Factors Associated with Uninterpretable Spirometry During Asthma Screening in Children with Sickle Cell Disease: An Expanded Multicenter Study in French Guiana

Background/Objectives: Spirometry is essential for objective asthma assessment in children with sickle cell disease (SCD), but technically uninterpretable examinations may reduce the effectiveness of systematic screening. This study aimed to determine their frequency and identify associated demographic, clinical, social, disease-related, and center-level factors in French Guiana. Methods: We conducted a prospective multicenter observational study involving children and adolescents with confirmed SCD who underwent systematic asthma screening at Cayenne, Kourou, and Saint-Laurent-du-Maroni hospitals between January 2025 and May 2026. Spirometry technical quality was assessed according to the 2019 American Thoracic Society/European Respiratory Society technical standards and classified as interpretable or technically uninterpretable according to the acceptability, usability, and repeatability of the recorded maneuvers. Across the three sites, spirometry was performed on the recorded MicroLab platform using GLI-2012 reference equations. Salbutamol was delivered by pressurized metered-dose inhaler with a valved holding chamber when bronchodilator testing was technically feasible; the exact device submodel/manufacturer metadata, center-specific software versions, and administered salbutamol dose were not retained in the exported analytical dataset. Participant characteristics were compared between groups, and associated factors were examined using univariable and multivariable logistic regression. Results: After removal of duplicate records, 143 unique children were included. Spirometry was technically uninterpretable in 34 participants (23.8%). Children with uninterpretable examinations were significantly younger than those with interpretable spirometry (8.9 ± 3.0 vs. 10.5 ± 4.0 years; p = 0.015). In univariable analysis, each additional year of age was associated with a 12% reduction in the odds of uninterpretable spirometry (OR 0.88, 95% CI 0.78–0.99; p = 0.036). After adjustment for sex, recruitment center, and health-insurance status, the inverse association persisted in direction and magnitude but did not reach conventional statistical significance (adjusted OR 0.89, 95% CI 0.79–1.01; p = 0.075). Given the limited number of outcome events, this attenuation may reflect reduced statistical power. No other investigated factor was independently associated with non-interpretability. Conclusions: Nearly one-quarter of children had technically uninterpretable spirometry. Younger children may benefit from enhanced preparation, age-adapted coaching, experienced operators, and planned repeat testing to improve asthma-screening yield and reduce missed respiratory disease.