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Triglycerides, hypertension, and smoking predict cardiovascular disease in dysbetalipoproteinemia
Journal Pre-proof Triglycerides, Hypertension, and Smoking Predict Cardiovascular Disease in Dysbetalipoproteinemia Martine Paquette, M.Sc., Sophie Bernard, MD, PhD, Guillaume Paré, MD, M.Sc., Alexis Baass, MD, M.Sc. PII:
S1933-2874(19)30366-6
DOI:
https://doi.org/10.1016/j.jacl.2019.12.006
Reference:
JACL 1531
To appear in:
Journal of Clinical Lipidology
Received Date: 13 September 2019 Revised Date:
18 December 2019
Accepted Date: 18 December 2019
Please cite this article as: Paquette M, Bernard S, Paré G, Baass A, Triglycerides, Hypertension, and Smoking Predict Cardiovascular Disease in Dysbetalipoproteinemia, Journal of Clinical Lipidology (2020), doi: https://doi.org/10.1016/j.jacl.2019.12.006. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc. on behalf of National Lipid Association.
Triglycerides, Hypertension, and Smoking Predict Cardiovascular Disease in Dysbetalipoproteinemia
Martine Paquette, M.Sc. a, Sophie Bernard, MD, PhD
a,b
, Guillaume Paré, MD, M.Sc. c,
Alexis Baass, MD, M.Sc. a,d *
a
Lipids, Nutrition and Cardiovascular Prevention Clinic of the Montreal Clinical
Research Institute (Québec, Canada). b Department of Medicine, Division of Endocrinology, Université de Montreal (Québec, Canada). c Genetic Molecular Epidemiology Lab, Population Health Research Institute (Ontario, Canada). d Department of Medicine, Divisions of Experimental Medicine and Medical Biochemistry, McGill University (Québec, Canada).
*To whom correspondence should be addressed: Alexis Baass, Lipids, Nutrition and Cardiovascular Prevention Clinic of the Montreal Clinical Research Institute, 110 avenue des Pins Ouest, Montreal, (Québec, Canada) H2W 1R7. Phone: 1-514-987-5650, Fax: 514-987-5689, E-mail: [email protected]
Number of Tables: 3 Number of Figures: 2 Number of Supplemental Material: 0
SHORT TITLE: Predicting CVD in DBL
ABSTRACT 1
Background: Dysbetalipoproteinemia (DBL) is an autosomal recessive lipid disorder
2
associated with a reduced clearance of remnant lipoproteins and is associated with an
3
increased cardiovascular disease (CVD) risk. The genetic cause of DBL is apoE2
4
homozygosity in 90% of cases. However, a second metabolic hit must be present to
5
precipitate the disease. However, no study has investigated the predictors of CVD,
6
peripheral artery disease (PAD) and coronary artery disease (CAD) in a large cohort of
7
DBL patients.
8
Objective: The objectives of this study were to describe the clinical characteristics of a
9
DBL cohort and to identify the predictors of CVD, PAD and CAD in this population.
10
Methods: The inclusion criteria included age ≥ 18 years, apoE2/E2, triglycerides (TG) >
11
135 mg/dL and VLDL-C/ plasma TG ratio > 0.30.
12
Results: We studied 221 adult DBL patients, of which 51 (23%) had a history of CVD.
13
We identified three independent predictors of CVD, namely hypertension (OR 5.68, 95%
14
CI 2.13-15.16, p=0.001), pack year of smoking (OR 1.03, 95% CI 1.01-1.05, p=0.01) and
15
TG tertile (OR 1.82, 95% CI 1.09-3.05, p=0.02). The CVD prevalence was 51% in
16
patients with hypertension and 18% in those without hypertension (p=0.00001), and 30%
17
in the highest TG tertile vs 15% in the lowest tertile (p=0.04). Similarly, the CVD
18
prevalence was higher in heavy smokers compared to non-smokers (36% vs 13%,
19
p=0.006).
