You know that kindly older doctor you have been seeing for years? Very experienced, wonderfully reassuring. Silver-haired and authoritative, with a warm bedside manner. Sort of like Marcus Welby, M.D.

Turns out you might be better off with Doogie Howser.

According to a study by Harvard researchers, patients of older physicians have a higher mortality rate than those of their younger colleagues.

The study, published in the British Medical Journal, looked at more than 700,000 patients being treated by about 19,000 doctors from 2011 to 2014, reported Ars Technica, a tech and science website. All the patients were aged 65 or older and on Medicare. From the data, researchers found a clear rise in mortality rates as the age of the doctors increased.

Patients with doctors under the age of 40 had a 30-day mortality rate of 10.8 percent. With doctors aged 40 to 49, mortality rates inched up to 11.1 percent, then to 11.3 percent with doctors 50 to 59, and 12.1 percent with doctors aged 60 or above.

And a British newspaper, The Independent, reported that the data point to one more death per 77 patients between a 40-year-old doctor and a 60-year-old one. Meanwhile, the paper said, a 2014 census of registered American physicians found that 26.3 percent of doctors in the U.S. are 60 years or older, with nine percent of those over 70.

The researchers, however, were careful to note that the study was “observational” and that more detailed work needed to be done to confirm the results.

And there was, sorry, a wrinkle in the data – older doctors with high numbers of patients didn’t see their patients’ mortality rates increase, a factor, reported Ars Technica, that the researchers attributed to the possibility that these busier doctors may be impelled to brush up on the latest developments. Added to that, they may get more patients because they keep up and are therefore more highly regarded.

The findings “suggest that continuing medical education of physicians could be important and that continual assessment of outcomes might be useful,” the researchers, headed by Harvard’s Dr. Yusuke Tsugawa, said.

“One thing I want to emphasize is that we don’t think as doctors get old that their quality gets worse,” Tsugawa told CBS News. “It is more likely that what we are observing is the differences in training they have received,” with younger doctors more likely to be familiar with the latest technology and techniques.

“Medical technologies are evolving all the time and it might be harder for older doctors to keep up with the evidence,” added Tsugawa, who also participated in a study that said the patients of female doctors were four percent less likely to die than those treated by men. “Newer doctors train based on the newest evidence and skills and technologies. Therefore, they may be more up-to-date when they start providing care.”

Matthew Diebel, USATODAY