The study included a review of previously published papers with a large sample size of doctors. These studies included measures of physician knowledge or quality of care as well as the time since the physician’s medical school graduation or the physician’s age. The majority of these studies showed a decline in performance with time.

Co-author Stephen Soumerai, Harvard Medical School professor of ambulatory care and prevention, says that recently adopted medical techniques may be difficult to accept for more experienced doctors.

In the study, Harvard Medical School instructor Niteesh Choudhry and his colleagues categorized the 62 studies into groups based on a doctor’s knowledge. The results indicate that older and longer-practicing doctors are less knowledgeable, less likely to adhere to appropriate standards of care, and may also have poor patient outcomes.

Twenty-four of the 62 studies examined a doctor’s use of diagnostic and screening tests and preventative health care. Sixty-three percent of these studies demonstrated that more experienced doctors were less likely to adhere to current standards. Doctors who graduated more than 20 years ago were less likely to adhere to recommended cancer screening guideline practices.

The influence of a doctor’s age or years in practice on performance was examined; 74 percent of these studies found that older physicians were less likely to adhere to therapeutic standards.