The iStep Study: Development and Validation of an Incremental Exercise Step Test for Children With Cystic Fibrosis

The progression of lung disease in cystic fibrosis (CF) results inevitably in a reduction in exercise capacity. The assessment of fitness and exercise capacity in CF is an important measure of the impact of the disease process, particularly if it is repeated over time. With recent advances in clinical management, CF lung disease in children can be relatively mild and exercise tolerance good. The currently available field tests e.g. 3 minute step test, are often completed too easily. These tests provide limited information relating to maximal exercise performance. By contrast, the maximal CardioPulmonary Exercise Test (CPET), a progressive, incremental, gold standard exercise test with breath by breath analysis of expired gas, has proved to be a valuable means of assessing exercise response in patients with CF. Its only limitation is the requirement for specialist laboratory facilities, equipment and staff.

A new field test for evaluating exercise capacity in children is needed. This should be portable, easy to administer and simple to perform by young children, while providing a higher intensity of exercise which correlates with day to day activity patterns of children, and clinically relevant information in the short term and longitudinally. This test needs to be a good surrogate measure of exercise capacity when formal CPET is unable to be undertaken. By providing accurate and useful information the results can be used to prescribe and train individuals with CF safely and effectively and can also be used in the short and long term for guidance of the medical management of these complex patients.

The aim of this study is to develop and validate the use of a new incremental step test to assess exercise tolerance/capacity in children with CF, compare this with the gold standard CPET and to provide normative healthy control comparison data The main objectives of the study are

1. To develop an incremental step test to assess exercise tolerance / capacity in children with CF.
2. To compare the incremental step test with the gold standard CPET
3. To assess the level of exercise response produced by the incremental step test
4. To assess the correlation between independent variables of lung function measurements, age, weight and height with VO2peak and other exercise test outcomes
5. To assess the repeatability and evaluate the normal variability of the new incremental step test
6. To provide healthy control normative data for comparison

Study Overview

• Status: Completed
• Conditions: Cystic Fibrosis
• Intervention / Treatment: Other: iStep exercise test; Other: CPET exercise test

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, wc1n 1eh
    • Great Ormond Street Hospital For Children NHS Foundation Trust

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 6 years to 16 years (Child)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

Clinical population inclusion

• Parental/guardian consent
• Participant assent
• Male or female
• Confirmed Cystic fibrosis diagnosis (by genetic genotype or positive sweat test)
• Receiving physiotherapy as part of their usual care
• Height >125cm to allow cycle ergometer use
• 6-16 years

Healthy control population inclusion

• Parental/guardian consent
• Participant assent
• Male or female
• 6-16 years

Exclusion Criteria:

Clinical population exclusion

• <6 years and >16 years
• No consent / assent
• Frank haemoptysis in the last 48 hours
• Acute infective exacerbation (defined as increased temperature, additional antibiotics)
• Poor dietary intake/hydration
• Oxygen dependent at rest
• Arterial oxygen saturation (SaO2) <90% at rest
• Burkholderia cepacia
• Coexisting insulin dependent diabetes mellitus
• Methicillin-resistant Staphylococcus aureus (MRSA) positive

Healthy control population exclusion

• <6 years and >16 years
• No consent / assent
• Acute infection (defined as increased temperature and antibiotics)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cystic fibrosis; iStep exercise test; CPET exercise test	Other: iStep exercise test; newly developed submaximal exercise test; Other: CPET exercise test; maximal gold standard exercise test
Active Comparator: Healthy control; - iStep exercise test	Other: iStep exercise test; newly developed submaximal exercise test

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak oxygen uptake (VO2peak)	Gold standard exercise test to determine peak oxygen uptake during exercise	Measured during the exercise test, day 1, maximum of 20 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Secondary breath by breath analysis outcome measures		Measured during the exercise test, day 1, maximum of 20 minutes
Newly developed iStep exercise test outcome variables	Standard field exercise test outcomes of heart rate, oxygen saturations, time, level achieved, rate of perceived exertion, perceived breathlessness	Measured during the exercise test, day 1, maximum of 20 minutes
Height, weight and body mass index measures	Height, weight and body mass index will be measured for descriptive purposes only	Measured at baseline on the day of testing, day 1, maximum of 5 minutes
Reasons for termination of the incremental step test		Measured at the end of the exercise test, day 1, maximum of 5 minutes

Collaborators and Investigators

• Sponsor: Great Ormond Street Hospital for Children NHS Foundation Trust
• Investigators: Principal Investigator: Sarah Rand, BA, BSc, MSc, UCL Institute of Child Health

Study record dates

Study Major Dates

• Study Start: July 1, 2011
• Primary Completion (Actual): October 1, 2014
• Study Completion (Actual): October 1, 2014

Study Registration Dates

• First Submitted: June 12, 2014
• First Submitted That Met QC Criteria: July 22, 2014
• First Posted (Estimate): July 24, 2014

Study Record Updates

• Last Update Posted (Estimate): April 19, 2016
• Last Update Submitted That Met QC Criteria: April 18, 2016
• Last Verified: April 1, 2016

More Information

Terms related to this study

• Keywords: Children; Exercise capacity; Exercise testing
• Additional Relevant MeSH Terms: Digestive System Diseases; Pathologic Processes; Respiratory Tract Diseases; Lung Diseases; Infant, Newborn, Diseases; Genetic Diseases, Inborn; Pancreatic Diseases; Fibrosis; Cystic Fibrosis
• Other Study ID Numbers: 11AR14

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided