About 47% of US adults have an underlying condition strongly tied to severe COVID-19 illness, researchers at the Centers for Disease Control and Prevention (CDC) have found.
The model-based study, published today in the CDC's Morbidity and Mortality Weekly Report, used self-reported data from the 2018 Behavioral Risk Factor Surveillance System and the US Census.
Researchers analyzed the data for the prevalence of chronic obstructive pulmonary disease (COPD), heart disease, diabetes, chronic kidney disease (CKD), and obesity in residents of 3,142 counties in all 50 states and the District of Columbia. They defined obesity as having a body mass index (BMI) of 30 kg/m2 or higher.
They found that prevalence patterns generally followed population distributions, with high numbers in large cities, but that these conditions were more prevalent in rural than in urban areas. Counties with the highest prevalence of these conditions were generally clustered in the Southeast and Appalachia.
Severe COVID-19 disease, requiring hospitalization, intensive care, and mechanical ventilation or leading to death, is most common in people of advanced age and in those who have at least one of the previously mentioned underlying conditions.
A CDC analysis last month of US COVID-19 patient surveillance data from Jan 22 to May 30 showed that those with underlying conditions were hospitalized six times more often, needed intensive care five times more often, and had a death rate 12 times higher than those without these conditions. But the authors of today's reported noted that the earlier study defined obesity as a BMI of 40 kg/m2 or higher and included some conditions with mixed or limited evidence of a tie to poor coronavirus outcomes.
Prevalence of underlying conditions in rural, urban counties
Median estimated county prevalence of any underlying illness was 47.2% (range, 22.0% to 66.2%). Numbers of people with any underlying condition ranged from 4,300 in rural counties to 301,744 in large cities.
Prevalence of obesity was 35.4% (range, 15.2% to 49.9%), while it was 12.8% for diabetes (range, 6.1% to 25.6%), 8.9% for COPD (range, 3.5% to 19.9%), 8.6% for heart disease (range, 3.5% to 15.1%), and 3.4% for CKD, 3.4% (range, 1.8% to 6.2%).
Nationwide, the overall weighted prevalence of adults with chronic underlying conditions was 30.9% for obesity, 11.4% for diabetes, 6.9% for COPD, 6.8% for heart disease, and 3.1% for CKD.
The estimated median prevalence of any underlying condition generally increased with increasing county remoteness, ranging from 39.4% in large metropolitan counties to 48.8% in rural ones.
Resource allocation, preventive health measures
The authors noted that access to healthcare resources in some rural counties may be poor, adding to the risk of severe COVID-19 outcomes.
"The findings can help local decision-makers identify areas at higher risk for severe COVID-19 illness in their jurisdictions and guide resource allocation and implementation of community mitigation strategies," they wrote. "These findings also emphasize the importance of prevention efforts to reduce the prevalence of these underlying medical conditions and their risk factors such as smoking, unhealthy diet, and lack of physical activity."
The researchers called for future studies to include the weighting of the contribution of each underlying illness according to the risk of serious COVID-19 outcomes and identifying and integrating other factors leading to susceptibility to both infection and serious outcomes to better estimate the number of people at increased risk for COVID-19 infection.