In this prospective study, patients undergoing alcohol detoxification reported their motivation to change and lifetime Trauma Load at treatment entry and we studied whether these variables predicted the completion of treatment. Simple group comparisons showed that only the Maintenance component of motivation to change at treatment entry was higher in treatment completers and that patients who dropped out of treatment had a significantly higher Trauma Load. While these simple comparisons in the total sample represent moderate effect sizes, we found a clear interaction between Trauma Load and motivation to change: dropout was only predicted by the Maintenance subscale of the VSS-K/URICA - and to a lesser extent by the RTC composite scale- among those patients with high Trauma Load. That is, the higher the motivation, the better the chance for subsequent therapy completion. As predicted, this association was not found among patients with low Trauma Load. In the final logistic regression model, the odds ratio 1.047 of the interaction effect means that a one-unit increase of the Maintenance subscale leads to a significantly different increase in the odds for treatment completion when comparing it at different levels of Trauma Load. When depicting the result (Figure 2) it can be noted that higher levels of Trauma Load lead to a growing increase of the association between predictor (Maintenance) and dependent variable (treatment completion) - by the factor 1.047. Given the fact that Trauma Load is a continuous variable (mean 7.2, range from 0 to 19), the multiplying factor can theoretically determine an increase of this association of up to 139% comparing those with the lowest and highest Trauma Load. The reported results support the hypothesis that Trauma Load moderates the relationship between motivation to change and treatment completion, therefore, the potential causal relation between motivation and behavior in addiction treatment changes as a function of Trauma Load.
Other studies relating motivation to change with treatment outcomes have reported inconsistent results. This study emphasizes one important point: our results support that, in addiction therapy, personal characteristics determine the degree to which motivation predicts behavior. The moderator approach opens up new possibilities for studying the effect of treatment motivation and other theoretically relevant predictors of treatment success: patient characteristics matter in the attempts to improve treatment for substance-use disorders.
Our findings revealed that especially the motivational component Maintenance (and, to a smaller extent, Contemplation) is related to treatment completion. Maintenance, as measured by the VSS-K/URICA, encompasses the motivation to avoid drawbacks and to secure the behavioral changes that have already been achieved. Moreover, it also includes a positive attitude towards treatment (in this case detoxification) – seeing this as chance and a means of assistance to reach or maintain one’s own goals. In the lives of alcohol-dependent patients, long-term abstinence is often only achieved after repeated attempts to quit followed by relapses. Alcohol patients with a high score on the Maintenance scale seem advanced in this learning development because they appear to have realized that they cannot manage this on their own and that they need to accept therapeutic and medical assistance. The Contemplation component of the VSS-K/URICA contains a general acceptance of alcohol dependence as a problem as well as a positive view of therapeutic and medical assistance. In contrast, the Action component, which is not related to positive outcomes in this study, does not explicitly contain this positive attitude towards professional assistance, but rather the focus on one’s own attempts to solve the problem. This difference might explain why the statistical association of treatment completion with Action - in theory, a positive motivational component - diverges from its association with Maintenance and Contemplation. This also explains why the composite RTC score is not better for predicting outcome than Maintenance and Contemplation. The multivariate model construction reported above furthermore shows that single motivational components of the TTM (e.g. Maintenance) cannot be seen in isolation of the other motivational components, since, as seen for example in Model 4 (Additional file 1), the association of Action and the dependent variable was also revealed to be modified by the moderator. Based on this, we can assume that the different motivational components are also not independent from each other in their relationship to the moderator and thus need to be studied together.
The main finding of our study is that Trauma Load moderates the aforementioned motivational components of Maintenance and Contemplation – that is, only in the subgroup of patients with high Trauma Load are these components associated with detoxification treatment completion. In order to understand this moderation effect, we need to have a closer look at the subgroup with high Trauma Load and find out how they differ from the other patients. It is well documented that high Trauma Load among alcohol patients is related to a higher prevalence of comorbid disorders . From psychiatric research it is known that individuals who greatly suffer from psychiatric disorders are more likely to seek treatment . Our previous finding with this group supports this: alcohol patients with high Trauma Load have significantly shorter periods of time between the onset of regular drinking and their first alcohol treatment - approximately five years . We thus believe that high Trauma Load among alcohol patients might be related to higher suffering as well as a higher subjective need for and acceptance of treatment. The Transtheoretical Model and the VSS-K/URICA measure motivational tendencies towards behavioral change. Therefore, the motivational components measured in this study might not just be related to addiction but rather to all problems, including addiction. This might be one aspect that explains why the patients with a higher Trauma Load have a higher motivation to change. However, high Trauma Load is a two-edged factor because it might at the same time increase the risk of dropout: we previously observed that inpatient alcohol detoxification is more stressful to those who are burdened by high Trauma Load, as, for instance, the crowded and sometimes chaotic detoxification wards might frequently trigger trauma-related intrusions. In turn, these individuals are more likely to drop out . Especially among these patients at risk, a low motivation to change (i.e. less awareness that the current detoxification is a form of assistance to achieve one’s goals), might be related to lesser ability to tolerate this kind of stress. Other studies have also found that comorbid psychopathology constitutes a risk for premature termination of alcohol detoxification  and less favorable treatment outcomes . However, our results might also indicate that the dropout risk of a high Trauma Load might be compensated by a high motivation to change, for example, when a patient has already started to change (e.g. by reducing alcohol use or integrating traumatic experiences) and wants to maintain this initial success (Maintenance) he or she might better tolerate the stress of detoxification. Another study has additionally found that only those patients with a high motivation to change at treatment entry profit from motivational interventions .
