(CNN) Donald Trump's doctor told CNN in an interview he stands by the letter he wrote for the Republican nominee vouching for his good health and has no regrets about being embroiled in the controversy over it.

When asked if Trump has the physically capability of being president, Dr. Harold Bornstein told CNN's Drew Griffin on Thursday, "Absolutely, no question about it."

Bornstein, a 69-year-old New York City gastroenterologist, has been Trump's physician for more than three decades and came under scrutiny for an unusual letter he wrote in 2015 describing Trump's physical health, which other doctors have said includes strange wording, medically incorrect terms and an unprofessional conclusion.

Trump's lab "test results were astonishingly excellent," he wrote, mimicking the grandiose verbiage of his candidate-patient. "If elected, Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency."

Bornstein told CNN that he was rushed for time when writing the letter since he had patients to see.

"The only thing I wanted to do in my life is practice with my father, which I managed to do for 35 years."

Bornstein told CNN that his father started his medical practice at the same Park Avenue office location in 1947.

Trump was first under the care of his father Dr. Jacob Bornstein, according to the letter. Harold Bornstein joined the practice in 1980, and when his father passed away in 2010, continued it.

When asked if he had any regrets about getting involved in the presidential election, Bornstein said, "No. My patients, I take care of them the right way."

The CNN interview was cut short when Dr. Bornstein's wife approached, and covered the camera with her hand. Bornstein had warned it might happen. "My wife will come back, she'll get angry," he said as the interview began.

At least four medical malpractice lawsuits have been filed against Dr. Harold Bornstein in the state of New York dating back to 1986.

In a 1999 lawsuit, New York resident Kenneth Levin accused Bornstein of negligence in failing to properly diagnose and treat his wife by "overmedicating" her with prescription drugs and not following proper medical procedures, which Levin argued led to her death.

The case argues Bornstein "prescribed unnecessary barbiturates and other drugs to the decedent with full knowledge that these medications were not necessary" and that some were "greatly in excess of appropriate dosages."

Bornstein denied the allegations and settled the case in 2002 for $86,000 with no finding of liability.

Another case charged both Bornstein and his father of recklessness in overdosing and improperly performing a colonoscopy on Vincent Pollifrone, which the case argued led to his death in 2000. The case was disposed in 2006, after the defendants denied the claims.

The plaintiff's lawyer in that case, Joseph Miklos, told CNN the parties signed a confidentiality agreement so he could not discuss the terms of any settlement.

When asked about the lawsuits Thursday, Bornstein defended his credentials and said the number of malpractice suits he has faced is "normal."

Professor David Studdert of Stanford University, an expert on health law who has tracked data on medical malpractice lawsuits, said gastroenterologists such as Bornstein have about a 10% chance of facing a new medical malpractice suit each year.

"Over a career, it would be the norm rather than the exception that a gastroenterologist would have a few claims filed against him. That's not an outlier situation," Studdert said.

Dr. G Kevin Donovan, a bioethicist at Georgetown University Medical School, agrees that the existence of four disposed malpractice suits does not provide enough information to draw conclusions about Bornstein, but he said Bornstein's letter describing Trump's health is light on detail and heavy on bombast.

Donovan said most physicians "don't use that kind of hyperbole for a medical statement."

Donovan added that most letters written by doctors for presidential candidates contain a level of subjectivity since candidates select the doctors who write their assessments and can stipulate what information they include.

"They can only tell us what the candidate allows them to reveal," Donovan said, adding, "Is it likely that a candidate would go to a physician that would not speak well of them?"

Former patients and a classmate of Bornstein reached by CNN described him as competent yet eccentric.

New York resident Roger Friedman, who said he was a patient of Bornstein's in the 80's and early 90's, said he was surprised when he recently heard Bornstein had treated Trump for decades.

"He was a good doctor but he was peculiar, disorganized, and not at the level you expect for a billionaire," Friedman said.

Angelina Kaiserman, a New York jeweler who told CNN she has been in Bornstein's care for more than 20 years, said, "Honestly I give him five stars."

Dr. Edward Hurwitz, who attended medical school with Bornstein at Tufts University in the class of 1975, remembers Bornstein making sarcastic comments in class and often writing elaborate poems with colorful language he would share with friends.

"He was snide with his comments but he was certainly smart," Hurwitz said.