Pathophysiology/Complications ORIGINAL ARTICLE

Copeptin, a Surrogate Marker for Arginine , Is Associated With Cardiovascular and All-Cause Mortality in Patients With Type 2 Diabetes (ZODIAC-31)

1 2 INEKE J. RIPHAGEN, PHARMD KORNELIS J.J. VAN HATEREN, MD, PHD he prevalence of type 2 diabetes and 1 6 WENDY E. BOERTIEN , MD JOACHIM STRUCK, PHD 2 1 its complications are increasing ALAA ALKHALAF, MD, PHD GERJAN NAVIS, MD, PHD T 2,3,4 2,4 worldwide(1).Oneofthemajor NANNE KLEEFSTRA, MD, PHD HENK J.G. BILO, MD, PHD 1 1 complications in type 2 diabetes is cardio- RON T. GANSEVOORT, MD, PHD STEPHAN J.L. BAKKER, MD, PHD 2,5 vascular disease (CVD), and CVD is the KLAAS H. GROENIER, PHD main cause of morbidity and mortality in this patient group (2). Arginine vasopressin (AVP), or anti- OBJECTIVEdCopeptin, a surrogate marker for arginine vasopressin, has been associated with cardiovascular (CV) events and mortality in patients with type 2 diabetes complicated by diuretic hormone, is a hormone that end-stage renal disease or acute . For stable outpatients, these associations exerts cardiovascular (CV) and renal ef- are unknown. Our aim was to investigate whether copeptin is associated with CV and all-cause fects (3). Several studies have reported mortality in patients with type 2 diabetes treated in primary care. that AVP levels are elevated in animals and patients with diabetes (4–7). In- d RESEARCH DESIGN AND METHODS Patients with type 2 diabetes participating in creased levels of AVP may have long- the observational Zwolle Outpatient Diabetes Project Integrating Available Care (ZODIAC) study term deleterious effects. AVP acts through were included. Cox regression analyses with age as time scale were used to assess the relationship of baseline copeptin with CV and all-cause mortality. three different vasopressin receptors, the V1a,V2,andV3 (or V1b) receptors, which RESULTSdWe included 1,195 patients (age 67 6 12 years, 44% male). Median baseline mediate vasoconstriction, stimulate water copeptin concentration was 5.4 (interquartile range [IQR] 3.1–9.6) pmol/L. After a median retention, and facilitate secretion of follow-up of 5.9 (IQR 3.2–10.1) years, 345 patients died (29%), with 148 CV deaths (12%). ACTH, respectively (3). High concentra- – P Log2 copeptin was associated with CV (hazard ratio 1.17 [95% CI 0.99 1.39]; = 0.068) and all- tions of plasma AVP are known to stimu- cause mortality (1.22 [1.09–1.36]; P = 0.001) after adjustment for age, sex, BMI, smoking, late V1a receptors preferentially (8), which systolic blood pressure, total cholesterol to HDL ratio, duration of diabetes, HbA1c, treatment may contribute to the CV complications with ACE inhibitors and angiotensin receptor blockers, history of CV diseases, log serum creat- inine, and log albumin to creatinine ratio; however, copeptin did not substantially improve risk in type 2 diabetes. 2 DespitethepivotalroleofAVPin prediction for CV (integrated discrimination improvement 0.14% [IQR 0.27 to 0.55%]) and fi all-cause mortality (0.77% [0.17–1.37%]) beyond currently used clinical markers. CVD, technical dif culties related to AVP’s small size, short plasma half-life, CONCLUSIONSdWe found copeptin to be associated with CV and all-cause mortality in and association with platelets in the cir- patients with type 2 diabetes treated in primary care. Intervention studies should show whether culation have hindered the large-scale the high CV risk in type 2 diabetes can be reduced by suppression of vasopressin, for example by clinical use of AVP as a biomarker reducing salt intake. (3,9,10). Vasopressin is synthesized from Diabetes Care 36:3201–3207, 2013 a polypeptide precursor that contains AVP, neurophysin II, and copeptin (3). Copeptin, or COOH-terminal proarginine vasopressin, is released in equimolar amounts to AVP during precursor process- ccccccccccccccccccccccccccccccccccccccccccccccccc ing and has been found to be a stable and From the 1Department of Internal Medicine, Division of Nephrology, University of Groningen, University sensitive surrogate marker for AVP (11,12). Medical Center Groningen, Groningen, the Netherlands; the 2Diabetes Centre, Isala Clinics, Zwolle, the A recent study of Fenske et al. (8) Netherlands; the 3Langerhans Medical Research Group, Zwolle, the Netherlands; the 4Department of Internal showed copeptin levels to be strongly as- Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; the 5 sociated with CV events and mortality in Department of General Practice, University of Groningen, University Medical Center Groningen, Groningen, patients with type 2 diabetes and end- the Netherlands; and 6B.R.A.H.M.S. GmbH, Thermo Fisher Scientific, Hennigsdorf, Germany. Corresponding author: Ineke J. Riphagen, [email