Development and psychometric testing of the Adaptive Capacity Index, an instrument to measure adaptive capacity in individuals with advanced cancer.

Background: We have proposed that declines in adaptive capacity, defined as the ability to adapt to multiple stressors, may serve as an indicator of risk for fatigue. A comprehensive measure of adaptive capacity does not exist.

Objectives: In this paper we describe construction of an instrument to measure adaptive capacity, the Adaptive Capacity Index (ACI).