Pulmonary Function Test Abnormalities Common Among Patients With Childhood SLE

In patients with childhood-onset systemic lupus erythematosus (cSLE), the most common pulmonary function tests (PFT) abnormalities include alterations in diffusing capacity and restrictive lung disease, according to study results published in Lupus.

Using a retrospective chart review, researchers examined pulmonary involvement in cSLE using PFTs from July 2015 to 2020.

Obstructive ventilatory impairment was defined as forced expiratory volume/forced vital capacity (FEV1/FVC) below the lower limit of normal (LLN), which was the fifth percentile of the normal population. Restrictive ventilatory impairment was defined as a decrease in total lung capacity (TLC) below the LLN.

Researchers used the European Respiratory Society and American Thoracic Society guideline to interpret PFT results.

Of 42 patients with cSLE, 10 (23.8%) had PFT abnormalities and were included in the final analysis. Patients had a mean age at diagnosis of 13.0±2.9 years; 90% were women; and 20% self-identified as Asian, 20% as Hispanic, 10% as Black or African American, and the remaining 50% as other.

Of the 10 patients with PFT abnormalities, 3 had restrictive lung disease without diffusion impairment, 3 had only diffusion impairment without restrictive lung disease, and 4 had both restrictive lung disease and diffusion impairment. None of the patients demonstrated signs of obstructive lung disease during the study period. A total of 70% of patients had a TLC below the fifth percentile (LLN), with a mean TLC of 72.5±5.8. Patients with diffusion limitation had an average diffusing capacity of carbon monoxide of 64.8±8.3, which was corrected for hemoglobin.

Data on other SLE-associated organ involvement showed that 50% of the patients had lupus nephritis, of whom 20% had abnormalities in their PFTs (asthma and pneumonitis).

Study limitations included the small sample size and the single-center design, which may have limited the generalizability of the results.

Despite the small sample size, the study findings reinforced data from previous analyses, where primarily restrictive and diffusion pulmonary abnormalities were seen among patients with cSLE.

Study authors concluded, “These results reinforce the importance of screening all [patients with] cSLE with PFTs early in their disease course, regardless of clinical symptoms, to discover pulmonary abnormalities.”