Reliability and validity of the functional performance inventory in patients with moderate to severe chronic obstructive pulmonary disease.

The Functional Performance inventory (FPI) is a new instrument designed to measure functional status in terms of activities that people perform on a daily basis. Psychometric characteristics were examined by a survey of 45 men and 27 women with chronic obstructive pulmonary disease (COPD). Internal consistency reliability was high and no ceiling and floor effects were observed for the Total FPI. Concurrent validity was demonstrated by correlations with the Total Sickness Impact Profile (r = -.59). Construct validity was supported by correlations with the Medical Outcomes Study Short Form-36, Physical Functioning (r = .69), the Physical Activity Scale for the Elderly (r = .62) and American Thoracic Society-Division of Lung Disease Breathlessness scale (r = -.62). The Total FPI is a reliable and valid measure of functional performance in persons with COPD.