WEDNESDAY, Jan. 11 (HealthDay News) -- Surgeons aged 35 to 50 provide the safest care for patients, a new study suggests.

The findings raise concerns about ongoing training and motivation of surgeons during their careers, according to the researchers at the University of Lyon in France.

They analyzed data from 3,574 thyroidectomies (removal of the thyroid gland) by 28 surgeons at five French hospitals over a one-year period. The average age of the surgeons was 41 and they had an average of 10 years of experience.

The researchers looked at the rates of two major complications 48 hours and at least six months after surgery: permanent recurrent laryngeal nerve palsy (severe hoarseness) and hypoparathyroidism (damage to the parathyroid glands that results in low calcium levels, cramping and twitching).

The results showed that patients had a higher risk of permanent complications when their procedure was performed by inexperienced surgeons or those with 20 or more years of experience. Surgeons aged 35 to 50 with five to 20 years of experience had better outcomes than those who were younger or older.

Other unknown or unexamined factors may explain part of the variation in patient complication rates, the researchers noted. However, they said their findings suggest that surgeons' performance can vary over the course of a career and that surgeons cannot achieve or maintain optimal performance simply by accumulating experience.

This raises concerns about ongoing training and motivation throughout a career than can last several decades, the researchers said.

The study was published Jan. 10 online in the British Medical Journal.

More information

The U.S. Agency for Healthcare Research and Quality outlines what you need to know about surgery.