The validity of prospective and retrospective global change criterion measures

Abstract

Objective: To assess the validity of retrospective versus prospective criterions of change.

Design: Single cohort pretest-posttest design.

Setting: Physical or occupational therapy outpatient clinics.

Participants: Volunteer sample of 211 patients with upper-extremity musculoskeletal problems.

Interventions: Not applicable.

Main outcome measures: Disabilities of the Arm, Shoulder, and Hand questionnaire, the Shoulder Pain and Disability Index, the Patient-Rated Wrist Evaluation, the Medical Outcomes Study 12-Item Short-Form Health Survey; global disability rating (GDR), retrospective global rating of change (GRC), and patient satisfaction.

Results: Correlations were calculated among the baseline, 3-month follow-up, and change scores for each outcome measure with the change criterion instruments. Retrospective GRC and patient satisfaction ratings showed moderate correlations with the 3-month follow-up scores, but nonsignificant correlations with baseline scores. By contrast, the prospective GDR criterion showed significant correlations with both baseline and 3-month follow-up scores ranging between 0.3 and 0.4 (absolute value).

Conclusions: Retrospective self-report measures of change do not accurately reflect true change over time. The retrospective GRC and patient satisfaction were heavily influenced by current (posttreatment) status whereas the prospective global change measure reflected both baseline and posttreatment status equally and thus appeared to be a more valid measure of change over time. This study demonstrates the need for an alternative criterion for establishing true individual change.