Development and validation of the scale to assess satisfaction with medications for addiction treatment-methadone for heroin addiction (SASMAT-METHER).

OBJECTIVE

To develop and examine the psychometric properties of a scale to specifically assess satisfaction with methadone in heroin-dependent patients.

METHODS

The 44-item preliminary version of the scale to assess satisfaction with medications for addiction treatment-methadone for heroin addiction (SASMAT-METHER) was obtained from a pool of items designed to assess satisfaction with any medication-addiction combination. Theoretical domains of the initial SASMAT-METHER were overall satisfaction, pharmacotherapy, initiation, anti-addictive effect on heroin, mental state, physical state, personal functioning, acceptability, and anti-addictive effect on secondary substances. The Treatment Satisfaction Questionnaire for Medication 1.4 version (TSQM 1.4) and the Verona Service Satisfaction Scale for Methadone Treatment (VSSS-MT) were used for concurrent validation. Participants included heroin-dependent patients receiving methadone treatment for at least the last 3 months.

RESULTS

The preliminary version of the SASMAT-METHER scale was completed by 241 patients, with 180 surveys considered suitable for factor analysis. Principal component analysis of these SASMAT-METHER surveys revealed a 3-factor structure that accounted for 40.4% of total variance. Based on similarities between empirically-obtained factors and theoretical domains, factors 1 through 3 were named 'Personal Functioning and Well-Being' (7 items), 'Anti-Addictive Effect on Heroin' (5 items), and 'Anti-Addictive Effect on Other Substances' (5 items). All factors showed good to excellent internal consistency (Cronbach's α: 0.83-0.92) and test-retest reliability (intraclass correlation coefficients: 0.66-0.89). Correlations between overall SASMAT-METHER and TSQM 1.4 scores were stronger (Pearson r=0.69) than correlations between overall SASMAT-METHER and VSSS-MT scores (Pearson r=0.26).

CONCLUSION

These results present evidence for the validity and reliability of SASMAT-METHER.