Palanca et al. Cardiovasc Diabetol (2019) 18:93 https://doi.org/10.1186/s12933-019-0897-y Cardiovascular Diabetology ORIGINAL INVESTIGATION Open Access Subclinical atherosclerosis burden predicts cardiovascular events in individuals with diabetes and chronic kidney disease Ana Palanca1,2†, Esmeralda Castelblanco3,4†, Àngels Betriu5, Hèctor Perpiñán6, Berta Soldevila1,2,4, José Manuel Valdivielso5, Marcelino Bermúdez‑Lopez5, Carlos Puig‑Jové1, Manel Puig‑Domingo1,2, Per‑Henrik Groop7,8,9,10, Elvira Fernández5, Núria Alonso1,2,4* and Didac Mauricio2,3,4* Abstract Background: Individuals with diabetes have remarkably high rates of cardiovascular morbidity and mortality. How‑ ever, the incremental cardiovascular risk in diabetes is heterogeneous and has often been related to renal involve‑ ment. The purpose of this study was to analyse the prognostic value of subclinical atherosclerosis in determining the incidence of first cardiovascular events (CVEs) in individuals with diabetes and chronic kidney disease (CKD) compared to CKD individuals without diabetes. Methods: We included data from individuals with CKD with and without diabetes, free from pre-existing cardiovas‑ cular disease, from the NEFRONA cohort. Participants underwent baseline carotid and femoral ultrasound and were followed up for 4 years. All CVEs during follow-up were registered. Bivariate analysis and Fine–Gray competing risk models were used to perform the statistical analysis. Results: During the mean follow-up time of 48 months, a total of 203 CVE was registered. 107 CVE occurred among participants without diabetes (19.58 per 1000 person-years) and 96 CVE occurred among participants with diabetes (44.44 per 1000 person-years). Following the competing risk analysis, the variables predicting CVEs in CKD individu‑ als without diabetes were the number of territories with plaque at baseline (HR 1.862, 95% CI [1.432;2.240]), age (HR 1.026, 95% CI [1.003;1.049]) and serum concentrations of 25-OH vitamin D (HR 0.963, 95% CI [0.933;0.094]). The only variable predicting CVEs among CKD participants with diabetes was the number of territories with plaque at baseline (HR 1.782, 95% CI [1.393, 2.278]). For both models, concordance (C) index yielded was over 0.7. Conclusions: The burden of subclinical atherosclerosis is the strongest predictor of future CVEs in diabetic individuals with CKD. Early detection of subclinical atherosclerotic burden by multiterritorial vascular ultrasound could improve CVE prediction in this population. Keywords: Chronic kidney disease, Diabetes, Multiterritorial arterial ultrasound, Subclinical atherosclerosis, Cardiovascular events *Correspondence: nalonso32416@yahoo.es; didacmauricio@gmail.com † Ana Palanca and Esmeralda Castelblanco contributed equally to this study 1 Department of Endocrinology & Nutrition, Health Sciences Research Institute & University Hospital Germans Trias i Pujol, Carretera Canyet S/N, 08916 Badalona, Spain 3 Department of Endocrinology & Nutrition, Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomédica Sant Pau (IIB Sant Pau), Sant Quintí, 89, 08041 Barcelona, Spain Full list of author information is available at the end of the article © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat​iveco​mmons​.org/licen​ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creat​iveco​mmons​.org/ publi​cdoma​in/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 2 of 9 Background atherosclerotic status in CKD individuals with and with- It is well established that individuals with diabetes have out diabetes. an increased risk of developing cardiovascular disease (CVD) as well as poorer cardiovascular outcomes com- Methods pared to the general population [1]. For the last two Design and study population decades, diabetes has been considered an equivalent The present study included 1747 individuals with CKD condition to CVD [2], and this heightened cardiovascu- without diabetes and 698 individuals with CKD with dia- lar risk has been emphasized in former clinical guide- betes from the NEFRONA cohort. The design, objective lines [3, 4]. That said, some studies have reported that and methods