Routine pharmacological venous thromboembolism prophylaxis in frail older hospitalised patients: where is the evidence?

It has been claimed that there are over 25,000 preventable in-hospital deaths from venous thromboembolism annually in the UK. NICE and SIGN guidelines therefore recommend that all hospitalised patients are risk assessed for venous thromboembolism. The guidelines would recommend using pharmacological thromboprophylaxis for all patients aged 60 and above with reduced mobility and acute medical illness unless obvious contra-indications exist. Meta-analysis data regarding pharmacological thromboprophylaxis for medical patients demonstrate reductions in asymptomatic deep vein thrombosis (DVT) rather than fatal pulmonary embolism and mortality. There is also the potential for increased bleeding risk with this approach. Evidence for older medical in-patients, particularly those aged over 75, is more limited being derived from subgroup analyses of larger clinical trials. In addition, based on exclusion criteria such as increased bleeding risk, frailer older adults were unlikely to have been included within such trials. This commentary will (i) critically appraise available data on the incidence of DVT and PE in older hospitalised patients; (ii) review the evidence available from meta-analyses and subgroup analyses in older medical in-patients for the use of venous thromboembolism prophylaxis; (iii) discuss those situations out-with the guidelines where venous thromboprophylaxis may not be appropriate and even potentially harmful in this patient group and (iv) suggest future research directions.