Psychometric Properties and Factor Structure of 2 Chinese Opiate Withdrawal Rating Scales (2004)

Abstract Objective: This study aimed to examine the psychometric properties and factor structure of the Chinese versions of 2 rating scales: the revised Subjective Opiate Withdrawal Scale and the Objective Opiate Withdrawal Scale. Patients and Methods: The study comprised 2 parts. In study 1, fifty one patients with a diagnosis of opioid dependence (76.6% male, 23.4% female; mean age, 35.60 [+ or -] 11.15 years) were assessed with the revised Subjective Opiate Withdrawal Scale and Objective Opiate Withdrawal Scale after admission to Kwai Chung Hospital for detoxification. In study 2, sixteen patients with a diagnosis of opioid dependence (50.0% male, 50.0% female; mean age, 34.40 [+ or -] 10.84 years) admitted to Kwai Chung Hospital for detoxification, were recruited. The revised Subjective Opiate Withdrawal Scale and Objective Opiate Withdrawal Scale were administered on days 1, 2, 7, and 14 of a methadone detoxification programme. Results: The reliabilities of the 2 scales were shown to be satisfactory. Four meaningful factors emerged in the results of factor analyses for the revised Subjective Opiate Withdrawal Scale, whereas a single-factor solution was found to adequately account for the data-set of the Objective Opiate Withdrawal Scale. Consistent with expectations, a steady reduction profile of opiate withdrawal features was present in the measures of the revised Subjective Opiate Withdrawal Scale, whereas the Objective Opiate Withdrawal Scale was less sensitive in measuring the changes. Conclusion: The revised Subjective Opiate Withdrawal Scale and Objective Opiate Withdrawal Scale were found to have satisfactory psychometric properties and different factor structures. Salient findings and recommendations for future investigation were discussed. Key words: Factor structure, Opiate dependence, Psychometrics Introduction Opiate addiction remains a major problem among users of illicit drugs in Hong Kong. According to the statistics of the Central Registry of Drug Abuse (CRDA) from 1995 to 2000, opiate misuse accounted for approximately 80% of common drug abuses. (1) In the latest guide for drug addiction treatment, it is emphasised that effective drug interventions should adopt a biopsychosocial approach to address the complex and multiple needs of patients. Detoxification alone is insufficient to achieve long-term abstinence. (2) However, the principle of operant theory predicts that the undesirable consequences (the presence of withdrawal symptoms) of discontinuing drug-taking behaviours can serve as a powerful negative reinforcer to maintain drug use. (3,4) Indeed, local substance abusers have reported that the major reason for current drug use (approximately 55%) was to avoid discomfort of its absence. (1) Therefore, pharmacological treatment plays a pivotal role in reducing withdrawal symptoms and the associated fear that keep addicted people away from treatment. In recent decades, new treatment strategies for opiate addiction, such as using opiate receptor antagonists and rapid opiate detoxification under general anaesthesia, have become increasingly common. (5-7) Inventing novel pharmacological treatment can minimise withdrawal symptoms and hence facilitate participation in treatment. To document and compare the various treatment approaches for effective detoxification, psychometrically sound measures are necessary. The Subjective Opiate Withdrawal Scale (SOWS) and Objective Opiate Withdrawal Scale (OOWS) are 2 of the scales developed by Handelsman et al to measure opiate withdrawal signs and symptoms. (8) The former assesses 16 covert withdrawal symptoms reported by individuals, whereas the latter examines 13 overt signs checked by observers. Handelsman et al (8) showed that these measures had adequate reliability and validity, and Loimer et al (9) subsequently replicated the satisfactory validity of the scales. However, the latter revealed that the 2 scales did not have a significant correlation. …