Laboratory evaluation of potassium and creatinine among ambulatory patients prescribed spironolactone: are we monitoring for hyperkalemia?

Laboratory monitoring to reduce adverse drug-related events: a mixed methods study

BACKGROUND: Therapy with angiotensinconverting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) requires laboratory monitoring to avoid hyperkalemia and acute kidney failure. OBJECTIVE: To assess the frequency of recommended annual serum potassium and creatinine monitoring and determine potential factors associated with care gaps among adults dispensed an ACEI or ARB. METHODS: This mixed-methods study integrated findings from a retrospective cohort study and individual patient interviews. Adults aged 21 years and over within Kaiser Permanente Southern California with at least 180 treatment days of an ACEI and/or ARB in 2015 were included. Patients invited for qualitative interviews included those who did and did not complete the recommended laboratory tests. We assessed the proportion of patients completing both recommended laboratory tests, factors associated with not receiving laboratory monitoring, and patients' insights into barriers and facilitators of recommended monitoring. RESULTS: Of 437,544 patients who received an ACEI or ARB, 9.0% did not receive both a serum potassium and creatinine laboratory test during treatment (defined as a care gap). Lower risk of a care gap was observed for patients with increasing age (rate ratio [RR] per 10-year increase = 0.78, 95% CI = 0.77-0.79); diabetes mellitus (RR = 0.62, 95% CI = 0.60-0.64); hypertension (RR = 0.71, 95% CI = 0.71-0.74); Charlson Comorbidity Index score of at least 2 (RR = 0.62, 95% CI = 0.60-0.64); those who changed medication classes (RR = 0.53, 95% CI = 0.51-0.56); and patients with a cardiologist (RR = 0.81, 95% CI = 0.73-0.90) or nephrologist (RR = 0.60, 95% CI = 0.52-0.69) as their prescribing provider. Twenty-five patients completed the qualitative interviews. Patients often lacked knowledge about the need for laboratory monitoring, cited logistical barriers to accessing the laboratory, and deemed the reminders they received through an outpatient safety program as a facilitator to completing tests. CONCLUSIONS: Given the large patient population on ACEI and ARB medications, monitoring and support strategies such as electronic clinical surveillance could be important in addressing care gaps and potentially reducing adverse drug effects. DISCLOSURES: This project was supported by grant number R01HS024437 from the Agency for Healthcare Research and Quality. The funder had no role in the design of the study; collection, analyses, or interpretation of the data, or decision to submit this manuscript for publication. Harrison, Reynolds, Hahn, Munoz-Plaza, Yi, Fischer, Luong, Sim, Brettler, Handler, and Mittman are employees of the Southern California Permanente Medical Group. Danworth was employed by the Southern California Permanente Medical Group at the time of this study. Singh was partially supported by the Houston VA HSR&D Center for Innovations in Quality, Effectiveness and Safety (CIN13-413). Reynolds reports grants from Novartis, Amgen Inc., and Vital Strategies, Resolve to Save Lives, unrelated to this work. Yi reports grants from Novartis unrelated to this work. Kanter has nothing to disclose.

A real-world cohort study on the quality of potassium and creatinine monitoring during initiation of mineralocorticoid receptor antagonists in patients with heart failure

Aims

Clinical heart failure (HF) guidelines recommend monitoring of creatinine and potassium throughout the initial weeks of mineralocorticoid receptor antagonists (MRAs) therapy. We here assessed the extent to which this occurs in our health care.

