Short-term mortality risk of serum potassium levels in hypertension: a retrospective analysis of nationwide registry data.
Diuretics and renin–angiotensin–aldosterone system inhibitors are central in the treatment of hypertension, but may cause serum potassium abnormalities. We examined mortality in relation to serum potassium in hypertensive patients.



From Danish National Registries, we identified 44 799 hypertensive patients, aged 30 years or older, who had a serum potassium measurement within 90 days from diagnosis between 1995 and 2012. All-cause mortality was analysed according to seven predefined potassium levels: <3.5 (hypokalaemia), 3.5–3.7, 3.8–4.0, 4.1–4.4, 4.5–4.7, 4.8–5.0, and >5.0 mmol/L (hyperkalaemia). Outcome was 90-day mortality, estimated with multivariable Cox proportional hazard model, with the potassium interval of 4.1–4.4 mmol/L as reference. During 90-day follow-up, mortalities in the seven strata were 4.5, 2.7, 1.8, 1.5, 1.7, 2.7, and 3.6%, respectively. Adjusted risk for death was statistically significant for patients with hypokalaemia [hazard ratio (HR): 2.80, 95% confidence interval (95% CI): 2.17–3.62], and hyperkalaemia (HR: 1.70, 95% CI: 1.36–2.13). Notably, normal potassium levels were also associated with increased mortality: K: 3.5–3.7 mmol/L (HR: 1.70, 95% CI: 1.36–2.13), K: 3.8–4.0 mmol/L (HR: 1.21, 95% CI: 1.00–1.47), and K: 4.8–5.0 mmol/L (HR: 1.48, 95% CI: 1.15–1.92). Thus, mortality in relation to the seven potassium ranges was U-shaped, with the lowest mortality in the interval of 4.1–4.4 mmol/L.



Potassium levels outside the interval of 4.1–4.7 mmol/L were associated with increased mortality risk in patients with hypertension.
Faculty of Health Science, Aalborg University, Fredrik Bajers Vej 5, 9100 Aalborg, Denmark.
Maria Lukács
ML
Krogager
Department of Clinical Epidemiology, Aalborg University Hospital, Søndre Skovvej 15, 9000 Aalborg, Denmark.|Department of Health Science and Technology, Aalborg University Hospital, Søndre Skovvej 15, 9000 Aalborg, Denmark
Christian
C
Torp-Pedersen
Department of Clinical Epidemiology, Aalborg University Hospital, Søndre Skovvej 15, 9000 Aalborg, Denmark.
Rikke Nørmark
RN
Mortensen
Department of Cardiology, The Heart Center, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark.
Lars
L
Køber
Department of Cardiology, Copenhagen University Hospital Gentofte, Kildegårdsvej 28, 2900 Hellerup, Denmark|Denmark and National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
Gunnar
G
Gislason
Department of Cardiology, Aalborg University Hospital, Hobrovej 18-22, 9000 Aalborg, Denmark.|Heart Centre and Clinical Institute, Aalborg University Hospital, Aalborg, Denmark
Peter
P
Søgaard
Department of Cardiology, Aalborg University Hospital, Hobrovej 18-22, 9000 Aalborg, Denmark.
Kristian
K
Aasbjerg
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D017677:Age Distribution; D000368:Aged; D057911:Angiotensin Receptor Antagonists / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003718:Denmark / Q000453:epidemiology; D004232:Diuretics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000150:complications / Q000401:mortality*; D006973:Hypertension / Q000150:complications / Q000188:drug therapy / Q000401:mortality*; D007008:Hypokalemia / Q000150:complications / Q000401:mortality*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000378:metabolism*; D012042:Registries; D012189:Retrospective Studies
D000319:Adrenergic beta-Antagonists; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D004232:Diuretics; D011188:Potassium