• Pedro Henrique França Gois and Edison Regio de Moraes Souza.
• Department of Nephrology, Royal Brisbane and Women's Hospital, Herston, Australia.
• Cochrane Db Syst Rev. 2020 Sep 2; 9 (9): CD008652CD008652.

BackgroundThis is the second update of this systematic review. High blood pressure represents a major public health problem. Worldwide, approximately one-fourth of the adult population has hypertension. Epidemiological and experimental studies suggest a link between hyperuricaemia and hypertension. Hyperuricaemia affects 25% to 40% of those with untreated hypertension; a much lower prevalence has been reported in those with normotension or in the general population. However, whether lowering serum uric acid (UA) might lower blood pressure (BP), is an unanswered question.ObjectivesTo determine whether UA-lowering agents reduce BP in people with primary hypertension or prehypertension, compared with placebo.Search MethodsThe Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to May 2020: the Cochrane Hypertension Specialised Register, CENTRAL 2018, Issue 12, MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched LILACS (1982 to May 2020), and contacted authors of relevant papers regarding further published and unpublished work. The searches had no language or date restrictions.Selection CriteriaTo be included in this updated review, the studies had to meet the following criteria: 1) randomised or quasi-randomised, with a group assigned to receive a UA-lowering agent and another group assigned to receive placebo; 2) double-blind, single-blind, or open-label; 3) parallel or cross-over trial design; 4) cross-over trials had to have a washout period of at least two weeks; 5) minimum treatment duration of four weeks; 6) participants had to have a diagnosis of essential hypertension or prehypertension plus hyperuricaemia (serum UA greater than 6 mg/dL in women, 7 mg/dL in men, and 5.5 mg/dL in children or adolescents); 7) outcome measures included change in 24-hour ambulatory systolic or diastolic BP, or both; or clinic-measured systolic or diastolic BP, or both.Data Collection And AnalysisThe two review authors independently collected the data using a data extraction form, and resolved any disagreements via discussion. We assessed risk of bias using the Cochrane 'Risk of bias' tool. We assessed the certainty of the evidence using the GRADE approach.Main ResultsIn this review update, we screened 722 records, selected 26 full-text reports for evaluation. We identified no ongoing studies and did not add any new studies. We included three randomised controlled trials (RCTs), enrolling 211 people with hypertension or prehypertension, plus hyperuricaemia. Low-certainty evidence from three RCTs found inconclusive results between those who received UA-lowering drugs and placebo, in 24-hour ambulatory systolic (MD -6.2 mmHg, 95% CI -12.8 to 0.5) or diastolic BP (-3.9 mmHg, 95% CI -9.2 to 1.4). Low-certainty evidence from two RCTs found that UA-lowering drugs reduced clinic-measured systolic BP (-8.43 mmHg, 95% CI -15.24 to -1.62) but results for clinic-measured diastolic BP were inconclusive (-6.45 mmHg, 95% CI -13.60 to 0.70). High-certainty evidence from three RCTs found that serum UA levels were reduced by 3.1 mg/dL (95% CI 2.4 to 3.8) in the participants that received UA-lowering drugs. Low-certainty evidence from three RCTs found inconclusive results regarding the occurrence of adverse events between those who received UA-lowering drugs and placebo (RR 1.86, 95% CI 0.43 to 8.10).Authors' ConclusionsIn this updated Cochrane Review, the current RCT data are insufficient to know whether UA-lowering therapy lowers BP. More studies are needed.Copyright © 2020 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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