Methods and results

Observational study in 2007-2010 HF patients starting MRA therapy in Stockholm, Sweden. Outcomes included potassium and creatinine laboratory testing before MRA initiation and in the early (Days 1-10) and extended (Days 11-90) post-initiation periods. Exclusion criteria considered death/hospitalization within 90 days, and lack of a second MRA dispense. Of 4036 HF patients starting on MRA, 45% were initiated from a hospital, 24% from a primary care centre, and 30% from other private centres. Overall, 89% underwent pre-initiation testing, being more common among hospital (97%) than for primary care (74%) initiations. Only 24% were adequately monitored in all three recommended intervals, being again more frequent following hospital (33%) than private (21%) or primary care (17%) initiations. In multivariable analyses, adequate monitoring was more likely for hospital [odds ratio (OR) 2.85, 95% confidence interval (95% CI) 2.34-3.56] initiations, and for patients with chronic kidney disease (OR 1.79, 95% CI 1.30-2.43) and concomitant use of angiotensin-converting enzyme (OR 1.27, 95% CI 1.05-1.52), angiotensin receptor blockers (OR 1.19, 95% CI 1.01-1.40) or beta-blockers (OR 1.65, 95% CI 1.22-2.26). Age, sex, and prescribing centre explained a small portion of adequate monitoring (c-statistic 0.63). Addition of comorbidities and medications improved prediction marginally (c-statistic 0.65).

Conclusion

Although serum potassium and creatinine monitoring before MRA initiation for HF is frequent, rates of post-initiation monitoring remain suboptimal, especially among primary care centres.

Biochemical monitoring after initiation of aldosterone antagonist therapy in users of renin-angiotensin system blockers: a UK primary care cohort study

OBJECTIVE

To determine the frequency of biochemical monitoring after initiation of aldosterone antagonists(AA) in patients also using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEI/ARB).

SETTING

UK primary care.

PARTICIPANTS

ACEI/ARB users who initiated AA between 2004 and 2014.

OUTCOMES

We calculated the proportions with: (1) biochemical monitoring ≤2 weeks post initiation of AA, (2) adverse biochemical values ≤2 months (potassium ≥6 mmol/L, creatinine ≥220 µmol/L and ≥30% increase in creatinine from baseline) and (3) discontinuers of AA in those with an adverse biochemical value. We used logistic regression to study patient characteristics associated with monitoring and adverse biochemical values.

RESULTS

In 10 546 initiators of AA, 3291 (31.2%) had a record of biochemical monitoring ≤2 weeks post initiation. A total of 2.0% and 2.7% of those with follow-up monitoring within 2 months of initiation experienced potassium ≥6 mmol/L and creatinine ≥220 µmol/L, respectively, whereas 13.5% had a ≥30% increase in creatinine. Baseline potassium (OR 3.59, 95% CI 2.43 to 5.32 for 5.0-5.5 mmol/L compared with <5.0 mmol/L) and estimated glomerular filtration rate 45-59 ml/min/1.73 m² (OR 2.06, 95% CI 1.26 to 3.35 compared with ≥60 ml/min/1.73 m²) were independently predictive of potassium ≥6 mmol/L. Women and people with diabetes had higher odds of ≥30% increase in creatinine.

CONCLUSION

Less than one-third of patients taking ACEI/ARB had biochemical monitoring within 2 weeks of initiating AAs. Higher levels of monitoring may reduce adverse biochemical events.

Potassium homeostasis in health and disease: A scientific workshop cosponsored by the National Kidney Foundation and the American Society of Hypertension

While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.

Potassium Homeostasis in Health and Disease: A Scientific Workshop Cosponsored by the National Kidney Foundation and the American Society of Hypertension

While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.

Association of plasma potassium with mortality and end-stage kidney disease in patients with chronic kidney disease under nephrologist care - The NephroTest study

BACKGROUND

Low and high blood potassium levels are common and were both associated with poor outcomes in patients with chronic kidney disease (CKD). Whether such relationships may be altered in CKD patients receiving optimized nephrologist care is unknown.

METHODS

NephroTest is a hospital-based prospective cohort study that enrolled 2078 nondialysis patients (mean age: 59 ± 15 years, 66% men) in CKD stages 1 to 5 who underwent repeated extensive renal tests including plasma potassium (PK) and glomerular filtration rate (GFR) measured (mGFR) by 51Cr-EDTA renal clearance. Test reports included a reminder of recommended targets for each abnormal value to guide treatment adjustment. Main outcomes were cardiovascular (CV) and all-cause mortality before end-stage kidney disease (ESKD), and ESKD.

