Clinical use of the modified shuttle test in children with cystic fibrosis: Is one test sufficient?

OBJECTIVE: To evaluate the reproducibility of the modified shuttle test (MST) and to determine whether the test needs to be performed more than once to assess the exercise capacity of children and adolescents with cystic fibrosis (CF). METHODS: This was a longitudinal study including patients diagnosed with CF aged more than 6 years. The participants were followed for a period of 9 months and were evaluated at three different time points (visits 1, 2, and 3). Spirometric, anthropometric, clinical, and genetic data were collected, and two MSTs were performed at each visit. RESULTS: Forty-eight clinically stable volunteers with a mean age of 10.1 ± 2.7 years were initially included. The reproducibility of the test was evaluated using the distance achieved (DA) as the main variable. There were no significant differences in the DA (visit 1, p = .23; visit 2, p = .24; visit 3, p = .85), baseline heart rate (HR) (visit 1, p = .35; visit 2, p = .20; visit 3, p = .98), and peak HR (visit 1, p = .16; visit 2, p = .94; visit 3, p = .23) between the tests performed at each visit. The test-retest reliability demonstrated a high intraclass correlation coefficient at all visits (visit 1, 2, and 3: 0.83, 0.90, and 0.80, respectively) and the variation in HR was the main factor associated with the DA in the MST over time. CONCLUSION: The MST was found to be a reproducible and reliable test. The data presented here support the use of a single MST to evaluate and monitor exercise capacity of patients with CF during clinic visits.

The modified shuttle test as a predictor of risk for hospitalization in youths with cystic fibrosis: A two-year follow-up study

BACKGROUND: Patients with cystic fibrosis (CF) present exercise intolerance and episodes of pulmonary exacerbations. This study aimed to evaluate the association of the distance covered on the modified shuttle test (MST), as well as other clinical variables (anthropometry, chronic colonization by Pseudomonas aeruginosa, lung function), with the risk of hospitalization for pulmonary exacerbation. METHODS: Cohort study including CF patients older than 6 years, from two specialized CF centers. All patients underwent a MST and a lung function test at the time of inclusion. Demographic, anthropometric and clinical data were collected. Free time until the first hospitalization, total days of hospitalization and use of antibiotics during the two years of follow-up were recorded. RESULTS: Sixty-seven patients with a mean (SD) age of 12.4 (5.2) years and forced expiratory volume in the first second (FEV1) of 78.7% (22.4) were included. The mean distance covered (m) in the MST was 775.6 (255.7) (73.4 ± 19.5% of predicted). The distance achieved (MST) was considered as the main independent variable to predict the risk of hospitalization (Cox HR 0.97, p = 0.029). Patients who walked a distance of less than 80% of predicted in the MST showed an increase of 3.9 (95%CI 1.0-15.3) in the relative risk for hospitalization and significantly higher total number of days of hospitalization (p = 0.022). CONCLUSION: There is an association between the distance covered in the MST and the risk of hospitalization in youths with CF. Patients with reduced exercise capacity presented a 3.9 times increase in the relative risk for hospitalization due to pulmonary exacerbation.

FUNCTIONAL PERFORMANCE IN THE MODIFIED SHUTTLE TEST IN CHILDREN AND ADOLESCENTS WITH CYSTIC FIBROSIS.

OBJECTIVE: To evaluate factors associated with the performance of children and adolescents with cystic fibrosis (CF) in the Modified Shuttle Test (MST) and compare it with healthy children and adolescents. METHODS: This is a cross-sectional study, with children and adolescents divided into two groups: cystic fibrosis (CFG) and control (CG). Variables evaluated in the MST: walking distance, test level, heart rate variation (∆Hr), post-test mean arterial pressure (MAP Pt) and peripheral oxygen saturation variation (∆SPO2). Statistical analysis included Mann Whitney and Spearman coefficient tests, being significant p<0.05. RESULTS: Sixty individuals aged 6-16 years old were evaluated. Anthropometric data was similar between groups. Differences between groups were shown for: baseline heart rate (BHr), peak heart rate (PHr), ∆Hr, recovery heart rate (RHr), post-test respiratory rate (PtBr), saturation variables, peripheral oxygen level (SpO2B) and level test. The ∆Hr and MAP Pt had a moderate positive correlation with distance and level test for both groups (respectively: r=0.6 / p<0.001; r=0.6 / p<0.001). In CFG, the level test had a significant association (r=0.4 - p=0.02) with %FEV1. CONCLUSIONS: Children with cystic fibrosis presented functional limitation in the Modified Shuttle Test, which was influenced by lung function.