of the NEFRONA study have been pub- although individuals with diabetes show a two to fourfold lished in detail previously [21]. Briefly, the NEFRONA increased risk of CVD, this risk is not equivalent to that study is a multicentre, prospective observational study. of individuals who have had a cardiovascular event (CVE) We aimed to evaluate the prevalence and evolution of [5–8]. These data support the concept of heterogene- subclinical atheromatosis in CKD individuals, as well as ity in cardiovascular risk within the diabetic population the contribution of vascular imaging for a more precise and therefore underline the need for cardiovascular risk cardiovascular risk assessment. stratification [9, 10]. Between October 2010 and June 2012, 2445 CKD indi- On the other hand, quantification of the burden of viduals with and without diabetes who were free from atherosclerotic plaque assessed by noninvasive ultra- previous cardiovascular disease and were 18 to 75 years sonography is a strong predictor for CVEs and, hence, of age were recruited from 81 Spanish hospitals and is considered a valid tool for cardiovascular risk stratifi- dialysis clinics [19]. Participants with known CVD or cation [11, 12]. In addition, several studies support the who had undergone any carotid artery intervention were value of measuring subclinical atherosclerosis (SA) in excluded. Other exclusion criteria were pregnancy, life multiple arterial territories for an improved CVE pre- expectancy of less than 12 months, any active infection or dictive value and, thus, a more accurate cardiovascular previous organ transplantation. Participants underwent risk stratification [13, 14]. In addition, the substantial baseline carotid and femoral ultrasound examinations. impact of declining renal function and albuminuria on During a 4-year follow-up period, all cardiovascular cardiovascular risk has been broadly acknowledged in the events, noncardiovascular deaths and kidney transplan- literature [15]. In fact, it has been reported that in indi- tations were registered. viduals with diabetes, the presence of chronic kidney dis- The Ethical Committees of all involved Spanish neph- ease (CKD) is associated with an increased risk of CVD, rology centres approved this study with the final approval explaining in part their heightened burden of CVD [16]. by the Ethics committee board of the Hospital Universi- To date, there is limited evidence describing the spe- tario Arnau de Vilanova (Lleida, Spain). The investigation cific prevalence of SA in individuals with both diabetes has been conducted according to the principles expressed and CKD. Recently, our group reported that SA is more in the Declaration of Helsinki, and all the included par- prevalent, carries a higher plaque burden and is more ticipants provided written informed consents. rapidly progressive in individuals with CKD and diabe- tes [17]. In addition, our group also reported that renal Clinical data and laboratory examinations individuals show a higher prevalence of plaques [18, 19] Information on the participant’s medical history, cardio- and a higher incidence of future CVEs across all stages of vascular risk factors and drug use was collected at base- CKD compared with controls [20]. line. Dyslipidaemia was therefore defined as a recorded Therefore, we examined the prognostic value of mul- clinical diagnosis or current use of lipid-lowering medi- titerritorial vascular evaluation and the extent of SA in cation. A detailed history was taken. A physical examina- predicting the incidence of new CVEs in individuals with tion including standard vital tests and anthropometric renal disease and diabetes, using data from the National measures, such as height, weight and waist–hip ratio, Observatory of Atherosclerosis in Nephrology (NEF- was performed [21]. A routine fasting blood test was RONA) study [21]. We hypothesized that the additional carried out within 3 months of the vascular ultrasound atherosclerotic plaque burden that involves having both examination, and biochemical parameters were obtained. conditions would be a marker of an increased risk of The estimated