RESULTS

At baseline, median mGFR was 38.4 mL/min/1.73m2; prevalence of low PK (<4 mmol/L) was 26.5%, and of high PK (>5 mmol/L) 6.4%; 74.4% of patients used angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). After excluding 137 patients with baseline GFR < 10 mL/min/1.73m2 or lost to follow-up, 459 ESKD events and 236 deaths before ESKD (83 CV deaths) occurred during a median follow-up of 5 years. Compared to patients with PK within [4, 5] mmol/L at baseline, those with low PK had hazard ratios (HRs) [95% CI] for all-cause and CV mortality before ESKD, and for ESKD of 0.82 [0.58-1.16], 1.01 [0.52-1.95], and 1.14 [0.89-1.47], respectively, with corresponding figures for those with high PK of 0.79 [0.48-1.32], 1.5 [0.69-3.3], and 0.92 [0.70-1.21]. Considering time-varying PK did not materially change these findings, except for the HR of ESKD associated with high PK, 1.39 [1.09-1.78]. Among 1190 patients with at least two visits, PK had normalized at the second visit in 39.9 and 54.1% respectively of those with baseline low and high PK. Among those with low PK that normalized, ARB or ACEi use increased between the visits (68.3% vs 81.8%, P < .0001), and among those with high PK that normalized, potassium-binding resin and bicarbonate use increased (13.0% vs 37.0%, P < .001, and 4.4% vs 17.4%, P = 0.01, respectively) without decreased ACEi or ARB use.

CONCLUSION

In these patients under nephrology care, neither low nor high PK was associated with excess mortality.

Adherence to guidelines for creatinine and potassium monitoring and discontinuation following renin-angiotensin system blockade: a UK general practice-based cohort study

OBJECTIVES

To examine adherence to serum creatinine and potassium monitoring and discontinuation guidelines following initiation of treatment with ACE inhibitors (ACEI) or angiotensin receptor blockers (ARBs); and whether high-risk patients are monitored.

DESIGN

A general practice-based cohort study using electronic health records from the UK Clinical Practice Research Datalink and Hospital Episode Statistics.

SETTING

UK primary care, 2004-2014.

SUBJECTS

223 814 new ACEI/ARB users.

MAIN OUTCOME MEASURES

Proportion of patients with renal function monitoring before and after ACEI/ARB initiation; creatinine increase ≥30% or potassium levels >6 mmol/L at first follow-up monitoring; and treatment discontinuation after such changes. Using logistic regression models, we also examined patient characteristics associated with these biochemical changes, and with follow-up monitoring within the guideline recommendation of 2 weeks after treatment initiation.

RESULTS

10% of patients had neither baseline nor follow-up monitoring of creatinine within 12 months before and 2 months after initiation of an ACEI/ARB, 28% had monitoring only at baseline, 15% only at follow-up, and 47% both at baseline and follow-up. The median period between the most recent baseline monitoring and drug initiation was 40 days (IQR 12-125 days). 34% of patients had baseline creatinine monitoring within 1 month before initiating therapy, but <10% also had the guideline-recommended follow-up test recorded within 2 weeks. Among patients experiencing a creatinine increase ≥30% (n=567, 1.2%) or potassium level >6 mmol/L (n=191, 0.4%), 80% continued treatment. Although patients with prior myocardial infarction, hypertension or baseline potassium >5 mmol/L were at high risk of ≥30% increase in creatinine after ACEI/ARB initiation, there was no evidence that they were more frequently monitored.

CONCLUSIONS

Only one-tenth of patients initiating ACEI/ARB therapy receive the guideline-recommended creatinine monitoring. Moreover, the vast majority of the patients fulfilling postinitiation discontinuation criteria for creatinine and potassium increases continue on treatment.

Facility variation and predictors of serum potassium monitoring after initiation of a mineralocorticoid receptor antagonist in patients with heart failure

BACKGROUND

Mineralocorticoid receptor antagonists (MRAs) have been shown to reduce morbidity and mortality in patients with heart failure (HF) with reduced ejection fraction but are associated with hyperkalemia. We sought to evaluate the frequency, variation, and predictors associated with serum potassium monitoring in patients with HF initiated on an MRA among facilities in the Veterans Affairs (VA) Health Care System.

