Cross-Validity and Reliability of the Age Scale for Assessing Activities of Daily Living among Japanese Community-Dwelling Adults Aged 75 Years or Older

Abstract

The aim of this study was to evaluate the validity and reliability of the age scale for assessing activities of daily living (ADL) among community-dwelling adults aged 75 years or older. Participants comprised 89 older Japanese: 47 men (79.1±3.8 years) and 42 women (78.9±3.7 years). The ADL age (ADLA) equation is an instrument that estimates participants’ physical functioning regarding ADL using data obtained previously from 1006 subjects. The equation is as follows: ADLA for women = 0.447 (chronological age) -5.49ADLS + 44.17; and ADLA for men = 0.519CA – 4.27ADLS + 38.26. Validity was evaluated using cross-validation, and reliability was evaluated using internal consistency and test-retest methods. The correlation between the ADLA and chronological age (CA) in the cross-validation samples (r = 0.62 women, r = 0.61 men) was not significantly different from the relationship observed in the original sample (r = 0.72 women p = 0.636, and r = 0.75 men p = 0.571). Cronbach's alpha (< ) value (internal consistency) for the total ADLA was 0.97 for men and 0.92 for women, whereas the intra-class correlation coefficient (ICC) value (test-retest reliability) was 0.96 for men and 0.91 for women. The results suggest that the ADLA is a reliable and valid tool for the assessment of ADL with satisfactory psychometric properties and that is applicable for persons aged 75 years and older in Japan.