Hyperkalaemic and hypokalaemic states are common metabolic disorders that are associated with major adverse outcomes (1-5). Overall prevalence of hyperkalaemia in the US is reported to be at 1.56% in 2014 or 3.7 million adults (6) although studies suggest that the frequency of hypokalaemia and/or hyperkalaemia states is as high as 48% in hospitalised patients (7), with rates that far exceed those derived from cohort studies or clinical trials.
Emerging data suggest that substantial risks are associated with dyskalaemia states and that these are influenced by the level of kidney function (8). Evidence has also emerged that outpatient potassium levels above and below the normal range are consistently associated with all-cause mortality, CV mortality and end stage kidney disease (ESKD) (8, 9). These results would support the need for close monitoring of serum potassium concentrations within health systems, the identification and targeting of high-risk groups, and continuous surveillance of clinical outcomes for these risk-groups. Furthermore, economic modelling suggests that there are substantial health and economic gains from maintaining normokalaemia in CKD populations allowing use of RAAS therapy with the potential for increased life expectancy (+ 2.4 years), delay in progression to ESKD (+ 5.4 years), improved quality-adjusted life-year gains (10).
In Ireland and elsewhere, there is a lack of real-world data on the surveillance and outcomes of serum potassium in the health systems. It is unclear to what extent serum potassium is monitored within the health system and to what extent the rates of testing vary across departments and at-risk groups. Greater clarity on patterns of surveillance across locations and disciplines are required. Similarly, there is lack of data on the burden and rates of growth of dyskalaemia states in the health system. With rising burden of CKD, introduction of new therapeutic agents for heart failure, and increased frequency of acute kidney injury, it is conceivable that the prevalence and incidence of dyskalaemia states has also continued to increase (11). Individuals who have the greatest risk of hyperkalaemia need to be identified early in the course of disease in order to offset potentially preventable harms. Finally, it remains to be determined whether the association of serum potassium with mortality follows a linear pattern or whether threshold limits exist above which the risk becomes manifest. It is also unclear to what extent the risks are modified by co-existing diseases or metabolic derangements. For example, we recently have shown that the mortality impact of hyperkalaemia and hypokalaemia is modified by the level of kidney function with the greatest risk for non-dialysis CKD than those treated with dialysis (9). Given the emergence of hyperkalaemia as a “major modifiable mortality risk factor”, it is imperative that we critically evaluate its role and impact among patients within the Irish Health System.
The overall goal of this study is to describe the distribution of hypokalaemia and hyperkalaemia states among patients within the Irish Health system calculate testing rates across demographic characteristics, locations of medical supervision and high risk subgroups, and explore variability in detection and associated period trends. We also wish to further explore relationships of serum potassium with morbidity and mortality and determine the minimum thresholds for elevated mortality, and to examine the impact of potentially important risk modifiers including pre-existing CKD, previous potassium trajectories, anaemia, diabetes and location of supervision.
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