotype, cut offs of key variables were identified matching the results from previous studies in the field and the data available for the sample. The selection process consisted of 3 steps. At the end of each step, the subjects classified were excluded from the further classification stages. Patients meeting the criteria for more than one phenotype were classified separately into a ‘complex KOA’ group.

Results

Phenotype allocation (including complex KOA) was successful for 84% of cases with an overlap of 20%. Disease duration was shorter in the MJD while the CP phenotype included a larger number of Women (81%). A significant effect of phenotypes on WOMAC pain (F = 16.736 p <0.001) and WOMAC physical function (F = 14.676, p < 0.001) was identified after controlling for disease duration.

Conclusion

This study signifies the feasibility of a classification of KOA subjects in distinct phenotypes based on subgroup-specific characteristics.

中文翻译：

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临床表型对膝关节骨关节炎患者的分类：来自骨关节炎倡议的数据

目标

假设存在表型可以解释膝盖骨关节炎的巨大异质性。在先前对文献的系统评价中，鉴定出六种主要表型：最小关节病（MJD），生物力学不良（MB），慢性疼痛（CP），炎性（I），代谢综合症（MS）和骨与软骨代谢（ BCM）。这项研究的目的是将膝关节骨关节炎（KOA）的个体样本划分为以特定变量为特征的预先定义的组，这些变量可以与不同的疾病机制相关联，并比较这些表型的人口统计学和健康结果。

方法

在24个月的时间里，从OAI数据库FNIH中选择了599名患者进行了研究。对于每种表型，确定关键变量的临界值，使其与该领域先前研究的结果以及可用于样本的数据相匹配。选择过程包括3个步骤。在每个步骤的最后，被分类的主题将从进一步的分类阶段中排除。符合一种以上表型标准的患者被分为“复杂KOA”组。

结果

表型分配（包括复杂的KOA）在84％的案例中成功完成，重叠20％。MJD的病程较短，而CP表型包括较多的女性（81％）。在控制病程后，确定了表型对WOMAC疼痛（F = 16.736 p <0.001）和WOMAC身体功能（F = 14.676，p <0.001）的显着影响。

结论

这项研究表明了基于亚组特异性的特征将KOA受试者分类为不同表型的可行性。