Unsupervised clustering to differentiate rheumatoid arthritis patients based on proteomic signatures

OBJECTIVE

Patients with rheumatoid arthritis (RA) have different presentations and prognoses. Cluster analysis based on proteomic signatures creates independent phenogroups of patients with different pathophysiological backgrounds. We aimed to identify distinct pathophysiological clusters of RA patients based on circulating proteomic biomarkers.

METHOD

This was a cohort study including 399 RA patients. Clustering was performed on 94 circulating proteins (92 CVDII Olink®, high-sensitivity troponin T, and C-reactive protein). Unsupervised clustering was performed using a partitioning cluster algorithm.

RESULTS

The clustering algorithm identified two distinct clusters: cluster 1 (n = 223) and cluster 2 (n = 176). Compared with cluster 1, cluster 2 included older patients with a higher burden of comorbidities (cardiovascular and RA related), more erosive and longer RA duration, more dyspnoea and fatigue, walking a shorter distance in the Six-Minute Walk Test, with more severe diastolic dysfunction, and a 4.5-fold higher risk of death or hospitalization for cardiovascular reasons. Tumour necrosis factor (TNF) receptor superfamily-related pathways were mainly responsible for the model's discriminative ability.

CONCLUSION

Using unsupervised cluster analysis based on proteomic phenotypes, we identified two clusters of RA patients with distinct biomarkers profiles, clinical characteristics, and different outcomes that could reflect different pathophysiological backgrounds. TNF receptor superfamily-related proteins may be used to distinguish subgroups.

Predicting Volume of Distribution in Neonates: Performance of Physiologically Based Pharmacokinetic Modelling

The volume of distribution at steady state (Vss) in neonates is still often estimated through isometric scaling from adult values, disregarding developmental changes beyond body weight. This study aimed to compare the accuracy of two physiologically based pharmacokinetic (PBPK) Vss prediction methods in neonates (Poulin & Theil with Berezhkovskiy correction (P&T+) and Rodgers & Rowland (R&R)) with isometrical scaling. PBPK models were developed for 24 drugs using in-vitro and in-silico data. Simulations were done in Simcyp (V22) using predefined populations. Clinical data from 86 studies in neonates (including preterms) were used for comparison, and accuracy was assessed using (absolute) average fold errors ((A)AFEs). Isometric scaling resulted in underestimated Vss values in neonates (AFE: 0.61), and both PBPK methods reduced the magnitude of underprediction (AFE: 0.82-0.83). The P&T+ method demonstrated superior overall accuracy compared to isometric scaling (AAFE of 1.68 and 1.77, respectively), while the R&R method exhibited lower overall accuracy (AAFE: 2.03). Drug characteristics (LogP and ionization type) and inclusion of preterm neonates did not significantly impact the magnitude of error associated with isometric scaling or PBPK modeling. These results highlight both the limitations and the applicability of PBPK methods for the prediction of Vss in the absence of clinical data.

Ventricular-arterial coupling (VAC) in a population-based cohort of middle-aged individuals: The STANISLAS cohort

BACKGROUND AND AIMS

Data exploring normal values of different ventricular-arterial coupling (VAC) parameters and their association with anthropometric and cardiovascular (CV) factors are scarce. We aim to report values of two different methods of VAC assessment according to age and sex and explore their association with CV factors within a large population-based cohort of middle-aged individuals.

METHODS

For 1333 (mean age 48 ± 14) individuals participating in the 4th visit of the STANISLAS cohort, VAC was assessed by two methods [1]: arterial elastance (Ea)/end-systolic elastance (Ees) and [2] Pulse wave velocity (PWV)/Global longitudinal strain (GLS).

