High- versus low-intensity internet interventions for alcohol use disorders (AUD): A two-year follow-up of a single-blind randomized controlled trial

Alcohol Use Disorders (AUD) are widespread and have serious consequences, but are among the most undertreated mental disorders. Internet interventions have been found effective in treating AUD, but we know little about long-term outcomes, two years or more after treatment. This study explored 12- and 24-month outcomes in alcohol consumption following initial 6-month improvements after a therapist-guided high-intensity internet intervention and an unguided low-intensity internet intervention among individuals with alcohol use disorder. Between-group comparisons were analyzed, as well as within-group comparisons with (1) pre-treatment measurements (2) post-treatment measurements. Participants consisted of a general population sample of internet help-seekers in Sweden. A total of 143 adults (47% men) with a score of 14 (women)/16 (men) or more on the Alcohol Use Disorders Identification Test, alcohol consumption of 11 (women)/14 (men) or more standard drinks the preceding week and ≥ 2 DSM-5 alcohol use disorder (AUD) criteria based on a diagnostic interview were included. The high- and low-intensity internet interventions (n = 72 and n = 71 respectively) consisted of modules based on relapse prevention and cognitive-behavioral therapy. The primary outcome was self-reported alcohol consumption in the preceding week measured as (1) number of standard drinks and (2) number of heavy drinking days. Attrition from self-reported questionnaires was 36% at the 12-month follow-up and 53% at the 24-month follow-up. No significant between-group differences occurred in outcomes at either long-term follow-up. Regarding within-group differences, compared to pre-treatment, alcohol consumption was lower in both high- and low-intensity interventions at both long-term follow-ups [within-group standard drinks effect sizes varied between g = 0.38–1.04 and heavy drinking days effect sizes varied between g = 0.65–0.94]. Compared to post-treatment, within-group alcohol consumption in the high intensity intervention increased at both follow-ups; for the low-intensity intervention, within-group consumption decreased at 12-month follow-up, but did not differ compared to post-treatment at 24 months. Both high- and low-intensity internet interventions for AUD were thus associated with overall reductions in alcohol consumption at long term follow-ups, with no significant differences between the two. However, conclusions are hampered by differential and non-differential attrition.