glomerular filtration rate was determined CVEs and contribute to the prediction of the incidence using the Modification of Diet in Renal Disease Study of CVEs among CKD individuals with diabetes in our formula (MDRD-4). High-sensitive C reactive protein cohort. (hsCRP) plasma concentrations were measured with an Thus, the aim of our study was to analyse the incidence immunoturbidimetric method (Roche/Hitachi modu- of CVEs and its association with baseline subclinical lar analytics). Serum concentrations of 25-OH vitamin Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 3 of 9 D were determined by an ELISA (IDS, UK) as described accurately recorded. Noncardiovascular death and kid- previously [20]. ney transplants were also recorded during follow-up. Diagnosis of diabetes mellitus Statistical analysis The criteria used to make the diagnosis of diabetes and, Data for quantitative variables are presented as a median thus, to include a individual in the diabetes group have and interquartile range, and qualitative variables are pre- been reported previously [17]. The criteria used were sented as a number and percentage. Participant char- as follows: a previous diagnosis of diabetes recorded in acteristics were compared between nondiabetic and the individual’s medical history, a fasting plasma glu- diabetic participants using the Mann–Whitney U test cose ≥ 126 mg/dl or HbA1c ≥ 6.5% determined by labora- and Pearson’s Chi-square test for non-normal quantita- tory testing or a current prescription of any anti-diabetic tive and categorical variables, respectively. drug. The association between potential risk factors and CVEs was investigated using bivariate analyses (Cox pro- Carotid and femoral imaging portional hazards model). Significant variables in bivari- B-mode ultrasound and colour Doppler examinations ate analyses and potential confounding factors were used of carotid and femoral sites were performed using the to develop appropriate multiple models for estimating Vivid BT09 apparatus (GE Healthcare, Waukesha, WI) CVE risk under competitive risk conditions. equipped with a 6–13 MHz broadband linear array probe The Fine–Gray competing risk regression model was previously explained [21]. The presence of atheromatous used to estimate the contribution of baseline patient plaque was assessed in ten vascular territories: internal, characteristics to the cumulative incidence of CVEs. bulb and common carotid, and common and superfi- Noncardiovascular death and kidney transplantation cial femoral arteries. Atheromatous plaque was defined were both considered competing events. Different mod- as intima media thickness (cIMT) > 1.5 mm protruding els were fitted for CKD participants without diabetes as into the lumen, according to the ASE Consensus State- well as for CKD participants with diabetes. The model in ment [22] and the Mannheim cIMT Consensus [23]. The each case was selected using the Bayesian information ultrasound examination was performed in a blinded fash- criteria [24]. A concordance index (C-index) was used to ion by three itinerant teams belonging to the UDETMA measure the discriminative power of the Fine–Gray mod- (Unit for Detection and Treatment of Atherothrom- els at 24 and 48 months. A statistical significance level botic Diseases, Hospital Universitari Arnau de Vilanova, of 0.05 was used. The statistical analysis was carried out Lleida, Spain) using semi-automatic EchoPAC Dimension with R statistical software version 3.3.1. software (GE Healthcare) according to a standardized protocol. To evaluate intraobserver plaque assessment Results reliability, a sample of 20 randomly chosen subjects was Baseline patient characteristics and study endpoints assessed 3 to 5 times on different days, obtaining a kappa The participants included 1747 CKD individuals with- coefficient of 1 and, therefore, indicating excellent intrao- out diabetes and 698 CKD individuals with diabetes. The bserver reliability [20]. baseline characteristics of the participants are described in Table 1. The median follow-up time was 48 months in Follow‑up period and cardiovascular events both groups. Participants were