protected]. stage renal disease. Copeptin was also Received 23 October 2012 and accepted 8 April 2013. found to be associated with CV events in DOI: 10.2337/dc12-2165 patients with acute myocardial infarction This article contains Supplementary Data online at http://care.diabetesjournals.org/lookup/suppl/doi:10 and type 2 diabetes (13). To our knowl- .2337/dc12-2165/-/DC1. © 2013 by the American Diabetes Association. Readers may use this article as long as the work is properly edge, however, these associations have cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/ not been demonstrated for stable, ambu- licenses/by-nc-nd/3.0/ for details. latory patients with type 2 diabetes. This care.diabetesjournals.org DIABETES CARE, VOLUME 36, OCTOBER 2013 3201 Copeptin and mortality in type 2 diabetes is of particular interest, because it could measured twice with a Welch Allyn sphyg- than in women (19), tertiles were sex- point to a new modifiable system for momanometer in the supine position after stratified. P values for differences in co- treatment and prevention of CV events at least 5 min of rest. The creatinine-based peptin tertiles were assessed with ANOVA and mortality in type 2 diabetes (8,14). Chronic Disease Epidemiology for normally distributed continuous data, Our primary objective was to assess the Collaboration equation was used to obtain the Kruskal-Wallis test for nonnormally association of baseline plasma copeptin the estimated glomerular filtration rate distributed data, and the x2 test for nom- level with CV and all-cause mortality (eGFR) (18). inal data. Multivariable linear regression in a population of patients with type 2 Copeptin was measured in plasma analyses were used to investigate whether diabetes treated in primary care. Our sec- samples collected at baseline and kept baseline copeptin concentration was asso- ondary aim was to investigate the addi- frozen at 2808C until analysis in 2010. ciated with the clinical parameters. Be- tional predictive value of copeptin for Morgenthaler et al. (12) showed that pro- cause copeptin values were nonnormally risk prediction of CV and all-cause mor- longed frozen storage and repeated distributed, logarithmic transformation tality in patients with type 2 diabetes. freeze-thaw cycles have no effect on co- (base 2) was applied to fulfill the criteria peptin values. Plasma copeptin was for linear regression analyses. RESEARCH DESIGN AND measured with a sandwich immunoas- We investigated whether there were METHODS say (B.R.A.H.M.S. GmbH, Hennigsdorf, differences in baseline characteristics of Germany), which was based on the assay patients with and without copeptin mea- Study group described by Morgenthaler et al. (12). surement. P values for differences be- The Zwolle Outpatient Diabetes Project Measurement of copeptin was performed tween patients with and without copeptin Integrating Available Care (ZODIAC) in batches. The lower detection limit was measurement were assessed with the in- study was initiated in 1998 in the Zwolle 0.4 pmol/L, the interassay coefficient of dependent sample t test for normally region of the Netherlands. The design and variation was ,6% for copeptin concen- distributed continuous data, the Mann- details of this study have been published trations .6 pmol/L, and the functional as- Whitney U test for nonnormally distrib- elsewhere (15,16). In this study, general say sensitivity (20% interassay coefficient uted data, and the x2 test for nominal practitioners were assisted by hospital- of variation) was ,1 pmol/L. data. based diabetes specialist nurses in their Cox regression analyses were used to care of patients with type 2 diabetes. In Clinical end points test whether there were interactions be- the first year, 1,143 patients with type 2 In this study, we examined the association tween copeptin and clinical parameters diabetes were included in this prospective between baseline copeptin concentration including age, sex, history of CVD, and cohort study. In 2001, additional 546 pa- and two coprimary clinical end points: duration of diabetes. We used Cox re- tients with type 2 diabetes enrolled, for CV mortality and all-cause mortality. In gression analyses with age as time scale in a combined cohort of 1,689 patients 2009, vital status and cause of death were which we accounted for left truncation (17). Baseline plasma copeptin values retrieved from records maintained by the (delayed entry) to analyze the risk of were measured in 1,257 patients (74%). hospital and the general practitioners for CV and all-cause mortality during follow- In this study, we included 1,195 patients the first 1,143 patients. For the additional up. We applied log2 transformation of (95%) with complete data. The ZODIAC 546 