RESULTS

The mean values of Ea/Ees and PWV/GLS were 1.06 ± 0.20 and 0.42 ± 0.12, respectively. The two methods of VAC assessment were poorly correlated (Pearson's correlation coefficient r = 0.14 (0.08; 0.19)). Increased PWV/GLS was associated with older age and a higher degree of cardiovascular risk factors (i.e., BMI, blood pressure, LDL, diabetes, hypertension) in the whole population as well as in the parent generation. In contrast, higher Ea/Ees were associated with decreasing age, and lower prevalence of risk factors in the whole cohort but neutrally associated with risk factors in the parent generation.

CONCLUSIONS

Higher PWV/GLS is significantly associated with CV factors regardless of age. In contrast, worse Ea/Ees is associated with a better CV risk profile when considering individuals aged 30 to 70 but neutrally associated with CV factors when considering only older patients. These results may suggest that PWV/GLS should preferably be used to explore VAC. In addition, age-individualized threshold of Ea/Ees should be used.

Defining Myocardial Infarction in trials of people receiving hemodialysis: consensus report from the SONG-HD MI Expert Working group

Cardiovascular disease is the leading cause of death in patients receiving hemodialysis. Currently there is no standardized definition of myocardial infarction (MI) for patients receiving hemodialysis. Through an international consensus process MI was established as the core CVD measure for this population in clinical trials. The Standardised Outcomes in Nephrology Group - Hemodialysis (SONG-HD) initiative convened a multidisciplinary, international working group to address the definition of MI in this population.Based on current evidence, the working group recommends using the 4th Universal Definition of MI with specific caveats with regard to the interpretation of "ischemic symptoms" and performing a baseline 12-lead electrocardiogram to facilitate interpretation of acute changes on subsequent tracings. The working group does not recommend obtaining baseline cardiac troponin values, though does recommend obtaining serial cardiac biomarkers in settings where ischemia is suspected. Application of an evidence-based uniform definition should increase the reliability and accuracy of trial results.

NT-proBNP and stem cell factor plasma concentrations are independently associated with cardiovascular outcomes in end-stage renal disease hemodialysis patients

Aims

End-stage renal disease (ESRD) treated by chronic hemodialysis (HD) is associated with poor cardiovascular (CV) outcomes, with no available evidence-based therapeutics. A multiplexed proteomic approach may identify new pathophysiological pathways associated with CV outcomes, potentially actionable for precision medicine.

Methods and results

The AURORA trial was an international, multicentre, randomized, double-blind trial involving 2776 patients undergoing maintenance HD. Rosuvastatin vs. placebo had no significant effect on the composite primary endpoint of death from CV causes, nonfatal myocardial infarction or nonfatal stroke. We first compared CV risk-matched cases and controls (n = 410) to identify novel biomarkers using a multiplex proximity extension immunoassay (276 proteomic biomarkers assessed with Olink^TM). We replicated our findings in 200 unmatched cases and 200 controls. External validation was conducted from a multicentre real-life Danish cohort [Aarhus-Aalborg (AA), n = 331 patients] in which 92 Olink^TM biomarkers were assessed. In AURORA, only N-terminal pro-brain natriuretic peptide (NT-proBNP, positive association) and stem cell factor (SCF) (negative association) were found consistently associated with the trial's primary outcome across exploration and replication phases, independently from the baseline characteristics. Stem cell factor displayed a lower added predictive ability compared with NT-ProBNP. In the AA cohort, in multivariable analyses, BNP was found significantly associated with major CV events, while higher SCF was associated with less frequent CV deaths.

Conclusions

Our findings suggest that NT-proBNP and SCF may help identify ESRD patients with respectively high and low CV risk, beyond classical clinical predictors and also point at novel pathways for prevention and treatment.

Pragmatic Diagnostic and Therapeutic Algorithms to Optimize New Potassium Binder use in Cardiorenal Disease

BACKGROUND

Pivotal randomized trials demonstrating efficacy, safety and good tolerance, of two new potassium binders (patiromer and sodium zirconium cyclosilicate) led to their recent approval. A major hurdle to the implementation of these potassium-binders is understanding how to integrate them safely and effectively into the long-term management of cardiovascular and kidney disease patients using renin angiotensin aldosterone system inhibitors (RAASi), the latter being prone to induce hyperkalaemia.

