Effect of text messaging on depression in patients with coronary heart disease: A sub study analysis from the TEXT ME randomised controlled trial

Objective: We aimed to evaluate the effects on depression scores of a lifestyle-focused cardiac support program delivered via mobile-phone text messaging among patients with coronary heart disease (CHD). Design: Sub-study and secondary analysis of a parallel group, single-blind randomized controlled trial of patients with CHD Setting: A tertiary hospital in Sydney, Australia Intervention: The TEXT ME comprised 4 text messages per week for 6 months that provided education, motivation and support on diet, physical activity, general cardiac education and smoking, if relevant. The program did not have any specific mental health component. Outcomes: Depression scores at 6 months measured using the Patient Health Questionnaire-9 (PHQ-9). Treatment effect across sub-groups was measured using log-binomial regression model for the binary outcome (depressed/not depressed, where depressed is any score of PHQ-9 ≥5) with treatment, subgroup and treatment by subgroup interaction as fixed effects. Results: Depression scores at 6 months were lower in the intervention group compared to the control group, mean difference 1.9 (95% CI 1.5-2.4, p-value <0.0001). The frequency of mild or greater depressive symptoms (PHQ-9 scores ≥5) at 6 months was 21/333 (6.3%) in the intervention group and 86/350 (24.6%) in the control group (relative risk 0.26, 95% CI 0.16-0.40, p <0.001). This proportional reduction in depressive symptoms was similar across groups defined by age, sex, education, BMI, physical activity, current smoking, current drinking, and history of depression, diabetes, and hypertension. In particular, the rates of PHQ-9 ≥5 among people with a history of depression were 4/44 (9.1%) vs 29/62 (46.8%) in intervention vs control (RR 0.19, 95% CI 0.07 to 0.51, p<0.001), and were 17/289 (5.9%) vs 57/288 (19.8%) among others (RR 0.30, 95% CI 0.18 to 0.50, p