Schneider MT, Chang AY, Crosby SW, Gloyd S, Harle AC, Lim S, Lozano R, Micah AE, Tsakalos G, Su Y, Murray CJL, Dieleman JL. Trends and outcomes in primary health care expenditures in low-income and middle-income countries, 2000-2017. BMJ Glob Health. 2021