Why are physicians leaving their practices?

Physicians are leaving the practice of medicine in large numbers, but its probably not due to electronic medical records (EHRs) or ObamaCare, but a much more mundane reason–we are getting older.  Several articles over recent years have claimed the difficulty of practicing medicine with electronic medical records, or the bureaucratic requirements of the Affordable Care Act, are driving physicians into retirement in droves, most recently perhaps in an article by Charles Krauthammer, himself a physician, in Investors Business Daily last week.  Dr. Krauthammer laid the blame on EHRs and the time required for physicians to sit in front of a computer screen and not in front of a patient.  However, a recent article in Forbes calls into question these conclusions, not questioning whether physicians are quitting in historically high numbers, but why.  This article, at http://www.forbes.com/sites/dandiamond/2015/06/02/why-doctors-really-quit/?ss=pharma-healthcare, makes the point that we are quitting because we are getting older.  In 2012, for the first time, the number of physicians 55 and older equaled the number of physicians aged 35-54, whereas more typically for the last 40 years, the number of physicians practicing aged 55 or more was half or 2/3 of the number aged 35-54.  So basically we have had to work longer than before and now more of us are finally retiring, albeit at an older age then before.