METHODS

We performed a retrospective cohort analysis of patients with HF across 133 Veterans Affairs facilities from 2003 to 2013 who were given a new prescription of an MRA. The primary outcome was the mean percentage of patients per facility with serum potassium monitoring within 14 days of MRA dispensing. Univariate and covariate analyses were performed to determine factors associated with monitoring.

RESULTS

There were 142,880 patients identified with HF initiated on an MRA who met the study inclusion and exclusion criteria. The mean (SD) percentage of patients per facility with serum potassium monitoring within 14 days was 41.6% (standard deviation 8.0%; minimum 18.9%, maximum 56.7%). Facilities with a higher frequency of monitoring were associated with membership in the Council on Teaching Hospitals (n = 70, P < .0001), had academic affiliations (n = 100, P < .0001), and a higher annual volume of patients with HF (≥200 patients, P < .0001).

CONCLUSIONS

In a large multicenter national sample of patients with HF receiving a new MRA prescription, the frequency of serum potassium monitoring was below recommended guidelines. Academic facilities and those with a higher volume of patients with HF were associated with an increased frequency of monitoring.

Prediction and management of hyperkalemia across the spectrum of chronic kidney disease

Hyperkalemia commonly limits optimizing treatment to slow stage 3 or higher chronic kidney disease (CKD) progression. The risk of hyperkalemia is linked to dietary potassium intake, level of kidney function, concomitant diseases that may affect potassium balance such as diabetes, and use of medications that influence potassium excretion. The risk predictors for developing hyperkalemia are an estimated glomerular filtration rate of less than 45 mL/min/1.73 m(2) and a serum potassium level greater than 4.5 mEq/L in the absence of blockers of the renin-angiotensin-aldosterone system (RAAS). Generally, monotherapy with RAAS blockers does not increase risk substantially unless hypotension or volume depletion occur. Dual RAAS blockade involving any combination of an angiotensin-converting enzyme inhibitor, angiotensin-receptor blocker, renin inhibition, or aldosterone-receptor blocker markedly increases the risk of hyperkalemia in patients with stage 3 or higher CKD. Moreover, dual RAAS blockade further reduces albuminuria by 25% to 30% compared with monotherapy, it has failed to show a benefit on CKD progression or cardiovascular outcome, and thus is not indicated in such patients because of its marked increase in hyperkalemia potential. Although sodium polystyrene resins exist to manage hyperkalemia in patients requiring therapy that increases serum potassium levels, they are not well tolerated. Newer, more predictable, better-tolerated polymers to bind potassium are on the horizon and may be approved within the next 1 to 2 years.

Guideline concordance of testing for hyperkalemia and kidney dysfunction during initiation of mineralocorticoid receptor antagonist therapy in patients with heart failure

BACKGROUND

Mineralocorticoid receptor antagonists (MRA) reduce morbidity and mortality in heart failure with reduced ejection fraction but can cause hyperkalemia and acute kidney injury. Guidelines recommend measurement of serum potassium (K) and creatinine (Cr) before and serially after MRA initiation, but the extent to which this occurs is unknown.

METHODS AND RESULTS

Using electronic data from 3 health systems 2005 to 2008, we performed a retrospective review of laboratory monitoring among 490 patients hospitalized for heart failure with reduced ejection fraction who were subsequently initiated on MRA therapy. Median age at time of MRA initiation was 73 years, and 37.1% were women. Spironolactone accounted for 99.4% of MRA use. Initial ambulatory MRA dispensing occurred at hospital discharge in 70.0% of cases. In the 30 days before MRA initiation, 94.3% of patients had a K or Cr measurement. Preinitiation K was >5.0 mmol/L in 1.4% and Cr>2.5 mg/dL in 1.7%. In the 7 days after MRA initiation among patients who remained alive and out of the hospital, 46.5% had no evidence of K measurement; by 30 days, 13.6% remained untested. Patient factors explained a small portion of postinitiation K testing (c-statistic, 0.67).

