Metabolic syndrome and risk of COVID-19-related hospitalization: a large, population-based cohort study carried out during the first European outbreak of SARS-CoV-2 infection in the Metropolitan area of Milan (Lombardy Region, Northern Italy).

BACKGROUND since the beginning of the COVID-19 pandemic, specific characteristics of the infected subjects appeared to be associated with a severe disease, leading to hospitalization or death. OBJECTIVES to evaluate the association between three components of the metabolic syndrome (diabetes mellitus, dyslipidaemia, and hypertension), alone and in combination, and risk of hospitalization in subjects with nasopharyngeal swab-confirmed COVID-19. DESIGN cohort study. SETTING AND PARTICIPANTS the study subjects were all COVID-19 cases diagnosed in the area of the Agency for Health Protection of the Metropolitan Area of Milan (Lombardy Region, Northern Italy) between 10.02.2020 and 25.04.2020, whose data were gathered with an ad hoc information system developed at the beginning of the pandemic. MAIN OUTCOME MEASURES the association between metabolic syndrome components (alone and in combination) and hospitalization (both in any ward and in intensive care unit) was measured by means of cause-specific Cox models with gender, age, and comorbidities as potential confounders. RESULTS the cohort included 15,162 subjects followed from diagnosis up to 20.07.2020. Adjusted hazard ratios (HRs) of hospitalization in any ward estimated by the Cox model were 1.26 for uncomplicated diabetes mellitus (95%CI 1.18-1.34); 1.21 for complicated diabetes mellitus (95%CI 1.05-1.39); 1.07 for dyslipidaemia (95%CI 1.00-1.14); and 1.11 for hypertension (95%CI 1.05-1.17). When all components coexisted in the same subject, the HR was 1.46 (95%CI 1.31-1.62). A significant increase in risk of hospitalization in intensive care unit was found for uncomplicated diabetes mellitus (HR 1.38; 95%CI 1.15-1.66). CONCLUSIONS this population-based study confirms that metabolic syndrome components increase the risk of hospitalization for COVID-19. The HR increases in an additive manner when the three components are simultaneously present.