Elizabeth E. Marfeo, Pengsheng Ni, Leighton Chan, Elizabeth K. Rasch, Christine M. McDonough, Diane E. Brandt, Kara Bogusz, Alan M. Jette
Boston University School of Public Health, Health & Disability Research Institute, 715 Albany Streeet, T5W Boston, MA 02118, USA. E-mail: emarfeo@bu.edu
DOI: 10.2340/16501977-1947

Objective: To develop a system to guide interpretation of scores generated from 2 new instruments measuring work-related physical and behavioral health functioning (Work Disability – Physical Function (WD-PF) and WD – Behavioral Function (WD-BH)).
Design: Cross-sectional, secondary data from 3 independent samples to develop and validate the functional levels for physical and behavioral health functioning.
Subjects: Physical group: 999 general adult subjects, 1,017 disability applicants and 497 work-disabled subjects. Behavioral health group: 1,000 general adult subjects, 1,015 disability applicants and 476 work-disabled subjects.
Methods: Three-phase analytic approach including item mapping, a modified-Delphi technique, and known-groups validation analysis were used to develop and validate cut-points for functional levels within each of the WD-PF and WD-BH instrument’s scales.
Results: Four and 5 functional levels were developed for each of the scales in the WD-PF and WD-BH instruments. Distribution of the comparative samples was in the expected direction: the general adult samples consistently demonstrated scores at higher functional levels compared with the claimant and work-disabled samples.
Conclusion: Using an item-response theory-based methodology paired with a qualitative process appears to be a feasible and valid approach for translating the WD-BH and WD-PF scores into meaningful levels useful for interpreting a person’s work-related physical and behavioral health functioning.