The VA group experienced significantly higher levels of coercion than the IA group in two of the six subscales (Table 2). For example, the mean score for the items on the Self subscale was 0.5 point higher in the VA group (3.3 versus 3.8 for the IA and VA groups, respectively). Closer examination of the Self subscale revealed that the VA group scored higher on three items: ‘Entering this programme is my last and only hope’; ‘I feel horrified and ashamed of the person I have turned into’; and ‘I am sick and tired of losing everything (things, people etc.) because of my drug/alcohol problem’ (Table 3). Notably, only 2/3 of the IA group agreed or strongly agreed with the assertion ‘I felt pressured to enter this drug/alcohol treatment programme, because I was legally required’. Paradoxically, some (12%) of the patients admitted voluntarily agreed or strongly agreed to that same assertion. In the linear regression model, we found that only the Global Score Index of the Scl-90-R was significantly associated with perceived coercion; however, this factor explained only 3% of the variance in the PCQ (Table 4).Table 2Perceived Coercion Questionnaire (PCQ) scoresVariableInvoluntarily admittedVoluntarily admitted P-valueSelf subscale16.7 (5.0)18.9 (4.4)0.003Family subscale15.5 (6.0)15.0 (6.4)0.555Legal subscalea 5.6 (2.2)3.1 (2.1)0.001Finance subscale12.8 (5.5)13.8 (5.9)0.259Health subscaleb 10.3 (3.5)11.2 (3.1)0.076Work subscale9.2 (5.2)10.1 (5.1)0.256Total PCQ76.2 (18.9)78.0 (18.5)0.536Number of patients63129Values represent the mean (standard deviation) aThe Legal subscale of the PCQ underwent minor revisions to account for differences in the Norwegian legal system (see Additional file 1) bThe Health subscale of the PCQ has been validated, but it was altered for the present study (see Additional file 1) Table 3Scores for the Perceived Coercion Questionnaire Self subscaleSelf subscaleIAVA P-valueSelf subscale, total score16.7 (5)18.9 (4)0.003I know that I’m an addict/alcoholic and that I need rehab to get off drugs/alcohol4.0 (1)4.3 (1)0.132Entering this programme is my last and only hope2.8 (1)3.3 (1)0.023I don’t know where else to go and what else to do3.0 (1)3.4 (1)0.053I feel horrified and ashamed of the person I have turned into3.2 (1)3.7 (1)0.013I am sick and tired of losing everything (things and people) to my drug/alcohol problem3.7 (1)4.2 (1)0.012Number of patients63129All values represent the mean (standard deviation); IA involuntarily admitted group, VA voluntarily admitted group Table 4Multivariable linear regression analysis results show the effects of independent variables on perceived coercion. N = 192 patientsVariableBeta (95 % CI) P-valuea R2c Female gender−0.13 (−11.16–1.07)0.117Age−0.09 (−0.50–0.12)0.441Living alone−0.01 (−5.80–5.57)0.713Global Score Index: Scl-90-R0.19 (0.82–9.35)0.0153 %Severity scores Injected drug abuse0.01 (−5.99–6.09)0.720 Drug overdoses (lifetime)0.10 (−2.85–9.99)0.970 Suicide attempts (lifetime)−0.10 (−6.84–5.40)0.340Treatment variable Treated for somatic diseasesb 0.12 (−1.39–11.12)0.113 Involuntary hospital admission−0.03 (−7.90–5.43)0.536 a p-value obtained from bivariate linear regression. Only one independent variable showed a p-value <0.20 in bivariate analyses bDuring the 6 months prior to admission c R2 adjusted = squared correlation coefficient to obtain a measure of explained variance