Aims: (1) To cross-validate Australian findings on the Impaired Control Scale (ICS) in an English sample of problem drinkers. (2) To examine a possible improvement to the scoring of the ICS. (3) To explore the relationship of the ICS to treatment outcome.
Design: In a repeated measures design, questionnaires and interviews were administered by trained staff during treatment and again at 6 months follow-up.
Setting: Two alcohol and drug treatment services in Newcastle and Liverpool (UK).
Participants: Two hundred and twenty-nine problem drinkers attending as in- or outpatients, with abstinence or moderation treatment goals.
Measurements: ICS scores; typical weekly alcohol consumption (units); degree of alcohol-related problems; severity of alcohol dependence; and classification of outcome using consumption levels and current alcohol-related problems, with collateral confirmation of self-reports.
Findings: The satisfactory reliability and validity of the ICS was confirmed in an English sample of problem drinkers in treatment. An improved "substitution method" of scoring was developed to give a single measure of impaired control for all subjects irrespective of degree of attempted control. ICS scores were significantly correlated with treatment outcome and, among a subgroup of subjects who had aimed at abstinence but failed, predicted outcome status after the effects of degree of dependence had been extracted.
Conclusions: Impaired control over alcohol consumption can be measured in a reliable and valid fashion by the ICS. The ICS has potential uses in research on impaired control and as a clinical assessment tool.