POTENTIAL MISINTERPRETATION OF INFANT LUNG FUNCTION UNLESS PROSPECTIVE HEALTHY CONTROLS ARE STUDIED

Sooky Lum (1) , Ah-Fong Hoo (1, 2) , Georg Huelskamp (3) , Angie Wade (4) , Janet Stocks (1)

1 Portex Respiratory Unit
2 GOSH - Great Ormond Street Hospital for Children [London]
3 Department of Paediatrics
4 Centre for Paediatric, Epidemiology and Biostatistics Unit

SUMMARY Rationale: Reliable interpretation of pulmonary function tests relies on appropriate reference data which remain very limited for infants. Objectives: This study aimed to assess the validity of published reference equations for forced expiratory flow-volume (FEFV) data in infants when using current, commercially available equipment, and how this could impact on interpretation of results from infants with lung disease. Methods: The Jaeger Masterscreen BabyBody (v4.67) equipment was used to perform partial and raised volume FEFV maneuvers in healthy infants and those with cystic fibrosis (CF). Results were initially expressed as Z-scores using published reference equations. Multilevel modelling was used to calculate differences, if any, from predicted scores in healthy infants. Results: Data were available from 66 healthy fullterm infants on 89 test occasions; [median (range) postnatal age 49.4(12–101) weeks. All FEFV outcomes were significantly lower than predicted, with mean (SD) Z-score differences of -0.4(1.1) for FVC; -0.6(1.0) for FEV0.5; -1.0(1.0) for FEF25-75 and -1.4(1.1) for V'maxFRC. After adjustments using multilevel modelling, mean Z-scores were within 0.1(SD~1.0) predicted for all outcomes in healthy infants. Among 50 infants with CF, studied on 85 test occasions, results were ‘abnormal' (< -1.96 Z-scores) on 35 (41%) and 37 (45%) test occasions for FEV0.5 and FEF25-75 respectively when using published equations. This fell to 24 (28%) and 20 (24%) respectively, after adjustment. Conclusions: Dependence on published equations for interpreting FEFV data in infants may lead to misinterpretation of lung function status, which could impact adversely both in the research setting and on clinical management. Use of a contemporary control group or establishment of equipment-specific reference data is essential for meaningful interpretation of infant lung function data.

Mots clés: Medicine

Sooky Lum, Ah-Fong Hoo, Georg Huelskamp, Angie Wade, Janet Stocks. POTENTIAL MISINTERPRETATION OF INFANT LUNG FUNCTION UNLESS PROSPECTIVE HEALTHY CONTROLS ARE STUDIED. Pediatric Pulmonology, 2010, 45 (9), pp.906. ⟨10.1002/ppul.21255⟩. ⟨hal-00557755⟩