Direct impact of 2 years of COVID-19 on chronic disease patients: a population-based study in a large hard-hit Italian region

Objectives: We aimed to provide a region-wide comprehensive account of the direct effects of COVID-19 on chronic disease patients, in terms of disease incidence, severity and mortality, over a 2-year pandemic period (2020-2021).

Design: Population-based retrospective study.

Setting/participants: Adult patients, affected by at least 1 of 32 prevalent chronic conditions, residing in the Emilia-Romagna Region in Italy, during the years 2020 (N=1 791 189, 47.7% of the overall adult regional population) and 2021 (N=1 801 071, 47.8%).

Results: COVID-19 incidence among chronic disease patients was 4.1% (74 067 cases) in 2020 and 7.3% (126 556 cases) in 2021, varying across pathologies, with obesity and dementia showing the highest incidence. Hospitalisation rate for pneumonia or acute respiratory distress syndrome among SARS-CoV-2-positive patients was 15.4%. COVID-19-related excess mortality, that is, deaths from COVID-19 as either main or contributing (1.5% of the total) cause of death, was observed during the three pandemic waves, with observed/expected death ratios ranging from +38% (March 2020) to +11% (December 2021). Increased risks of both COVID-19-related hospitalisation and death were associated with male gender, elderly age and many pre-existing pathologies, including cardiovascular, cerebrovascular and respiratory diseases, neurological and psychiatric disorders, and metabolic dysfunctions. The higher the number of concomitant pathologies, the greater the risk of COVID-19-related adverse outcomes: the likelihood of hospitalisation and death more than doubled for people with more than two comorbidities, compared with those with one underlying condition.

Conclusions: This study presents a thorough and up-to-date quantification of the direct impact of COVID-19 on chronic disease patients. The results obtained are particularly relevant considering that people with pre-existing chronic conditions accounted for almost all cases of COVID-19-related hospitalisation (82.6%) and death (91.5%) in a vast region of Italy, among the hardest hit by the pandemic.