METHODS

a multidisciplinary academic panel including nephrologists and cardiologists was convened to develop consensus therapeutic algorithm(s) aimed at optimizing the use of the two novel potassium binders (patiromer and sodium zirconium cyclosilicate) in stable adults who require treatment with RAASi and experience(d) hyperkalaemia in a non-emergent setting.

RESULTS

Two dedicated pragmatic algorithms are proposed. The lowest intervention threshold (i.e. 5.1mmol/L or greater) was the one used in the patiromer and sodium zirconium cyclosilicate) pivotal trials, both drugs being indicated to treat hyperkalaemia in a non -emergent setting. Acknowledging the heterogeneity across specialty guidelines in hyperkalaemia definition and thresholds to intervene when facing hyperkalaemia, we have been mindful to use soft language i.e. "it is to consider", not necessarily "to do".

CONCLUSIONS

Providing the clinical community with pragmatic algorithms may help optimize the management of high-risk patients by avoiding the risks of both hyper and hypokalaemia and of suboptimal RAASi therapy.

The association of smoking to cardiovascular death differs according to age and sex following myocardial infarction complicated by heart failure or left ventricular dysfunction

Background

Smoking is associated with higher morbidity and mortality following myocardial infarction (MI), but reports of the impact on cardiovascular (CV) death in aged and female patients experiencing MI complicated with left ventricular dysfunction or overt heart failure are limited.

Methods

In an individual patient data meta-analysis of high-risk MI patients, the association of smoking to CV death was investigated. Cox proportional hazard models exploring smoking status and risk according to age and sex were performed to study the relationship of smoking to independently adjudicated CV death endpoints.

Results

28,771 patients from the CAPRICORN, EPHESUS, OPTIMAAL and VALIANT trials were assessed. 18,325 (64%) reported smoking (9185 (32%) current and 9051 (32%) past), 2662 (9%) were above ≥80 years and 8607 (30%) were women. Overall, using non-smokers as referent, the association of smoking to CV mortality was neutral (HR=1.07, 0.98 to 1.16, p=0.12 for active smoking and HR=1.10, 1.02 to 1.18, p=0.01 for past smoking). The associations for active and past smokers with outcome, adjusted for age and sex in the overall study sample and according to different age and sex categories, are presented in figure 1. In analyses that included interaction terms, the association for active smokers depended on age and sex; the risk of CV mortality was weakened in women (interaction HR=0.81, 0.69 to 0.96, p=0.01) and older age (interaction HR per 10 years increase=0.88, 0,82 to 0.95, p=0.001). In contrast, the association to CV death for past smokers was not modified by sex or age (p=0.86 and p=0.17 respectively).

Conclusions

The association of smoking to CV death differed according to age and sex in MI complicated with left ventricular dysfunction or overt heart failure. Significant association of active and/or past smoking with increased risk of CV death was mainly observed in the 60–69 years category. The underlying reasons of the lack of association of smoking with outcome in older patients in this specific context should be explored further in future studies.

Figure 1

Funding Acknowledgement

Type of funding source: None

Non-fatal cardiovascular events preceding sudden cardiac death in patients with an acute myocardial infarction complicated by heart failure: insights from the High-Risk-Myocardial-Infarction database

Background

Sudden cardiac death (SCD) is responsible for 20–40% of mortality following acute myocardial infarction (AMI). The risk of SCD is even higher among patients with AMI complicated by heart failure (HF) (either clinically apparent HF or left ventricular dysfunction). The temporal relationship between an AMI complicated by HF and subsequent SCD and the association of non-fatal cardiovascular (CV) events following AMI with SCD has yet to be described.

Purpose

Among patients with AMI complicated by HF, we evaluated the probability and temporal association of subsequent non-fatal cardiovascular (CV) events (HF hospitalization, recurrent MI, or stroke) and SCD.

