People with systemic lupus erythematosus (SLE) are three times more likely than people in the general population to have up to five or more comorbidities, according to the results of two separate US population-based studies.
The higher comorbidity rate included many of the previously commonly reported conditions such as cardiovascular and kidney disease, but also some that may be less commonly associated with SLE, particularly chronic obstructive pulmonary disease (COPD) and cardiac arrhythmias.
“Historically, characterization of SLE comorbidities has relied on individual comorbidity assessment,” said Alí Duarte García, MD, on 14th and autoimmunity (CORA).
“However, a patient-centered approach that looks at the patient as a whole and how many comorbidities they have has not been followed.” added Duarte García, a rheumatologist at the Mayo Clinic in Rochester, Minnesota.
Several disorders “overrepresented” in SLE patients
Duarte García reported the results of one of the studies, both of which used data from the Rochester Epidemiology Project, a record-linkage system that brings together clinical and hospital data from people living in 19 counties in southeast Minnesota and eight counties in western Wisconsin Life; these patients have agreed to share their medical records for research purposes.
The study population included 479 people diagnosed with SLE according to the joint 2019 European Alliance of Associations for Rheumatology
and criteria of the American College of Rheumatology. These were assigned to 479 people without SLE according to age, sex, race and district.
The mean age of the study population was 53 years, 82% were women and 86% were white.
“We defined multimorbidity as patients with two or more comorbidities and substantial multimorbidity as patients with five or more comorbidities,” said Duarte-García.
A previously published list of 44 comorbidity categories was used to classify the observed multimorbidity, of which 27 were “overrepresented” in patients with SLE.
Patients with SLE had an average of 5.3 comorbidities, while controls had 2.9. When comparing SLE with non-SLE patients, the odds ratio (OR) was 2.96 for two or more comorbidities and 3.06 for five or more comorbidities.
The highest OR when comparing SLE with non-SLE individuals was observed in lung diseases (39.0).
Duarte García highlighted four comorbidities that occurred in SLE patients that were perhaps more unusual: congestive heart failure (OR, 13.3), valvular heart disease (OR, 4.2), cardiac arrhythmias (OR, 2.85), and COPD (OR , 2.7).
“Given the association of multimorbidity with poor outcomes, care strategies are needed to manage multimorbidity in SLE,” concluded Duarte García.
Similar findings in cutaneous lupus
There is also an excess of comorbidities in people with cutaneous lupus erythematosus (CLE), said Mehmet Hocaoglu, MD when reporting on the results of the second study.
Hocaoglu, an intern in internal medicine at the University of Maryland Medical Center in Baltimore and part of the same research team as Duarte García, found that skin-related lupus roughly doubled the risk of multimorbidity.
For this separate analysis, a total of 303 patients with cutaneous lupus were assigned to 303 controls from the general population. ORs for two or more or five or more comorbidities were 2.27 and 1.65, respectively.
Among the comorbidities observed, which were higher in patients with cutaneous lupus than in the general population, were fibromyalgia, liver disease, hypertension, anemia, hypothyroidism, and COPD.
“More research is definitely needed to determine whether the driver of this multimorbidity in CLE patients is the disease itself, the treatments CLE patients receive, or a multifactorial cause that drives the disease association,” Hocaoglu said.
Commentary and perspective
“Comorbidities unsuitable for the general population compared to SLE” appear to have been included in the total SLE and cutaneous lupus analyzes, suggested Raquel Faria, MD.
Faria, specialist in internal medicine at the Unidade de Imunologia Clínica – CHU Porto in Portugal, chaired the poster discussion in which the two studies were presented.
She wondered if the researchers analyzed the data while considering “the comorbidities that they knew were due to lupus activity, such as anemia”.
The number of patients with SLE who suffered from pulmonary circulatory disorders – 7.5% versus 0.2% of the general population – also caught Faria’s attention.
That is “a really huge number,” said Faria. “I think she’s pretty overrepresented.”
Duarte García admitted that they were taking a “very broad approach” using a “very large comorbidity index”.
“What we observed at the beginning is exactly what you mention,” he replied to Faria.
“We have drawn patients who have had a disease manifestation rather than comorbidity,” said Duarte-García.
These are the first and very exploratory data, he emphasized. “We have now started changing the index.” Some of the changes they made were to include the SLICC Damage Index score and streamline the list of ICD codes used.
No third-party funding was received for either study. Duarte García and Hocaoglu individually stated that they had no actual or potential conflicts of interest in relation to their presentations.
14th International Congress on Systemic Lupus Erythematosus (LUPUS 2021) and 6th International Congress on Controversies in Rheumatology and Autoimmunity (CORA). Poster 030, Poster 031. Presented October 7, 2021.
Sara Freeman is a UK-based medical journalist specializing in medical conference coverage and content for websites. Follow her on Twitter @Sara_MedWriter.
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