Among patients randomized to cinacalcet , a 30 % reduction in FGF23 between baseline and week 20 was associated with a nominally significant reduction in the primary composite end point ( relative hazard , 0.82 ; 95 % confidence interval , 0.69-0 .98 ) , cardiovascular mortality ( relative hazard , 0.66 ; 95 % confidence interval , 0.50-0 .87 ) , sudden cardiac death ( relative hazard , 0.57 ; 95 % confidence interval , 0.37-0 .86 ) , and heart failure ( relative hazard , 0.69 ; 95 % confidence interval , 0.48-0 .99 ) .