Chicago ? Many patients stop taking their medicine far sooner than they should, researchers say, and that decision can be deadly when the drugs treat heart disease or diabetes.

It took only one month after leaving the hospital for 1 out of 8 heart attack patients to quit taking the lifesaving drugs prescribed to them, a study of 1,521 patients found.

“One month is very surprising,” said study co-author Dr. Michael Ho of the Denver Veterans Affairs Medical Center.

The heart patients who stopped taking three proven drugs were three times more likely to die during the next year than patients who stayed on the pills.

The study didn’t examine why people stopped taking their medicine, but the patients who quit were more likely to be older, single and less educated.

They’re in good company. Former President Bill Clinton – a younger, married and well-educated patient – was prescribed a statin for high cholesterol when he left office. But he stopped taking it at some point. And at age 58, he had to have quadruple bypass surgery because of severely clogged arteries that doctors said put him danger of a heart attack.

The study of heart patients appears in Monday’s Archives of Internal Medicine. The issue features a group of studies on patients who stopped taking their medications.

One of the studies reviewed medical records of 11,532 diabetes patients. It found that those who didn’t take their drugs had higher rates of hospitalization and death. The link was not as pronounced as in the heart attack research, but was still significant.

In recordings of 185 patient visits, doctors failed to mention a new drug’s side effects or how long to take the drug in about two-thirds of the visits.

One entire conversation about a new prescription captured on tape went like this:

Doctor: “If I’m writing antibiotics, are you allergic to penicillin?”

Patient: “No. I’m not allergic to anything.”

Doctor: “Okey dokey.”

Study co-author Dr. Derjung Tarn of the University of California, Los Angeles, said, “We need to find quick and easy ways to communicate in ways patients can easily understand and remember.”

Some patients assume they quit their pills if the doctor says their cholesterol looks good, said Dr. Kim Eagle of the University of Michigan.

“Generally, these medications need to be continued to have their benefit,” he said of drugs that fight heart disease. But many factors, he said, conspire against regular drug-taking: cost, side effects, depression, carelessness and a desire not to be someone who takes a lot of pills.