Based on our findings several clinical recommendations for alcohol detoxification can be proposed. Our results suggest that motivation enhancement strategies might be useful tools for improving detoxification treatment completion, as shown by certain recent studies . However, they also question the current thinking that all patients need the same form of assistance. Other researchers have also concluded that detoxification treatment needs to pay more attention to vulnerable groups by applying individualized interventions [2, 41]. Several studies have recently reported that specific psycho-educational group interventions on stress, trauma and alcohol use increase addiction treatment completion, especially among traumatized patients [24, 45]. This approach needs further empirical support. Expanding upon this approach, patients who are at high risk of dropping out of detoxification might additionally profit from special wards that are smaller, less crowded and have a higher rate of therapy contacts. We believe that psycho-education about psychopathology and trauma should be an early part of detoxification for this subgroup in addition to information on integrated treatment possibilities for addiction and comorbid disorders. Subsequent addiction treatment should integrate psychotherapy components for comorbid disorders such as posttraumatic stress disorder . This might prevent, reduce or reverse ‘bounceback’ developments and increase the patients’ hope that a change of behavior is possible.
Our study has several limitations: first, it was underpowered and did not detect small effects. Secondly, the reported study was conducted with a selected sub-sample of the patients who received alcohol detoxification in our clinic. The participation rate of 45% was low. Thus, the sample was not representative. The most important reason for questionnaires not being returned was that some patients needed several days to regain sobriety and to overcome severe withdrawal effects so that they were about to leave the hospital before finalizing their study participation. In detoxification, this is inevitable due to short treatments. Short treatment stays are common in German detoxification and have been cited as problems by other studies . However, we confirmed that patients who did not return the questionnaires did not differ from the ones who were included in the analysis. Third, our assessment did not include measures of posttraumatic symptom load, PTSD or other relevant psychopathology. We could not directly assess PTSD as establishing this diagnosis is not reliable during and in the weeks following after detoxification . Our assessment did also not include a measure of baseline substance use severity; differences in this variable might explain that dropouts remained the same number of days in treatment than completers. In other studies, substance addicted patients with PTSD had a more severe substance use ; thus, the amount of baseline substance use might be a mediating variable between motivation to change and treatment outcome. Future studies should include a more detailed assessment of posttraumatic and other psychiatric symptoms as well as substance use severity. The study can also be criticized because of its restricted range of socio-demographic measures used to characterize individual study participants and of potential predictors of dropout such as level of education. In previous studies, a younger age predicted dropout . In the current study, no such tendencies occurred and statistical methods confirmed that socio-demographic covariates seemed not to have a great influence on our outcome measure. However, a broader range of potential predictors of dropout needs to be assessed in future studies. Furthermore, the large number of statistical tests used in the current article increased the chance for a Type I error. Further limitations include the fact that the data had already been acquired four years ago and that the range of variables measuring treatment success was limited.
Future research should look into how patients with high and low Trauma Loads differ from each other. Not just different levels of psychopathology (as suggested above) but also different trajectories of addiction development and different types of substance use might exist. It is important to better understand exactly which behavioral changes the patients want to achieve or maintain: are they only related to substance use or do they encompass other goals such as relief of general psychological suffering? Future studies should also include a hypothesis on gender as moderating variable. A wide range of studies has shown that females have on average a higher risk of developing PTSD  and that Trauma Load is associated with more severe substance abuse among women . Our data are compatible with the view that Trauma Load and female gender might interact and influence treatment completion; however, because we only had 15 female participants in our sample, this question could not be addressed here.
This study suggests that dropout from detoxification treatment more likely occurs in individuals with a high Trauma Load who have a low treatment motivation (especially Maintenance and Contemplation). While future empirical studies are certainly necessary to replicate and explain this finding, this study challenges the assumption that one kind of detoxification treatment fits all and warrants new thinking into individualized detoxification programs. It is urgently required that such interventions are further studied and that these become an integral part of detoxification. We believe that traumatized alcohol patients need special assistance during detoxification in order to prevent dropout and repeated admissions. In times of restricted public budgets such interventions will serve patients’ health and economic needs.