Objective: To investigate quantitatively the risk factors of hyperkalaemia or increased blood potassium associated with ACE-inhibitor therapy
Design: Nested case-control study
Methods: We used the antihypertensive drug database(72,379 subjects)developed by the RAD-AR Council, Japan and the Institute of Statistical Mathematics based on the post-marketing surveillance(PMS) data of pharmaceutical companies. Of 37,372 subjects taking ACE-inhibitors, the case group was composed of 64 patients who experienced hyperkalaemia or blood potassium increase while taking ACE-inhibitors, and the control group was composed of 1,280 patients(20 patients per case)randomly selected from patients who did not experience hyperkalaemia or blood potassium increase while taking ACE-inhibitors. The relevant factors that can be extracted from the database were the followings: age, WHO classification of hypertension, complications, antihypertensive drugs used before the PMS survey, and concomitant drugs.
Results: Among the subjects taking antihypertensive agents, 65 patients experienced hyperkalaemia orincreased blood potassium, 64(98.5%)of whom were taking ACE-inhibitors. The factors that were significantly different between two groups(p<0.05)by univariate analysis were WHO classification of hypertension(p=0.005), complications of nephritis/nephrosis(p<0.001), other disorder of urinary system(p<0.001), unclear symptom or diagnosis(p=0.005), taking diuretics as antihypertensive drugs before study(p=0.032), and concomitant treatment with diuretics(p=0.004), vasodilators(p<0.001), and antigout agents(p=0.001). Conditional multivariate logistic analysis of these factors yielded adjusted odds ratio of 21.31 for complications of nephritis/nephrosis(p<0.001), 6.83 for other disorder of urinary system(p<0.001), and 2.30 for concomitant therapy with diuretics(p=0.049).
Conclusion: The risk factors of hyperkalaemia or blood potassium increase associated with taking ACE-inhibitors were nephritis/nephrosis, other disorder of urinary system and concomitant therapy with diuretics.