patients, vital status and cause of copeptin values so the hazard ratios (HRs) study was approved by the local medical death were retrieved in 2005. Cause of derived from Cox regression analyses were ethics committee, and all patients pro- death was coded according to the ICD-9. expressed as an increase in risk per dou- vided informed consent. CV death was defined as any death in bling of baseline copeptin values. Various which the principal cause of death was CV models were built to adjust for possible Data collection and measurements in nature (ICD-9 codes 390–459). confounders. First, the univariable associ- Baseline data, which were collected in ation of log2 copeptin with CV and all- 1998 and 2001, consisted of a full medical Statistical analyses cause mortality was investigated. Second, history, including a history of CVD, use of Statistical analyses were performed with the model was adjusted for age and sex. medication, and tobacco consumption. SPSS version 18.0 for Windows (IBM Finally, the model was additionally ad- Patients were considered to have a history Corp., Armonk, NY) and STATA version justed for CV risk factors and medication of CVD if they had a history of angina 11 (StataCorp LP, College Station, TX). that could potentially influence copeptin pectoris, myocardial infarction, percuta- Results are expressed as mean 6 SD or secretion (BMI, smoking, systolic blood neous transluminal coronary angioplasty, median (interquartile range [IQR]) for pressure, total cholesterol to HDL ratio, coronary artery bypass grafting, , or normally distributed and nonnormally duration of diabetes, HbA1c,historyof transient ischemic attack. Laboratory and distributed data, respectively. Nominal CVD, use of ACE inhibitors or angiotensin physical assessment data were collected data are presented as the total number of receptor blockers, log SCr, and log ACR). annually and included nonfasting lipid patients with percentage (n [%]). A two- The assumption of proportional hazards fi P , pro le, HbA1c, serum creatinine (SCr), sided 0.05 was considered to indicate for baseline predictors was investigated urinary albumin to creatinine ratio (ACR), statistical significance. by inspecting the Schoenfeld residuals. and blood pressure. SCr was measured For illustrative purposes, the study As sensitivity analyses, we repeated the by a kinetic colorimetric Jaffe method population was subdivided into tertiles Cox regression analyses with follow-up (Modular P Analyzer; Roche Almere, the according to baseline copeptin concen- time as time scale. Furthermore, we inves- Netherlands), ACR was measured by im- tration, and data are presented accord- tigated the effect of inclusion of time- munonephelometry (Behring Nephelom- ingly to visualize associations with dependent covariates (age, systolic blood eter; Behring Diagnostics, Mannheim, copeptin. Because copeptin concentra- pressure, total cholesterol to HDL ratio, Germany), and blood pressure was tions are significantly higher in men duration of diabetes, HbA1c,SCr,and

3202 DIABETES CARE, VOLUME 36, OCTOBER 2013 care.diabetesjournals.org Riphagen and Associates

ACR) in Cox regression analyses. In addi- classification (,10, 10–20, 20–30, and were significantly different between ter- tion, Cox regression analyses were used to .30%) for events and nonevents sepa- tiles of copeptin concentrations were age, test whether an association existed be- rately. Calibration, a measure to evaluate history of CVD, BMI, total cholesterol to tween the presence or absence of a copep- how well predicted probabilities agree HDL ratio, duration of diabetes, HbA1c, tin measurement and CV and all-cause with observed risks, was assessed with ACR, SCr, and eGFR (Table 1). Multivari- mortality in the combined cohort of the Grønessby and Borgan goodness-of- able linear regression analyses showed 1,689 patients. fit likelihood ratio test (22). that sex (b = 20.57; P , 0.001), age Discrimination, a measure to evaluate (b=0.01;P , 0.001), BMI (b = 0.03; how well a model distinguishes between RESULTS P , 0.001), HbA1c (b = 0.11; P , 0.001), patients who died and those who sur- systolic blood pressure (b = 20.004; P , vived while taking follow-up time into Patient characteristics 0.001), log ACR (b = 0.21; P , 0.001), and account, was assessed with the Harrell’sC A total of 1,195 patients with type 2 log SCr (b = 3.69; P , 0.001) were associ- statistic (20). The additional value of co- diabetes were included in this study. ated with baseline copeptin concentrations. peptin for the risk prediction of CV and Mean age of the study population was In addition, we investigated whether all-cause mortality was assessed in terms 67 6 12 years, and 524 patients (44%) there were differences in baseline