OBJECTIVES: A greater burden of depressive symptoms in those with diabetes was observed during COVID-19 pandemic. Here, we investigated the cumulative effect of depression before the pandemic on health worsening during the COVID-19 lockdown in Europe.

METHODS: Individuals aged 65 years or more who responded to the fifth wave (in 2013) from 29 European countries, and reporting treated diabetic condition within the Survey of Health, Aging and Retirement in Europe (SHARE) study were identified. These individuals were followed through the sixth (in 2015) and eighth (2019) waves. The cumulative effect of depression, as the cumulated number of times that depression was declared across multiple waves, was evaluated after identifying health worsening during the COVID-19 pandemic based on a single question in the questionnaire survey conducted within SHARE in the period June-September 2020. The effect of depression was estimated using a marginal structural model accounting for baseline characteristics and time-dependent confounding.

RESULTS: In the fifth, six and eighth waves, 5062, 3622 and 1579 patients were identified, respectively, and among the latter, 1140 patients participated in the COVID-19 questionnaire. A logistic regression using baseline covariates yielded an increasing odds ratio of depression on health worsening (OR=3.24; 95%CI=3.17-3.31) during the lockdown. For the marginal structural model, the effect of depression was significant but reduced (OR=1.12; 95%CI=1.01-1.23), suggesting overestimation when accounting for baseline characteristics only.

CONCLUSIONS: In our study, a significant effect of depression before the pandemic on health worsening during lockdown was revealed. This study highlights the importance of taking control measures on isolated depressive diabetic patients from multiple stakeholder perspectives, including health professionals and health policy makers.