Population-Based Incidence and Time to Classification of Systemic Lupus Erythematosus by Three Different Classification Criteria

A Lupus Midwest Network (LUMEN) Study

Alí Duarte-García; Mehmet Hocaoglu; Shirley-Ann Osei-Onomah; Jesse Y. Dabit; Rachel E. Giblon; Charles G. Helmick; Cynthia S. Crowson

Disclosures

Rheumatology. 2022;61(6):2424-2431. 

In This Article

Abstract and Introduction

Abstract

Objective: To estimate the incidence and time-to-classification of SLE by the 1997 ACR (ACR97) criteria, the SLICC criteria, and the European Alliance of Associations for Rheumatology/ACR (EULAR/ACR) criteria.

Methods: We identified all incident SLE cases from 2000–2018 in the well-defined Olmsted County population. Clinical data included in the ACR97, SLICC and EULAR/ACR criteria were manually abstracted from medical records. All incident cases met at least one of the three classification criteria. Time-to-classification was estimated from the first documented lupus-attributable disease manifestation to the time of criteria fulfilment by each of the three definitions. Annual incidence rates were age or age/sex adjusted to the 2000 US population.

Results: Of 139 incident cases there were 126 cases by the EULAR/ACR criteria, corresponding to an age/sex-adjusted incidence of 4.5 per 100 000 population (95% CI: 3.7, 5.2). The age/sex-incidence was higher than that of the SLICC criteria (113 cases; 4.0 per 100 000 [95% CI: 3.3, 4.7], P = 0.020) and the ACR97 (92 cases; 3.3 per 100 000 [95% CI: 2.6, 3.9], P < 0.001). The median time from first disease manifestation to criteria fulfilment was shorter for the EULAR/ACR criteria (29.4 months) than the ACR97 criteria (47.0 months, P < 0.001) and similar to the SLICC criteria (30.6 months, P = 0.83).

Conclusion: The incidence of SLE was higher by the EULAR/ACR criteria compared with the ACR97 and the SLICC criteria, and the EULAR/ACR criteria classified patients earlier that the ACR97 criteria but similar to the SLICC criteria.

Introduction

SLE is a systemic autoimmune disease that can affect virtually any organ and requires a complex clinical workup to diagnose. The systemic nature of the disease, its numerous generic clinical manifestations and the heterogeneous US health system have made it difficult to perform population-based epidemiological studies to estimate the frequency of the disease. Through an initiative of the Centers for Disease Control and Prevention (CDC), five surveillance registries were created to provide incidence and prevalence of SLE across populations of different racial and ethnic groups: in 2002–2004 the Georgia Lupus Registry[1] and the Michigan Lupus Epidemiology and Surveillance Program;[2] and in 2007–2009 the California Lupus Surveillance Project,[3] the Manhattan Lupus Surveillance Program[4] and the Indian Health Service Lupus registry.[5]

Classification criteria are standardized definitions used for research purposes to identify well-defined cohorts of patients with heterogeneous clinical manifestations, as is the case in SLE. The aforementioned registries used the ACR 1997 (ACR97) classification criteria to define SLE cases.[6] Since the development of the registries, new classification criteria were developed and endorsed by the European Alliance of Associations for Rheumatology (EULAR) and the ACR.[7] The sensitivity and specificity of the new EULAR/ACR criteria are different from the ACR97 criteria and the SLICC criteria, which can impact the incidence estimates of the disease.[8] Furthermore, one of the reasons to develop the new EULAR/ACR criteria was to classify patients earlier in their disease process, but it has not been proven if this was accomplished.

In this study we aimed to estimate the incidence of SLE in Olmsted County, Minnesota using the ACR97, SLICC and EULAR/ACR criteria. A secondary aim was to estimate the time to classification among the three different classification criteria.

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