charac- of integrated discrimination improve- were male. Median copeptin concentra- teristics of patients with and without ment (IDI) and net reclassification im- tion was 5.4 (IQR 3.1–9.6) pmol/L. copeptin measurement (Supplementary provement (NRI) (21). The IDI can be Median copeptin concentration was Table 1). Only baseline serum creatinine interpreted as the difference between significantly higher in men than in women values were slightly higher in patients model-based probabilities for events and (7.4 [4.5–11.5] vs. 4.1 [2.6–7.3] pmol/L, without copeptin measurements (98 6 nonevents for the models with and with- respectively; P , 0.0001). Baseline pa- 23 mmol/L) than in patients with copeptin out copeptin. The NRI is calculated by tient characteristics are presented as sex- measurements (95 6 22 mmol/L, P = 0.04). assessing the net improvement in risk stratified tertiles in Table 1. Variables that We found no other significant differences

Table 1dBaseline patient characteristics of the study population presented as sex-stratified tertiles of copeptin concentration

Tertile 1 Tertile 2 Tertile 3 P value Copeptin tertile cutoffs (pmol/L) Male ,5.2 5.2–9.9 .9.9 d Female ,3.1 3.1–5.9 .5.9 d n Male 175 174 175 d Female 224 227 219 d Demographics Age (years) 65 6 10 66 6 12 69 6 12 ,0.001 Smoking 79 (19.8) 73 (18.2) 61 (15.5) 0.3 History of CVD 114 (28.5) 129 (32.2) 167 (42.4) ,0.001 Body composition BMI (kg/m2) 28.5 6 4.2 29.3 6 4.8 29.9 6 5.2 ,0.001 Blood pressure Systolic blood pressure (mmHg) 153 6 24 153 6 25 151 6 24 0.3 Diastolic blood pressure (mmHg) 84 6 10 83 6 10 84 6 10 0.8 Use of ACE inhibitors or ARBs 102 (25.5) 102 (25.4) 117 (29.7) 0.3 Lipids Total cholesterol (mmol/L) 5.4 6 1.0 5.6 6 1.1 5.6 6 1.1 0.1 HDL cholesterol (mmol/L) 1.2 6 0.4 1.2 6 0.3 1.2 6 0.6 0.5 Triglycerides (mmol/L) 2.0 (1.5–2.8) 2.1 (1.5–3.1) 2.1 (1.5–3.2) 0.2 Total cholesterol to HDL ratio 4.7 6 1.5 5.0 6 1.5 5.0 6 1.4 0.04 Use of lipid-lowering drugs (n,%) 61(15.3) 62(15.5) 50(12.7) 0.5 Glucose homeostasis Duration diabetes (years) 4.0 (1.8–9.0) 4.0 (1.8–8.9) 5.0 (2.0–10.0) 0.002 – – – , HbA1c (%) 6.8 (6.2 7.8) 7.0 (6.3 8.2) 7.3 (6.5 8.4) 0.001 HbA1c (mmol/mol) 51 (44–62) 53 (45–66) 56 (48–68) ,0.001 Renal function ACR (mg/mmol) 1.6 (0.9–4.0) 1.7 (0.8–6.1) 2.7 (1.0–8.2) ,0.001 SCr (mmol/L) 90 6 14 91 6 16 103 6 29 ,0.001 eGFR (mL/min/1.73 m2)686 14 67 6 15 59 6 18 ,0.001

Data are mean 6 SD, n (%), and median (IQR). ACE, angiotensin-converting enzyme; ACR, urinary albumin to creatinine ratio; ARB, angiotensin receptor blocker; BMI, body mass index; CVD, cardiovascular diseases; eGFR, estimated glomerular filtration rate per Chronic Kidney Disease Epidemiology Collaboration equation (18); HDL, high-density lipoprotein.

care.diabetesjournals.org DIABETES CARE, VOLUME 36, OCTOBER 2013 3203 Copeptin and mortality in type 2 diabetes between baseline characteristics of patients time as time scale (Table 3). The HRs and mortality), so the models were well cali- with and without copeptin measurements. 95% CIs of the adjusted models in the brated. The IDI and NRI values for model sensitivity analyses were not materially 2 predicting CV mortality were 2.68% Copeptin as a predictor of mortality different from the analyses with age as and 16.93%, respectively, indicating After a follow-up period of 10 years for time scale. In the Cox regression models that copeptin had additional value on the patients entering the study in 1998 with follow-up time as time scale, the as- top of age and sex for risk prediction of and 3 years for those included in 2001, sociations of copeptin with CV and all- CV mortality. In the fully adjusted mod- 345 of 1,195 included patients had died cause mortality remained significant after els, however, the IDI and NRI values ap- (29%), with 148 deaths (12%) attribut- adjustment for the different confounders peared to be ,2%, indicating that able to CV causes. All-cause deaths (152 (Table 3). copeptin did not substantially improve males [29%] vs. 193 females [29%]; P = We also investigated the influence of risk prediction for CV and all-cause mor- 0.9) and CV deaths (64 males [12%] vs. time-dependent covariates in Cox regres- tality beyond currently used clinical 84 females [13%]; P =0.9)werenotmore sion analyses (Supplementary Table 2). In markers. common among male subjects than the fully adjusted models, log2 copeptin among female subjects. Furthermore, was significantly associated with CV mor- CONCLUSIONSdIn this prospective there was no difference in median follow- tality (HR 1.21 [95% CI 1.03–1.42]; P = cohort of 1,195 patients with type 2 up time for male and female subjects 0.02) and all-cause mortality (1.23 [1.10– diabetes treated in primary care, we found (5.5 [IQR 3.1–10.1] vs. 