followed-up for 4 years. During the During the mean follow-up time of 48 months, a total follow-up period, data on fatal and nonfatal cardiovas- of 203 CVE was registered, of which 107 occurred among cular events were recorded by the referring physician as participants without diabetes and 96 among participants reported previously [20]. The CVE were defined accord- with diabetes. Corresponding CVE rates were 19.58 ver- ing to the International Classification of Diseases, Ninth sus 44.44 per 1000 person-years, respectively (Additional Revision, Clinical Modification [ICD9-CM], which file 1: Figure S1). We also observed that among diabetes includes unstable angina, myocardial infarction, tran- participants, CVE rates increased with declining renal sient ischaemic attack, cerebrovascular accident, conges- function: CVE rates were 30.90 per 1000 person-years tive heart failure, arrhythmia, peripheral arterial disease in CKD-3 versus 41.14 per 1000 person-years in CKD- or amputation due to peripheral arterial disease, and 4/5 and 100.67 per 1000 person-years in individuals on aortic aneurism [21]. Cardiovascular mortality causes renal replacement therapy (RRT) (p-trend < 0.001). This included myocardial infarction, arrhythmia, congestive tendency was milder among renal participants with- heart failure, stroke, abdominal aortic aneurism, mesen- out diabetes: CVE rates were 15.04 per 1000 person- teric infarction, and sudden death. CVEs and death were years in CKD-3 versus 18.19 per 1000 person-years in Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 4 of 9 Table 1 Population baseline characteristics CKD without diabetes CKD with diabetes p-value N = 1747 N = 698 Gender, male 1047 (59.9%) 461 (66.0%) 0.006 CKD stage < 0.001 CKD-3 662 (37.9%) 288 (41.3%) CKD-4/5 551 (31.5%) 256 (36.7%) RTT​ 534 (30.6%) 154 (22.1%) Age [years] 59.0 [48.0;67.0] 65.0 [56.0;70.0] < 0.001 Current smoker 967 (55.4%) 404 (57.9%) 0.275 Hypertension 1554 (89.0%) 673 (96.4%) < 0.001 25-OH vitamin D [ng/ml] 15.4 [11.4;19.6] 13.8 [10.4;18.5] < 0.001 eGFR [ml/min per 1.73 ­m2] 31.6 [20.9;44.3] 31.7 [21.5;44.2] 0.812 Glucose [mg/dl] 92.0 [85.0;101] 133 [108;164] < 0.001 Total cholesterol [mg/dl] 177 [153;205] 171 [143;197] < 0.001 HDL cholesterol [mg/dl] 48.0 [39.0;59.0] 44.0 [36.0;53.9] < 0.001 LDL cholesterol [mg/dl] 103 [82.0;123] 92.0 [71.4;113] < 0.001 non-HDL cholesterol [mg/dl] 128 [105;153] 122 [100;148] 0.011 Triglycerides [mg/dl] 118 [89.0;162] 147 [103;205] < 0.001 hsCRP [mg/dl] 1.86 [0.90;4.17] 2.58 [1.16;5.84] < 0.001 Antidiabetic treatment < 0.001 Diet – 166 (23.8%) Oral hypoglycemic drugs – 164 (23.5%) Insulin treatment – 368 (52.7%) HbA1c [g/dl] 5.40 [5.10;5.70] 6.80 [6.10;7.80] < 0.001 Albumin/creatinine ratio mg/g 89.1 [11.2;384] 149 [18.6;601] 0.001 Pulse pressure [mmHg] 56.0 [47.0;69.0] 68.0 [54.0;81.0] < 0.001 Antihypertensive treatment 1506 (86.2%) 650 (93.1%) < 0.001 Lipid-lowering drugs 975 (55.8%) 465 (66.6%) < 0.001 Number of plaques 1.00 [0.00;3.00] 3.00 [1.00;5.00] < 0.001 Presence of any plaque 1138 (65.1%) 570 (81.7%) < 0.001 Presence of carotid plaques 901 (51.6%) 502 (71.9%) < 0.001 Carotid plaque [only] 291 (16.7%) 165 (23.6%) < 0.001 Presence of femoral plaques 847 (48.5%) 405 (58.0%) < 0.001 Femoral plaque [only] 237 (13.6%) 68 (9.74%) 0.012 > 2 territories with plaque 853 (48.8%) 465 (66.6%) < 0.001 Carotid and femoral plaques 610 (34.9%) 337 (48.3%) < 0.001 Follow-up time [months] 48.4 [27.1;52.0] 48.3 [25.7;52.0] 0.675 CKD chronic kidney disease, RRT​ renal replacement therapy, eGFR estimated glomerular filtration rate determined by the Modification of Diet in Renal Disease Study formula (MDRD-4), HDL high density lipoprotein, LDL low density lipoprotein, hsCRP high sensitivity C-reactive protein CKD-4/5 versus 31.72 per 1000 person-years for RRT p = 0.0019), and this was observed consistently across (p-trend < 0.001). (Additional file 1: Figure S1). all stages of CKD. In line with this result, stage 3 CKD Among women without diabetes, the CVE rate during women with diabetes experienced a slightly higher rate follow-up was 16.04 per 1000 person-years and in men of incident CVEs compared to men with diabetes and without diabetes, it was 22.05 per 1000 person-years. stage 3 CKD (31.52 versus 30.67 per 1000 person-years, Among women with diabetes, the CVE rate was 32.17 per respectively) (Additional file 1: Figure S1). 