# Is one additional phone call enough? - Effectiveness of additional human support to reduce dropout from an internet-based intervention for depressive symptoms: A randomized-controlled trial

## TL;DR

This study tested if an extra phone call could reduce dropout rates in an online depression treatment, but found no significant effect.

## Contribution

The study evaluates a minimal human support intervention to reduce dropout in internet-based mental health treatments.

## Key findings

- Pooled dropout rates were 30.5% in the phone call group and 36.1% in the control group.
- All effect estimates were non-significant despite descriptive trends favoring the study group.
- The results suggest the need for further research on how to effectively use additional contact to reduce dropout.

## Abstract

Internet-Based Interventions (IBIs) are effective treatments for mental disorders, but their implementation faces challenges, particularly in addressing high dropout rates. Adding more human support or guidance might reduce treatment dropout rates in IBIs, but it may also limit scalability. Therefore, small, easy-to-implement, guidance-based add-on interventions are warranted to reduce dropout rates. This study tests if offering one additional brief phone contact reduces treatment dropout rates in an IBI for depressive symptoms with written guidance.

We analyze data from N = 394 individuals participating in an IBI for depression. The intervention comprises seven CBT-based modules with module-wise written semi-standardized feedback from psychotherapists (guided IBI). Previous research applying the same IBI in adults with self-reported symptoms of depression found increased dropout rates after the second module. In the study group, therapists offered an additional brief phone call after the second module (n = 206). In the control group, no additional phone calls were offered (n = 188). We present descriptive statistics regarding the intervention course for both groups. We conducted a logistic regression to examine the preventive effect of the additional phone call on treatment dropout.

Pooled dropout rates in the study group were 30.5 % (n = 63), and in the control group 36.1 % (n = 68), with a risk difference of about 6 % points favoring the study group. The odds ratios ranged from 1.25 to 1.33, and the relative risks ranged from 1.08 to 1.10. However, all confidence intervals overlap zero, indicating that all effect estimates are statistically non-significant.

We tested a strategy of additional human contact to reduce treatment dropout rates in a guided IBI for depressive symptoms. All estimates descriptively favored the study group, but were small and non-significant. Further research is needed to determine how additional contact can be employed to reduce treatment dropout.

•Offering additional phone contact was tested to reduce treatment dropout rates.•Results suggest additional phone contact may help, but no significant effect found.•Identifying who benefits is key for reducing treatment dropout rates effectively.•Additional contact shows promise, but how to best leverage it is unclear.

Offering additional phone contact was tested to reduce treatment dropout rates.

Results suggest additional phone contact may help, but no significant effect found.

Identifying who benefits is key for reducing treatment dropout rates effectively.

Additional contact shows promise, but how to best leverage it is unclear.