Methods

The High-Risk Myocardial Infarction (HRMI) database contains 28,771 patients with signs of HF or reduced LV ejection fraction (<40%) after AMI. Among patients with an AMI complicated by HF, we used adjudicated cause of death from the HRMI Database to identify: 1) the temporal distribution of SCD among patients following an index AMI; 2) the probability of having SCD following a non-fatal CV event following the index AMI.

Results

Median follow-up was 1.9 years. Mean age was 65.0±11.5 years and 70% were male. The incidence of CV death was 7.9 per 100 patient-year [py] and for SCD was 3.1 per 100py (40% of CV deaths). SCD rates were highest in the early period (<90 days) after AMI and decreased over time. Recurrent MI preceded 9.6% of SCD after a median time of 145 days; HF hospitalization preceded 17.0% of SCD after a median 144 days; and stroke preceded 2.7% of SCD after a median of 138 days (vs. non-sudden CV death: MI 46.6% at 1 days, HF hospitalization: 30.9% at 67 days, stroke 12.9% at 9 days). The incidence of SCD preceded by HF hospitalization was significantly higher than SCD without preceding HF hospitalization.

Conclusion

Among patients with AMI complicated by HF, SCD predominantly occurred in the early “high-risk” period after AMI; SCD rates decreased afterwards. Patients with non-fatal HF hospitalizations during follow-up may have a higher subsequent SCD risk. Preventing HF onset after MI may help decreasing SCD.

Proportion of sudden cardiac death

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Lucien Award, McGill University

Impact of timing of randomization after an acute coronary syndrome and subsequent events in patients with type 2 diabetes mellitus: an analysis of the EXAMINE trial

Background

The timing of enrolment following an acute coronary syndrome (ACS) may influence cardiovascular (CV) outcomes and potentially treatment effect in clinical trials. Using a large contemporary trial in patients with type 2 diabetes mellitus (T2DM) post-ACS, we examined the impact of timing of enrolment on subsequent CV outcomes.

Methods

EXAMINE was a randomized trial of alogliptin versus placebo in 5380 patients with T2DM and a recent ACS. The primary outcome was a composite of CV death, non-fatal myocardial infarction [MI], or non-fatal stroke. The median follow-up was 18 months. In this post hoc analysis, we examined the occurrence of subsequent CV events by timing of enrollment divided by tertiles of time from ACS to randomization: 8–34, 35–56, and 57–141 days.

Results

Patients randomized early (compared to the latest times) had less comorbidities at baseline including a history of heart failure (HF; 24.7% vs. 33.0%), prior coronary artery bypass graft (9.6% vs. 15.9%), or atrial fibrillation (5.9% vs. 9.4%). Despite the reduced comorbidity burden, the risk of the primary outcome was highest in patients randomized early compared to the latest time (adjusted hazard ratio [aHR] 1.47; 95% CI 1.21–1.74) (Figure 1). Similarly, patients randomized early had an increased risk of recurrent MI (aHR 1.51; 95% CI 1.17–1.96) and HF hospitalization (1.49; 95% CI 1.05–2.10).

Conclusion

In a contemporary cohort of T2DM with a recent ACS, early randomization following the ACS increases the risk of CV events including recurrent MI and HF hospitalization. This should be taken into account when designing future clinical trials.