20
Conclusion: Hypertension, smoking and triglycerides are independently associated with
21
CVD risk in DBL patients. Aggressive treatment should be initiated in DBL patients due
22
to the increased risk of CVD.
2
1 2
KEYWORDS: Dysbetalipoproteinemia; cardiovascular disease; hypertension; smoking;
3
triglycerides; risk stratification; type III hyperlipoproteinemia.
3
1
INTRODUCTION
2
Dysbetalipoproteinemia (DBL), traditionally known as type III hyperlipoproteinemia
3
according to the Fredrickson classification (OMIM# 617347), is a lipid disorder
4
associated with an altered metabolism of remnant lipoproteins resulting in the
5
accumulation of chylomicron remnants and intermediate-density lipoproteins (IDLs) in
6
the circulation. The prevalence of DBL is estimated to be approximately 0.12 to 0.40%,
7
but varies substantially according to the definition of DBL [1]. The most common genetic
8
defect underlying DBL is the apolipoprotein (apo) E2 homozygosity (90% of cases). In
9
the remaining 10% of cases, DBL is rather caused by an autosomal dominant mutation in
10
APOE gene [1,2]. However, the majority of E2/E2 individuals are not affected by DBL.
11
Indeed, the overall prevalence of E2/E2 is 0.7-1.0% [3], but less than 20% of these
12
individuals develop DBL, although the estimated prevalence is highly discordant
13
throughout the literature [reviewed in 1-4]. The presence of secondary factors such as
14
insulin resistance, obesity, type 2 diabetes, diet, alcohol, hypothyroidism, pregnancy,
15
oestrogen therapy, menopause or high polygenic burden must also be present to
16
precipitate DBL [5]. These precipitating factors act by either decreasing remnants
17
clearance, increasing very-low-density lipoprotein (VLDL) production and/or decreasing
18
the lipoprotein lipase (LPL) activity [6]. In E2/E2 individuals, the DBL phenotype
19
generally does not occur until the third or fourth decade of life.
20
The clearance of remnant lipoproteins from the circulation is mediated through apoE.
21
ApoE is a ligand for the hepatic low-density lipoprotein (LDL) receptor (LDLR), but also
22
for the LDLR-related protein (LRP) and the HSPG receptor (HSPG-R) [1]. The apoE2
4
1
isoform possesses a low affinity for the LDLR, causing a delayed clearance of the
2
remnant lipoproteins only when a second metabolic hit occurs [7].
3
In terms of the basic lipid profile, DBL patients are characterized by elevated total
4
cholesterol and triglycerides (TG), and often present with reduced high-density
5
lipoprotein cholesterol (HDL-C) and LDL-C as well [3,8,9]. The gold standard to
6
diagnose DBL requires ultracentrifugation. In patients with triglycerides value between
7
150 and 1000 mg/dL (1.7 and 11.3 mmol/L), a VLDL-C/ plasma TG ratio > 0.30 (0.69 in
8
SI units) is considered to be the cut off to establish a DBL diagnosis [10-12].
9
Concerning the treatment of DBL patients, a combination treatment with statin and
10
fibrate is often used. However, fenofibrate is preferred over gemfibrozil due to risk of
11
myopathy when gemfibrozil-statin combination therapy is employed [13,14].
12
The clinical manifestations frequently seen in DBL include tuberous xanthomas and
13
pathognomonic palmar striated xanthomas, which are caused by subcutaneous ectopic
14
deposition of remnant lipoproteins [for pictures, see 11,15]. Furthermore, the coronary
15
artery disease (CAD) risk has been reported to be 5 to 10 fold higher in DBL than in the
16
general population [16]. The risk of peripheral artery disease (PAD) is also increased in
17
this population, with a reported prevalence of 11-19% [17,18] compared to 4% in the
18
general US population [19]. The E2/E2 genotype itself has been associated with a 2-fold
19
higher risk of PAD compared to the E3/E3 [20]. Hopefully, DBL patients generally
20
respond well to treatment and lifestyle changes [2,21].
