B79-05 Oscillometry in Sarcoidosis: Pulmonary Function Phenotypes and Health-related Quality of Life

Rationale Pulmonary sarcoidosis is heterogeneous and can manifest as either restrictive or obstructive, necessitating physiologic endpoints that are more universal than forced vital capacity (FVC). Oscillometry is a noninvasive, non-effort-dependent technique for measuring airway biomechanics that shows promise for distinguishing early lung disease and assessing treatment response in both restrictive and obstructive lung disease. As sarcoidosis lacks a single clinical endpoint, oscillometric parameters may fill this gap in assessing disease activity and treatment response. Our group previously demonstrated a range of pulmonary function impairments in a diverse cohort of sarcoidosis patients; however, the range of oscillometric parameters across pulmonary function phenotypes has not been defined. We aimed to assess differences in oscillometric parameters across pulmonary function phenotype groups and determine the association between oscillometric parameters and health-related quality of life (HRQoL) in sarcoidosis. Methods Participants with biopsy-proven sarcoidosis on immunosuppression in a prospective cohort underwent oscillometry and spirometry testing according to ATS/ERS guidelines. Clinical data collected included demographics, clinical features, spirometry, DLCO, and St. George’s Respiratory Questionnaire (SGRQ). Associations between oscillometric parameters and SGRQ were tested in multivariable linear regression. Each oscillometric parameter (resistance at 5 Hz [Rrs5], resistance at 5 Hz minus 20 Hz [Rrs5-20], reactance at 5 Hz [Xrs5], and area under the reactance curve [AX]) was an independent predictor in a separate model, adjusted for self-reported race, gender, disease duration, and Charlson comorbidity index (CCI). Participants were classified into pulmonary function phenotypes using Global Lung Function Initiative criteria as previously described, categorized as normal, obstruction, restriction, and isolated reduced DLCO. Rrs5, Rrs5-20, Xrs5, and AX were compared across pulmonary function phenotypes using ANOVA with post hoc Tukey pairwise comparisons. Results In total, 54 participants (52% Black, 57% female, median age 60 years, median diagnosis duration 9 years) underwent oscillometry. In multivariable regression, higher AX (β = 0.48±0.16, p = 0.005) and Rrs5 (β = 3.9±1.4, p = 0.009) and lower Xrs5 (β= -5.4±1.9, p = 0.007), but not Rrs5-20, were associated with worse SGRQ. Across pulmonary function phenotypes, AX and Xrs5 were significantly higher in participants with isolated reduced DLCO and obstruction than in participants with normal spirometry (Table 1). Conclusion Xrs5, Rrs5, and AX were associated with HRQoL among individuals with sarcoidosis. Xrs5 and AX may have utility in sarcoidosis as physiologic clinical endpoints as they were significantly different from normal across multiple pulmonary function phenotypes. Further exploration is warranted to determine if oscillometric parameters have utility as clinical endpoints in sarcoidosis across pulmonary function phenotypes. This abstract is funded by: NHLBI HL148527-01A1