The US has the highest number of COVID-19 cases, with almost a third of the global burden present in the country. A study published in JAMA yesterday is the largest and most comprehensive look at COVID-19 health outcomes in the US so far.
The health data of 5,700 patients within the Northwell Health system (which includes New York City) between March 1 and April 4 were analyzed. Hypertension (57%), obesity (42%) and diabetes (34%) were the most common underlying conditions amongst all the patients; many of them had more than one. Of the 2,634 patients that had a conclusive diagnosis before the study ended (meaning they were either discharged or passed away) 21% died.
What were the major findings of the study?
The median age of the patients was 63, and 60% were male. Interestingly, 70% of the patients did not have a fever on admittance to the hospital. 17% were having respiratory distress, which means that they were breathing at more than 24 breaths per minute. Of the 2,634 patients whose outcomes were studied, 14% required treatment in the ICU, and 12% required ventilator support. About 88% of those on ventilator support passed away. There were no mortalities for those under 20, and mortality rates were higher for males at every 10-year interval past 20 years of age. Only 6% of those admitted to the hospitals had no underlying conditions, whereas 88% had more than one. The study provides corroboratory evidence that asthma is underrepresented with COVID-19 hospitalizations; only 9% of those admitted had asthma.
Overall, the study suggests that older people, (particularly older men), and those with underlying conditions such as hypertension and diabetes are at an increased risk to COVID-19.
Making sense of the data
What can explain the high association with comorbidities such as hypertension and diabetes? Some evidence seems to suggest that the virus directly attacks the lining of blood vessels (which may already be damaged by hypertension and diabetes), which are rich in ACE2 receptors, which is what the virus latches onto. This could explain the significant numbers of patients who experience cardiac damage and blood clotting disorders from severe cases of COVID-19.
About 38% of 184 COVID-19 patients in a Dutch ICU had blood clotting abnormalities, and anecdotal reports of ischemia in fingers and toes (less blood circulation to the extremities) resulting in swollen digits and even tissue death. Blood vessel constriction may also explain some reports of patients with low blood-oxygen levels and no breathlessness. This would imply that oxygen saturation is impeded by clogged vessels and not by mucus in the alveoli.
As for why asthma remains weakly associated with COVID-19 adverse outcomes, we still do not know. Some researchers think that it is simply a matter of a dearth of data and more studies will clear up the discrepancy.
This study adds to our understanding of the pandemic and the researchers recommend that those with hypertension and diabetes should proactively seek medical guidance if they display classical symptoms. Early interventions make for more favourable outcomes.