Does the modified shuttle test exhibit a ceiling effect in healthy and cystic fibrosis children and adolescents?

The modified shuttle test-15 (MST-15) is a valid alternative for assessing exercise capacity when a cardiopulmonary exercise testing is not feasible. This study aims to describe the percentage of healthy and cystic fibrosis (CF) children and adolescents reaching the MST-15 ceiling. Additionally, it examines associations between MST-15 distance and demographic, anthropometric, and lung function data.

This retrospective cross-sectional study involved 286 healthy volunteers (11.5 ± 3.3 years) and 70 CF patients (11.9 ± 4.4 years). Data on age, gender, weight, height, body mass index, lung function, and MST-15 were collected. The ceiling effect was determined by the absolute and relative number of participants reaching the 15th level. Univariate linear regression and correlation analyses were conducted to explore associations with MST-15 distance.

A ceiling effect for the MST-15 was found in 19 healthy participants (6.6%) and 1 CF patient (1.4%). The ceiling effect was correlated with age (r = 0.777 for healthy; r = 0.538 for CF), with no cases under 10 years and reaching 25% in healthy participants aged 17-19. Regression analysis showed significant associations between age and MST-15 distance in healthy participants (β = 53.6) and CF patients (β = 32.1). Additionally, sex was significantly associated with MST-15 distance in healthy participants (β = 107.0), and FEV₁ with MST-15 distance in CF patients (β = 31.0).

The ceiling effect on the MST-15 is age-dependent, with no occurrences observed in children under 10 years and a gradual increase in incidence as participants age.