34% of doctors don’t think they should disclose serious medical errors to patients, and nearly 20% said they didn’t disclose an error last year for fear of a malpractice case.Almost two-fifths of doctors don’t think they need to share their financial relationships with drug companies to patients.Just over 10% of physicians say they told their patients something that wasn’t true in the past year.55% of doctors say they often or sometimes describe a patient’s prognosis in a more positive manner than the facts might support.

So what’s up with the lying? Doctors may not be 100 percent truthful for a range of reasons—from fear of malpractice suits to finding it difficult to deliver a dire diagnosis. “We don’t know the exact reasons for many of these findings, but it is a sign of caution that patients need to be aware of,” says Lisa Iezzoni, MD, lead study author and professor of medicine at Harvard Medical School.  Because all patients aren’t created equal, a one-size fits all treatment approach may not be the most effective—and it could also be contributing to less than full disclosure on the part of physicians. “Doctors are trying to do the right thing, but patients have to speak up about their individual values and lifestyle needs,” says Dale Collins, MD, director of The Center for Informed Choice at the Dartmouth-Hitchcock Medical Center. “If you don’t speak up, doctors will make assumptions based on their own experiences and perceptions of what you might want—and their approach may not be the best fit for you.”  More from Prevention: Cures Your Doctor Won’t Reveal  Try these five tips for honest communication with your doctor:

  1. Tell her what you want. “Don’t assume your physician knows what you want,” says Dr. Iezzoni. “There are some patients who don’t want to know everything and would rather their doctor simply tell them what to do. Tell your doctor if you want her to be very frank and open with you, and if you want to play an active role in the decision making.” 
  2. Educate yourself. “I’m a big believer in reviewing information about your treatment decisions before your appointment,” says Dr. Collins. Ask your doctor for recommendations on the best resources for your diagnosis before your next visit. “This arms you with knowledge about your condition so you can have a more informed conversation about treatment,” says Dr. Collins.
  3. Have a face-to-face. Schedule a time to talk in person rather than over the phone or email. “It’s much easier to know if someone is being open and frank with you when you’re looking into their eyes,” says Dr. Iezzoni.
  4. Jot down questions beforehand. Sitting in a doctor’s office can be nerve-wracking, making it easy for your mind to go blank. “Prepare questions in writing so you won’t forget what you want to say,” says Dr. Collins. 
  5. Don’t be shy about speaking up. “When something doesn’t feel right, it can be hard for patients to speak up because they don’t want to contradict their doctors,” says Dr. Collins. But you know your body better than anyone else. If you don’t understand something, or something just doesn’t sound right, ask your doctor point-blank, and be specific. “Maybe you misunderstood, or maybe the doctor misspoke because she was tired,” says Dr. Iezzoni. “Doctors are human.” More from Prevention: 15 Ways to Improve Your Relationship With Your Doctor