What question did this study set out to answer?

This research aims to determine if lung function changes, as measured by forced vital capacity (FVC), correlate with patients' perceptions of their quality of life.

May 20, 2026

B39-09 Stable by Feel, Not by Flow: Disconnect Between Patient Perception and Forced Vital Capacity Change in Interstitial Lung Disease

Key Points

This research aims to determine if lung function changes, as measured by forced vital capacity (FVC), correlate with patients' perceptions of their quality of life.
Patients from three ILD centers were enrolled and assessed about their FVC trajectory based on their feelings during follow-up.
Each patient received their previous FVC values and descriptions related to disease progression before guessing their future FVC percent predicted values.
Data was collected over a mean interval of 128 days.
66 patients were included, with only 37% accurately predicting their FVC trajectory.
A strong correlation was found between guessed and actual FVC % values (r = 0.86, p = 2E-20).
Most patients (55%) perceived their condition as 'stable,' indicating a disconnect between clinical measures and patient perceptions.

Abstract

Abstract Introduction Serial trends of pulmonary function testing values such as the forced vital capacity (FVC) remain a cornerstone for clinicians in determining disease trajectory in interstitial lung disease (ILD). While FVC has been validated as a surrogate for survival, it remains unclear how well short-term FVC changes during follow-up visits reflect patient-centered metrics such as quality of life. To investigate whether or not FVC changes correlate with patient-perceived quality of life, we asked patients across three ILD centers to guess their own FVC trajectory at their follow-up visit based on how they felt during that follow-up period. Methods Patients were enrolled at the University of Kansas, University of Florida and St. James Hospital in Dublin Ireland ILD centers. At each follow-up visit, patients were told their previous FVC percent predicted values and date of collection. Each patient was given a description of FVC and the nature of FVC changes as it relates to disease progression and then asked to guess their follow-up FVC percent predicted value. Results This study included 66 patients (14 idiopathic pulmonary fibrosis, 7 hypersensitivity pneumonitis, 15 autoimmune ILD, 11 sarcoidosis, and 19 other). The average age was 68 ± 10.1 years, with mean FVC % predicted 74 ± 20.2. The mean interval between FVC measures was 128 ± 175 days. The mean absolute difference between guessed and measured FVC % values was 7.8 percentage points. There was a strong correlation between guessed and actual FVC % (r = 0.86, p = 2E-20). However, only 37% of patients correctly predicted their trajectory (improved +3%, stable -3 to + 3%, worsened -3%), with most patients (55%) guessing “stable” (Figure 1). Discussion Despite a strong correlation between guessed and actual FVC % (r = 0.86), only 37% of patients accurately identified their trajectory. Most patients (55%) guessed they were “stable,” which suggested that the small magnitude of physiologic change over typical 3-month follow-up likely renders these changes imperceptible to them. These findings suggest that short-term FVC changes, while clinically meaningful, may not reflect patient-perceived health status or quality of life. The predominance of “stable” guesses underscores the importance of integrating physiologic and patient-reported measures when assessing ILD trajectory. Longer follow-up or use of sensitive tools—such as home spirometry or digital symptom tracking—may better align patient perception with objective change. This abstract is funded by: None

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