1000 person-years, whereas among men with diabetes, it was 50.92 per 1000 person-years. Women with diabetes presented with more CVEs than men without diabetes Factors associated with CVE (32.17 versus 22.05 per 1000 person-years, respectively; Among CKD participants without diabetes, the bivariate analysis showed that age (HR 1.04, 95% CI [1.02;1.06]), Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 5 of 9 RRT (HR 2.23, 95% CI [1.40;3.55]), current smoker (HR 5.83, 95% CI [2.95;11.54] and HR 3.39, 95% CI [1.48;7.75], 1.60, 95% CI [1.08;2.39]), serum concentration of HDL- respectively) and the number of territories with basal cholesterol (0.98, 95% CI [0.96;0.99]), serum concentra- plaque (HR 1.26, 95% CI [1.18;1.35] and HR 1.18, 95% CI tion of hsCRP (HR 1.01, 95% CI [1.00;1.03]) and pulse [1.09;1.27], respectively) as well as having more than two pressure values (1.02, 95% CI [1.01;1.03]) were associ- vascular territories affected with plaque at baseline (HR ated with the occurrence of CVEs during the follow-up 3.26, 95% CI [2.09;5.07] and HR 3.35, 95% CI [1.87;6.01], period (Additional file 1: Table S1). Among CKD partici- respectively) were associated with suffering from a CVE pants with diabetes, factors associated with a CVE were during follow-up (Table 2). To the same extent, the pres- RRT (HR 3.58, 95% CI [2.16;5.93]) and insulin treatment ence of atherosclerotic plaques in both vascular sites, (HR 1.87, 95% CI [1.06;3.30]). Additionally, in this group carotid and femoral, was also found to be positively asso- of CKD participants with diabetes, being a female was ciated with incident CVEs in both groups (HR 2.57, 95% associated with fewer CVEs (0.63, 95% CI [0.40;1.00]) CI [1.75;3.78] and HR 2.09, 95% CI [1.37;3.17], respec- as well as having better renal function (HR 0.98, 95% CI tively) (Table 2). [0.96;1.00]) (Additional file 1: Table S1). In both groups, Following the competing risk model analysis, the vari- it was found that serum concentrations of 25-OH vita- ables predicting CVE in CKD participants without diabe- min D were inversely associated with the incidence of tes were the number of territories with plaque at baseline CVE, participants without diabetes HR 0.96, 95% CI (HR 1.862, 95% CI [1.432;2.240]), age (HR 1.026, 95% CI [0.93;0.99], and participants with diabetes HR 0.95, 95% [1.003;1.049]) and serum concentrations of 25-OH vita- CI [0.92;0.98] (Additional file 1: Table S1). min D (HR 0.963, 95% CI [0.933;0.094]) (Table 3). On In both the nondiabetic and diabetic study groups, the the other hand, among CKD participants with diabetes, bivariate analysis showed that the presence of plaque (HR the only variable that predicted CVEs was the number Table 2 Bivariate unadjusted analysis of the plaque at baseline according to the incidence of cardiovascular events CKD without diabetes CKD with diabetes No CVE N = 1640 CVE N = 107 HR [95% CI] p value* No CVE N = 602 CVE N = 96 HR [95% CI] p value* Territories with plaque 1.0 [0.0;3.0] 3.0 [2.0;5.0] 1.26 [1.18;1.35] < 0.001 2.0 [1.0;5.0] 4.0 [2.0;6.0] 1.18 [1.09;1.27] < 0.001 Presence of plaque 1040 (63.4%) 98 (91.6%) 5.83 [2.95;11.54] < 0.001 480 (79.7%) 90 (93.8%) 3.39 [1.48;7.75] 0.004 Presence of carotid 815 (49.7%) 86 (80.4%) 3.80 [2.36;6.12] < 0.001 418 (69.4%) 84 (87.5%) 2.86 [1.56;5.24] 0.001 plaque Carotid plaque [only] 267 (16.3%) 24 (22.4%) 1.41 [0.90;2.22] 0.137 143 (23.8%) 22 (22.9%) 0.92 [0.57;1.49] 0.748 Presence of femoral 773 (47.1%) 74 (69.2%) 2.42 [1.60;3.64] < 0.001 337 (56.0%) 68 (70.8%) 1.81 [1.17;2.82] 0.008 plaque Femoral plaque [only] 225 (13.7%) 12 (11.2%) 0.83 [0.45;1.51] 0.538 62 (10.3%) 6 (6.25%) 0.56 [0.25;1.29] 0.173 > 2 territories with plaque 772 (47.1%) 81 (75.7%) 3.26 [2.09;5.07] < 0.001 382 (63.5%) 83 (86.5%) 3.35 [1.87;6.01] < 0.001 Carotid and femoral 548 (33.4%) 62 (57.9%) 2.57 [1.75;3.78] < 0.001 275 (45.7%) 62 (64.6%) 2.09 [1.37;3.17] 0.001 plaque CVE fatal