Capturing the patient's view of change as a clinical outcome measure.
BACKGROUND
Measurement of change in patients' health status is central to both clinical trials and clinical practice. Trials commonly use serial measurements by the patients at 2 points in time while clinicians use the patient's retrospective assessment of change made at 1 point in time. How well these measures correlate is not known.


OBJECTIVE
To compare the 2 methods in measurement of changes in pain and disability.


METHODS
Longitudinal survey of patients starting new therapy for chronic arthritis in 1994 and 1995. Surveys were completed at baseline (before intervention) and at 6 weeks and 4 months.


METHODS
Community health education program and university medical and orthopedic services.


METHODS
A total of 202 patients undertaking self-management education (n = 140), therapy with prednisone or methotrexate (n = 34), or arthroplasty of the knee or hip (n = 28).


METHODS
Concordance between serial (visual analog scale for pain and Health Assessment Questionnaire for disability) and retrospective (7-point Likert scale) measures, sensitivities of these measures, and their correlation with patients' satisfaction with the change (7-point Likert scale).


RESULTS
When change was small (education group), serial measures correlated poorly with retrospective assessments (eg, r=0.13-0.21 at 6 weeks). With greater change, correlations improved (eg, r = 0.45-0.71 at 6 weeks). Average agreement between all pairs of assessments was 29%. Significant lack of concordance was confirmed in all 12 comparisons by McNemar tests (P = .02 to <.001) and by t tests (P = .03 to <.001). Retrospective measures were more sensitive to change than serial measures and correlated more strongly with patients' satisfaction with change.


CONCLUSIONS
The 2 methods for measuring health status change did not give concordant results. Including patient retrospective assessments in clinical trials might increase the comprehensiveness of information gained and its accord with clinical practice.
Fischer
D
D
Palo Alto Medical Clinic, CA, USA.
Stewart
A L
AL
Bloch
D A
DA
Lorig
K
K
Laurent
D
D
Holman
H
H
D000368:Aged; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001168:Arthritis / Q000628:therapy*; D001178:Arthroplasty; D002908:Chronic Disease; D002986:Clinical Trials as Topic; D006233:Persons with Disabilities; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010146:Pain; D010353:Patient Education as Topic; D017060:Patient Satisfaction; D018434:Sickness Impact Profile; D014481:United States
D000893:Anti-Inflammatory Agents