Figure 1

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Takeda Pharmaceutical

Prise en charge de l’hyperkaliémie aux urgences

L’hyperkaliémie est l’un des désordres hydroélectrolytiques les plus fréquemment rencontrés aux urgences. Les étiologies principales sont l’insuffisance rénale aiguë ou chronique, le diabète et l’insuffisance cardiaque. L’hyperkaliémie aiguë peut être une urgence vitale, car elle est potentiellement létale du fait du risque d’arythmie cardiaque. Sa prise en charge aux urgences manque actuellement de recommandations claires en ce qui concerne le seuil d’intervention et les thérapeutiques à utiliser. Les thérapeutiques couramment appliquées sont fondées sur un faible niveau de preuve, et leurs effets secondaires sont mal connus. Des études supplémentaires sont nécessaires pour évaluer l’utilisation de ces traitements et celle de nouveaux traitements potentiellement prometteurs. Nous faisons ici une mise au point sur les données connues en termes d’épidémiologie, de manifestations cliniques et électrocardiographiques, et des différentes thérapeutiques qui peuvent être proposées dans la prise en charge de l’hyperkaliémie aux urgences.

Evaluation of Subclinical Fluid Overload Using Lung Ultrasound and Estimated Plasma Volume in the Postoperative Period Following Kidney Transplantation

AIM

B-lines count measured with lung ultrasound (LUS) quantifies extravascular lung water and is validated in the setting of acute cardiac failure or chronic dialysis. Patients are often kept in moderately overhydrated states during the early postoperative period following kidney transplantation (KT). We described congestion changes during the early postoperative period following KT and the feasibility of LUS in this setting.

METHODS

LUS (28 scanning-points method) and inferior vena cava (IVC) measurements were routinely performed in 36 patients after KT. Estimated plasma volume (ePV) was calculated from hemoglobin and hematocrit levels.

RESULTS

No patient had >15 B-lines during the hospital stay. B-lines slightly increased until Day 4 after KT (Day 1, 1.7 ± 1.7; Day 4, 2.5 ± 2.5) and decreased up to Day 10 (1.4 ± 2.2; P vs Day 4 <.05). More B-lines were observed in patients aged older than 60 (P = .01 at Day 4) whereas IVC diameter and ePV were similar. In patients older than 60, B-lines had weak correlation with body weight variation (r = 0.64; P < .05), IVC diameters (r = 0.59 at Day 4 and r = 0.58 at Day 10; P < .05) but a strong correlation with ePV (r = 0.93 at Day 14; P < .05). B-line changes from Day 1 to Day 10 correlated with IVC diameter changes (r = 0.62; P < .05).

CONCLUSION

LUS identifies subtle congestion changes during the early postoperative period following KT. The hyperhydration strategy usually followed during this period does not result in overt pulmonary congestion as assessed by LUS, even in older recipients.

Interactions cardiorénales

Hypertension is common in patients with chronic renal disease particularly those with diabetes. It is sometimes resistant to the pharmacological treatment. The mineralocorticoid receptor antagonist spironolactone may be indicated here. The mineralocorticoid receptor antagonists have a Class 1, Level A indication for the treatment of heart failure with reduced ejection fraction. There is an associated risk of worsening renal function and of hyperkalemia which does not hinder their clinical benefit. However, an appropriate biological monitoring is warranted, along with potential dose adaptations. Cardiorenal syndrome significantly worses the prognosis of congestive heart failure. The use of ultrafiltration can be effective when conventional treatments failed. Its place in the front line needs to be evaluated.

Combined baseline and one-month changes in big endothelin-1 and brain natriuretic peptide plasma concentrations predict clinical outcomes in patients with left ventricular dysfunction after acute myocardial infarction: Insights from the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) study

OBJECTIVE

Increased levels of neuro-hormonal biomarkers predict poor prognosis in patients with acute myocardial infarction (AMI) complicated by left ventricular systolic dysfunction (LVSD). The predictive value of repeated (one-month interval) brain natriuretic peptides (BNP) and big-endothelin 1 (BigET-1) measurements were investigated in patients with LVSD after AMI.

METHODS

In a sub-study of the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS trial), BNP and BigET-1 were measured at baseline and at 1month in 476 patients.