and non-fatal cardiovascular event *p values correspond to HR. Chi-squared test for trend in proportions p < 0.005 Table 3 Fine and Gray multiple regression to model incidence of cardiovascular events CKD without diabetes CKD with diabetes HR [95% CI] p-value HR [95% CI] p-value Age 1.026 [1.003;1.049] 0.024 – – Baseline PL [sq] 1.862 [1.432;2.420] < 0.001 1.782 [1.393;2.278] < 0.001 25-OH vitamin D 0.963 [0.933;0.994] < 0.001 – – C-index (24 months) 78.88 71.82 C-index (48 months) 75.63 71.49 The variables introduced to build the model were: gender, age in years, smoking, CKD stage, HDL cholesterol, 25-OH vitamin D and the square root of number of territories with plaque(s) at baseline, and glycated haemoglobin, oral treatment, and insulin treatment only for DM patients CKD chronic kidney disease, Baseline PL [sq] the square root of number of territories with plaque Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 6 of 9 of territories with plaque at baseline (HR 1.782, 95% CI Concerning individuals with diabetes, the atheroscle- [1.393;2.278]) (Table 3). Estimated C-index values over rotic burden measured by the CAC score has been shown 0.7 were found for the selected model in each group to predict CVEs in asymptomatic subjects [7], while the (Table 3). presence of carotid and/or lower limb atherosclerosis assessed by ultrasonography has been shown to be asso- ciated with the prevalence of CVD [37], with the risk Discussion being greater in those subjects with concomitant carotid In the present study, we found that in CKD participants and femoral atherosclerosis. with diabetes and without known CVD, an increased burden of basal atherosclerotic plaque translates into an increased risk of incident CVEs. We also demonstrated Other factors associated with CVE that the number of vascular territories affected with The analysis of associated factors with the incidence of plaque is the strongest associated factor for future CVEs CVEs in our cohort of individuals has shown that age and in CKD individuals with diabetes, whereas in nondiabetic serum 25-OH vitamin D concentrations were predictive CKD individuals, other factors influenced the occurrence of CVEs only in CKD individuals without diabetes, while of CVE, such as age and serum concentrations of 25-OH the number of territories with plaque at baseline was vitamin D. To the best of our knowledge, this is an origi- predictive of CVEs both in individuals with and without nal work showing that in individuals with CKD and dia- diabetes. betes, multiterritorial vascular ultrasonography could Age is a well-known factor for CVD [38]. In our study, help in future CVE prediction. age was independently associated with CVEs in CKD individuals without diabetes but not in those with diabe- tes, inferring that individuals with diabetes present with Atherosclerosis burden and CVE a higher incidence of CVEs at younger ages, as has been Atherosclerosis is a diffuse condition. Historically, nec- reported in the literature [39]. Likewise, the association ropsy examinations have revealed extensive atheroscle- between 25-OH vitamin D serum concentrations and the rotic lesions in subjects experiencing fatal CVEs [25], incidence of CVE found in the present study in individu- thus linking CVD and atherosclerosis burden. Data from als without diabetes is in keeping with studies that appear the literature have shown that the detection of preclinical to link vitamin D deficiency to CVD [40]. atherosclerosis improved cardiovascular risk prediction In the current analysis, there were no other risk factors beyond traditional cardiovascular risk factors [26, 27]. In that improved the assessment of CVE risk once added to addition, the quantification of plaque burden improved the number of territories with plaque. Strikingly, the only risk prediction even further [27–29]. Proxy measures factor predicting CVEs in this group with diabetes was of atherosclerosis burden, including noninvasive tech- atherosclerotic burden. niques, such as coronary artery calcification (CAC) score In fact, in our study, sex was not a risk factor for the and vascular ultrasonography, have been