6.2 [3.2–10.1] 1.36]; P , 0.001). copeptin to be associated with CV and all- years, respectively; P = 0.4). The median Furthermore, we tested whether an cause mortality. After adjustment for es- baseline copeptin concentration for survi- association existed between the presence tablished CV risk factors, we observed vors (4.9 [IQR 3.0–8.5] pmol/L) was sig- or absence of a copeptin measurement only a trend between copeptin and CV nificantly lower than both the median and CV and all-cause mortality in the mortality, whereas the association of copeptin level of patients who had died combined cohort of 1,689 patients. In baseline plasma copeptin with all-cause of CV causes (7.9 [3.9–13.8] pmol/L) univariable and multivariable Cox regres- mortality remained significant. Our find- and the median copeptin level of patients sion analyses we found no association of ings are of particular interest because the who had died of all causes during follow- the presence or absence of a copeptin mea- AVP system is potentially modifiable up (7.3 [3.7–13.0] pmol/L; P , 0.0001). surement with CV and all-cause mortality. through pharmacological and nonphar- Cox regression analyses were used to macological interventions and could investigate whether there were interac- Predictive value of copeptin provide a possible target for treatment tions between copeptin and clinical pa- The additional value of copeptin for risk and prevention of CV events and mortality rameters including age, sex, history of prediction of CV and all-cause mortality in type 2 diabetes. CVD, and duration of diabetes. We found was assessed in terms of discrimination Several studies have reported that no significant interactions between co- (Harrell’s C statistic), NRI, and IDI (Table plasma AVP levels are elevated in animals peptin and these clinical parameters. 4). Harrell’s C statistics for models 2 and 3 and patients with diabetes (4–7). AVP In univariable Cox regression ana- without copeptin predicting CV mortality promotes water reabsorption through lyses with age as time scale, log2 copeptin were 0.75 (0.71–0.78) and 0.80 (0.77– stimulation of V2 receptors, and it is sug- was significantly associated with CV mor- 0.84), respectively. Harrell’sCstatistics gested that increased levels of AVP limit tality (HR 1.55 [95% CI 1.34–1.80]; P , for models 2 and 3 without copeptin pre- glucose-induced water loss in patients 0.001) and all-cause mortality (1.39 dicting all-cause mortality were 0.77 with diabetes (23). [1.26–1.53]; P , 0.001). The association (0.75–0.80) and 0.79 (0.77–0.82), re- Increased levels of AVP may, how- of copeptin with all-cause mortality re- spectively. Harrell’s C statistics in Table ever, have long-term deleterious renal mained significant after adjustment for 4 show that the more confounders we ad- and CV effects. In experimental animal the various confounders (Table 2). The justed for, the better the model pre- studies, as well as in humans, it has been Schoenfeld residuals showed no substan- dicted CV and all-cause mortality. The shown that AVP contributes to hyper- tial deviations, supporting the assump- Grønessby and Borgan P values in Table filtration, albuminuria, and renal hyper- tion of proportional hazards. 4 indicate that predicted probabilities trophy in diabetes (24,25). This notion is As sensitivity analyses, we repeated the correspond well with observed risks (ex- supported by the renal protective effects Cox regression analyses with follow-up cept for model 1 predicting all-cause of AVP inhibition by drinking water or chronic treatment with a V2 receptor an- d tagonist in rats with renal failure (26,27) Table 2 Association of baseline log2 copeptin concentrations with CV and all-cause and diabetes (28). mortality in Cox regression analyses with age as time scale High concentrations of plasma AVP are known to stimulate V1a receptors pref- CV mortality All-cause mortality erentially (8), which results in coronary Model HR (95% CI) P value HR (95% CI) P value vasoconstriction (29), increasing after- load, ventricular , and cardiac hy- 11.55(1.34–1.80) ,0.001 1.39 (1.26–1.53) ,0.001 pertrophy (8,30,31). Several studies 21.51(1.30–1.77) ,0.001 1.36 (1.22–1.51) ,0.001 have reported that copeptin, a surrogate 31.17(0.99–1.39) 0.068 1.22 (1.09–1.36) 0.001 for AVP, is associated with CV events and Model 1 is the crude model; model 2 is adjusted for age and sex; model 3 is adjusted for age, sex, BMI, mortality in patients with CVD (acute myo- smoking, systolic blood pressure, cholesterol to HDL ratio, duration of diabetes, HbA1c, history of CVD, use cardial infarction, , and stroke) of ACE inhibitors or angiotensin receptor blockers, log SCr, and log ACR. (3). A recent study of Fenske et al. (19)

