New-onset non-infectious pulmonary manifestations among patients with systemic lupus erythematosus in Sweden

Lindsy J Forbess,Marios Rossides,Julia F Simard,Michael H Weisman

doi:10.1186/s13075-018-1804-8

Abstract

ObjectiveThe objective was to estimate the incidence of lung disease among patients with systemic lupus erythematosus (SLE).MethodsUsing Swedish register data, we identified patients with SLE and pulmonary diagnoses from the National Patient Register through ICD codes. We matched patients with SLE with individuals from the general population. Patients with SLE with a history of pulmonary disease were excluded. Incidence rates (IR) and 95% confidence intervals (CI) were calculated overall and by type of pulmonary disease for incident (2003–2013) and prevalent SLE separately. Hazard ratios (HR) and 95% CI of the association between SLE and pulmonary disease were estimated using adjusted Cox regression models. Sensitivity analyses using a semi-automated approach to quantitative probabilistic bias analysis accounted for potential bias due to unmeasured confounding by smoking.ResultsThere were 3209 incident and 6908 prevalent cases of SLE identified. The IRs for pulmonary disease were similar in prevalent and incident SLE (∼14 cases per 1000 person-years). Patients with incident SLE had a nearly sixfold higher rate of pulmonary disease compared to the non-SLE population (HR 5.8 (95% CI 4.8–7.0)). Incident and prevalent SLE was associated with an increased rate of interstitial lung disease (HR 19.0 (95% CI 10.7–34.0) and 14.3 (95% CI 10.8–18.8), respectively). Bias due to unmeasured confounding by smoking was unlikely to explain our findings.ConclusionLung disease is relatively common in patients with SLE compared to the general population. Clinicians caring for patients with SLE should have heightened suspicion of lung disease, including interstitial lung disease, even early within the disease course or at the time of diagnosis of SLE.

Highlights

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease that has the potential to affect many organ systems
This is the first population-based register study of lung disease in systemic lupus erythematosus (SLE) and shows that lung disease occurs at a much higher rate in patients with SLE compared to the general population
* Correspondence: jsimard@stanford.edu 2Division of Clinical Epidemiology, Department of Medicine Solna, Karolinska Institutet, Stanford School of Medicine, Stockholm, Sweden 3Division of Epidemiology, Department of Health Research and Policy, Stanford School of Medicine, Stanford, CA, USA Full list of author information is available at the end of the article patients with SLE in the early stages of their disease experience interstitial lung disease at similar rates to those with longer standing disease Clinicians caring for patients with SLE should have heightened suspicion of lung disease even early within the disease course

Summary

Introduction

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease that has the potential to affect many organ systems. Much of what is known about lung disease in SLE comes from relatively small studies in selected clinical cohorts, such as the US multiethnic LUMINA cohort along with North American and European cohorts [1– 3]. The true prevalence and incidence of lung disease in SLE may be underestimated in these studies because of patient selection, small sample sizes, and short follow-up periods. It is important to identify pulmonary manifestations in a larger population-based cohort of individuals with SLE. Using such population-based data, less common phenotypes of SLE-related lung disease may be identified along with their onset relative to SLE diagnosis

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