A method is provided for a medical risk stratification system. The olefinic thermoplastic elastomer composition is characterized in that the glass transition temperature in dynamic visco-elasticity measurement derived from the polypropylene resin is lower than that of the polypropylene resin itself and that the -olefinic copolymer is at least one selected from the following and :. Optionally, a fifth component made be added, namely a hydrocarbon based refrigerant such as iso-butane or propane, to further improve characteristics of refrigerant.