Global meta-analysis identifies comorbid conditions linked to COVID-19 mortality

Cancer, chronic kidney disease, diabetes and hypertension are the four main comorbidities leading to death from COVID-19, a Griffith University meta-analysis published in mBio has found.

The researchers analysed global databases MEDLINE, Scopus, Web of Science and EMBASE of 375,859 participants from 14 countries and found chronic kidney disease was statistically the most prominent comorbidity leading to death.

Hypertension (abnormally high blood pressure) was the most common comorbidity in COVID-19 patients, followed by obesity and diabetes, however, despite having high prevalence, obesity was not associated with mortality in COVID-19 patients.

Dr Adam Taylor
Dr Adam Taylor

Co-lead author Dr Adam Taylor said previous systematic reviews and meta-analysis had been limited by the lack of peer-reviewed data and the lack of global clinical data.

“Comorbidities are frequently cited as risk factors for severe COVID-19 outcomes, however, the degree to which specific comorbidities impact the disease is debatable,’’ he said.

“This is a global study covering all comorbidities reported to be involved in the exacerbation of COVID-19 leading to death. It allows us to identify specific comorbidities that have higher risk in patients and identify COVID-19 high-risk groups.”

“Further investigation is required to explain the higher prevalence of these comorbidities in COVID-19 patients, but studies may focus on the SARS-CoV-2 cell entry mechanism.”

Professor Suresh Mahlingham

Lead author Professor Suresh Mahlingam said the higher prevalence of these comorbidities in COVID-19 patients could be explained by the increased expression of the receptor (ACE2), used by SARS-CoV-2 for cell entry.

“For example, diabetic patients can be prescribed drugs to control blood glucose that have also been shown to increase ACE2 expression.”

He said COVID-19 was associated with increased clot strength, so the severe outcomes in patients with hypertension and diabetes could be partially explained by the increased incidence of thrombotic complications as they have an elevated risk.

“These patients are commonly reported to have weakened immunological function which could predispose them to infections.

“In patients with chronic kidney disease, the risk of in-hospital mortality in COVID-19 patients also appears higher in cases with end-stage renal disease compared to chronic renal disease.”

PhD student Ng Wern Hann, who carried out the study, said patients with autoimmune diseases and cancer also suffered from weakened immunological function from the use of immunosuppressive drugs.

“This may explain the increased risk of hospitalisation observed in these patients particularly in those that are critically ill.”