CONCLUSIONS

Although laboratory monitoring before MRA initiation for heart failure with reduced ejection fraction is common, laboratory monitoring after MRA initiation frequently does not meet guideline recommendations, even in patients at higher risk for complications. Quality improvement efforts that encourage the use of MRA should also include mechanisms to address recommended monitoring.

Feasibility of point-of-care creatinine testing in community pharmacy to monitor drug therapy in ambulatory elderly patients

WHAT IS KNOWN AND OBJECTIVE

It is often necessary to adjust drug therapy if renal function is impaired in elderly patients taking drugs for diabetes and/or cardiovascular disease that are cleared by the kidneys. Although clinical guidelines recommend regular monitoring of renal function in these patients, in practice adherence to these recommendations varies from 28% to 75%. To determine whether drug dosing is appropriate, pharmacists need have up-to-date information about patients' renal function. In this study, the feasibility of point-of-care creatinine testing (POCCT) in a community pharmacy was evaluated as part of monitoring the drug therapy of ambulatory elderly patients.

METHODS

Elderly patients on maintenance therapy with renally excreted drugs for diabetes or cardiovascular disease were eligible for POCCT. After informed consent was obtained, POCCT was performed by trained personnel. A pharmacist assessed the clinical relevance of electronically generated drug alerts based on the patient's calculated renal function and the Dutch guidelines for adjusting drug dosage in patients with chronic kidney disease. If appropriate, the patient's general practitioner (GP) was consulted and adjustments to treatment were communicated to the patient. The feasibility of POCCT was evaluated by means of questionnaires completed by patients and healthcare professionals (GPs and pharmacists).

RESULTS

Of 338 potentially eligible patients, 149 (44%) whose renal function was not known were asked, by letter, to participate in the study. Of these individuals, 46 (31%) gave their informed consent and underwent POCCT. Response rates for completing the patient and professional questionnaires were 87% and 100%, respectively. More than half of the patients who underwent POCCT had mild-to-moderate renal impairment. On the basis of information provided by patients and healthcare professionals, POCCT would appear to be feasible in community pharmacies.

WHAT IS NEW AND CONCLUSION

POCCT improves the management of drug therapy by community pharmacists and is feasible in daily practice.

Mineralocorticoid receptor activation in myocardial infarction and failure: recent advances

The classical view of aldosterone actions via the mineralocorticoid receptor (MR) limited to control of fluid balance and blood pressure homoeostasis has been progressively overcome by clinical and experimental evidence emphasizing the pleiotropic role of MR activation in the pathogenesis of cardiovascular disease. Clinical studies have shown the benefit of MR blockade in patients with left ventricular dysfunction and heart failure after myocardial infarction (MI), hypertension or diabetic nephropathy. Deleterious effects of MR activation include cardiac structural and electrical remodelling, cardiovascular fibrosis, inflammation and oxidative stress. Complexity of pathophysiological role of MR derives from the presence of circulating glucocorticoids at higher concentrations than aldosterone and the equal affinity of the MR for aldosterone, cortisol and corticosterone. Recent experimental studies using different animal models and genetic tools have deeply explored the cell-specific functional role of MR in cardiovascular pathology. This review addresses emerging preclinical studies as well as ongoing clinical trials regarding MR activation in MI and failure.

Mineralocorticoid receptor antagonists for heart failure with reduced ejection fraction: integrating evidence into clinical practice

Mineralocorticoid receptor antagonists (MRAs) improve survival and reduce morbidity in patients with heart failure, reduced ejection fraction (HF-REF), and mild-to-severe symptoms, and in patients with left ventricular systolic dysfunction and heart failure after acute myocardial infarction. These clinical benefits are observed in addition to those of angiotensin converting enzyme inhibitors or angiotensin receptor blockers and beta-blockers. The morbidity and mortality benefits of MRAs may be mediated by several proposed actions, including antifibrotic mechanisms that slow heart failure progression, prevent or reverse cardiac remodelling, or reduce arrhythmogenesis. Both eplerenone and spironolactone have demonstrated survival benefits in individual clinical trials. Pharmacologic differences exist between the drugs, which may be relevant for therapeutic decision making in individual patients. Although serious hyperkalaemia events were reported in the major MRA clinical trials, these risks can be mitigated through appropriate patient selection, dose selection, patient education, monitoring, and follow-up. When used appropriately, MRAs significantly improve outcomes across the spectrum of patients with HF-REF.

