Risk factors associated with a high velocity of the development of hyperkalaemia in hospitalised patients.

BACKGROUND/OBJECTIVE: Drugs have been recognised as a primary or contributing cause of hyperkalaemia, especially when administered to patients with underlying risk factors. The objective of this study was to analyse the influence of the known risk factors for hyperkalaemia on the velocity of the development of hyperkalaemia. STUDY DESIGN/METHODS: Clinical characteristics, laboratory data and medication profiles of patients developing hyperkalaemia (serum potassium>or=5.0 mmol/L) hospitalised between 2000 and 2004 in the University Hospital Basel, Switzerland, were recorded. Factors associated with a high velocity of the development of hyperkalaemia were detected using a multiple logistic regression model. Subsequently, the velocity during a defined observation period was compared between patients with one risk factor and patients with two or more risk factors. Finally, the dose effects of drugs identified as risk factors for a high velocity of the development of hyperkalaemia were analysed using two sample comparisons. RESULTS: A random sample of 551 hospitalised patients was analysed. Compared with the drug treatment at entry, significantly more patients during the hospitalisation were treated with drugs associated with hyperkalaemia, such as heparins (p<0.001), ACE inhibitors or angiotensin receptor blockers (ARBs) [p=0.002], potassium supplements (p<0.001), potassium-sparing diuretics (p<0.001) and/or NSAIDs or selective cyclo-oxygenase (COX)-2 inhibitors (p<0.001). Risk factors associated with a high velocity of the development of hyperkalaemia were use of potassium supplements (adjusted odds ratio [OR] 3.386; 95% CI 2.251, 5.091), severe renal impairment (OR 3.119; 95% CI 2.007, 4.850), use of ACE inhibitors or ARBs (OR 2.642; 95% CI 1.742, 4.006), use of potassium-sparing diuretics (OR 2.065; 95% CI 1.310, 3.254), and diabetes mellitus (OR 1.525; 95% CI 1.005, 2.313). The velocity of the development of hyperkalaemia significantly increased in patients with two or more risk factors. Dose effects could be found for potassium supplements (p=0.006) and potassium-sparing diuretics (p=0.007), but not for ACE inhibitors or ARBs (p=0.289). In contrast, the use of kaliuretics (loop diuretics or thiazides) was associated with a decreased velocity of the development of hyperkalaemia in patients with serious renal impairment (p=0.016) and in patients treated with two or more drug classes associated with a high velocity of the development of hyperkalaemia (p=0.001). CONCLUSIONS: Risk factors associated with a high velocity of the development of hyperkalaemia are use of potassium supplements>severe renal impairment>use of ACE inhibitors or ARBs>use of potassium-sparing diuretics>diabetes mellitus. The presence of two or more of these risk factors is associated with an even faster development of hyperkalaemia. Clinicians should be aware of these risk factors in order to avoid a rapid development of potentially life-threatening hyperkalaemia.