Comorbidities and COVID-19

Hospital Ward
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COVID-19 is an infection that sets off the body’s stress responses. If a patient has a comorbidity (pre-existing medical condition), their ability to mount these responses is lower. For example, even for regular infections, a diabetic patient is more prone to develop severe forms because their ability to fight the infection is lower.

There are two aspects to the COVID-19 infection. The first is the virus itself. If a patient has diabetes, is old, or has undergone chemotherapy, their immune system is weakened, and the virus has a field day. It flourishes because their system is not able to curb its numbers.

The second part is what we call a “cytokine storm”, which appears around 8-10 days later. Our immune system starts working hyper-actively against the virus. It produces inflammatory cascades which cause further damage. This is normally controlled by the body’s stress responses, but those are skewed in people with existing diseases. 

Diabetes is the most common comorbidity that we are seeing in a majority of COVID-19 patients, followed by hypertension and cardiac diseases, kidney diseases, asthma and cancer.


If a person has diabetes, they are twice as likely to end up with severe disease and more likely to be admitted in an ICU compared to a non-diabetic patient. At a given time in our hospital ward, about 30-40 percent of admitted patients are those on diabetic medication.
We are seeing two effects related to diabetes. First, controlled diabetes is becoming uncontrolled. To tackle the cytokine storms, steroids are given to patients. But these are immune suppressors, which cause sugar levels to rise further. Secondly, people who have never had diabetes before are developing the disease when infected with COVID-19. A Global Registry of COVID-19-related diabetes has now been started by King’s College London to track such patients.


Hypertension is another risk factor. The pathway for the virus to enter our cells is the ACE2 receptor (a target for treating hypertension). It is found mainly in the lungs, but also in the pancreas and small intestine, which is likely why the patient’s endocrine system is hit badly. One theory is that patients who are on drugs that are ACE2 inhibitors are at risk for severe infection. For this reason, no patient who has newly been diagnosed with hypertension is being started on ACE2 inhibitors.

Chronic kidney disease

Another subset that is tricky is those with chronic kidney disease who are undergoing dialysis treatment. For one, they are facing shortages of centres where they can get dialysis treatment once they get COVID-19. They also have to frequently come to a hospital for dialysis, so they are at higher risk. For them, COVID-19 testing is done every 10-15 days.

COVID-19 affects not just the lungs, but also the blood vessels. The disease causes increased blood clots. When a patient is on dialysis treatment, the machine is run with blood thinners. Despite this, their blood sometimes becomes so thick due to COVID-19 that we have to increase the dose, or use a different type of cleaning in the CRRT (Continuous Renal Replacement Therapy) machines during dialysis.


Most elderly COVID-19 patients come to the hospital with just electrolyte disturbances or mental confusion, but no fever or respiratory symptoms. They just feel malaise. This may be because in many infections, elderly patients do not have the ability to develop fever as an immune response. Even at home, they are kept isolated and are not active, so they do not experience breathlessness. Once they are admitted, they are even less active and are therefore more susceptible to developing clots. 


Those who have BMI (Body Mass Index) above 30 appear to be at higher risk for more complications. Even without other factors, obesity by itself may make people vulnerable.

Managing patients with comorbidities

For patients with different comorbidities, the treatment and monitoring protocols are tailored differently. Even the choice of steroid is different. For example, we use dexamethasone instead of methylprednisolone for diabetics because the latter can hike sugar levels. Elderly patients tend to have more cardiac side-effects from some drugs. If liver functions tests are higher than normal, or if there is an underlying infection such as tuberculosis, cytokine inhibitors such as tocilizumab can be contraindicative. We have to screen patients for underlying infections and be careful when giving these drugs.

For each patient, we score certain parameters and work with charts to look at the risk factors. Even for admission, we use the National Early Warning Score (NEWS) score. This will tell us whether the patient can be managed at home, or whether they need to come to the hospital. To find out who is at a higher risk of developing clots, we use the Sepsis-Induced Coagulopathy score.

We also keep patients with comorbidities in the hospital for a little longer. For diabetics, we keep them until they are clinically stable and their sugars are at levels that can be managed by themselves. For the elderly, we keep them until we are able to bring the medications down to the minimum amount that they can handle on their own. We watch to see if there are no symptoms persisting for at least five days. We also make them do a six-minute walk test to see if they are able to maintain their vitals at safe levels.

Treating specially-abled children has also been challenging, because there is a shortage of caretakers, and therefore we have had to keep their family members as well in wards. We have also had schizophrenic patients who would not take treatment from anybody.

COVID-19 has also done a lot of collateral damage on non-COVID-19 diseases. For example, there has been a 69% drop in measles, mumps and rubella immunization in India this year, according to an editorial in The Lancet. Many people with TB or cancer may have not gone to hospitals even for diagnosis, either out of fear of contracting COVID-19, or because of the restrictions on movement. We are likely going to see more advanced stages of such diseases when we start seeing more patients.

As told to Ranjini Raghunath, Communications Officer at the Office of Communications, Indian Institute of Science (IISc). Maheema Bhaskar is a pulmonary physician at the Tata Memorial Centre and Dr. L H Hiranandani Hospital in Mumbai