The Readiness to Change Questionnaire:: Reliability and validity of a Swedish version and a comparison of scoring methods

Objectives. The aim of this study was to investigate the relative merits of three methods of scoring the Swedish version of the Readiness to Change Questionnaire (RTCQ), either by assigning a stage in the Prochaska and DiClemente (1986) Stages of Change Model or by treating the scores as a continuous readiness to change variable. Assigning a stage of change was achieved with both the quick method and the refined method. Design and methods. Out of 563 patients screened at an emergency surgical ward for risky alcohol consumption, 165 met risk criteria and responded to the RTCQ. The three scoring methods were examined with regard to internal consistency, test-retest reliability, construct and predictive validity. Results. All three methods of treating the RTCQ scores had satisfactory reliability. Since stages of change (quick method) were significantly but modestly correlated to alcohol consumption and to change-related behaviours at intervention, and moderately correlated to alcohol problems, the quick method had reasonable construct validity. The refined method had higher construct validity; however, this method left 32% of the patients without a stage assignment. The continuous readiness scale had higher construct validity than the quick method, but was not in par with the refined method. No scoring method was found to have predictive validity. Conclusions. The RTCQ scores treated as a continuous readiness scale were a viable alternative to the original ways of assigning a stage of change to a patient. The Swedish RTCQ is reliable and has reasonable construct validity, but its predictive validity needs further investigation.