Page 127 - Livre électronique des RFTP 2025

P72. FROM LUNG FUNCTION TO EXERCISE RISK: A

COMPOSITE SCORE FOR DESATURATION IN ILD

CHAIMA BRIKI¹⁻², KHOULOUD KCHAOU¹⁻², NOUR BEN MRAD¹, YOSSRA ABDELHEDI¹,
SOUMAYA KHALDI¹⁻², SALOUA BEN KHAMSA JAMELEDDINE¹⁻²

¹ DEPARTMENT OF PHYSIOLOGY AND FUNCTIONAL EXPLORATIONS, ABDERRAHMENE MAMI
HOSPITAL, ARIANA.

² LABORATORY OF PHYSIOLOGY, NUTRITION, AND BIOMOLECULES (LR-17-ES-03), BIOTECHNOLOGY
CENTER OF SIDI THABET, UNIVERSITY OF MANOUBA, TUNIS

Introduction : Interstitial lung disease (ILD) is often associated with impaired gas
exchange and ventilatory mechanics, contributing to desaturation during exercise.
Identifying patients at risk of desaturation is essential for guiding rehabilitation and
oxygen therapy. We aimed to develop a simple composite ventilatory score based
on routine pulmonary function tests to predict exercise-induced desaturation
during the six-minute walk test (6MWT) in ILD.

Methods : We performed a retrospective study of 110 ILD patients. Pulmonary
function included FEV₁, TLC, DLCO, and RV/TLC ratio. A composite score ranging
from 0 to 4 points was created by attributing 1 point for each abnormal ventilatory
parameter: FEV₁ < 60% predicted, TLC < 80% predicted, DLCO < 60% predicted, and
RV/TLC > 35%. Each patient’s final score was obtained by summing the number of
criteria met. Based on the total score, patients were categorized into three groups:
low score (0–1 points), intermediate score (2 points), and high score (3–4 points).
Desaturation was defined as a ≥ 5% drop in SpO₂ during the 6MWT. Chi-square tests,
ROC analysis, and t-tests were used to explore associations.

Results : The mean age was 56.4 ± 11.6 years and the mean BMI was 30.2 ±
7.0 kg/m ². Sarcoidosis (54.1%) and idiopathic pulmonary fibrosis (34.9%) were the

most frequent ILD subtypes. Desaturation ≥ 5% occurred in 29.2% of patients.
Patients who desaturated had significantly lower FEV₁ (67.8% vs 77.3%, p = 0.04), TLC
(68.7% vs 90.0%, p < 0.001), and DLCO (55.8% vs 78.0%, p < 0.001), and higher
composite scores (2.0 ± 1.1 vs 1.1 ± 0.9, p = 0.001). The composite score demonstrated
a significant association with exercise-induced desaturation. Desaturation rates
increased progressively with higher scores: 14% in the low-score group (0–1 points),
39% in the intermediate group (2 points), and 67% in the high-score group (3–4
points) (p = 0.001), supporting a relationship between ventilatory impairment and
desaturation risk. ROC analysis showed fair discrimination (AUC = 0.728).

Conclusion : The composite ventilatory score may help identify ILD patients at risk
of desaturation during exercise. This simple tool could assist clinicians in targeting
patients for optimized rehabilitation and oxygen prescription strategies.

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