the object of incidence of CVEs in individuals with or without diabe- multiple investigations as a tool to predict incident CVEs. tes. In the general population, it is known that nondia- In individuals without established CVD, previous stud- betic women have fewer CVEs than nondiabetic men of ies have reported that atherosclerosis burden, meas- the same age. However, this advantage appears to be lost ured either by CAC score or plaque burden at carotid in the presence of diabetes [41–45]. The present study is or femoral sites, is a strong and independent predictor in agreement with these findings showing that the loss of of CVEs [30, 31]. A high atherosclerotic burden has also the protective cardiovascular sex effect is also observed been associated with increased cardiovascular and total in women with diabetes and CKD. This statement is rein- mortality risk [32–34], even in very elderly people [35]. forced by the fact that the incidence of CVEs in women Additionally, data from prior studies including renal par- from our cohort with diabetes was higher than that in ticipant cohorts have also demonstrated the relationship men without diabetes, as well as by the data that the inci- between atherosclerosis burden and CVD. A study from dence of CVEs was similar in women with diabetes in our group published in 2017 [20] found that the number stage 3 CKD compared to males with diabetes with simi- of arterial territories affected with atherosclerotic plaque lar kidney function. predicted the occurrence of CVEs in a cohort of asymp- Regarding cardiovascular risk prediction in patients tomatic renal individuals, including all-stages of CKD. with diabetes, Colom et al. have recently described that Likewise, in a work that followed 226 individuals on hae- in patients with type 1 diabetes without previous cardio- modialysis for 5 years with carotid ultrasonography [36], vascular disease alterations in the composition of HDL plaque number was found to be an independent marker are associated with subclinical coronary artery disease of fatal CVEs. as well as with an increased volume of epicardial adipose Palanca et al. Cardiovasc Diabetol (2019) 18:93 Page 7 of 9 tissue suggesting that HDL composition may be a link Additional file between coronary atherosclerosis and the accumulation of this type of adipose tissue in these subjects [46]. Also Additional file 1: Figure S1. Cardiovascular event incidence rates per in subjects with type 1 diabetes free from CV disease, our 1000 person-years according to chronic kidney disease stage, diabetes status and gender. Table S1. Bivariate analysis of baseline characteristics group has recently described that presence of advanced in the NEFRONA cohort by incidence of cardiovascular events. stages of diabetic retinopathy are associated with pres- ence and burden of subclinical carotid atherosclerosis Abbreviations [47]. On the other hand, in healthy normotensive and CKD: chronic kidney disease; CVEs: cardiovascular events; SA: subclinical normoglycaemic subjects classical risk factors, such as atherosclerosis; CVD: cardiovascular disease; cIMT: carotid intima media thick‑ age and blood pressure, have been found to be associated ness; RRT​: renal replacement therapy; CAC​: coronary artery calcification; MI: myocardial infarction. with subclinical vascular damage while no association has been found with plasma biomarkers involved in the Acknowledgements inflammatory process of atherosclerosis [48]. We particularly acknowledge the participants, the NEFRONA team (Teresa Vidal, Eva Castro, Virtudes María, Teresa Molí, Meritxell Soria) and the Biobank Finally, as we have demonstrated in the present work, of RedInRen for their collaboration. quantification of atherosclerotic lesions by vascular ultra- sonography is a feasible and reliable tool for CVE predic- Authors’ contributions AP and EC contributed to the study design, conduct of the study, data analy‑ tion. It should also be noted that new three-dimensional sis, and the writing of the manuscript. JMV, MB-L and AB contributed to the [28] and contrast-enhanced ultrasonography [49] could data collection and conduct of the