Principal Findings
depression, anxiety
This study aimed to identify different trajectories of symptom change across supported iCBT treatment for depression and anxiety using continuous outcomes data from patients treated in a mental health service setting. In addition, this study aimed to explore the relationship between the identified trajectories and use data. Overall, we found high heterogeneity in treatment response, with 5 latent classes emerging from data for both depression and anxiety. Across the 5 classes for depression and anxiety, we identified 3 improving classes and 2 classes that showed little to no change in symptoms. Across all classes, we also found an effect of time, with most use occurring in the first 4 weeks.Understanding the different types of responses to an intervention as well as factors that may influence those responses could help improve the quality and delivery of iCBT interventions. This study found that approximately 70% of the sample improved across treatments; however, these individuals experienced different trajectories of change based on 3 characteristics: their baseline score, the pace of the improvement, and their posttreatment symptom scores. Some of the improver classes identified in this study are consistent with other iCBT studies that found individuals who started with moderate or moderate-severe scores and progressed toward recovery at a steady, moderate pace [It is perhaps even more important to understand the class characteristics of the individuals that see smaller to no gains so that in future, we could identify them early on, monitor their trajectory of symptoms, and make any necessary treatment decisions earlier to maximize treatment benefits. In particular, the 2 classes of nonresponders that start in the moderate severity range and see limited improvements (depression class 4 and anxiety class 4) could be ripe candidates for monitoring more closely symptom change trajectories and perhaps identify symptom change thresholds, whereby, from week to week, if thresholds are not met for symptom change, it could result in treatment decisions being made. Although some prior iCBT studies [It is also worth mentioning that we did not find a deterioration class similar to others [A better understanding of the attributes of the classes identified has implications for tailoring, intervention delivery, and the early identification of individuals who are not on an improving path. We found no significant associations between the classes and baseline sociodemographic variables (ie, age, sex, employment status, and LTC), which is consistent with some studies [The results did not show a time-varying relationship between use and the various trajectories of change, indicating that the effect of platform use did not result in immediate clinical gains. This is consistent with findings from a study by Zeng et al [The predictors of use were also investigated to better understand overall platform use. Age was a significant predictor for some of the use metrics, with older clients logging in more frequently and for longer periods, which is consistent with previous findings [