RESULTS

When included in the same Cox regression model, baseline BNP (p=0.0003) and BigET-1 (p=0.026) as well as the relative changes (after 1month) from baseline in BNP (p=0.049) and BigET-1 (p=0.045) were predictive of the composite of cardiovascular death or hospitalization for worsening heart failure. Adding baseline and changes in BigET-1 to baseline and changes in BNP led to a significant increase in prognostic reclassification as assessed by integrated discrimination improvement index (5.0%, p=0.01 for the primary endpoint).

CONCLUSIONS

Both increased baseline and changes after one month in BigET-1 concentrations were shown to be associated with adverse clinical outcomes, independently from BNP baseline levels and one month changes, in patients after recent AMI complicated with LVSD. This novel result may be of clinical interest since such combined biomarker assessment could improve risk stratification and open new avenues for biomarker-guided targeted therapies.

KEY MESSAGES

In the present study, we report for the first time in a population of patients with reduced LVEF after AMI and signs or symptoms of congestive HF, that increased baseline values of BNP and BigET-1 as well as a further rise of these markers over the first month after AMI, were independently predictive of future cardiovascular events. This approach may therefore be of clinical interest with the potential of improving risk stratification after AMI with reduced LVEF while further opening new avenues for biomarker-guided targeted therapies.

Adherence to Antihypertensive Treatment and the Blood Pressure–Lowering Effects of Renal Denervation in the Renal Denervation for Hypertension (DENERHTN) Trial

Background:

The DENERHTN trial (Renal Denervation for Hypertension) confirmed the blood pressure–lowering efficacy of renal denervation added to a standardized stepped-care antihypertensive treatment for resistant hypertension at 6 months. We report the influence of adherence to antihypertensive treatment on blood pressure control.

Methods:

One hundred six patients with hypertension resistant to 4 weeks of treatment with indapamide 1.5 mg/d, ramipril 10 mg/d (or irbesartan 300 mg/d), and amlodipine 10 mg/d were randomly assigned to renal denervation plus standardized stepped-care antihypertensive treatment, or the same antihypertensive treatment alone. For standardized stepped-care antihypertensive treatment, spironolactone 25 mg/d, bisoprolol 10 mg/d, prazosin 5 mg/d, and rilmenidine 1 mg/d were sequentially added at monthly visits if home blood pressure was ≥135/85 mm Hg after randomization. We assessed adherence to antihypertensive treatment at 6 months by drug screening in urine/plasma samples from 85 patients.

Results:

The numbers of fully adherent (20/40 versus 21/45), partially nonadherent (13/40 versus 20/45), or completely nonadherent patients (7/40 versus 4/45) to antihypertensive treatment were not different in the renal denervation and the control groups, respectively ( P =0.3605). The difference in the change in daytime ambulatory systolic blood pressure from baseline to 6 months between the 2 groups was –6.7 mm Hg ( P =0.0461) in fully adherent and –7.8 mm Hg ( P =0.0996) in nonadherent (partially nonadherent plus completely nonadherent) patients. The between-patient variability of daytime ambulatory systolic blood pressure was greater for nonadherent than for fully adherent patients.

Conclusions:

In the DENERHTN trial, the prevalence of nonadherence to antihypertensive drugs at 6 months was high (≈50%) but not different in the renal denervation and control groups. Regardless of adherence to treatment, renal denervation plus standardized stepped-care antihypertensive treatment resulted in a greater decrease in blood pressure than standardized stepped-care antihypertensive treatment alone.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01570777.

Neural modulation for hypertension and heart failure

Hypertension (HTN) and heart failure (HF) have a significant global impact on health, and lead to increased morbidity and mortality. Despite recent advances in pharmacologic and device therapy for these conditions, there is a need for additional treatment modalities. Patients with sub-optimally treated HTN have increased risk for stroke, renal failure and heart failure. The outcome of HF patients remains poor despite modern pharmacological therapy and with established device therapies such as CRT and ICDs. Therefore, the potential role of neuromodulation via renal denervation, baro-reflex modulation and vagal stimulation for the treatment of resistant HTN and HF is being explored. In this manuscript, we review current evidence for neuromodulation in relation to established drug and device therapies and how these therapies may be synergistic in achieving therapy goals in patients with treatment resistant HTN and heart failure. We describe lessons learned from recent neuromodulation trials and outline strategies to improve the potential for success in future trials. This review is based on discussions between scientists, clinical trialists, and regulatory representatives at the 11th annual CardioVascular Clinical Trialist Forum in Washington, DC on December 5-7, 2014.