21
However, to date, little is known about the cardiovascular risk factors in DBL patients.
22
The objectives of this study were to describe the clinical characteristics of a large DBL
5
1
cohort and to investigate what are the predictors of cardiovascular disease (CVD) in this
2
population.
3 4
MATERIALS AND METHODS
5
Study Population and Data Collection
6
We screened 17 109 patients from the Institut de recherches cliniques de Montreal
7
(IRCM) lipid clinic research database and identified 339 (2% of the 14 346 tested
8
patients) with apoE2/E2 and 335 of them were adults. In the present study, the criteria
9
used to establish a diagnosis of DBL among E2/E2 individuals is based on the gold
10
standard criteria of Fredrickson that require ultracentrifugation: triglycerides > 135
11
mg/dL (1.5 mmol/L) as well as VLDL-C/plasma TG > 0.30 (in mg/dL) [10-12]. As
12
presented in the Figure 1, a total of 221 DBL patients were included in the present
13
retrospective study according to these criteria. Baseline clinical data corresponding to the
14
first visit at the lipid clinic were collected over a thirty-five year period (from 1969 to
15
2004). Each patient underwent a 4-week washout of fibrate before the baseline lipid
16
profile. The statin therapy was also stopped, with the exception of patients in secondary
17
prevention. The main outcome of this study was the presence of prevalent cardiovascular
18
disease and included the following events: angina, myocardial infarction, coronary
19
angioplasty, coronary bypass surgery, claudication, peripheral angioplasty, peripheral
20
arterial surgery, transient ischemic attack, stroke, and carotid endarterectomy. The CVD
21
events were self-reported by the patients and validated in the majority of cases with
22
copies of relevant tests and progress notes of emergency visits and hospitalizations.
23
Diagnosis of hypertension was established according the Canadian Hypertension 6
1
Education Program (CHEP) criteria. Written informed consent was obtained from each
2
patient included in the study. The study protocol conforms to the ethical guidelines of the
3
1975 Declaration of Helsinki. The study protocol has been priorly approved by the IRCM
4
ethics institutional review board on research on humans.
5 6
Biochemical analysis
7
Blood samples were obtained after a 12-h overnight fast. Lipid measurements including
8
the ultracentrifugation and electrophoresis were performed according to standardized
9
methods and performed at the laboratory of the IRCM lipid clinic. LDL-C values were
10
measured using the gold standard beta quantification method. A commercial ELISA kit
11
(Macra EIA Kit; Strategic Diagnostics Industries, Inc, Newark) was used to measure
12
circulating lipoprotein (a) (Lp(a)), whereas apolipoprotein B concentration was measured
13
by electroimmunoassay (Behringwerke, Marburg, Germany). ApoE isoforms were
14
determined either by phenotyping or genotyping. Briefly, apoE phenotype was
15
determined by isoelectric focusing of delipidated VLDL, which is highly concordant with
16
APOE genotyping [22]. APOE genotype was determined by restriction enzyme analysis
17
as previously described [23].
18 19
Statistical Analyses
20
Statistical analyses were performed using both the SPSS statistical software version 25
21
(IBM Corp, Armonk, NY) and SAS 9.4 (SAS Institute, Cary NC). The p values are
22
considered statistically significant when < 0.05. All p values are two-sided. Continuous
23
normally distributed variables are expressed as mean ± standard deviation (SD), whereas
7
1
continuous abnormally distributed variables are presented as median (Q1-Q3). These
2
skewed variables were log-transformed prior the analysis. Categorical variables are
3
expressed as frequency (n (%)). Differences between the CVD and the non-CVD groups
4
were assessed by a Student’s t-test, the Chi2 test or the Fisher’s exact test. Univariate and
5
multivariate logistic regression models were used to study the predictors of CVD.
6
7
RESULTS
8
The general baseline characteristics of the 221 DBL patients are presented in Table 1.
