A meta-analysis of internet-based cognitive behavioral therapy for military and veteran populations

Background
Military and veteran populations are unique in their trauma exposures, rates of mental illness and comorbidities, and response to treatments. While reviews have suggested that internet-based Cognitive Behavioral Therapy (iCBT) can be useful for treating mental health conditions, the extent to which they may be appropriate for military and veteran populations remain unclear. The goals of the current meta-analysis are to: (1) substantiate the effects of iCBT for military and veteran populations, (2) evaluate its effectiveness compared to control conditions, and (3) examine potential factors that may influence their effectiveness.

Methods
This review was completed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting and Cochrane review guidelines. The literature search was conducted using PsycInfo, Medline, Embase, and Proquest Dissertation & Theses on June 4, 2021 with no date restriction. Inclusion criteria included studies that: (1) were restricted to adult military or veteran populations, (2) incorporated iCBT as the primary treatment, and (3) evaluated mental health outcomes. Exclusion criteria included: (1) literature reviews, (2) qualitative studies, (3) study protocols, (4) studies that did not include a clinical/analogue population, and (5) studies with no measure of change on outcome variables. Two independent screeners reviewed studies for eligibility. Data was pooled and analyzed using random-effects and mixed-effects models. Study data information were extracted as the main outcomes, including study condition, sample size, and pre- and post-treatment means, standard deviations for all assessed outcomes, and target outcome. Predictor information were also extracted, and included demographics information, the types of outcomes measured, concurrent treatment, dropout rate, format, length, and delivery of intervention.

Results
A total of 20 studies and 91 samples of data were included in the meta-analysis. The pooled effect size showed a small but meaningful effect for iCBT, g = 0.54, SE = 0.04, 95% CI (0.45, 0.62), Z = 12.32, p < .001. These effects were heterogenous across samples, (I2 = 87.96), Q(90) = 747.62, p < .001. Predictor analyses found length of intervention and concurrent treatment to influence study variance within sampled studies, p < .05. Evaluation of iCBT on primary outcomes indicated a small but meaningful effect for PTSD and depression, while effects of iCBT on secondary outcomes found similar results with depression, p < .001.

Conclusions
Findings from the meta-analysis lend support for the use of iCBT with military and veteran populations. Conditions under which iCBT may be optimized are discussed.