Development of a self-report measure of fearful activities for patients with low back pain: the fear of daily activities questionnaire.

BACKGROUND: Self-report measures for assessing specific fear of activities have not been reported in the peer-reviewed literature, but are necessary to adequately test treatment hypotheses related to fear-avoidance models.
OBJECTIVE: This study described psychomotor properties of a novel self-report measure, the Fear of Daily Activities Questionnaire (FDAQ).
DESIGN: A prospective cohort design was used.
METHODS: Reliability and validity cohorts were recruited from outpatient physical therapy clinics. Analyses for the reliability cohort included internal consistency and 48-hour test-retest coefficients, as well as standard error of measurement and minimal detectable change estimates. Analyses for the validity cohort included factor analysis for construct validity and correlation and multiple regression analyses for concurrent and predictive validity. Four-week responsiveness was assessed by paired t test, effect size calculation, and percentage of patients meeting or achieving MDC criterion.
RESULTS: The FDAQ demonstrated adequate internal consistency (Cronbach alpha=.91, 95% confidence interval=.87-.95) and 48-hour test-retest properties (intraclass correlation coefficient=.90, 95% confidence interval=.82-.94). The standard error of measurement for the FDAQ was 6.6, resulting in a minimal detectable change of 12.9. Factor analysis suggested a 2- or 3-factor solution consisting of loaded spine, postural, and spinal movement factors. The FDAQ demonstrated concurrent validity by contributing variance to disability (baseline and 4 weeks) and physical impairment (baseline) scores. In predictive validity analyses, baseline FDAQ scores did not contribute variance to 4-week disability and physical impairment scores, but changes in FDAQ scores were associated with changes in disability. The FDAQ scores significantly decreased over a 4-week treatment period, with an effect size of .86 and 55% of participants meeting the minimal detectable change criterion. LIMITATIONS: The validity cohort was a secondary analysis of a clinical trial, and additional research is needed to confirm these findings in other samples.
CONCLUSIONS: The FDAQ is a potentially viable measure for fear of specific activities in physical therapy settings. These analyses suggest the FDAQ may be appropriate for determining graded exposure treatment plans and monitoring changes in fear levels, but is not appropriate as a screening tool.