9
The cohort comprised 59% of men and the mean age was 50 years. A total of 23 % of the
10
cohort had a previous history of CVD (n=51), with a prevalence of 14% for CAD, 12%
11
for PAD, and 5% for cerebrovascular disease (CeVD). The prevalence of hypertension,
12
smoking (both former and current), diabetes, statin use, fibrate use, tuberous xanthomas
13
and tuberoeruptive xanthomas was significantly higher in the CVD group than in the non-
14
CVD group (p< 0.05). The pack year of smoking was also significantly higher in the
15
CVD group (p=0.02). Total cholesterol and plasma TG were not statistically different
16
between groups (p=NS).
17
The univariate ORs for each significant predictors of CVD, PAD and CAD are presented
18
in Table 2. In the multivariate model where each predictors were entered in the model by
19
a forward stepwise method, only hypertension (OR 5.68, 95% CI 2.13-15.16, p=0.001),
20
pack year of smoking (OR 1.03, 95% CI 1.01-1.05, p=0.01) and TG tertile (OR 1.82,
21
95% CI 1.09-3.05, p=0.02) remained independent predictors of CVD (Table 3). The
22
multivariate predictors of PAD were pack year of smoking (OR 1.04, 95% CI 1.01-1.07,
8
1
p=0.006), tuberous xanthomas (OR 14.01, 95% CI 2.12-92.5, p=0.006) and VLDL-C/
2
plasma TG ratio (OR 18.85, 95% CI 1.18-300.21, p=0.04), whereas the multivariate
3
predictors of CAD were hypertension (OR 3.92, 95% CI 1.58-9.75, p=0.003) and TG
4
tertile (OR 2.13, 95% CI 1.24-3.67, p=0.006).
5
As illustrated in the Figure 2A, the prevalence of CVD was 51 % in the patients with
6
hypertension compared to 18% in patients without hypertension (p=0.00001). When
7
patients were stratified into TG tertiles, the prevalence of CVD was 15% in the lowest
8
tertile, 24% in the second tertile and 30% in the highest tertile (p=0.04) (Figure 2B).
9
Finally, the CVD prevalence according to the smoking status is illustrated in Figure 2C.
10
The smoking status has been divided in non-smokers (pack year = 0), mild-smokers (pack
11
year ≤ 15) and heavy-smokers (pack year > 15). The CVD prevalence is 13% in the non-
12
smokers group, 27% in the mild-smokers group and 36% in the heavy smokers group
13
(p=0.006).
14
15
DISCUSSION
16
DBL patients are characterized by accumulation of remnant lipoproteins in circulation,
17
which consists of triglyceride-rich lipoproteins that are enriched in cholesterol. These
18
remnant particles are highly atherogenic [24,25] and are associated with an increased risk
19
of CVD [16]. The present study is the first to identify independent clinical predictors of
20
total CVD, PAD and CAD in a cohort of well characterized DBL patients. Specific
21
strengths of this study include the fact that the gold standard diagnostic criteria were used
9
1
to confirm DBL diagnosis. Furthermore, this cohort of 221 patients represents the largest
2
cohort for which a strict definition of DBL was used.
3
We identified hypertension, pack year of smoking and elevated triglycerides as
4
independent predictors of cardiovascular disease in DBL.
5
Among all the patients attending our lipid clinic, 2% (339 /14 346) of them were found to
6
be E2/E2. This prevalence is twice the prevalence observed in the general population
7
(0.7-1%). Furthermore, 66% of the E2/E2 patients (221/335) had DBL, which is
8
dramatically higher than the estimated rate of less than 20%. The referral bias probably
9
explains these differences. Indeed, only the worst cases of dyslipidemia are referred to
10
our specialized lipid clinic.
11
In the present cohort of DBL patients, the prevalence of PAD is 12%, whereas the
12
prevalence of CAD is 14%. These prevalences of PAD and CAD seem similar or slightly
13
lower than the reported prevalences, even though it remains difficult to make inter-
14
studies comparisons due to the differences in the criteria used for the diagnosis of DBL.
