Post-surgery Complication Risk is Lower for Patients Whose Surgeons Perform More Thyroidectomies Annually, Study Says

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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The probability a patient has of developing hypoparathyroidism and other complications after undergoing thyroid surgery tends to decrease if the procedure is performed by a surgeon who undertakes a high number of surgeries every year, a study has found.

Results from the study, “Association Between Annual Surgeon Total Thyroidectomy Volume and Transient and Permanent Complications,” were published in JAMA Otolaryngology – Head & Neck Surgery.

Although research has shown a direct relationship between the number of surgical procedures a surgeon performs every year and patients’ post-surgical outcomes, the specific number of annual procedures needed to significantly reduce the chances that a patient has of developing complications is still unclear.

In the case of thyroidectomies (a surgical procedure to remove the entire thyroid gland that can also damage the parathyroid glands), a recent study suggested that the recommended number of 20 annual procedures for a surgeon to be deemed competent in the U.K. should be increased to approximately 50 procedures per year to reduce patients’ risk of permanent hypoparathyroidism.

In this study, Kaiser Permanente researchers came up with a model to estimate the exact number of surgeries a surgeon must perform every year to significantly reduce the risks of hypoparathyroidism and vocal cord paralysis (VCP) in patients undergoing total thyroidectomy.

The retrospective cohort study involved a total of 10,546 patients who underwent the procedure between January 2008 and December 2015, and were closely monitored until December 2017 at two different Kaiser Permanente centers (in northern and southern California).

The relationship between the annual number of surgeries performed every year and patients’ clinical outcomes was used as a basis for the model, after data adjustments for sociodemographic factors and other parameters.

Most patients (40.6%) were operated by surgeons who performed 20 or more thyroidectomies every year. Approximately a quarter of the patients (27.7%) were operated by surgeons who had the lowest rates of annual procedures (between one to nine total thyroidectomies per year).

According to their generalized additive model, the incidence rates of VCP started to decrease substantially when surgeons performed a minimum of 18.2 thyroidectomies per year, and the rates of hypoparathyroidism decreased when they performed a minimum of 18.1 procedures.

A refined model also confirmed that, as expected, the incidence rates of complications decreased as the number of annual procedures increased.

Findings also showed that 6.0% of the patients participating in the study developed temporary hypoparathyroidism following surgery, and fewer (1.6%) developed permanent hypoparathyroidism. Equally low was the percentage of patients developing transient (4.2%) or permanent VCP (1.7%).

When the annual rates of thyroidectomies were set to a minimum of 40 procedures per year, the incidence rates of permanent and temporary VCP and hypoparathyroidism dropped slightly (between 0.6% and 1.5%), according to the model.

“The very low overall rates of these complications in our system limit the degree to which the statistically significant findings may have practical utility,” the researchers wrote, adding that “shifting patients to higher-volume surgeons to realize these reductions may be of variable attractiveness in systems with low baseline complication rates.”

“Although our results suggest that the impact of surgeon volume on important complications of thyroidectomy may be less than that previously reported, they should be generalized with great caution to settings where access issues and fragmented care may be more likely,” the researchers said.