It was only later that he learned his doctor had been fired by the Iowa Clinic and planned to start a urology practice with clinic colleagues. And, under the terms of their contract with their former employer, the doctors were banned for a year from practicing within 35 miles of the clinic, and from recruiting former patients to follow them.

Contracts with so-called restrictive covenants are now common in medicine, although some states limit their use. Noncompete clauses — common in many commercial sectors — aim to stop physicians and other health care professionals from taking patients with them if they move to a competing practice nearby or start their own. But what may be good for business can be bad for patient care — and certainly disquieting for those whose doctors seem to simply disappear.

One survey of nearly 2,000 primary care physicians in five states found that roughly 45 percent were bound by such clauses.

Continuity of care is important, doctors say, especially for patients with ongoing medical issues. Cutting off access to a doctor is different from disrupting someone’s relationship with a favorite hairstylist or money manager, they say.

“When doctors want to move from one practice to another, if they’ve got good therapeutic relationships with their patients, you’d think that public policy would want them to continue to treat these patients that trust them,” said Judy Conti, government affairs director at the National Employment Law Project.