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d Table 3 Association of baseline log2 copeptin concentrations with CV and all-cause for these known causes of CVD and there- mortality in Cox regression analyses with follow-up time as time scale fore useful to discriminate patients who could benefitfromintensification of ther- CV mortality All-cause mortality apy (38). We acknowledge that this study has Model HR (95% CI) P value HR (95% CI) P value several limitations. First, given the obser- 11.74(1.49–2.04) ,0.001 1.57 (1.42–1.74) ,0.001 vational nature of this study, it is impos- fi 21.54(1.32–1.80) ,0.001 1.37 (1.24–1.52) ,0.001 sible to draw a de nite conclusion about 31.19(1.00–1.41) 0.04 1.23 (1.10–1.37) ,0.001 the causality of the association of copeptin with CV and all-cause mortality. Second, Model 1 is the crude model; model 2 is adjusted for age and sex; model 3 is adjusted for age, sex, BMI, selection bias may have occurred because smoking, systolic blood pressure, cholesterol to HDL ratio, duration of diabetes, HbA1c, history of CVD, use patients whose copeptin had not been of ACE inhibitors or angiotensin receptor blockers, log SCr, and log ACR. measured were excluded from statistical analysis. In additional Cox regression showed that copeptin is associated with CV with the literature on CV risk in diabetes, analyses, however, we found no signifi- events, sudden death, and all-cause mortal- which indicates that women with diabetes cant association of the presence or ab- ity in patients with type 2 diabetes and end- have a higher relative risk for CV events sence of a copeptin measurement with CV stage renal disease. than men with diabetes (36,37). Further- and all-cause mortality. Third, blood Stimulation of V3 (V1b) receptors more, copeptin values have consistently samples were taken without restriction through AVP results in the release of been shown to be higher in males than on food or water intake, which could have ACTH, which stimulates cortisol release in females, even in healthy subjects influenced plasma osmolarity and conse- from the adrenal gland (3). AVP-induced (12,19). Risk categories that are based quently copeptin concentration. Further- ACTH release is reported to be less sensi- on copeptin level or reference values for more, measured plasma osmolarity, data tive to feedback inhibition by gluco- copeptin concentrations should therefore fi required to calculate plasma osmolarity, corticoids than ACTH induced by be sex speci c. and data on the use of diuretics were not corticotropin-releasing hormone (32), Several studies have shown that co- available in this study group, which is a which might worsen multiple aspects of peptin measurement has diagnostic and limitation of the current study because the metabolic syndrome. prognostic value in patients with acute plasma osmolality and plasma volume are Median copeptin concentration of CVD (3). Because copeptin was found to – determinants of AVP secretion. In addi- this study group was 5.4 (range 0.9 be associated with CV and all-cause mor- tion, no data on plasma albumin levels 85.7) pmol/L, which is higher than the tality in patients with type 2 diabetes, – and total plasma protein were available in median value of 4.2 (range 1 13.8 we investigated whether copeptin had ad- the current study. It could have been pmol/L) pmol/L measured in healthy sub- ditional value for risk prediction of CV interesting to include these measures, jects (33). In line with previous studies, and all-cause mortality. In this study pop- because plasma albumin and protein we found baseline plasma copeptin to be ulation, copeptin did not substantially may influence plasma osmolality and associated with renal function and albu- improve risk prediction for CV and all- subsequently levels of AVP. Finally, the minuria (34,35). cause mortality beyond currently used number of CV deaths in this study pop- In addition, we found that baseline clinical markers; however, copeptin was ulation was relatively small, which limits copeptin concentration was associated found to be associated with several CV the number of covariates used in Cox with CV and all-cause mortality; however, risk factors (BMI, HbA1c, systolic blood regression analyses. It has been suggested we found no differences in the number of pressure, SCr, and ACR), and copeptin that for each variable included in the deaths, number of CV deaths, or follow- substantially improved risk prediction model at least 10 events are required up time between male and female sub- for CV mortality beyond age and sex. fi (20). With inclusion of 13 variables in jects. This lack of difference is consistent Thus copeptin might be a uni ed marker the final Cox regression models, we are approaching the