Encouraging immigrants to visit primary care doctors creates a striking decline in costly emergency room use, according to a new study co-authored by an MIT economist. The findings are from a New York City program that helped arrange medical appointments for undocumented immigrants with limited incomes, from May 2016 to June 2017. Those who received assistance in scheduling visits with primary care physicians experienced a 21 percent drop in emergency department use. For individuals with high-risk medical profiles who received the same help, emergency department use dropped by 42 percent….