Hospital volume and outcomes for acute pulmonary embolism: multinational population based cohort study

Jiménez D, et al. Hospital volume and outcomes for acute pulmonary embolism: multinational population based cohort study. BMJ 2019;366:l4416

Discussion

Acute pulmonary embolism (PE) remains a world wide major cause of cardiovascular mortality and the most frequent potentially preventable cause of hospital-admission related death. Because the incidence of acute PE and venous thromboembolism (VTE) in general is high, almost all physicians from primary to tertiary care deal with patients with suspected or confirmed PE. Notably, the diagnostic and therapeutic management of patients with PE often is complex and requires dedicated expertise. While the acute treatment of other cardiovascular diseases such as stroke and myocardial infraction are being increasingly centralized because of a clear association between expertise and survival, this trend is not seen in the setting of acute PE. Professor Jiménez and colleagues set out to evaluate the association between experience in the management of acute PE and PE-related mortality.

The authors used data of the RIETE Registry, a well known international prospective registry of patients with confirmed VTE, to test their hypothesis that experience in the management of acute PE would be associated with a reduction in PE related mortality at 30 days, after adjustment for differences in patient case mix and hospital status. Experience was measured by comparing hospital case volume of the RIETE sites in a continuous way and by comparing the quartiles of volume, rather than be predefining a ‘minimum’ volume that would fit the definition of ‘sufficient’ expertise. To confirm the accuracy of that approach, the authors linked 16 random Spanish RIETE sites to the Spanish National Patient Registry. The linked data showed that the RIETE registry captured an impressive more than 80% of the patients with a final diagnosis of PE from each hospital, reflecting the external validity of the RIETE registry. The main finding of the authors was that hospital volume was indeed associated with a significant reduction in the adjusted odds of 30-day PE related mortality rates, even though high volume centers cared for elderly patients with more comorbidities. The adjusted 30-day all-cause mortality was not different between patients admitted to a hospital in the lowest quarter compared with the highest quarter (Odds Ratio 0.78, 95% confidence interval 0.50-1.2), nor were 7-day PE related or all-cause mortality. The final conclusion of the authors was that "they observed an inverse association between annual hospital volume of PE and outcomes among patients with acute symptomatic PE.”

This paper sends us a clear message: experience counts for the optimal care of patients with PE. Importantly, experience is not only reflected by hospital case volumes. In many hospitals, multiple physicians may be involved in the diagnosis and management of patients with PE, e.g. emergency doctors, cardiologists, pulmonary physicians, internists or haematologists, intensive care physicians, (interventional) radiologists and others, sometimes without harmonisation of treatment protocols. Likely, the solution to the challenge of providing the optimal care to the individual PE patient therefore is not primarily the obligatory centralisation of PE patients in high volume centers. Rather and as argued by the authors, strict implementation of evidence based guideline recommendations in local protocols, dedicated education, triage and transfer of selected high risk patient subgroups, and use of PE response teams (PERT) in all hospitals treating PE are likely to result in better patient outcomes. World thrombosis day (October 13^th) may be an excellent opportunity to call upon our colleagues around the world to evaluate the care for PE patients in their hospitals, harmonize local treatment protocols and introduce a multidisciplinary PERT.

Comments by the Author (Prof. D. Jiménez)

• Experience improves outcomes of patients with acute symptomatic pulmonary embolism.
• Future research might clarify whether experience involves accumulation of cases in referral centers, strict adherence to clinical practice guidelines, development of local protocols, or a combination of them.