Relative kidney hyperfiltration in primary aldosteronism: a meta-analysis

Introduction: Since the phenomenon of hyperfiltration in primary aldosteronism (PA) was first noted in 1996, subsequent clinical studies have produced conflicting results. To determine the development of relative hyperfiltration in PA, we performed a meta-analysis. Methods: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched through to July 2009. Reference sections of original articles, meta-analyses, and reviews on hyperfiltration in PA were reviewed. Hypertensive patients provided the controlled data for hyperfiltration. Two authors independently extracted the data. Results: A total of seven studies were included. One study was from the data of the TAIPAI group. Overall, there was strong evidence that relative kidney hyperfiltration existed in PA (fixed-effects model: standardised mean difference (SMD), 0.13; 95% confidence interval (CI), 0.03-0.22, p = 0.007; random-effects model: SMD, 0.35; 95% CI, -0.01-0.71, p = 0.05), though with a significant heterogeneity (p < 0.0001). In the secondary meta-analysis with five top-quality studies, the relative kidney hyperfiltration was more significant. Mean age in each enrolled study was the only factor significantly associated with the existence of heterogeneity among the selected studies in the meta-regression analysis. Conclusions: Current evidence suggests that relative kidney hyperfiltration is the hallmark in PA and the phenomenon is beyond the effect of hypertension of PA. Clinicians should be aware of the possibility of occult renal damage in patients with PA.