Nashville-area hospitals are adding more services closer to where people live, hoping to attract better-paying, commercially insured patients — as well as provide basic care and medical tests in settings that don’t require an overnight stay. After taking a pause on construction amid a slower economy, hospitals here are once again starting to invest in outpatient services — often in suburban settings — to bring medical tests and minor surgeries to the places where many people live. … The outpatient boom is part of a national trend. In the past two years, hospital outpatient care has accounted for the most growth in health-care spending for the typical American family of four, according to actuarial consulting firm Milliman. From 2009 to 2010, it rose to 17.1 percent of total costs, outpacing growth in other categories such as inpatient care, physician services and prescription drugs.