maximum number of d Table 4 Additional value of baseline log2 copeptin concentrations in risk prediction variables allowed by the number of 148 compared with established CV risk markers CV deaths. A strength of this study is that it is the fi Grønnessby and rst to investigate the association of co- Model Harrell’s C (95% CI) IDI (%) (95% CI) NRI (%) (95% CI) Borgan peptin with CV and all-cause mortality in patients with type 2 diabetes. In addition, CV mortality this study included a relatively large ob- 1 0.63 (0.59–0.68) NA NA 0.10 servational cohort of patients with type 2 0.76 (0.72–0.80) 2.68 (1.43–3.93) 16.93 (6.53–27.33) 0.98 2 diabetes with a relatively long follow- 3 0.81 (0.77–0.84) 0.14 (20.27 to 0.55) 1.82 (24.11 to 7.76) 0.15 up period (10 years) and a reasonable All-cause mortality number of events (all-cause mortality). 1 0.63 (0.59–0.66) NA NA 0.01 We therefore could prospectively inves- 2 0.78 (0.75–0.80) 2.47 (1.45–3.50) 2.14 (22.99 to 7.27) 0.84 tigate the association of baseline plasma 3 0.80 (0.77–0.82) 0.77 (0.17–1.37) 0.55 (23.36 to 4.46) 0.53 copeptin levels with CV and all-cause Model 1 is the crude model; model 2 is adjusted for age and sex; model 3 is adjusted for age, sex, BMI, mortality. smoking, systolic blood pressure, cholesterol to HDL ratio, duration of diabetes, HbA1c, history of CVD, use In conclusion, in this cohort of pa- of ACE inhibitors or angiotensin receptor blockers, log SCr, and log ACR. NA, not applicable. tients with type 2 diabetes, plasma care.diabetesjournals.org DIABETES CARE, VOLUME 36, OCTOBER 2013 3205 Copeptin and mortality in type 2 diabetes copeptin, a surrogate marker for AVP, Congest Heart Fail 2010;16(Suppl. 1): a marker of fatal cardiovascular events, all- was associated with CV and all-cause S37–S44 cause mortality, and new-onset albumin- mortality. These findings suggest that 4. Bankir L, Bardoux P, Ahloulay M. Vaso- uria in type 2 diabetes? (ZODIAC-29). pressin and diabetes mellitus. Nephron Diabetes Care 2012;35:2354–2358 AVP may play a role in CV complications – of type 2 diabetes and that interventions 2001;87:8 18 17. Lutgers HL, Gerrits EG, Graaff R, et al. 5. Zerbe RL, Vinicor F, Robertson GL. Plasma Skin autofluorescence provides additional intended to lower AVP (e.g., by limiting vasopressin in uncontrolled diabetes mel- information to the UK Prospective Di- sodium intake, improving glycemic con- litus. Diabetes 1979;28:503–508 abetes Study (UKPDS) risk score for the trol, and improving or preventing 6. Kamoi K, Ishibashi M, Yamaji T. Thirst estimation of cardiovascular prognosis in nephropathy-associated albuminuria) and plasma levels of vasopressin, angio- type 2 diabetes mellitus. Diabetologia may be beneficial for the prevention of tensin II and atrial natriuretic in 2009;52:789–797 CV complications in type 2 diabetes. patients with non-insulin-dependent di- 18. Levey AS, Stevens LA, Schmid CH, et al.; Water supplementation in patients with- abetes mellitus. Diabetes Res Clin Pract CKD-EPI (Chronic Kidney Disease Epi- out low serum albumin, edema, or risk 1991;11:195–202 demiology Collaboration). A new equa- 7. Iwasaki Y, Kondo K, Murase T, Hasegawa tion to estimate glomerular filtration rate. forhyponatremiawouldalsobeapossi- – ble means of lowering AVP secretion. H, Oiso Y. Osmoregulation of plasma va- Ann Intern Med 2009;150:604 612 sopressin in diabetes mellitus with sus- Furthermore, copeptin might be a unified 19. Fenske W, Störk S, Blechschmidt A, Maier tained hyperglycemia. J Neuroendocrinol SG, Morgenthaler NG, Allolio B. Copeptin marker for known causes of CVD and 1996;8:755–760 in the differential diagnosis of hyponatremia. might be useful to discriminate patients 8. Fenske W, Wanner C, Allolio B, et al.; J Clin Endocrinol Metab 2009;94:123– who would benefitfromintensification of German Diabetes, Dialysis Study Inves- 129 therapy. tigators. Copeptin levels associate with 20. Harrell FE Jr, Lee KL, Mark DB. Multi- cardiovascular events in patients with variable prognostic models: issues in de- ESRD and type 2 diabetes mellitus. J Am veloping models, evaluating assumptions Soc Nephrol 2011;22:782–790 and adequacy, and measuring and re- AcknowledgmentsdI.J.R. and S.J.L.B. re- 9. Voors AA, von Haehling S, Anker SD, ducing errors. Stat Med 1996;15:361– ceived support from the Netherlands Heart et al.; OPTIMAAL Investigators. C-terminal 387 Foundation, the Dutch Diabetes Research provasopressin (copeptin) is a strong prog- 21. Steyerberg EW, Vickers AJ, Cook NR, Foundation, and the Dutch Kidney Founda- nostic marker in patients with heart failure et al. Assessing the performance of pre- tion, together participating in the framework of after an acute myocardial infarction: results diction models: a framework for tradi- the Center for Translational Molecular Medi- from the OPTIMAAL study. Eur Heart J tional and novel measures. Epidemiology cine (www.ctmm.nl), project PREDICCt (grant 2009;30:1187–1194 2010;21:128–138 01C-104). 