Construct validity of the late life function and disability instrument for adults with chronic conditions

Abstract

Objectives. To evaluate the validity of the late life function and disability instrument (LLFDI) when applied to adults aged 44–65 years with chronic conditions.Design. We applied a convergent cross-sectional construct validity design to examine the association between the LLFDI subscales and the medical outcomes study (MOS) 36-Item Health Survey Physical Component Score (SF36 PCS), MOS Physical Functioning scale (PF10), 2-minute walk distance (2MWD) and 8-foot walk test (8FWT).Participants. Our sample consisted of 174 community-dwelling adults age 45–65 years with one or more chronic conditions.Setting. Participants were enrolled at a multidisciplinary family health practice.Results. The LLFDI function correlated strongly with the PF10 (r = 0.84) and moderately with the 2MWD (r = 0.53) and 8FWT (r = −0.48). The LLFDI disability limitation correlated moderately with the SF36 PCS, 2MWD and 8FWT (r = 0.67, 0.45, −0.32, respectively). The LLFDI disability frequency correlated moderately with the SF36 PCS, 2MWD and 8FWT (r = 0.44, 0.33, −0.31). Ninety-five percent confidence intervals on all correlation coefficients excluded zero.Conclusion. Cross-sectional convergent validity of the LLFDI was supported when applied to adults 45–65 years of age with chronic conditions.