Study: Patients With SLE, AF Experience Higher In-Hospital Mortality Rate

Patients with systemic lupus erythematosus (SLE) and atrial fibrillation (AF) had higher rates of severe cardiac complications, along with increased in-hospital mortality, total costs, and length of stay (LOS), according to a study published in the Journal of Clinical Medicine.

The researchers explained that recent epidemiologic studies have identified infections and cardiovascular diseases as the leading causes of death in patients hospitalized with SLE. Studies have also shown that SLE is associated with a higher risk of AF, in particular, which may be due to the chronic and systemic inflammation linked to SLE.

Although it is well known that AF can increase complications in hospitalized patients, the researchers explained that there is limited literature about in-hospital AF outcomes in patients hospitalized with SLE. Consequently, the researchers conducted a study to assess the association between AF and in-hospital outcomes in patients with SLE.

Their primary outcome of interest was inpatient mortality between patients with a secondary diagnosis of AF compared to those without AF. Their secondary outcomes included the development of non-ST-elevation myocardial infarction (NSTEMI), cardiac tamponade, pericardial effusion, cardiac arrest, or cardiogenic shock. Other secondary outcomes were patients' length of stay (LOS) and total hospital costs.

Patient's heart monitor | Image Credit: sudok1 - stock.adobe.com

The researchers conducted their study using data from the National Inpatient Sample (NIS) database, the largest all-payer publicly available database of US hospitalizations, from January 2016 to December 2019; they aimed to identify US patients 18 and older with a history of SLE with or without a secondary diagnosis of AF.

The researchers identified 41,004 eligible patients in the NIS database with SLE as their primary diagnosis who were hospitalized between January 2016 and December 2019. They divided the study population into 2 groups: SLE without AF (control group) and SLE with AF (study group). The study group consisted of 1495 patients, while the control group consisted of 39,504 patients.

The mean age of patients in the study group was 56.22 years vs 37.33 years in the control group. Additionally, in terms of racial distribution, almost half of the patients in the study group were White (49.83%; P < .001), while most patients in the control group were Black (46.68%; P < .001). The study population was predominately female across groups. Also, the researchers reported no significant differences between the 2 groups in terms of hospital location, region, or bed size.

The researchers found that unadjusted all-cause in-hospital mortality was significantly higher for patients in the study group than the control group (4.01% vs 1.06%). In-hospital mortality remained higher in the study group after multivariate logistic regression analysis where they adjusted for potential confounders (adjusted odds ratio [aOR], 2.07; 95% CI, 1.08-3.94; P = .028).

Also, the researchers noted that patients in the study group had a mean in-hospital LOS of 9.03 days, while those in the control group had a mean LOS of 6.47 days. After multivariate linear regression analysis, LOS remained higher in the study group (aOR, 1.44; 95% CI, 0.28-2.60; P = .015).

Consequently, the mean total hospital charge was higher in the study group than the control group ($100,191 vs $69,604), which also remained true after multivariate linear regression analysis (adjusted mean difference [aMD], $19,915.93; 95% CI, $946.87-$38.884.99; P = .040).

Additionally, compared with the control group, those in the study group had higher rates of severe cardiac complications, namely pericardial effusion (14.72% vs 7.30%), NSTEMI (2.34% vs 0.53%), cardiac tamponade (2.34% vs 0.77%), and cardiogenic shock (2.01% vs 0.25%). However, patients in the study group did not have increased cardiac arrest rates compared to the control group (0.33% vs 0.39%).

The researchers acknowledged their study’s limitations, one being that it relied heavily on ICD-10 codes, which are susceptible to coding errors that can affect outcomes. Also, the NIS lacks “present on admission” secondary diagnosis flags, which makes it difficult to distinguish between patients with a pre-existing versus new-onset AF diagnosis. Despite these limitations, the researchers suggested areas for future research based on their findings.

“Cardiac disease is common among patients with SLE and having underlying arrhythmias such as AF can cause significant morbidity, mortality, and financial burden in these patients,” the authors concluded. “Further research is required to assess potential interventions that can decrease the incidence of these cardiac complications among patients with SLE and AF.”

Reference

Mittal S, Siva C. Incidence of atrial fibrillation and related outcomes among hospitalized patients with systemic lupus erythematosus: analysis of United States nationwide inpatient sample database 2016-2019. J Clin Med. 2024;13(6):1675. doi:10.3390/jcm13061675