A study on 201 AS patients recorded that total SC has a median value of 31, 19 million VND (IQR: 23, 92 million - 45, 63 million VND), in which direct medical costs dominated with median value of 25, 83 million VND (IQR: 20, 52 million - 39, 22 million VND), non-medical direct costs - 1, 03 million VND (IQR: 0, 62 million - 1, 84 million VND), indirect costs - 2, 27 million VND (IQR: 1, 31 million - 4, 09 million VND).