A study of more than 16,000 Swedish citizens diagnosed as having long COVID after an initial infection suggests that having a severe initial illness and having high blood pressure may be risk factors for developing the chronic condition. The study is published in BMJ Public Health.
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Researchers looked at 1,057,174 Swedish residents who tested positive for SARS-CoV-2 from February 1, 2020, to May 25, 2021. Long COVID, or post-COVID syndrome (PCS), was defined as new or persistent symptoms at least 3 months after the initial illness was diagnosed.
A total of 16,151 people (1.5%) received a PCS diagnosis.
60% with long COVID needed significant treatment
The strongest link for developing long COVID was between severity of early illness and long COVID; 61% of those with long COVID had been hospitalized or had needed intensive care or noninvasive or mechanical ventilation. Use of mechanical ventilation during initial illness correlated with PCS (odds ratio [OR], 114.7; 95% confidence interval [CI], 105.1 to 125.3) compared with requiring no medical care during initial COVID-19.
When looking at healthcare use among those with PSC, the most common diagnosis was hypertension (26.6% of PCS patients vs 3.1% of COVID-negative controls). The second most common diagnosis was dyspnea, or shortness of breath (17.2% in PCS patients vs 0.4% in controls).
The authors noted, however, that 76% of the PCS patients with hypertension were diagnosed prior to contracting COVID. For dyspnea, however, 75% were diagnosed after initial COVID-19 infections.
"Understanding the clinical and demographic characteristics of PCS is crucial to develop targeted care strategies for those suffering from long-term effects of COVID-19," said Hanna Ollila, PhD and study author, in a press release from Umea University.