Pattern of Venous Thrombosis events in 2020 associated with COVID, in a large teaching hospital

ABSTRACT

University Hospitals Plymouth, NHS trust, is a teaching hospital of 850 beds which has been a venous thromboembolism (VTE) exemplar centre since 2010. Data on VTE events, importantly whether hospital acquired, have been produced over the same period (Table 1). Data are also collected on the number and type of radiology scans used. Specifically, computed tomography pulmonary angiography (CTPA), ventilation perfusion scans (V/Q) and Doppler ultrasound of upper and lower limbs (DUS). The first COVID positive patient was admitted in March 2020;subsequently a flood of such patients led to many hospital services being paused and initially a reduction in number of patients admitted including those with VTE. In 2020 the total number of VTE events were relatively similar to data from the previous 10 years, being 765 against an average of 793 (SD 57.33) over the preceding 10 years. Hospital acquired VTE (HAT) in 2020 was 175 compared with an average of 189 (24%) per year previously. Compared with the last 3 years, similar numbers of CTPA were carried out in 2020 at 2229 against 2152. V/Q scans were significantly reduced (270) over concerns related to using inhaled gases in COVID patients. This compares with an average of 636. For DUS similar numbers 2714 were undertaken (previously 2785). Over 2021 there has been an increase in total VTE (944, an increase of 23 %), in particular an increase in total PE from an average of 454 over the preceding 11 years to 590 (30% increase) last year. DVT totalled 336, compared to 354 last year, being relatively similar. There has also been a similar increase in scan numbers for 2021 with CTPA registering 3171 an increase in 942 scans. For DUS scans similar numbers for 2021, at 2927 compared to the average over the last 3 years of 2785. Hospital acquired VTE was 206 (22%) a similar percentage from immediately previous years. Of the positive VTE events 72 (8%) were associated with a positive COVID diagnosis with a significant increase presenting as PE (93%) over DVT (7%). There is likely to be an association between VTE increase relating to shielding and furlough, causing a decrease in usual physical activity. It is not entirely clear why there has been such a significant increase in total PE diagnosed as there has been no change to protocol or scanning equipment used. However, COVID is a respiratory virus and causes significant inflammation within the lungs, which may well have an impact in increasing PE risk. An initial review of the data seems to confirm there are no significant differences in other VTE risk factors. We will continue to collect outcome data on all VTE events next year, to identify whether this increase continues or whether 2021 was an exceptional year for positive VTE events..