Electronic health record-based monitoring of primary care patients at risk of medication-related toxicity

BACKGROUND

Timely laboratory monitoring may reduce the potential harm associated with chronic medication use. A study was conducted to determine the proportion of patients receiving National Committee for Quality Assurance (NCQA)-recommended laboratory medication monitoring in a primary care setting and to assess the effect of electronic health record (EHR)-derived, paper-based, provider-specific feedback bulletins on subsequent patient receipt of medication monitoring.

METHODS

In a single-arm, pre-post intervention in two federally qualified community health centers in Baltimore, patients targeted were adults prescribed at least 6 months (in the preceding year) for at least one index medication (digoxin, statins, diuretics, angiotensin-converting enzyme inhibitors/ angiotensin II-receptor blockers) in a 12-month period (August 2008-July 2009).

RESULTS

Among the 2,013 patients for whom medication monitoring was recommended, 42% were overdue for monitoring at some point during the study. As the number of index medications the patient was prescribed increased, the likelihood of ever being overdue for monitoring decreased. Being listed on the provider-specific monitoring bulletin doubled the odds of a patient receiving recommended laboratory monitoring before the next measurement period (1-2 months). Limiting the intervention to the most overdue patients, however, mitigated its overall impact.

CONCLUSIONS

Recommended laboratory monitoring of chronic medications appears to be inconsistent in primary care, resulting in potential harm for individuals at risk for medication-related toxicity. EHRs may be an important component of systems designed to improve medication monitoring, but multimodal interventions will likely be needed to achieve high reliability.

Biochemical monitoring of patients treated with antihypertensive therapy for adverse drug reactions: a systematic review

Biochemical monitoring of patients treated with antihypertensive therapy is recommended in order to identify potential adverse reactions to treatment. We aimed to review the literature investigating the nature of biochemical monitoring in adults treated in primary care with antihypertensive drugs. Specifically, we wished to establish (i) the proportion of patients with biochemical baseline testing prior to the initiation of antihypertensive therapy; (ii) the proportion of patients with biochemical monitoring after initiation of antihypertensive therapy; (iii) the patient characteristics associated with biochemical monitoring; (iv) the frequency of biochemical monitoring after the initiation of antihypertensive therapy; and (v) the relationship, if any, between biochemical monitoring and adverse patient outcomes. We searched MEDLINE, EMBASE and Google Scholar from 1948 to 31 December 2010 using a combination of text words and search terms. Retrospective and prospective cohort studies, cross-sectional studies, randomized controlled trials or quasi-randomized controlled trials, and audits of current clinical practice were included. Clinical trials, case reports and case series were excluded. Studies were included if they provided data on the proportion of patients treated with antihypertensive therapy in primary care who had any biochemical monitoring before or after the initiation of therapy. In total, 15 studies were included in our review, which used a wide variety of definitions of monitoring prior to and after the initiation of antihypertensive therapy. From 17% to 81% of patients treated with antihypertensive drugs had a baseline biochemical test and from 20% to 79% had any follow-up monitoring. In only 7 of the 12 studies that examined follow-up monitoring did more than half of the patients have any monitoring. Overall, this systematic review provides evidence that monitoring as recommended by published guidelines is not commonly undertaken. Only two studies were identified that examined patients with both baseline testing and follow-up monitoring. Omission of one or the other limits the ability to analyse the effect of treatment on electrolyte concentrations or renal function. There is limited research on the patient factors associated with monitoring and further work is required to determine the impact of monitoring on adverse patient outcomes. Important barriers to effective monitoring exist and this review emphasizes that these have not yet been overcome.

