Table 1.

Challenges with Studies Evaluating Cross-Age Response to Asthma Treatment

Issue	Example(s)
Recruitment	· Need for culturally diverse recruitment materials
	· Need for Age-appropriate recruitment strategies
Consent/Assent	· Requirement of parental/guardian consent for minors
	· Incorporation of Assent procedures for children
Intervention Selection	· Difficulty in maintaining consistency of intervention therapy due to differences in dosing and drug availability
Control Selection	· Limitations in the use of placebo controls for children
Outcome Measurement	· Dependence on proxy reporting of outcomes for children
	· Dearth of cross-age instruments to measure quality of life, asthma control, symptoms and exacerbations
Participant Growth & Development	· Need to account for physical growth (e.g., weight, height) of pediatric participants
Physical Limitations in Data Collection	· Physical and developmental limits for testing and data collection (e.g., phlebotomy, spirometry, sputum induction)
	· Increased safety restrictions in testing of children (e.g., methacholine bronchoprovocation)
Consideration of Long-term Effects	· Careful monitoring and follow-up for long term developmental effects in children
Reporting of Results	· Determination of how data across ages will be subdivided (e.g., age cut-offs, including adolescents as adults or children)