That the Sars-CoV-2 infection can cause a real disruption in the coagulation system, also affecting the ability of platelets to aggregate and therefore facilitating the onset of thrombosis or more rarely, on the other hand, of hemorrhages, it is well known. But now a Swedish study published in the British Medical Journal says that there would be an exponential increase in the risk of phenomena of this type after Covid-19 compared to those who are healthy.
Long Covid, the risks of thrombosis and embolism after infection
In the first month after infection there is a 5-fold increase in the risk of deep vein thrombosisa 33-fold increase in the risk of pulmonary embolism and almost doubles the incidence of bleeding. All this, although the probabilities tend to decrease over time, is also maintained in the checks at three and six months, so much so that the Swedish experts who conducted the survey report how important it is to carry out targeted prophylaxis to reduce the risks.
There would in fact be an increased risk of deep vein thrombosis with clot formation in the vessels of the legs up to three months after Covid-19, of pulmonary embolism up to six months, and of haemorrhage up to two months later. The frail ones run the greatest dangers, those with other chronic pathologies and those who have had more complex pictures. But a risk, albeit lower, also exists for those who have “made” the disease in a mild way.
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The analyzed sample
The survey (author of reference Anne-Marie Fors Connolly of the Swedish University of Umeå) was conducted using the Swedish national registries database, which collects information on over one million people with confirmed Sars-CoV-2 infection from February 2020 to May 2021, compared with as emerged from an unaffected control population of more than four million people.
The study envisaged two different modalities. We first calculated the rates of deep vein thrombosis, pulmonary embolism and bleeding in individuals with Covid-19 before and long after the diagnosis of Covid-19, compared with the rates at different time intervals after the disease diagnosis ( days 1-7, 8-14, 15-30, 31-60, 61-90 and 91-180).
In the second analysis, the experts calculated the rates of deep vein thrombosis, pulmonary embolism and bleeding within one month after the diagnosis of Covid-19 in the Covid-19 group and compared them to the corresponding rates in the control group. The results show that compared to the control period, the risks were significantly increased 90 days after Covid-19 for deep vein thrombosis, 180 days for pulmonary embolism and 60 days for bleeding.
After eliminating other factors that could affect the results, the researchers found a 5-fold increase in the risk of deep vein thrombosis, a 33-fold increase in the risk of pulmonary embolism, and an almost two-fold increase in the risk of bleeding in the 30s. days after infection.
Higher risks for those who developed the disease in the first wave
The risks were greater in patients with more severe Covid-19 and during the first wave of the pandemic than in the second and third waves. According to experts, improvements in treatment and vaccine coverage in older patients after the first wave may have impacted this trend.
Caution: Even among mild, non-hospitalized covid-19 patients, researchers found an increased risk of deep vein thrombosis and pulmonary embolism. There was no increased risk of bleeding in mild cases, but a noticeable increase was seen in more severe cases.
Conclusion: Covid-19 could be considered an independent risk factor for deep vein thrombosis, pulmonary embolism, and bleeding, and the risk of these outcomes increased for one, six, and two months after the disease, respectively.
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“Clinical, laboratory and autopsy data show that there is an association between Covid-19 disease and thromboembolic disease (with deep vein thrombosis and pulmonary embolism) – he explains Giovanni Esposito, President of the Italian Society of Interventional Cardiology – GISE. The “coagulation” disorders associated with the diagnosis of Covid-19 were recognized from the beginning, even when knowledge of the disease was poor, as one of the main pathophysiological mechanisms that determined the prognosis of patients. To date we know much more about SARS-COV2 infection and more and more emerges from a number of studies that are unprecedented in history. Certainly such a large and rigorous study adds a further piece to the complex picture of this disease “.
Problems in clinical practice
Be careful though. “Although anticoagulant therapy aimed at preventing thromboembolic complications, which can lead to an increased risk of bleeding, has become an important therapeutic strategy in patients with Covid-19, the type, duration and intensity of anticoagulant therapy to be prescribed is still today. , as well as any differences on the basis of the severity of the disease itself, are still the subject of extensive discussion yet to be clarified, with some important studies still in progress – specifies the expert. Therefore in clinical practice there has not been and is not all ‘now uniformity in the management of these therapies and inevitably this can significantly influence the rates of thrombotic events and bleeding observed in such a large population, without necessarily having to attribute these differences to the virus and to the disease itself “.
Covid, a disease still with many unknowns
One last aspect should not be forgotten: in the long months of the research there were different effects of the disease and its consequences, possibly related to different variants and the different immune status of affected patients thanks to the availability and diffusion of vaccines. Possible conclusions? “This is a study that is both interesting and important because it highlights that there could be clinically relevant risks even after the infection and also in those who have had less severe disease – says Esposito. But above all it highlights that we have no certainties, rather more hypotheses to work on and therefore there are still many things that science still has to do to clarify the mechanisms, consequences and optimal management of these patients in the acute phase and in the months following the disease “.
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