“…Nevertheless, several hard issues preventing drug evaluation using biomarkers need to be solved [ 10 ]. With the aim to elucidate whether correction of hyponatremia is a treatment stratification biomarker [ 11 ], a two-stage systematic review and meta-analysis were performed to summarize the efficacy of the V 1A /V 2 -receptor antagonist conivaptan [ 12 , 13 , 14 , 15 ] and the V 2 -receptor antagonists lixivaptan [ 16 , 17 , 18 , 19 , 20 ], satavaptan [ 21 , 22 , 23 ] and tolvaptan [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] in relation to changes in [Na + ] serum in patients with worsening HF or cirrhotic ascites.…”