15
Indeed, while some studies use criteria based on ultracentrifugation results [8], others rely
16
mainly on the presence of E2/E2 genotype [17] or criteria based on apoB value [26]. The
17
reported prevalence of PAD among DBL patients varies between 11%-27%, whereas the
18
reported prevalence of CAD is between 19%-28% [6,8,17]. Furthermore, the prevalence
19
of tuberous and tuberoeruptive xanthomas in the whole DBL cohort is only 4% for each
20
type of xanthoma. This prevalence is surprisingly low compared to the prevalence found
21
in other cohorts. Indeed, some studies found that up to 51 to 64% of DBL patients had
22
tuberous and tuberoeruptive xanthomas [1,27]. Similarly, the prevalence of striated
23
palmar xanthomas found in our cohort is only 8%, compared to the reported prevalence 10
1
of 55 to 64% [1,27]. However, data on the prevalence of xanthomas in DBL are very
2
scarce. Furthermore, the presence of xanthomas in E2/E2 patients is not systematically
3
screened in the clinical context, even in specialized lipid clinics. Therefore any
4
comparison between DBL cohorts is difficult to establish.
5
Previously, the only other study investigating cardiovascular risk in a small DBL cohort
6
(n=67) identified sex as a CVD risk predictor [28]. It is interesting to note that in our
7
cohort, there was a higher proportion of men in the CVD group than in the non-CVD
8
group, but this difference was not statistically significant. Surprisingly, both age and sex,
9
which are considered traditional CVD risk factors, were not significant predictors of
10
CVD in our DBL cohort. This could be due to the fact that the mean age in our cohort is
11
only 50 years, which limits the detrimental effect of age on the CVD risk, or simply due
12
to the referral bias. In a previous study, the authors found a 30.6% higher Lp(a) value
13
among DBL individuals with atherosclerosis, but the difference was not significant [28].
14
Similarly, in our study we did not find any difference in Lp(a) values between the CVD
15
and the non-CVD groups. Interestingly, the CVD, PAD and CAD risk in DBL patients
16
does not seem to be mainly predicted by lipid parameters. The sole exception is
17
triglycerides which in DBL patients are carried in atherogenic remnant lipoproteins.
18
Indeed, other non-lipidic clinical risk factors including smoking (for CVD and PAD),
19
hypertension (for CVD and CAD), as well as tuberous xanthomas and diabetes (for PAD
20
only) represent independent predictors in the present study.
21
Contrarily to what is observed in the general population, LDL-C is not a risk factor for
22
cardiovascular disease in our DBL cohort [29]. Indeed, due to several mechanisms related
23
to the presence of apoE2 such as an upregulation of the LDLR, a preferential binding of 11
1
LDL to LDLR or a decreased conversion of VLDL to LDL, DBL patients usually have
2
lower LDL-C values than the general population [24,30]. Therefore, LDL-C is not the
3
most appropriate target of treatment in DBL patients, in which the accumulation of
4
remnant lipoproteins is the main driver of the increased CVD risk.
5
The major limitation of this study is the retrospective nature of the cardiovascular events
6
reporting. Indeed, the prospective CVD events that occurred during the follow-up at the
7
lipid clinic have not been documented in the research database. Furthermore, our study
8
did not include non-E2/E2 DBL patients who carry an autosomal dominant mutation in
9
APOE gene. Therefore, the results of the present study can not be generalized to all DBL
10
patients.
11
12
CONCLUSIONS
13
In conclusion, this study reported cardiovascular risk factors among DBL patients using
14
data from the largest cohort of DBL patients for which a strict definition was used for the
15
diagnosis. In this cohort, hypertension, smoking and triglycerides were independent
16
predictors of CVD events. Therefore, not all DBL patients are at the same risk of
17
developing CVD and this risk can be stratify. Treatment that focus on lifestyle changes
18
should be initiated in all DBL patients, but more aggressive treatment should be initiated
19
in those at higher CVD risk. In particular, smoking cessation and adequate blood pressure
20
control beside hypolipidemic drugs are of major importance for these patients.
