Risk of symptomatic venous thromboembolism following emergency appendicectomy in adults

Abstract

Background: Appendicectomy is the commonest intra-abdominal emergency surgical procedure, and little is known regarding the magnitude and timing of the risk of venous thromboembolism (VTE) after surgery. This study aimed to determine absolute and relative rates of symptomatic VTE following emergency appendicectomy.

Methods: A cohort study was undertaken using linked primary (Clinical Practice Research Datalink) and secondary (Hospital Episode Statistics) care data of patients who had undergone emergency appendicectomy from 2001 to 2011. Crude rates and adjusted incidence rate ratios (IRRs) for VTE were calculated using Poisson regression, compared with baseline risk in the year before appendicectomy.

Results: A total of 13 441 patients were identified, of whom 56 (0·4 per cent) had a VTE in the first year after surgery. The absolute rate of VTE was highest during the in-hospital period, with a rate of 91·29 per 1000 person-years, which was greatest in those with a length of stay of 7 days or more (267·12 per 1000 person-years). This risk remained high after discharge, with a 19·1- and 6·6-fold increased risk of VTE in the first and second months respectively after discharge, compared with the year before appendicectomy (adjusted IRR: month 1, 19·09 (95 per cent c.i. 9·56 to 38·12); month 2, 6·56 (2·62 to 16·44)).

Conclusion: The risk of symptomatic VTE following appendicectomy is relatively high during the in-hospital admission and remains increased after discharge. Trials of extended thromboprophylaxis are warranted in patients at particularly high risk.