As the COVID-19 pandemic continues to spread and research into potential risk factors for COVID-19 mortality continues, it is becoming clear that people with underlying comorbidities are at greater risk of dying from COVID-19. However, the exact contribution of various comorbidities is unclear. Now, a new study published in the journal PLOS ONE analyzes this topic and can help quantify the risk of certain conditions and help with forecasting.
Study: Association of Cardiovascular Disease and 10 Other Pre-Existing Comorbidities with COVID-19 Mortality: A Systematic Review and Meta-Analysis. Photo credit: SvetaZi / Shutterstock
Previous studies provide conflicting results
With many different studies, the contradictions increase. While some say chronic illness increases the risk of COVID-19 and its severity, others disagree. The differences can arise from the small number of studies, the variety of methods used and the causes of bias. There is no doubt that the regions with the highest mortality rate are the regions with the highest prevalence of chronic diseases.
Coronavirus 2 (SARS-CoV-2) with severe acute respiratory syndrome invades human host cells and infects them with angiotensin converting enzyme 2 (ACE2), an enzyme and receptor that is found in many tissues such as the heart, kidney and type II pneumocytes. Some researchers suggest that the use of Angiotensin II Type 1 Receptor Blockers (ARBs) improve the expression of ACE2 on cell membranes, making the individual more susceptible to infection and at a higher risk of developing progressive and severe disease can make. This would include people with high blood pressure and chronic heart failure who are treated with ARBs.
Most of the studies carried out in this area to date have only covered certain countries, part of the research and certain conditions. The presence of significant bias from various sources prevents their conclusions from being fully accepted. To counteract this tendency, the current study used a panoramic view of most pre-existing chronic conditions.
These include high blood pressure, cardiovascular disease, chronic kidney disease, chronic liver disease, cancer, asthma, chronic obstructive pulmonary disease, asthma, and HIV / AIDS. The researchers estimated the risk of dying from COVID-19-related illnesses in people with these diseases.
The researchers found 25 studies that were eligible for quantitative analysis, including ~ 65,500 patients. Almost four fifths of the studies came from China. The mean patient age was 61 years and 57% of the patients were male. The study also had a median of 7, which indicates an adequate standard of quality.
Cardiovascular disease and mortality in COVID-19
There was a significant negative or positive association in half of the studies that reported this risk, with the estimated risk of mortality in an uninfected population being between 30% and 9 times higher than expected. The summary of the studies showed a doubling of the risk of death.
Other chronic diseases and COVID-19 mortality
The researchers showed that the risk of death was ~ 80% higher in patients with high blood pressure, 1.5 times higher in diabetic and cancer patients, double in patients with heart failure, and triple in those with chronic kidney disease. Other illnesses were not associated with a higher risk of death with COVID-19.
Sources of distortion
The researchers suspect that some diseases, especially cerebrovascular diseases, cancer, and high blood pressure, have a publication bias, and these receive more attention than other diseases. However, even after adjustment, hypertension remains a risk factor for mortality, but not for cancer.
The results of different studies differed significantly in whether or not these conditions were associated with a high risk of mortality. However, examining only the conditions involved in more than 10 studies, they found that neither age nor male sex were associated with a higher risk.
The risk that a single study had an undue impact on the risk estimate was also excluded by removing them individually from the meta-analysis, whereby no significant change in the pooled risk was found.
The researchers therefore concluded that the presence of pre-existing cardiovascular disease, high blood pressure, diabetes, heart failure, chronic kidney disease, and cancer in hospitalized patients with COVID-19 are at higher risk of death from the Brings infection. This is in line with previous studies showing that people with cardiovascular disease, chronic kidney disease, and cancer are at higher risk of mortality with COVID-19.
However, in contrast to the conclusion of an earlier study, the risk of cerebrovascular disease was not significantly increased. This may be due to the larger sample size in this study as well as the ability to use data from recent studies.
Why this effect?
The researchers believe that these chronic diseases may be linked to a higher risk of death because the body's functions are already under stress from the pre-existing disease. The body's endocrine system is in disarray, and so is the sympathetic nervous system and immune system. Since these are responsible for homeostasis, chronic stress leads to a slow and progressive deterioration in the ability to regulate.
The possible result of a disturbed metabolism is the build-up of pro-inflammatory cytokines that trigger an abnormal immune response. It is widely believed that this is responsible for the severe complications known as Severe or Critical COVID-19, as previously seen with flu, SARS, and MERS.
The study concludes that patients with COVID-19 with six specific pre-existing chronic conditions are at greater risk of dying from the disease than those who do not. This may indicate the role of protecting such individuals and providing targeted treatment at the onset of infection or giving preference to a vaccine for this high risk group.
Implications for Research and Clinical Practice
Renin-angiotensin-aldosterone system (RAAS) blockers are used by most patients with heart or vascular disease, high blood pressure, diabetes, chronic kidney disease, and heart failure. These have not been found to increase the percentage of COVID-19 patients who have died from the disease, although experiments have shown that they can increase levels of the host receptor molecule ACE2. Thus, even with COVID-19, these drugs remain an optimal choice for the treatment of high blood pressure and other cardiovascular diseases.
The current study therefore shows that when a vaccine is available, vaccinations need to be prioritized in order to reduce the mortality rate. This has been known as targeted vaccination and is a strategy backed by history, especially with regards to the flu. Similar to this latter disease, SARS-CoV-2 can become a seasonal virus that requires annual vaccinations, some researchers predict.