Centralization of adrenal surgeries and improved surgeon volume outcomes

The incidence of adrenal surgeries continues to rise worldwide due to increasing use of imaging techniques, and detection of subclinical functional adrenal tumours. Adrenalectomies are complex procedures with the potential for increased peri- and postoperative morbidity and mortality. Majority of adrenal surgeries are performed using minimally invasive techniques either via anterior or posterior approach depending on the size of tumours, bilaterality, nature of disease and patient factors. Shorter hospital stays, reduced postoperative pain, early return to work and routine activities, reduced complications and lower costs are the main advantages of a laparoscopic/retroperitoneoscopic surgical approach (1,2). However open adrenalectomy is the preferred choice in adrenocortical malignancies or very large adrenal tumours in order to maintain safe and oncological principles (3).

A lot of previous published studies focused on surgical volume/outcome relationships since the first introduction of the topic by Luft et al. in 1979 (4). Subsequently over the years improved outcomes have been correlated when surgeries performed by high-volume surgeons in high-volume hospitals such as aortic and vascular procedures, surgery for colorectal, pancreatic and esophagogastric cancers, and thyroidectomy (5,6). Findings from these studies prompted the drive for “centralization” of services for complex high-risk procedures in the UK, US and a few other countries (7). In relation to adrenal surgery, guidelines pertaining to the optimal management of adrenal conditions recommend that adrenalectomy should only be performed by high-volume surgeons and centralized at high-volume centers (8-10).

How can a high-volume adrenal surgeon be best described? The definition of high-volume adrenal surgeon varies between countries, ranging on an average of over 4 to 7 adrenalectomies per year. Anderson et al. in a study of 6,712 adrenalectomies (performed over a period of 11 years) found the optimal volume threshold of 6 cases per year for a surgeon to perform in order to have low postoperative complication rates, shorter hospital stay and better financial costs (11). However, a large number of adrenal surgeries tend to be performed by low volume surgeons, with some performing only up to one case per year, which is not ideal (11,12). As regards adrenocortical carcinoma, the data on outcomes and surgeon volume is less abundant, with one study showing a lower recurrence rate and improved outcomes in a high-volume centre (13), whereas another study showed no difference between high- and low-volume centre on outcomes (14).

Majority of studies reporting on surgeon volume outcomes in adrenal surgery were very heterogeneous. The studies did not show outcomes relating to approaches (anterior versus posterior), and were not tailored to specific patient populations and tumours that require a definitive multidisciplinary input such as pheochromocytoma (15). In a recent study published in the Br J Surg by Rajan et al. the authors showed that the incidence of postoperative complications appeared to be significantly lower when the threshold was above 12 operations per year (P=0.034) and 20 per year (P<0.001), but not six per year (P=0.540) (16). Nearly half of the surgeries undertaken by the surgeons were for adrenal carcinoma (6.2%), adrenal metastasis (8.1%) and phaeochromocytoma in (30.8%), which require a multidisciplinary approach, and therefore emphasizes the fact that such cases be best undertaken by high-volume surgeons or centres. The study also reported lower outcomes for bilateral surgery with a posterior approach. The authors of the study questioned the rationale of restricting surgery for pheochromocytoma to high-volume surgeons as was found not to be an independent risk factor for complications or death. If one were to consider this argument to be valid, then a significant number of adrenalectomies, especially pheochromocytomas might end up being done by low volume surgeons, which may be associated with adverse outcomes.

Evaluating volume outcomes in adrenal surgery can be challenging as the procedure may be performed by general surgeons, urologists and endocrine surgeons. The proceduralist of choice for adrenal pathologies varies with countries, with endocrine surgeons performing most of the cases in the UK whereas in the US it is the urologist (16,17). However, studies have showed no difference in volume outcomes based on the specialists performing adrenal surgeries (17). There is also a difference in benign adrenal pathologies between Asia and the West, with a higher rate of Conn’s in the East and pheochromocytoma/paraganglioma in the west (18). Besides the difference in pathologies seen, data pertaining to volume-based outcomes is lacking in the many countries outside of Europe and US, especially from the developing and low-income countries.

Centralization of adrenal procedures to a hospital with an established multidisciplinary team seems to be the best way forward to reduced complication rates, deaths and avoid unnecessary surgical procedures. The number of cases recommended to be done per year by a surgeon performing adrenal surgery is increasing as new studies are being published and it looks this will be the trend in the upcoming years. It is difficult to apply these recommendations in countries outside of Europe and US as medical systems are different and volume-based outcome data is lacking currently.

Acknowledgments

Funding: None.

Footnote

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