Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials

Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials

Por: WheltonP K, HeJ, CutlerJ A, BrancatiF L, AppelL J, FollmannD and KlagM J, . Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials. JAMA 1997;277(20) :1624-1632.

Authors’ objectives

To assess the effects of supplementation with oral potassium on blood-pressure (BP) in humans.

Searching

MEDLINE was searched using the terms ‘blood pressure’, ‘dietary potassium’, ‘potassium’ and ‘potassium chloride’. Bibliographies of original articles and reviews, and the authors’ own reference files were also examined. Only English-language articles published before 1995 were considered.

Study selection: study designs

Randomised controlled trials (RCTs) of either parallel or crossover design were included. The duration of the studies varied from 4 days to 3 years.

Study selection: specific interventions

Potassium supplementation administered as a pill (in the form of potassium chloride, potassium citrate and bicarbonate) or as part of the diet. Dosage of potassium prescribed in the intervention arm was at least 60 mmol/day in all but 2 trials, and at least 100 mmol/day in 10 trials (median, 75 mmol/day). The intervention arm was compared to a control group of either placebo, lower dose of potassium, or no supplementation. Antihypertensive medications were administered concurrently in 4 of the trials.

Study selection: participants

Both hypertensive and normotensive participants (aged 19 years) were included in the review.

Study selection: outcomes

The net change from pre-treatment to end of follow-up in urinary excretion of sodium and potassium, body weight, and BP (systolic and diastolic) for treatment and control conditions. The mean 24-hour urinary sodium excretion during follow-up, recorded at the trial’s end.

Study selection: how were decisions on the relevance of primary studies made?

The primary studies were assessed independently for relevance by two of the review’s authors. Areas of disagreement or uncertainty were adjudicated by other authors.

Validity assessment

No formal validity assessment was carried out, although study design details were recorded during the data extraction phase; these included whether the trial was of parallel, crossover or open design, single-blind or double-blind. Details of the study design were recorded independently by two of the authors who were blinded to each other’s coding. This process was carried out during the data extraction phase.

Results of the review

Thirty-three RCTs (1,560 hypertensive and 1,005 normotensive participants) were included: 3 of crossover open design, 2 crossover single-blind, 16 crossover double-blind, 4 parallel open, 1 parallel single, and 7 parallel double-blind.

Due to significant variation in effect size across the 33 trials, only results from the random-effects model are presented.

CRD database number: DARE-11997008171

Index terms

Subject index terms
Subject indexing assigned by NLM: Medical Subject Headings (MeSH): Administration, Oral; Blood Pressure[drug effects]; Food, Fortified; Hypertension[prevention & control]; Potassium[administration & dosage]; Potassium[pharmacology]; Potassium[urine]; Randomized Controlled Trials as Topic; Sodium[urine]; Statistics as Topic