Changing pattern of venous thrombosis events in 2021 associated with COVID in a teaching hospital

Background: University Hospitals Plymouth, NHS trust, is a teaching hospital which has been a venous thromboembolism (VTE) exemplar centre since 2010. Data on VTE events, whether hospital acquired (HAT) and radiology scans performed, has been collected since 2010. Aim(s): To review whether COVID had an impact on number of VTE events diagnosed, number of HAT events and radiological investigations performed. Method(s): Collect VTE outcome data from computed tomography pulmonary angiography (CTPA), ventilation perfusion scans (V/Q) and Doppler ultrasounds of upper and lower limbs. Review positive VTE events as to whether they meet criteria for HAT and compare outcome data for 2021 with an average from 2010 -2020. Result(s): In 2021 number of VTE events was 944, an increase of 153 (19%) over previous 11 years. HAT events were 206, increased by 17 (9%) though as a percentage of total VTE fell from 24% to 22%. Total pulmonary embolism (PE) was 590, increase of 136 (30%), although deep vein thrombosis (DVT) events were 354, representing an increase of 18 (5%). CTPA scans rose by 891 (41%) to 7021 though DUS remained similar with 2714 scans against an average of 2704 and VQ scans reduced to 339 compared with 545. Of the positive VTE events, 72 (8%) were associated with a COVID diagnosis and a significant number 67 (93%) being PE compared to 5 (7%) DVT. Conclusion(s): There is likely to be an association between VTE increase and shielding as well as positive COVID events causing a decrease in usual physical activity. It is not entirely clear why PE increased significantly but as COVID is a respiratory virus and causes significant inflammation within the lungs, this may have impacted on these figures. Initial review of data confirms no significant changes to VTE risk factors. We will continue to collect and monitor this data in 2022. (Table Presented).

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

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..