Characteristics of the studies included in the meta-analysis
| Author (year) | Country | Population | Participants (n) | Age (range), years | Design | Quality* | Control | Potassium | Duration (weeks) | Quantity of K (mmol/day) | Urinary K (mmol/day) | Plasma/serum K (mmol/L) | Comment |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MacGregor (1982) | UK | HPT | 23 12 men; 18 white | 45 (26–66) | RCT-DBX | 25 | Placebo | KCl (slow-K) | 4 | 64 | Pl: 62 K: 118 | Pl: 3.84 K: 4.02 | |
| Richards (1984) | New Zealand | HPT | 12 | (19–52) | RCT-X (not blinded) | 23 | Control diet | KCl (elixir) | 4 | 140 | C: ∼60 K: ∼170 | C: 3.84 K: 3.99 | Control diet 180 Na/ 60 K |
| Bulpitt (1985) | UK | HPT | 33 (K=14; C=19) 55% women | 55 | RCT-P (open) | 21 | No supplement | KCl (slow-K) | 12 | 64 | C: 55 K: 95 | C: 3.5 K: 3.8 | On loop diuretics |
| Kaplan (1985) | USA | HPT with hypokalaemia | 16 10 women; 13 black | 48.8 (35–66) | RCT-DBX | 25 | Placebo | KCl | 6 | 60 | Pl: 36 K: 82 | Pl: 3.00 K: 3.56 | Hypokalaemic on diuretics |
| Smith (1985) | UK | HPT | 20 11 men; 18 white | 53 (30–66) | RCT-DBX | 26 | Placebo | KCl (slow-K) | 4 | 64 | Pl: 67 K: 117 | Pl: 3.9 K: 4.1 | Reduced Na to 70 |
| Zoccali (1985) | UK | HPT | 19 10 men | M: 41 (26–53) W: 35 (26–53) | RCT-SBX | 20 | Placebo (lactose) | KCl (Selora) | 2 | 100 | Pl: 58 K: 139 | Pl: 3.9 K: 4.0 | Selora (92% KCl, 6% K gluconate, 1% Ca silicate, 1% glutamic acid) |
| Matlou (1986) | South Africa | HPT | 32 Black women | 51 (34–62) | RCT-SBX | 21 | Placebo (teaspoon as glucose) | KCl (teaspoon as salt) | 6 | 65 | Pl: 52 K: 114 | Pl: 3.87 K: 4.32 | |
| Grobbee (1987) | The Netherlands | HPT | 40 34 men | (18–28) | RCT-DBX | 23 | Placebo | KCl (slow-K) | 6 | 72 | Pl: 74 K: 131 | Pl: 3.76 K: 4.00 | Na restriction |
| Siani (1987) | Italy | HPT | 37 23 men | 45 (21–61) | RCT-DBP | 25 | Placebo | KCl (Lento-Kalium) | 15 | 48 | Pl: 57 K: 87 | Pl: 4.4 K: 4.3 | |
| Barden (1987) | Australia | NT | 44 women | (18–55) | RCT-DBX | 20 | Placebo | KCl (slow-K) | 4 | 80 | Pl: ∼55 K: ∼115 | Pl: 3.725 K: 3.86 | Dietary K <60 mmol/day |
| Obel (1989) | Kenya | HPT | 48 black | 40 | RCT-DBP | 21 | Placebo | KCl (slow-K) | 16 | 64 | Pl: 62 K: 102 | Pl: 4.0 K: 4.0 | |
| Patki (1990) | India | HPT | 37 8 men | 49.9 | RCT-DBX | 24 | Placebo | KCl (Kesol B, liquid) | 8 | 60 | Pl: 60 K: 82 | Pl: 3.6 K: 3.7 | |
| Valdes (1991) | Chile | HPT | 24 | RCT-DBX | 23 | Placebo | KCl | 4 | 64 | Pl: 55 K: 123 | Pl: 3.8 K: 4.1 | ||
| Fotherby (1992) | UK | HPT | 18 5 men | 75 (66–79) | RCT-DBX | 26 | Placebo | KCl | 4 | 60 | Pl: 60 K: 99 | Pl: 4.3 K: 4.4 | |
| Geleijnse (1994) | The Netherlands | General population | 100 | (55–75) | RCT-DBP | 24 | Control (common salt) | KCl (mineral salt) | 24 | 22 | Pl: 86 K: 97 | Pl: 4.23 K: 4.35 | Mineral salt: 41% KCl, 17% Mg salt, 1% trace minerals |
| Kawano (1998) | Japan | HPT | 55 26 men | 62.3 (36–77) | RCT-DBX | 20 | Placebo | KCl (slow-K) | 4 | 64 | Pl: 54 K: 96 | Pl: 4.15 K: 4.42 | |
| He (2010) | UK | HPT | 42 30 men | 51 (18–75) | RCT-DBX | 26 | Placebo | KCl (slow-K) KHCO3 | 4 4 | 64 64 | Pl: 77 KCl: 122 KHCO3: 125 | Pl: 4.4 KCl: 4.6 KHCO3: 4.4 | |
| Yusuf (2012) | India | High risk | 518 308 men | 57.5 | RT-Open label | 16 | None | KCl | 8 | 30 | – – | Pre: 4.3 K: 4.4 | |
| Graham (2014) | North Ireland | HPT CVD>10% | 40 32 men | 54.8 (40–70) | RCT-DBX | 23 | Placebo | KCl (slow-K) | 6 | 64 | – – | Pl: 3.9 K: 4.1 | On doxazosin; 6 weeks washout |
| Gijsbers (2015) | The Netherlands | Non-smokers | 36 24 men white | 65.8 (47–80) | RCT-DBX | 25 | Placebo | KCl capsules | 4 | 72 | Pl: 55.3 K: 118.1 | Pl: 4.29 K: 4.41 | Untreated |
*Downs and Black score (max 27).
C, control; DB, double blind; HPT, hypertension; K, potassium; P, parallel group; Pl, placebo; RCT, randomised controlled trial; SB, single blind; X, crossover.