Diabetes and drug-associated hyperkalemia: effect of potassium monitoring

BACKGROUND

Renin-angiotensin-aldosterone system (RAAS) inhibitors are associated with hyperkalemia, but there is little evidence demonstrating patients who receive potassium monitoring have a lower rate of hyperkalemia.

OBJECTIVE

To evaluate the association between potassium monitoring and serious hyperkalemia-associated adverse outcomes among patients with diabetes newly initiating RAAS inhibitor therapy.

DESIGN

Retrospective observational study.

PARTICIPANTS

Patients with diabetes without end-stage renal disease initiating RAAS inhibitor therapy between 2001 and 2006 at three integrated health care systems.

MEASUREMENTS

Potassium monitoring and first hyperkalemia-associated adverse event during the initial year of therapy. Hyperkalemia-associated adverse events included hospitalizations, emergency department visits or deaths within 24 h of hyperkalemia diagnosis and/or diagnostic potassium >or=6 mmol/l. Incidence rates were calculated in person-years (p-y). We used inverse probability propensity score weighting to adjust for differences between patients with and without monitoring; Poisson regression was used to obtain adjusted relative risks.

RESULTS

A total of 19,391 of 27,355 patients (71%) received potassium monitoring. Serious hyperkalemia-associated events occurred at an incidence rate of 10.2 per 1,000 p-y. Compared to patients without monitoring, adjusted relative risk of hyperkalemia-associated adverse events among all patients with monitoring was 0.50 (0.37, 0.66); in the subset of patients who also had chronic kidney disease (n = 2,176), adjusted relative risk was 0.29 (0.18, 0.46).

CONCLUSIONS

Patients prescribed RAAS inhibitors who have both diabetes and chronic kidney disease and receive potassium monitoring are less likely to experience a serious hyperkalemia-associated adverse event compared to similar patients who did not receive potassium monitoring. This evidence supports existing consensus-based guidelines.

Incidence of risk factors for developing hyperkalemia when using ACE inhibitors in cardiovascular diseases

STUDY OBJECTIVE

To determine the incidence of and the risk factors associated with hyperkalemia, induced by ACEI-drug interactions among cardiac patients.

SETTING

Five medical and cardiology wards of a tertiary care center in Malaysia.

SUBJECTS

Five hundred cardiac inpatients, who received ACEIs concomitantly with other interacting drugs.

METHOD

This was a prospective cohort study of 500 patients with cardiovascular diseases admitted to Penang Hospital between January to August 2006, who received ACEIs concomitantly with other interacting drugs. ACEI-drug interactions of clinical significance were identified using available drug information resources. Drug Interaction Probability Scale (DIPS) was used to assess the causality of association between ACEI-drug interactions and the adverse outcome (hyperkalemia).

MAIN OUTCOME MEASURE

Hyperkalemia as an adverse clinical outcome of the interaction was identified from laboratory investigations.

RESULTS

Of the 489 patients included in the analysis, 48 (9.8%) had hyperkalemia thought to be associated with ACEI-drug interactions. Univariate analysis using binary logistic regression revealed that advanced age (60 years or more), and taking more than 15 medications were independent risk factors significantly associated with hyperkalemia. However, current and previous smoking history appeared to be a protective factor. Risk factors identified as predictors of hyperkalemia secondary to ACEI-drug interactions by multi-logistic regression were: advanced age (adjusted OR 2.3, CI 1.07-5.01); renal disease (adjusted OR 4.7, CI 2.37-9.39); hepatic disease (adjusted OR 5.2, CI 1.08-25.03); taking 15-20 medications (adjusted OR 4.4, CI 2.08-9.19); and taking 21-26 medications (adjusted OR 9.0, CI 1.64-49.74).

CONCLUSION

Cardiac patients receiving ACEIs concomitantly with potentially interacting drugs are at high risk of experiencing hyperkalemia. Old age, renal disease, hepatic disease, and receiving large number of medications are factors that may significantly increase their vulnerability towards this adverse outcome; thus, frequent monitoring is advocated.