Patients with systemic lupus erythematosus (SLE) who develop pneumonia have a high risk of adverse prognosis, according to a new study. The findings also revealed that common scales of pneumonia severity can misclassify cases of SLE and pneumonia as low risk.
The research, “Pneumonia in patients with systemic lupus erythematosus. Epidemiology, microbiology and outcomes,” appeared in the journal Lupus.
Patients with SLE are commonly treated with immunosuppressants, which inhibit the immune system. Consequently, these patients have a high risk for infections. Pneumonia is one of the most severe and common infections, leading to higher risk for hospitalization among SLE patients than the general population.
Data on prognostic factors after SLE patients develop pneumonia are scarce. Also, little is known about the microorganisms involved, thereby limiting treatment efficacy. There are also few recommendations on how to treat SLE patients who have pneumonia.
Researchers from Mexico analyzed the clinical characteristics, microbiology, and risk factors for poor prognosis in adult SLE patients with pneumonia. All participants had visited the emergency room of a tertiary care center in Mexico City between 2010 and 2015.
Pneumonia was defined as having a respiratory symptom — cough, dyspnea (shortness of breath) or expectoration — evidence of systemic inflammatory response syndrome, and pulmonary infiltrate on a chest X-ray or computed tomography scan.
The patients’ medical records were analyzed for age, sex, treatment, and disease activity as measured by the Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K).
Pneumonia severity was assessed with the CURB-65 scale — confusion, urea nitrogen in the blood, respiratory rate, blood pressure, 65 or older — and Pneumonia Severity Index (PSI).
There were 158 patients (mean age 34.5 years, 76% women). They had 187 episodes of pneumonia. Most hospitalized patients were young women, representing a younger population than the one usually reported with pneumonia, the investigators saw.
There were 137 patients who had one episode, 17 had two episodes, two had three episodes, and two had five episodes. Seventy-eight episodes of pneumonia occurred during the winter, 37 in summer, 38 in autumn, and 34 during spring.
Forty-six of the 187 episodes (28.3%) required intubation, 13 patients developed shock (7%), and 12 died (6.4%). At the first pneumonia episode, 92 patients (58.2%) had not received prior vaccination, three (1.9%) reported influenza vaccination, and two (1.3%) reported vaccination against Streptoccocus pneumoniae and influenza.
The data showed no differences in age, SLE duration and activity, treatment or comorbidities between patients with negative composite outcome — defined as death, septic shock, or the need for mechanical ventilation following pneumonia up to 30 days after hospital discharge — versus those with positive outcomes.
A total of 123 patients had a low score on CURB-65, and 82 had a low PSI score. However, nearly 15% of patients with low values on CUR-65 and PSI presented with a negative composite outcome.
“This means that these indexes may underestimate the risk of complications in SLE patients and should not be used as the only instrument to decide the potential ambulatory management of patients with SLE and pneumonia,” the investigators noted.
The most common bacteria detected was S. aureus, in nine of 48 patients, three of whom were resistant to the antibiotic oxacillin. S. pneumoniae, Pseudomonas aeruginosa, Klebsiella and Escherichia coli were found in fewer patients, most of whom were resistant to other antibiotics.
Also, the team found an association between complications in SLE patients and factors such as heart rate, respiratory rate, temperature and arterial pH, and body mass index lower than 18.5 (underweight).
“Summing up, a high percentage of patients with SLE who developed pneumonia had an adverse prognosis,” the scientists said.
The investigators cautioned that Hispanic populations have a reported greater severity of SLE compared to non-Hispanic whites, indicating that studies in other populations are needed.