Abstract: By making use of the data of China Family Panel Studies (CFPS), this paper constructs a panel threshold model of the response differences in the medical economic risk expectations to family medical burdens of relatively poor families. The findings show that the standard of catastrophic medical expenditures of relatively poor families is that medical expenditures account for 21.02% of other expenditures except food, education and housing. Then it constructs a Tobit Durbin model of spatial metrology and a spatial Durbin Tobit mediation model to empirically test the spatial transmission mechanism of catastrophic medical expenditures among relatively poor families with social networks as medium and the spatial impacting mechanism of medical security system on catastrophic medical expenditures of relatively poor families respectively. These findings suggests that, by influencing the transfer expenditure pressure and the health level of community families through social relations, catastrophic medical expenditures can be transmitted among relatively poor families. However, the medical security system can effectively alleviate the transfer expenditure pressure among relatively poor families and improve the overall health welfare of community families, thus hindering the transmission of catastrophic medical expenditures among relatively poor families.

Key words: catastrophic medical expenditures, relatively poor families, the spatial transmission mechanism, the spatial Durbin Tobit model