Similarly , SDMA in the 4th quartile was independently associated with all-cause mortality ( HR , 4.56 ; 95 % CI , 2.15-9 .71 ; P < 0.001 ) , and there was a strong borderline significant trend for an association with cardiovascular mortality ( HR , 2.86 ; 95 % CI , 0.99-8 .21 ; P = 0.051 ) .