VTE after arthroplasty is 1.5% at six months, and a third is invisible to hospital data

Design

Retrospective cohort, linked UK primary care, hospital and death data

Population

476,620 knee, hip and shoulder arthroplasties, 2007-2019

Primary outcome

VTE within 6 months of surgery

Effect

1.5% overall (knee 1.6%, hip 1.4%, shoulder 1%); over 30% found only in linked data

This UK cohort linked the CPRD Aurum primary care database with hospital and death records for 476,620 knee, hip and shoulder arthroplasties from 2007 to 2019.

Six-month VTE incidence was 1.5%: 1.6% after knee, 1.4% after hip and 1% after shoulder arthroplasty. More than 30% of events were found only through the linked data. Rates fell over time for hip and knee, but the NICE guidelines of 2010, 2012 and 2018 did not produce a detectable change in them. Shoulder arthroplasty VTE fell 9% after 2018. Seasonal patterns differed by joint.

Hospital-only audits undercount VTE because many events are diagnosed in the community after discharge. Units benchmarking their rates on readmissions alone will look better than they are.

The practical point is that VTE after arthroplasty is not rare, not confined to the admission, and deserves explicit discharge advice.

• Do not rely on readmission data alone to audit VTE after joint replacement.
• Give written advice on calf pain, swelling and breathlessness for the months after discharge.
• Make sure patients know how long to take thromboprophylaxis and why.
• Shoulder arthroplasty carries a real, if lower, VTE risk.

Why it matters

Hospital-based VTE rates miss about a third of events, so many units are underestimating their own complication rate.

Don't overread it

The lack of a guideline effect is an ecological time-trend analysis and cannot show that thromboprophylaxis does not work.

The statistics, in plain English

A 1.5% incidence means about 15 VTE events per 1,000 joint replacements within six months. Trend tests over time can detect gradual declines but struggle to isolate the effect of a single guideline when practice was already changing.

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