21 22
CONFLICT OF INTEREST 12
1
A.B. received research grants from Akcea, Amgen, Astra Zeneca, the Fondation Leducq,
2
Merck Frosst and Sanofi. He has participated in clinical research protocols from Acasti
3
Pharma Inc., Akcea, Amgen, Astra Zeneca, Ionis Pharmaceuticals, Inc., The Medicines
4
Company, Merck Frosst, Novartis, Pfizer, Regeneron Pharmaceuticals Inc. and Sanofi.
5
He has served on advisory boards and received honoraria for symposia from Akcea,
6
Amgen and Sanofi.
7
S.B. has participated in clinical research protocols from Akcea, Amgen, The Medicines
8
Company and Sanofi. She has served on advisory boards for Akcea, Amgen, Eli Lilly,
9
Merck Frosst, Novo Nordisk, Sanofi and Valeant Pharmaceuticals, and received
10
honoraria for symposia from Akcea, Amgen, Boehringer Ingelheim, Merck Frosst, Novo
11
Nordisk and Sanofi-Aventis.
12
G.P. Received research funding from Sanofi and received honoraria from Akcea, Amgen
13
and Sanofi.
14
M.P. has nothing to declare.
15 16
FINANCIAL SUPPORT
17
This work was supported by The Fondation Leducq Transatlantic Networks of
18
Excellence [grant number 13CVD03]. The study funders had no role in the study design,
19
in the collection, analysis and interpretation of data, in the writing of the report and in the
20
decision to submit the article for publication.
21 22
AUTHOR CONTRIBUTIONS
13
1
The authors' contributions were as follows: All authors contributed to the discussion,
2
analysis and interpretation of data and have reviewed the article for the intellectual
3
content. M.P performed statistical analysis and has drafted the manuscript. All authors
4
have approved the final article. A.B. had primary responsibility for final content.
5 6
ACKNOWLEDGEMENTS
7
The authors want to thank the Montreal Clinical Research Institute (IRCM) research team
8
and the nursing staff for their everyday help, support and implication.
14
1
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[26] Sniderman AD, de Graaf J, Thanassoulis G, Tremblay AJ, Martin SS, Couture P.
10
The spectrum of type III hyperlipoproteinemia. J Clin Lipidol. 2018;12(6):1383-9.
11
[27] Davignon J, Dufour R. Primary Hyperlipidemias: An Atlas of Investigation and
12
Diagnosis (2007). Clinical Publishing, Oxford, United Kingdom. ISBN 1-904-392-44-X;
13
156 pages.
14
[28] Feussner G, Wagner A, Ziegler R. Relation of cardiovascular risk factors to
15
atherosclerosis in type III hyperlipoproteinemia. Hum Genet. 1993;92(2):122-6.
16
[29] Stein EA, Raal FJ. Targeting LDL: is lower better and is it safe? Best Pract Res Clin
17
Endocrinol Metab. 2014;28(3):309-24.
18
[30] Schaefer JR. Unraveling hyperlipidemia type III (dysbetalipoproteinemia), slowly.
19
Eur J Hum Genet. 2009;17(5):541-2.
18
1
TABLES
2
Table 1. Baseline characteristics of the DBL cohort. Variables
Reference
Total cohort
DBL Sex Age Hypertension Smoking prevalence Smoking Diabetes BMI Total cholesterol Triglycerides LDL-C HDL-C Non-HDL-C VLDL-C VLDL-TG VLDL-C/ plasmaTG ratio Apolipoprotein B Lipoprotein (a) Statin at baseline Fibrate at baseline Tuberous xanthoma Tuberoeruptive xanthoma Striated palmar xanthoma Eruptive xanthoma Broad-beta band on electrophoresis
Male (%) (year) n (%) former (%) current (%) Pack year n (%) (kg/m2) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (g/L) (g/L) n (%) n (%) n (%) n (%) n (%) n (%) n (%)
N=221 120/202 (59%) 50 ± 14 35 (16%) 41/155 (26%) 59/155 (38%) 16 ± 18 16 (7%) 27.9 ± 3.7 333 ± 133 352 (244-597) 101 (81-134) 34 ± 9 299 ± 135 140 (94-247) 291 (197-532) 0.39 (0.35-0.46) 1.23 (0.98-1.68) 0.10 (0.04-0.26) 38 (17%) 73 (33%) 8 (4%) 9 (4%) 17 (8%) 7 (3%) 106/113 (94%)
n (%) 51 (23%) Retrospective CVD 32 (14%) CAD 26 (12%) PAD 11 (5%) CeVD 3 p values between CVD and non-CVD groups.
