Discussion

This study demonstrates that our pragmatic approach to the ambulatory assessment and management of selected low risk patients with possible or proven PE is safe, efficient and cost effective.

There is increasing evidence in the literature that patients who are at low risk of death from PE can be identified and treated successfully as an outpatient. The most extensively validated clinical scoring system is the PESI.2 It comprises 11 scored domains. Patients with surrogate clinical markers of right heart strain score highest on the PESI, that is, pulse >110, systolic BP <100 mm Hg, oxygen saturations <90%, respiratory rate >30 bpm or a history of collapse or altered mental status. Thus, we adopted these clinical parameters as markers of higher risk patients who were not suitable for ambulatory management. However, a cut-off for oxygen saturations of 92% rather than 90% was selected to maximise patient safety while enabling those suitable to be managed as outpatients. Patients with cancer were included as their risk of death was judged to be due to their condition rather than associated with PE. There were no PE related deaths in our study.

Two recent meta-analyses have demonstrated the safety of outpatient treatment of PE in low risk patients.3 ,4 Most studies have only considered the safety of outpatient treatment once PE has been diagnosed. The number of patients potentially available is limited by this approach. We chose to apply the same criteria to all patients with suspected PE, the vast majority of whom did not have PE and in whom admission could be avoided.

One of the only comparable studies examining the suitability of outpatient diagnosis of PE was published in 2006.1 Hogg et al prospectively studied 408 emergency admissions with pleuritic chest pain. Of these, 353 (86.5%) were safely investigated as outpatients.

Using our service model, we estimated that we saved 692 bed days per year for our catchment population of one million. If this model is adopted across a population of 64 million in the UK, it is postulated a 44 000 bed-day reduction annually will result.

The average forecast income is £921 for each patient seen in the clinic. The majority of patient episodes (chest pain, lower respiratory tract infection, PE, etc) would receive the ‘best practice tariff’ for same day emergency care which was introduced in 2012 by the Department of Health to incentivise ambulatory services. Equivalent inpatient episodes are estimated to attract an average of £764. The main additional cost incurred by running this service is the salary of a fulltime specialist nurse (approximately £45 000). There is no saving related to investigations as the same number and type are performed.

In summary, this is the largest study demonstrating the feasibility and safety of investigating and managing suspected PE in an ambulatory setting for selected patients. The modified PESI criteria we use to select patients for outpatient investigation successfully identify a low risk group who do not require inpatient monitoring. Additionally, it illustrates the financial advantages of ambulatory care and the resulting avoided admissions. Our cohort is unlikely to be significantly different to other patient populations of a similar age group and hence our results are likely to be reproducible.