Table 2.

Target Populations for Clinical Trials in the Area of Sarcopenia: Factors that Influence Selection

Goal of Intervention	Prevention	Treatment
Need for Treatment (Indication)	Weak, low muscle mass. decreased mobility performance, no current mobility disability but increased risk of future mobility disability	Weak, low muscle mass, decreased mobility performance, mobility disability
Ability to Respond to Treatment	Presence of treatable contributor to low muscle mass	Presence of treatable contributor to low muscle mass
Factors that prevent increased mass, from producing increased strength	Rate limiting neurological conditions ? severe pain	Rate limiting neurological conditions ? severe pain?
Factors that prevent increased strength from producing increased mobility performance	Rate limiting cardiopulmonary conditions	Rate limiting cardiopulmonary conditions
Factors that prevent increased mobility performance from affecting mobility disability	Cognitive and mood disorders	Cognitive and mood disorders
	Environmental factors	Environmental factors
	Physical activity	Physical activity
Factors that are likely to modify response to treatments that increase muscle mass	Gender	Gender
	?age	?age
	Body fart	Body fat
	Genetics	Genetics Nutrition Activity
Prevalence	Prevalence of indication is high BUT the population size is reduced by other requirements eg presence of a treatable contributor and absence of factors that limit treatment	Prevalence of indication is high BUT the population size is reduced by other requirements eg presence of a treatable contributor and absence of factors that limit treatment
Safety issues	Presence of conditions that affect tolerance eg diabetes, fluid retention	Presence of conditions that affect tolerance eg diabetes, fluid retention
Feasibility	Outcome rate eg onset of mobility disability is critical	Presence of mobility disability affects ability to travel and participate in trial
	Consider attrition issues in sample size estimates	Consider attrition issues in sample size estimates
	Effect of criteria on recruitment screening activities eg screen to recruit ratio and related costs	Effect of criteria on recruitment screening activities eg screen to recruit ratio and related costs
Reproducibility	Reliability of key measures of mass, strength, performance in clinical hands	Reliability of key measures of mass, strength, performance in clinical hands
Regulatory factors	Validity and specificity of definition Ability to determine eligibility eg can clinicians detect the indication?	Validity and specificity of definition