CVD N=51 33/48 (69%) 52 ± 13 18 (35%) 17/41 (41%) 17/41 (41%) 22 ± 19 8 (16%) 27.7 ± 3.9 353 ± 135 371 (282-617) 100 (84-142) 33 ± 9 320 ± 138 165 (107-279) 334 (219-564) 0.38 (0.35-0.44) 1.30 (0.99-1.83) 0.08 (0.04-0.26) 19 (37%) 28 (55%) 6 (12%) 5 (10%) 3 (6%) 3 (6%) 31/32 (97%)
Non-CVD N=170 87/154 (56%) 49 ± 14 17 (10%) 24/114 (21%) 42/114 (37%) 14 ± 18 8 (5%) 27.9 ± 3.7 327 ± 132 337 (233-555) 102 (80-133) 34 ± 9 293 ± 134 137 (91-243) 285 (185-469) 0.39 (0.34-0.46) 1.21 (0.98-1.65) 0.11 (0.03-0.53) 19 (11%) 45 (26%) 2 (1%) 4 (2%) 14 (8%) 4 (2%) 75/81 (93%)
51 (100%) 32 (63%) 26 (51%) 11 (22%)
-
p value 0.13 0.29 0.00001 0.006 0.02 0.008 0.75 0.21 0.14 0.47 0.71 0.21 0.18 0.11 0.90 0.43 0.88 0.00002 0.0002 0.002 0.03 0.77 0.20 0.67 -
19
1
BMI: body mass index; CAD: coronary artery disease; CeVD: cerebrovascular disease;
2
CVD: cardiovascular disease; DBL: dysbetalipoproteinemia; HDL-C: high-density
3
lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; PAD: peripheral
4
artery disease; TG: triglycerides; VLDL: very-low-density lipoprotein.
20
1
Table 2. Univariate predictors of CVD, PAD and CAD among DBL individuals. Predictors
OR (95%CI)
Univariate p value
CVD Hypertension
4.91 (2.29-10.52)
0.00004
Smoking pack year
1.02 (1.00-1.04)
0.02
Diabetes
3.77 (1.34-10.62)
0.01
Tuberous xanthoma
11.20 (2.19-57.38)
0.004
Tuberoeruptive xanthoma
4.51 (1.16-17.48)
0.03
TG tertile †
1.51 (1.02-2.25)
0.04
PAD Smoking pack year
1.03 (1.00-1.05)
0.03
Diabetes
7.61 (2.55-22.75)
0.0003
LDL-C
3.43 (1.14-10.30)
0.03
VLDL-C/ plasma TG ratio
9.55 (1.52-59.89)
0.02
28.95 (5.48-153.05)
0.00008
6.91 (1.73-27.65)
0.006
Tuberous xanthoma Tuberoeruptive xanthoma
CAD Hypertension
5.19 (2.26-11.96)
0.0001
Triglycerides
2.06 (1.11-3.82)
0.02
VLDL-TG
2.12 (1.17-3.84)
0.01
TG tertile †
1.86 (1.14-3.06)
0.01
2
† OR for third vs first tertile.
