'Reassuring' Data On VTE Risk In COVID-19 Outpatients

Although blood clots do occur in COVID-19 patients who don't require hospitalization, they do not occur more often than they do in patients who are similarly ill but do not have COVID-19, according to a new analysis.

"Within the first few months of the pandemic, it was clear that patients with COVID-19 were having more blood clots in the hospital and in the intensive-care unit than other patients who were similarly ill. But most people with COVID-19 do not need to be hospitalized, and we needed to know what they were experiencing," Dr. Nareg Roubinian of Kaiser Permanente Northern California, in Oakland, told Reuters Health by email.

"It was surprising and reassuring to see that the incidence of blood clots in people with COVID-19 who were not hospitalized was similar to what we saw in patients who did not have COVID-19," Dr. Roubinian said.

​

The researchers did a retrospective analysis including more than 220,000 adult members of the Kaiser Permanente Northern California health plan who had symptoms of COVID-19 and were tested for SARS-CoV-2. Their mean age was 47 years and 59% were women. A total of 26,104 individuals, or 11.8%, had a positive PCR test for the virus.

Viral testing took place in an outpatient setting for 117 of 198 (59%) patients who had a positive SARS-CoV-2 test result and later developed VTE. Of these 117 patients, 89 (76%) were subsequently hospitalized.

Compared with patients with a negative SARS-CoV-2 test, those with a positive test had a higher 30-day incidence of hospital-associated but not outpatient VTE.

According to the JAMA Internal Medicine report, the incidence of outpatient VTE among symptomatic patients with SARS-CoV-2 infection was not significantly different from that of patients without the virus (2.2 vs. 1.8 cases per 1,000 tested; P=0.16).

The incidence of VTE was higher in the patients with COVID-19 who were hospitalized compared with peers who did not have the virus (5.8 vs. 3.0 cases per 1,000 tested; P<0.001). Post-hospital VTE incidence did not differ by SARS-CoV-2 status.

"These findings suggest that VTE incidence outside of the hospital is not significantly increased with SARS-CoV-2 infection and argue against the routine use of outpatient thromboprophylaxis outside of clinical trials," the authors write.

"While blood clots do occur in COVID-19 outpatients, they occur infrequently. Our findings suggest that we should wait for the results of clinical trials to determine the best treatment approach and not routinely put outpatients on blood thinners," Dr. Roubinian told Reuters Health.

"These clinical trials will also tell us if giving blood thinners to certain outpatients with COVID-19 will keep their illness from worsening and prevent hospitalization. Guidelines continue to recommend blood thinners to prevent blood clots in patients who are hospitalized with COVID-19," he added.

Funding for this work was provided by The Permanente Medical Group Delivery Science and Applied Research Program. The authors have indicated no relevant conflicts of interest.

—Megan Brooks

Source