Treating Chronic Symptoms of Depression in the Virtual Clinic: Findings on Chronicity of Depression in Patients Treated with Internet-Based Computerized Cognitive Behaviour Therapy for Depression

of their first depressive episode (before the age of 22 years), 59.8% experienced 8 or more depressive episodes, and 69.4% have been depressed for 4 years or more in their life. When comparing the patients who fulfilled the chronicity criterion (chronic group) with the patients who did not fulfil the chronicity criterion (nonchronic group) on demographic and social characteristics, we did not find any statistically significant differences between the two groups. Regarding clinical characteristics, the patients in the chronic group were significantly more often depressed for 4 years or more in their life compared to the patients in the non-chronic group (78.8 vs. 45.2%, p = 0.001) and scored significantly higher on the Beck Depression Inventory (BDI-II) [14] before treatment (p = 0.02). No other statistically significant differences were found between the two groups ( table 1 ). The main outcome measures of this study were the 9-item Patient Health Questionnaire (PHQ-9) [15] and the BDI-II. Univariate analysis of covariance was used to examine whether chronicity predicted treatment outcome on the PHQ-9 and BDI-II. Entering chronicity of depression as a fixed factor and controlling for age, sex, education, medication use, treatment group and pretreatment scores revealed no significant differences between the chronic group and the non-chronic group in treatment outcome on the PHQ-9 and BDI-II (p = 0.12 and p = 0.75, respectively). The standardized method of Jacobson and Truax [16] was used to determine statistically reliable change. A reliable change on the PHQ-9 is defined as a decrease of at least 5 points (pre-post change). Patients were considered recovered when their PHQ-9 score was below 5 after treatment. Of the chronic group, 64.6% demonstrated reliable change and 22.8% were considered recovered versus 70.0 and 53.3%, respectively, of the non-chronic group (p = 0.59 and p = 0.002, respectively) ( table 1 ). Adjusting for medication use and treatment group using logistic regression did not change the effects of reliable change and recovery. To the best of our knowledge, this is the first study that explicitly examined chronicity of depression in patients diagnosed with major depressive disorder who used Internet-based CCBT as treatment for their depression. Our findings demonstrate that 72% of the patients in our sample fulfilled the chronicity criterion. Although we found that chronicity of depression did not predict treatment outcome, and that there were no significant differences regarding reliable change between patients with and without chronic symptoms of depression, they did differ regarding recovery. Patients in the chronic group reached significantly less often full recovery compared to patients in the non-chronic group. It is often the case that chronically depressed patients do not fully recover after treatment [12] , and these residual symptoms might explain their chronic course of depression, since residual symptoms are known to be a strong predictor of relapse and chronicity [17, 18] . To prevent or alternate a chronic course of depression, patients should continue treatment until they are fully recovered from their depression [19–21] . For the current study, this would mean that most of the patients in the chronic group, and Internet-based computerized cognitive behaviour therapy (CCBT) is a very promising line of treatment for depression [1–4] . Several randomized controlled trials have confirmed the efficacy of clinician-guided CCBT for depression [5–11] , with effect sizes comparable to those associated with face-to-face treatment. However, little is known about CCBT and chronicity of depression, while many patients suffer from chronic forms of depression [12] . Moreover, the increasing demands of managed health care to improve cost-effectiveness of treatment in combination with the likelihood that chronically depressed patients need longer periods of intervention suggest the utility of a form of therapy for chronic depression that can be self-administered, such as CCBT [12] . The purpose of the current study was to determine the prevalence of chronicity of depression in patients diagnosed with major depressive disorder who have used Internet-based CCBT as a treatment for their depression and to examine whether chronicity of depression predicted treatment outcome in CCBT. In order to do so we used the sample of a recent randomized controlled trial on the efficacy of Internet-based CCBT for depression. Further details and results of this trial are described elsewhere [11] . To determine chronicity of depression we developed a 4-item self-report questionnaire based on the DSM-IV criteria of chronic depression [13] that could be administered online. Patients were considered to have chronic symptoms when they reported that they had not been completely free of depression for 2 months or more in the past 2 years. To provide additional information of chronicity of depression, patients were asked about the age of onset of their first depressive episode, number of depressive episodes, and the total amount of time they have been depressed for in their life. We found that 72.3% (n = 81) of the sample fulfilled the chronicity criterion. In addition, 63.4% reported an early age of onset Received: July 1, 2010 Accepted after revision: November 26, 2010 Published online: June 30, 2011