Quality of Spirometry Maneuvers in Interstitial Lung Disease Patients in a Tertiary Facility

Background/Objectives: The aim of this study was to analyze spirometry quality and compliance with the current protocol in interstitial lung disease (ILD) patients at a tertiary-level facility in Almaty, Kazakhstan. Methods: We consecutively enrolled 125 patients, aged 60 (interquartile range (IQR) 52; 67) years, including 40 (32%) patients with idiopathic pulmonary fibrosis (ILD-IPF). Relaxed and forced maneuvers were completed, and we hereinafter analyzed vital capacity (VC), forced VC (FVC) and forced expiratory flow in one second (FEV1) both as z-scores and % predicted values in addition to number of attempts, ΔVC, ΔFVC, ΔFEV1, expiratory plateau volume and back extrapolation volume (BEV) in both maneuvers. Multiple regression was used to test predictors of these. Results: In this predominantly female cohort (73%), CAT (median 12; IQR 9; 18) and mMRC (median 2; IQR 1; 3) scores reflected high symptom burden with most suggestive of a restrictive pattern (62% of all, median FVC in the entire group −2.17; IQR −3.28; −1.4 z-scores or 68%; IQR 52.5; 80.5). The median VC and FVC maneuver attempts was 3. ΔVC was 0.05 (IQR 0.03; 0.09) L; ΔFVC was 0.07 (IQR 0.03; 0.12) L; and ΔFEV1 was 0.05 (IQR 0.02; 0.09) L, whereas expiratory plateau volume was 0.04 (IQR 0.02; 0.06) L. Ninety-six percent of tests were graded A or B based on ΔFVC and 98% based on ΔFEV1. Conclusions: This study showed that despite dyspnea and cough in ILD patients with severe symptom burden, a high quality of spirometric maneuvers can be obtained in the majority of patients.