A large study published this month adds to the concerning body of research on COVID-19 complications and health effects. According to the new research that includes data for more than 70,000 patients in the U.K., half of all people hospitalized with COVID-19 will be diagnosed with at least one complication.
For the study, published in The Lancet, researchers collected data on 73,197 hospitalized COVID-19 patients over the age of 19 across 302 hospitals in the U.K. between January 17 and August 4, 2020. Most of the people in the study were male (56%) and white (73.5%). They were also older (with an average age of 71) and likely to have at least one underlying condition (81%), like diabetes, heart disease, or lung disease.
The researchers looked at how many of these patients were diagnosed with at least one complication—affecting organs and systems like the kidneys, heart, and respiratory system—during their hospital stay. The overall complication rate was 49.7%, meaning that just about half of the COVID-19 patients admitted to the hospital in this study developed at least one complication. (Nearly one-third, 31.5%, of all those admitted died, but among patients who survived, the complication rate was still quite high at 43.5%.)
By far, the most common frequent complications were renal (namely kidney failure), which were diagnosed in 24.3% of people overall. Complex respiratory complications (including bacterial pneumonia, acute respiratory distress syndrome, and collapsed lung) were also common and developed in 18.4% of patients. Systemic complications (such as blood clotting disorders) affected 16.3% of patients. Cardiovascular issues (like blood clots, heart failure, and arrhythmia) occurred in 12.3% of people; neurological complications (including meningitis and brain swelling) in 4.3% of people; and GI/liver issues (like liver failure and GI bleeding) in 10.8% of people.
Not everyone was equally likely to develop a complication. People with more severe cases of COVID-19 were at a higher risk, with 82.4% of those who received critical care and 91.7% of those who received invasive mechanical ventilation also developing at least one complication. Researchers also found that increasing age, male sex, and underlying conditions were all factors tied to a greater likelihood of experiencing complications (after adjusting for factors like socioeconomic status). The people most likely to experience complications were patients ages 60 to 69 who had at least two underlying conditions: 57.9% of them were diagnosed with at least one complication.
But complications were also relatively common in the youngest and healthiest patients. For instance, even though individuals ages 19 to 29 with no co-morbid conditions were the group least likely to have complications, 21.2% of them—about one in five—still had at least one complication.
Unsurprisingly, people who already had a health condition affecting a particular organ were much more likely to develop a complication affecting that organ. For instance, people with chronic kidney disease had a 39.8% chance of suffering from kidney failure, compared to 21.6% of people who did not have chronic kidney disease. Similarly, people who had heart disease were over twice as likely to develop a cardiac complication as people without heart disease (19.9% vs. 8.9%). And 22.4% of patients with moderate-to-severe liver disease suffered a liver injury, vs. 6.2% of patients without liver disease.
While it’s clear that COVID-19 can often have severe impacts on a wide array of systems in the body, there is still a lot that researchers have yet to understand about how exactly the virus causes these widespread health effects. Previous studies looking at a broad range of long-term health issues that linger or develop weeks or months after a COVID-19 infection (sometimes called long-haul COVID) have also found them to be relatively common.
While this new research didn’t capture long-term outcomes, it did find that people who were diagnosed with complications during their hospital stay were much more likely to have a reduced capacity to take care of themselves upon discharge (and a greater need for ongoing care). But as the authors note, we need more research to fully understand how these immediate COVID-19 complications may impact people’s health in the long term.