Salivary aldosterone as a diagnostic aid in primary aldosteronism

Recent evidence demonstrates an increased incidence of primary aldosteronism (PA) in approximately 10% of the hypertensive population, making noninvasive and simple screening methods necessary. The aim of the present study was to apply a time-resolved fluorescence immunoassay for the measurement of aldosterone in saliva and the establishment of a cut-off to identify patients with a high likelihood for PA requiring subsequent screening with the aldosterone to renin ratio. Saliva was collected (AM and PM) to ascertain an optimum time with best discriminating power between healthy and disease states. Plasma aldosterone, after overnight recumbency and 4 h later, was collected for posture testing. The participants included 53 PA patients (aged 14-78), 54 with essential hypertension (EH, aged 19-82), and 38 healthy volunteers (aged 19-56). Saliva aldosterone (SA) (median, 25-75(th)%) in PA was found at 90 pg/ml (61-139) compared to 53 pg/ml (40-85) in EH, with discrimination between PA versus EHs best in the morning (cutoff: 81 pg/ml, 77% sensitivity, 82% specificity). Saliva aldosterone decreases throughout the day in patients with adenomas [APA AM: 123 pg/ml (92-213) vs. PM: 79 pg/ml (41-116)], but not in those with bilateral hyperplasia [BAH AM: 85 pg/ml (59-115)] vs. pm 69 pg/ml (57-114). Morning SA alone allows discrimination between PA and controls, though with significant overlap against EHs, leading to a high number of false positives. More promising is the use of diurnal variation in SA in distinguishing between APA and BAH. The decline in SA seen in patients with APA presents a more constant finding compared to posture testing, which fails to correctly classify a large number of patients.

Saliva as a medium for aldosterone measurement in repeated sampling studies

BACKGROUND

Saliva is a readily available biological fluid, making it convenient in diagnosis of diseases and in multi-sampling protocols. Several salivary steroids give a useful index of free plasma levels. Increased incidence of primary aldosteronism (PA) in approximately 10% of the hypertensive population has increased interest in the mineralocorticoid aldosterone.

METHODS

A biotinylated-aldosterone tracer and a commercially available antibody are used in a time-resolved fluorescence immunoassay (TR-FIA) to measure salivary aldosterone (SA). Saliva was collected in various multi-sampling protocols: Investigation of diurnal rhythm in healthy and PA patients, ACTH stimulation test and posture test in healthy subjects.

RESULTS

Method validation showed a sensitivity of 19 ng/L and intra-/inter-assay precision between 7.2-10.1% and 8.7-15.7%, respectively. SA correlated significantly (y = 0.2995x +/- 0.01, r(2)=0.60) to plasma aldosterone measured by a commercial radioimmunoassay. SA (median; 95%CI) was at 111 (95-127)ng/L in PA (n=84) and 50 (44-56)ng/L in healthy subjects (n=60). After change in posture, aldosterone increased in both, saliva (57 (47-63)ng/L to 95 (84-117)ng/L) and plasma (26 (26-41)ng/L to 135 (110-181)ng/L). Peak levels were reached after 1h, and were higher in females than in males.

CONCLUSIONS

SA correlates well to plasma aldosterone and mirrors responses during conditions of stress. SA is significantly higher in PA, and the diurnal rhythm seen in the healthy is blunted in PA. We additionally found gender-dependent differential responses to posture, with higher increases in females. Measurement of aldosterone in saliva presents a useful and convenient method for application in multi-sampling studies.