Lifestyle Intervention for Symptoms of Depression wIth App Support in General Practice

Cost-effectiveness of the Personalized Lifestyle Intervention at 6 months after baseline

To assess the PLI's cost-effectiveness from a societal perspective, the Treatment Inventory of Costs in Patients with psychiatric disorders (TIC-P) will be used. The main outcome in the cost-effectiveness analysis is Quality-Adjusted Life-Years (QALYs) based on the EQ-5D-5L, measuring general quality of life. Also, additional treatments are measured within the TIC-P, for secondary analysis on additional care.

Change in quality of life using the EQ-5D-5L

Change in quality of life will be assessed using the EQ-5D-5L. This tool consists of 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, with each rated on a 5-level scale. The EQ-5D-5L also includes a visual analog scale (VAS) to assess overall health. Higher scores indicate better quality of life, while lower scores reflect greater limitations or discomfort. This measure helps track changes in health status and overall quality of life over time.

Change from baseline in the mean depression severity score measured by the PHQ-9 at 6 months after baseline

To evaluate the effectiveness of the PLI on depression symptomatology, general symptoms of depression will be assessed using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 is a 9-item self-reported questionnaire assessing the severity of depression symptomatology. The PHQ-9 is brief, easy to complete, and takes only a few minutes to fill out. The total score ranges from 0 to 27. Scores are interpreted as follows: 0-4 indicates minimal or no depression, 5-9 mild depression, 10-14 moderate depression, 15-19 moderately severe depression, and 20-27 severe depression. Higher scores suggest more severe symptoms, and professional treatment is recommended as the score increases.

Change in the severity of anxiety symptoms: GAD-7 (Generalized Anxiety Disorder-7)

To measure the severity of anxiety symptoms, the GAD-7 (Generalized Anxiety Disorder-7) will be used

Changes in quality of life according to the Recovering Quality of Life (ReQol)

Quality of life is measured using the Recovering Quality of Life (ReQol) questionnaire, a patient-reported outcome measure specifically developed for individuals with various mental health conditions. The ReQol provides a total score ranging from 0 to 80, with higher scores reflecting a better quality of life and overall recovery outcome.

Change in use of antidepressants

Use of antidepressants, when started/ended, type, dosage, and at follow-up: inquire about changes.

Change in use of anxiolytics

Use of anxiolytics by self-reported questions about the use of sedatives/sleep medication, when started/ended, frequency of use, type, dosage, and at follow-up: inquire about changes.

Socio-demographics at baseline

Baseline demographics include gender, age, education level, employment status and ethnicity.

Threatening Experiences: LTE

The List of Threatening Experiences (LTE, developed bij Brugha) measures the occurrence of 12 major categories of stressful life events (did you experience this: No, yes in the last 6 months, yes longer ago) The Dutch translation includes an additional thirteenth question: "Did you experience any other major severe negative events (yes/no)? If yes, briefly describe what happened?" The questionnaire is offered at baseline, and at 6 months a shorter version (did you experience this in the last 6 months?). Item scores are summed to derive a total score. Higher score indicates more threatening experiences.

History of depression and previous psychological treatment

History of depression and previous psychological treatment are assessed through self-reported questions. These include the number of previous depressive episodes treated, the number of hospitalizations for depression in a psychiatric hospital or mental health institution, age of onset, duration of the current episode (when it began), family history of depression, and any previous psychological treatment or psychotherapy.

Chronic diseases: TIC-P

Chronic diseases will be evaluated using questions of the TIC-P questionnaire e.g., health status, lung diseases, heart diseases, blood vessels, diabetes, stroke, joint degeneration, rheumatism, cancer, high blood pressure, and other diseases.