Impaired Control Scale: cross-validation and relationships with treatment outcome.

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.