Psychometric testing of the smoking cessation counseling scale.

PURPOSE: To conduct psychometric testing of an instrument, the Smoking Cessation Counseling (SCC) Scale, to measure evidence-based smoking cessation counseling interventions by nurses.
DESIGN: A cross-sectional study was conducted using a written Teleform survey, administered to Registered Nurses (N = 591) from 23 rural hospitals in the eastern United States.
METHODS: The SCC scale was developed from the U.S. Department of Health and Human Services guidelines for nurses. The survey includes 26 items, with 24 using a four-level response format indicating the extent to which the nurse implements each item (not at all, less than half the time, more than half the time, and all of the time). The total SCC score was computed for 24 items. Two additional items assess comfort in smoking cessation counseling skill and comfort in referral to resources and use a 10-point response format (1 = not at all comfortable to 10 = very comfortable). Reliability statistics for consistency of item measures were estimated using a two-way mixed model in which respondent effects were random and measures effects were fixed. The validity of the instrument was measured in the following ways: (a) total SCC score was correlated with overall comfort in smoking cessation counseling; (b) regression model was conducted for the total SCC score and comfort in smoking cessation counseling skills adjusted for demographic variables (education, gender, age, ethnicity); and (c) exploratory factor analysis on the item scale data to see if the scale was unidimensional or could be split into several subscales and independent components or factors.
FINDINGS: The estimated Cronbach's α intraclass correlation coefficient of 24 items for reliability was 0.955, indicating high internal consistency. The total SCC score is strongly positively correlated with comfort in smoking cessation counseling. Using exploratory factor analysis, four factors were extracted from 24 items that explained 68.3% of SCC score variation. The first factor explained 48.9% of variation representing an advanced SCC activity component. The second, third, and fourth extracted factors representing regulatory, referral, and basic components together explained 19.4% of SCC score variation.
CONCLUSIONS: Psychometric testing supports that the SCC is reliable (internally consistent) and valid for representing nursing compliance with evidence-based smoking cessation counseling. The extracted independent factors resulting from factor analysis can be used for investigating the impact of the SCC on patient outcomes. CLINICAL RELEVANCE: The SCC can be used by researchers or nurses in practice who are interested in assessing, improving, or testing evidence-based practices for smoking cessation counseling.