About a quarter of all U.S. health care spending — $760 billion to $935 billion per year — can be categorized as waste. But home-based care has already helped cut those costs in the past few years — and has even more potential to so in the future. That’s according to new research from Humana Inc. (NYSE: HUM) and the University of Pittsburgh School of Medicine published Tuesday in the Journal of the American Medical Association (JAMA). Specifically, researchers reviewed 71 was