Nk. Leidy, Psychometric properties of the functional performance inventory in patients with chronic obstructive pulmonary disease, NURS RES, 48(1), 1999, pp. 20-28
Background: The Functional Performance Inventory (FPI) is a subjective meas
ure of the performance dimension of functional status, based on an explicit
analytical framework and the experiences of patients themselves.
Objectives: To describe the conceptual foundation of the instrument, the pr
ocedures used to maximize content validity, and the results of the initial
psychometric testing of the FPI in patients with chronic obstructive pulmon
ary disease (COPD).
Method: Items and response structure for the instrument were drawn from the
literature and qualitative interviews with 12 men and women with COPD. Twe
nty-four clinical and scientific experts participated in content validation
. To assess the FPI's psychometric characteristics, 154 patients participat
ed in a cross-sectional mail survey; 54 took part in a 2-week reproducibili
ty assessment. Forty relatives were also included in validity testing.
Results: The instrument was internally consistent (alpha = .96) and reprodu
cible (ICC = .85). Validity was evident in the significant (p < .001) corre
lations found between the FPI total score and the Functional Status Questio
nnaire (activities of daily living, r= .68; instrumental activities of dail
y living, r= .68), Duke Activity Status Index (r= .61), Bronchitis-Emphysem
a Symptom Checklist (r = -.59), Basic Need Satisfaction Inventory (r = .61)
, and Cantril's Ladder of Life Satisfaction (r = .63). The relationship bet
ween patient FPI score and relative perception of functioning, using the Ka
tz Adjustment Scale for Relatives, was also significant (socially expected
activities, r = .53; free-time activities, r = .49, p < .01). The instrumen
t discriminated between patients with severe and moderate levels of perceiv
ed severity and activity limitation (t = 8.52, p <.001) and patients with F
EV, greater than and less than 1.0 liter (t = 4.25, p < .001).
Conclusions: Results suggest that the FPI is a useful measure of functional
performance in patients with COPD. Further development of the spiritual ac
tivities and work and school domains is in order, as is additional study of
the instrument's responsiveness to change.