0941 GMT - U.S. public finances are becoming more dependent on future interest-rate changes by the Federal Reserve, Scope Ratings' Eiko Sievert says in a note. The Treasury's growing reliance on T-bills helps to contain financing costs in the short term but entails significantly higher refinancing risk, he says. Scope expects U.S. public debt to rise to 138% of GDP in 2030 from 124% in 2025. This would be higher than in all eurozone countries, with Italy's the biggest at 136%, albeit lower than Japan's 200%, he says. However, a high debt-to-GDP ratio alone doesn't mean acute refinancing risks. Other factors are important too, including maturity structures and the U.S. dollar's role as a global safe-haven currency, he says.