On quitting smoking: development of two scales measuring the use of self-change strategies in current and former smokers (SCS-CS and SCS-FS).

Smoking-cessation advice may be more effective and acceptable if it is based on strategies used by people who quit smoking on their own. The objective of this study was to identify these self-change strategies and to develop and validate questionnaires measuring the frequency of their use in current and former smokers. Development of questionnaire items was based on qualitative data provided by 120 current and former smokers, and the validation study was conducted by mail in 638 smokers and ex-smokers in Geneva, Switzerland, from 1996 to 1998. We identified 5 distinct and interpretable self-change strategies in current smokers and 5 strategies in former smokers, and measured their frequency of use with a 19-item questionnaire in current smoker (SCS-CS) and with a 17 item questionnaire in former smokers (SCS-FS). Eight items and 2 strategies were common to both current and former smokers. the scales fulfilled criteria of test-retest reliability, and content, construct, and predictive validity. Participants who quit smoking between the baseline survey and the 1-month follow-up had higher baseline scores for all self-change strategies (+0.65 to +1.16 standard deviation units) than participants who remained smokers at follow-up. These scales may be used to describe and understand the processes of smoking cessation and relapse, as well as to produce input data for computer systems which produce individually-tailored smoking cessation advice.