Regional variations in pulmonary endarterectomy rates within the UK

To the Editors:

We were very interested in the paper by Toshner et al. 1 which highlights regional variations in pulmonary endarterectomy (PEA) rates for the UK population. The authors explore the reasons for this variability. Understandably they dismiss the possibility of differences due to variability in incidence or management. Their analysis looks at the PEA rate rather than the referral rate. This reduces, but does not abolish, the varying threshold for referral by designated centres as a cause. However, they conclude that the differences shown in the paper, are in a large part, due to the distance of patients from nationally designated centres for the management of pulmonary hypertension.

The one region that does not fit with this explanation is Scotland (UK) where there is a national centre for the management of pulmonary hypertension (the Scottish Pulmonary Vascular Unit (SPVU), Glasgow, UK) but the PEA rate appears to be similar to that seen in regions not served by pulmonary hypertension centres. In order to understand the reasons for the Scottish results, we have analysed the data on chronic thromboembolic pulmonary hypertension (CTEPH) patients seen by the SPVU between 2000 and 2008 (table 1⇓).

These data show a number of possible additional reasons for the low Scottish rate seen in the Toshner et al. 1 study. The first is that the period 2000–2006 was early in the existence of the SPVU when its referral base was building rapidly. PEA incidence in our patients has increased dramatically over the last 8 yrs leading to a three-fold increase in the number of patients with CTEPH referred to our unit between the two epochs analysed in table 1⇑. This occurred in parallel with an increase in referral rate to the SPVU of all forms of pulmonary hypertension, which doubled between 2003 and 2007. We do not know if the data for the English units show a similar activity trend. For the period 2004–2008, the annual Scottish PEA rate was 1.0 case·million⁻¹·yr⁻¹. This is much closer to the average East of England rate for 2000–2006 (1.27 cases·million⁻¹·yr⁻¹) than the figure calculated by Toshner et al. 1 for Scotland for 2000–2006 (0.57 cases·million⁻¹·yr⁻¹).

Secondly, the incidence of operable patients in Scotland between 2004 to 2008 was 1.3 cases·million⁻¹·yr⁻¹ (cf. the PEA rate for East of England patients 1.27 cases·million⁻¹·yr⁻¹). However, five (19%) of the Scottish CTEPH patients who were deemed operable declined surgery. This compares with 9% of patients who declined surgery in the UK as a whole 2. In four out of five of these cases, the patients had mild disease and did not consider the risk-b`enefit ratio of surgery to be in their interest. The fifth patient did have more severe disease but was aged 81 yrs and both distance and risks of surgery were deterrent factors. We do not know the proportion of operable patients who proceed to surgery for the other UK regions. It may be that this is lower in Scottish patients because of the greater distances involved or different interpretation of the risks of surgery.

Thirdly, it is the policy of our unit to refer all patients diagnosed with CTEPH to Papworth Hospital (Cambridge, UK) for their opinion on operability. Despite that policy, this opinion was not obtained in eight (12%) of our cases. We have reviewed these cases locally since the publication of the study by Toshner et al. 1 and are confident that these do not represent any missed operable cases.

In conclusion, current data from the Scottish Pulmonary Vascular Unit are closer to that seen in UK areas with nationally designated centres than estimated in the study by Toshner et al. 1 and add support to the conclusion that all such centres promote increased referral rates for pulmonary endarterectomy. Analysis of incidence of technically operable cases rather than pulmonary endarterectomys performed might give a more accurate comparison between regions.

Statement of interest

A statement of interest for A.J. Peacock can be found at www.erj.ersjournals.com/misc/statements.shtml