10. Preibisz JJ, Sealey JE, Laragh JH, Cody RJ, 22. May S, Hosmer DW. A simplified method J.S. is employed by B.R.A.H.M.S. GmbH, a Weksler BB. Plasma and platelet vaso- of calculating an overall goodness-of-fit company that manufactures and holds patent pressin in essential hypertension and test for the Cox proportional hazards model. rights on the CT-pro-AVP (copeptin) assay. congestive heart failure. Hypertension Lifetime Data Anal 1998;4:109–120 fl No other potential con icts of interest relevant 1983;5:I129–I138 23. Bankir L, Fernandes S, Bardoux P, Bouby to this article were reported. 11. Bolignano D, Zoccali C. Vasopressin be- N, Bichet DG. Vasopressin-V2 receptor I.J.R. researched data, contributed to the yond water: implications for renal dis- stimulation reduces sodium excretion in discussion, and wrote the manuscript. W.E.B. eases. Curr Opin Nephrol Hypertens 2010; healthy humans. J Am Soc Nephrol 2005; and K.H.G. researched data and reviewed and 19:499–504 16:1920–1928 edited the manuscript. A.A., K.J.J.v.H., J.S., 12. Morgenthaler NG, Struck J, Alonso C, 24. Bardoux P, Martin H, Ahloulay M, et al. and H.J.G.B. reviewed and edited the manu- Bergmann A. Assay for the measurement Vasopressin contributes to hyperfiltration, script. N.K., R.T.G., G.N., and S.J.L.B. reviewed of copeptin, a stable peptide derived from albuminuria, and renal hypertrophy in and edited the manuscript and contributed to the precursor of vasopressin. Clin Chem diabetes mellitus: study in vasopressin- the discussion. I.J.R. is the guarantor of this 2006;52:112–119 deficient Brattleboro rats. Proc Natl Acad work and, as such, had full access to all the data 13. Mellbin LG, Rydén L, Brismar K, Sci USA 1999;96:10397–10402 in the study and takes responsibility for the Morgenthaler NG, Ohrvik J, Catrina SB. 25. Bardoux P, Bichet DG, Martin H, et al. integrity of the data and the accuracy of the data Copeptin, IGFBP-1, and cardiovascular Vasopressin increases urinary albumin analysis. prognosis in patients with type 2 diabetes excretion in rats and humans: involvement Parts of this study were presented in abstract and acute myocardial infarction: a report of V2 receptors and the renin-angiotensin form at the 48th Annual Meeting of the Eu- from the DIGAMI 2 trial. Diabetes Care system. Nephrol Dial Transplant 2003;18: ropean Association for the Study of Diabetes, 2010;33:1604–1606 497–506 – 1 5 October 2012, Berlin, Germany, and at 14. Enhorning S, Bankir L, Bouby N, Struck J, 26. Bouby N, Bachmann S, Bichet D, Bankir L. the Kidney Week of the American Society Hedblad B, Persson M, Morgenthaler NG, Effect of water intake on the progression of Nephrology, San Diego, California, 30 Nilsson PM, Melander O. 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29. Maturi MF, Martin SE, Markle D, et al. coupling to phospholipase C. Endocrinol- recipients. Transplantation 2009;88:561– Coronary vasoconstriction induced by ogy 1998;139:3220–3226 567 vasopressin. Production of myocardial 33. Morgenthaler NG, Struck J, Jochberger S, 36. Kanaya AM, Grady D, Barrett-Connor E. ischemia in dogs by constriction of non- Dunser€ MW. Copeptin: clinical use of a Explaining the sex difference in coronary diseased small vessels. Circulation 1991; new biomarker. Trends Endocrinol Metab heart disease mortality among patients with 83:2111–2121 2008;19:43–49 type 2 diabetes mellitus: a meta-analysis. 30. Goldsmith SR. Vasopressin as vasopres- 34. Meijer E, Bakker SJ, Halbesma N, de Jong Arch Intern Med 2002;162:1737–1745 sor. Am J Med 1987;82:1213–1219 PE, Struck J, Gansevoort RT. Copeptin, a 37. Rivellese AA, Riccardi G, Vaccaro O. Cardio- 31. Fukuzawa J, Haneda T, Kikuchi K. Argi- surrogate marker of vasopressin, is associ- vascular risk in women with diabetes. Nutr nine vasopressin increases the rate of ated with microalbuminuria in a large pop- Metab Cardiovasc Dis 2010;20:474–480 protein synthesis in isolated perfused ulation cohort. Kidney Int 2010;77:29–36 38. Enhörning S, Struck J, Wirfält E, Hedblad adult rat heart via the V1 receptor. Mol 35. Meijer E, Bakker SJ, de Jong PE, et al. B, Morgenthaler NG, Melander O. Plasma Cell Biochem 1999;195:93–98 Copeptin, a surrogate marker of vaso- copeptin, a unifying factor behind the 32. Rabadan-Diehl C, Aguilera G. Glucocorti- pressin, is associated with accelerated re- metabolic syndrome. J Clin Endocrinol coids increase vasopressin V1b receptor nal function decline in renal transplant Metab 2011;96:E1065–E1072

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