study. HP and XD contributed to the data improve vascular assessment even further and thus con- analyses and writing of the manuscript. EF, PHG and MPD contributed to data interpretation and discussion. NA and DM contributed to the study design tribute to refining the early prediction of CVEs. and coordination, conduct of the study, data analysis, and writing of the manuscript. All authors critically reviewed the manuscript and approved the final version for publication. DM and NA are the guarantors of this work and, as such, had full access to all the data in the study and take responsibility for the Limitations integrity of the data and the accuracy of the data analysis. All authors read and A limitation of the current work relates to the baseline approved the final manuscript. clinical characteristics relevant to diabetes that were not Funding available due to the inherent nature of the NEFRONA This research was supported by grants from the Carlos III National Institute of study that was initially designed to investigate renal dis- Health (PI14/1772), the European Foundation for the Study of Diabetes (2014- ease and cardiovascular risk. In addition, the endpoints EFSD-00914) and European Regional Development Fund. CIBER for Diabetes and Associated Metabolic Diseases (CIBERDEM) is an initiative of ISCIII, Spain. registered during the observation period entailed the The NEFRONA study is funded by a research grant from AbbVie. discontinuation of the follow-up after a first CVE, after nonCV death or after renal transplantation. However, Availability of data and materials Primary material is held by the authors. this has been considered and mitigated with the compet- ing risk analysis. Ethics approval and consent to participate The Ethical Committees of all involved Spanish nephrology centres approved this study with the final approval by the Ethics committee board of the Hospital Universitario Arnau de Vilanova (Lleida, Spain). The investigation has Conclusions been conducted according to the principles expressed in the Declaration of CVD screening in asymptomatic individuals with dia- Helsinki, and all the included participants provided written informed consents. betes remains controversial [50]. Moreover, CVD risk Consent for publication stratification remains an important challenge in the CKD Not applicable. population. However, our results shed some light on this Competing interests matter. We have demonstrated that multiterritorial ultra- The authors declare that they have no competing interests. sonography is a valid and strong noninvasive tool to help predict CVEs among diabetic individuals with CKD. In Author details 1 Department of Endocrinology & Nutrition, Health Sciences Research this subgroup of high-risk individuals, quantifying SA by Institute & University Hospital Germans Trias i Pujol, Carretera Canyet S/N, the combined application of carotid and lower extremity 08916 Badalona, Spain. 2 Department of Medicine, Barcelona Autonomous vascular ultrasonography could improve CVE prediction University (UAB), Barcelona, Spain. 3 Department of Endocrinology & Nutrition, Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomédica Sant and may help identify those individuals with higher CV Pau (IIB Sant Pau), Sant Quintí, 89, 08041 Barcelona, Spain. 4 Center for Bio‑ risk. The strategies implemented in routine practice to medical Research on Diabetes and Associated Metabolic Diseases (CIBERDEM), efficiently quantify subclinical arterial lesions in diabetic Barcelona, Spain. 5 Vascular and Renal Translational Research Group, Institut de Recerca Biomèdica de Lleida, Lleida, Spain. 6 Biostatistics Unit, Institut de individuals with CKD might be of clinical benefit and Recerca Biomèdica de Lleida, Lleida, Spain. 7 Folkhälsan Institute of Genetics, should be considered with a special emphasis on younger Folkhälsan Research Center, Helsinki, Finland. 8 Abdominal Center Nephrol‑ women with diabetes. ogy, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland. 9 Research Program for Clinical and Molecular Metabolism, Faculty Palanca et al. 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