Functional performance in the modified shuttle test in children and adolescents with cystic fibrosis / Desempenho funcional no teste modificado de shuttle em crianças e adolescentes com fibrose cística

ABSTRACT Objective: To evaluate factors associated with the performance of children and adolescents with cystic fibrosis (CF) in the Modified Shuttle Test (MST) and compare it with healthy children and adolescents. Methods: This is a cross-sectional study, with children and adolescents divided into two groups: cystic fibrosis (CFG) and control (CG). Variables evaluated in the MST: walking distance, test level, heart rate variation (∆Hr), post-test mean arterial pressure (MAP Pt) and peripheral oxygen saturation variation (∆SPO2). Statistical analysis included Mann Whitney and Spearman coefficient tests, being significant p<0.05. Results: Sixty individuals aged 6-16 years old were evaluated. Anthropometric data was similar between groups. Differences between groups were shown for: baseline heart rate (BHr), peak heart rate (PHr), ∆Hr, recovery heart rate (RHr), post-test respiratory rate (PtBr), saturation variables, peripheral oxygen level (SpO2B) and level test. The ∆Hr and MAP Pt had a moderate positive correlation with distance and level test for both groups (respectively: r=0.6 / p<0.001; r=0.6 / p<0.001). In CFG, the level test had a significant association (r=0.4 - p=0.02) with %FEV1. Conclusions: Children with cystic fibrosis presented functional limitation in the Modified Shuttle Test, which was influenced by lung function.

RESUMO Objetivo: Avaliar os fatores que estão associados ao desempenho de crianças e adolescentes com fibrose cística (FC) no teste modificado de Shuttle (MST) e compará-los com os de crianças e adolescentes saudáveis. Métodos: Estudo de corte transversal com crianças e adolescentes divididos em dois grupos: grupo controle (GC) e grupo FC (GFC). As variáveis avaliadas no MST foram: distância caminhada, nível do teste, variação da frequência cardíaca (∆Fc), pressão arterial média pós-teste (PAMPt) e variação da saturação periférica de oxigênio (∆SpO2). Na análise dos dados, foram utilizados o Teste Mann-Whitney e o coeficiente de Spearman, sendo significante p<0,05. Resultados: Avaliaram-se 60 indivíduos (6-16 anos). Os grupos foram homogêneos em relação aos dados antropométricos. Foi observada diferença significante na frequência cardíaca basal (FcB), na frequência cardíaca de pico (FcP), na ∆Fc, na frequência cardíaca de recuperação (FcR), na frequência respiratória pós-teste (FRPt), na saturação periférica de oxigênio basal (SpO2B) e no nível do teste. A ∆Fc e a PAMPt tiveram correlação moderada positiva (respectivamente, r=0,6 / p<0,001; r=0,6 / p<0,001) com a distância caminhada e o nível do teste em ambos os grupos. No GFC o nível do teste teve associação (r=0,4 / p=0,02) com a porcentagem do predito do volume expiratório forçado do primeiro segundo (%VEF1). Conclusões: Crianças e adolescentes com FC apresentaram limitação funcional no teste modificado de Shuttle, influenciada pela função pulmonar.

Determinants of Exercise Capacity Assessed With the Modified Shuttle Test in Individuals With Cystic Fibrosis.

BACKGROUND: Patients with cystic fibrosis develop decreased exercise capacity. However, the main factors responsible for this decline are still unclear. Thus, the objective of this study was to evaluate the factors influencing exercise capacity assessed with the modified shuttle test (MST) in individuals with cystic fibrosis. METHODS: A cross-sectional study was carried out in subjects with a diagnosis of cystic fibrosis who were 6-26 y old and were regularly monitored at 2 cystic fibrosis reference centers in Brazil. Individuals who were unable to perform the tests or who exhibited hemodynamic instability and exacerbation of respiratory symptoms were excluded. Anthropometric, clinical, and genotype data were collected. In addition, lung function and exercise capacity were evaluated with the MST. RESULTS: 73 subjects (mean age 12.2 ± 4.9 y and FEV1 76.8 ± 23.3%) were included. The mean distance achieved in the MST was 765 ± 258 m (71.6% of predicted). The distance achieved on the MST correlated significantly with age (r = 0.49, P < .001), body mass index (r = 0.41, P < .001), resting heart rate (r = -0.51, P < .001), and FEV1 (r = 0.24, P = .042). Subjects with FEV1 > 67% of predicted (P = .02) and those with resting heart rate < 100 beats/min (P = .01) had a greater exercise capacity. Resting heart rate, age, and FEV1 (%) were found as significant variables to explain the distance achieved on the MST (R2 = 0.48, standard error = 191.0 m). CONCLUSIONS: The main determinants of exercise capacity assessed with the MST in individuals with cystic fibrosis were resting heart rate, age, and lung function.