There is a bi-directional relationship between depression and chronic illnesses such as diabetes and hypertension. This comorbidity is associated with higher mortality risk and diminishes the efficacy of interventions. The specific mechanisms of this mutual influence are still not fully understood, and most intervention protocols address these conditions separately. This study aims to improve our understanding of this relationship. We interviewed 18 patients and 24 health care professionals, focusing on understanding the different ways in which depression and chronic illness could influence each other. Our results show a common cyclical pattern and specific situations where the reported bi-directional relationship does not occur. We discuss the importance of opening a space for the patient’s grief process after the chronic illness diagnosis, managing the demands and stress of the patient’s treatment, and how to adjust the treatment to the different needs and possibilities of each person.

Background Depression and chronic diseases are frequently comorbid public health problems. However, clinical guidelines often fail to consider comorbidities. This study protocol describes a cluster randomized trial (CRT) aimed to compare the effectiveness of a collaborative, computer-assisted, psycho-educational intervention versus enhanced usual care (EUC) in the treatment of depressed patients with hypertension and/or diabetes in primary care clinics (PCC) in Santiago, Chile. Methods Two-arm, single-blind, CRT carried out at two municipalities in Santiago, Chile. Eight PCC will be randomly assigned (1:1 ratio within each municipality, 4 PCC in each municipality) to the INTERVENTION or EUC. A total of 360 depressed patients, aged at least 18 years, with Patient Health Questionnaire-9 Item [PHQ-9] scores ≥15, and enrolled in the Cardiovascular Health Program at the participating PCC. Patients with alcohol/substance abuse; current treatment for depression, bipolar disorder, or psychosis; illiteracy; severe impairment; and resident in long-term care facilities, will be excluded. Patients in both arms will be invited to use the Web page of the project, which includes basic health education information. Patients in the INTERVENTION will receive eight sessions of a computer-assisted, psycho-educational intervention delivered by trained therapists, a structured telephone calls to monitor progress, and usual medical care for chronic diseases. Therapists will receive biweekly and monthly supervision by psychologist and psychiatrist, respectively. A monthly meeting will be held between the PCC team and a member of the research team to ensure continuity of care. Patients in EUC will receive depression treatment according to clinical guidelines and usual medical care for chronic diseases. Outcome assessments will be conducted at 3, 6, and 12 months after enrollment. The primary outcome will be depression improvement at 6 months, defined as ≥50% reduction in baseline PHQ-9 scores. Intention-to-treat analyses will be performed. Discussion This study will be one of the first to provide evidence for the effectiveness of a collaborative, computer-assisted, psycho-educational intervention for depressed patients with chronic disease at primary care in a Latin American country. Trial registration retrospectively registered in ClinicalTrials.gov, first posted: November 3, 2020, under identifier: NCT04613076.