3
CAD:
4
dysbetalipoproteinemia; LDL-C: low-density lipoprotein cholesterol; PAD: peripheral
5
artery disease; TG: triglycerides; VLDL: very-low-density lipoprotein.
coronary
artery
disease;
CVD:
cardiovascular
disease;
DBL:
21
1
Table 3. Independent multivariate predictors of CVD, CAD and PAD among DBL
2
individuals. Predictors
OR (95%CI)
Multivariate p value
CVD Hypertension
5.68 (2.13-15.16)
0.001
Smoking pack year
1.03 (1.01-1.05)
0.01
TG tertile †
1.82 (1.09-3.05)
0.02
PAD Tuberous xanthomas VLDL-C/ plasma TG ratio Smoking pack year
14.01 (2.12-92.5)
0.006
18.85 (1.18-300.21)
0.04
1.04 (1.01-1.07)
0.006
CAD Hypertension
3.92 (1.58-9.75)
0.003
TG tertile †
2.13 (1.24-3.67)
0.006
3
† OR for third vs first tertile.
4
CAD:
5
dysbetalipoproteinemia; PAD: peripheral artery disease; TG: triglycerides; VLDL: very-
6
low-density lipoprotein.
coronary
artery
disease;
CVD:
cardiovascular
disease;
DBL:
22
1
FIGURE LEGENDS
2
Figure 1. Flowchart of patients’ selection. IRCM: Montreal Clinical Research Institute;
3
TG: triglycerides; VLDL: very-low-density lipoprotein.
4
Figure 2. CVD prevalence according to category of independent predictors.
5
A. CVD prevalence according to the presence or absence of hypertension.
6
B. CVD prevalence according to TG tertile. OR and p value for third vs first tertile.
7
C. CVD prevalence according to pack year group of smoking. OR and p value between
8
groups 0 and > 15.
9
CVD: cardiovascular disease; HTN: hypertension; TG: triglycerides.
23
Patients in the IRCM lipid clinic research database N=17109 Patients with E2/E2 N=339 (2%) Patients with E2/E2 ≥ 18 years N=335 Triglycerides > 135 mg/dL N=284 VLDL-C/TG > 0.30 N=221
Figure 1.
Total included N=221
A 100 p=0.00001 OR 4.91 (2.29-10.52)
90 CVD prevalence (%)
80 70 60
51
50 40 30 18
20 10 0 HTN
Figure 2A.
non-HTN
B
35
p=0.04 OR 1.51 (1.02-2.25)
CVD prevalence (%)
30
30
24
25 20 15
15
10 5 0 tertile 1 (0-274)
tertile 2 (275-462) TG tertiles
Figure 2B.
tertile 3 (≥ 463)
C
40
p=0.006 OR 1.95 (1.21-3.13)
CVD prevalence (%)
35 30
36
27
25 20 15
13
10 5 0 0
Figure 2C.
≤ 15 Pack year
> 15
HIGHLIGHTS 1. Dysbetalipoproteinemia (DBL) is a rare autosomal recessive lipid disorder. 2. DBL is associated with an increased cardiovascular disease (CVD) risk. 3. Triglycerides, hypertension and smoking are independent predictors of CVD in DBL.
S1933-2874(19)30366-6
DOI:
https://doi.org/10.1016/j.jacl.2019.12.006
Reference:
JACL 1531
To appear in:
Journal of Clinical Lipidology
Received Date: 13 September 2019 Revised Date:
18 December 2019
Accepted Date: 18 December 2019
Please cite this article as: Paquette M, Bernard S, Paré G, Baass A, Triglycerides, Hypertension, and Smoking Predict Cardiovascular Disease in Dysbetalipoproteinemia, Journal of Clinical Lipidology (2020), doi: https://doi.org/10.1016/j.jacl.2019.12.006. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc. on behalf of National Lipid Association.
Triglycerides, Hypertension, and Smoking Predict Cardiovascular Disease in Dysbetalipoproteinemia
Martine Paquette, M.Sc. a, Sophie Bernard, MD, PhD
a,b
, Guillaume Paré, MD, M.Sc. c,
Alexis Baass, MD, M.Sc. a,d *
a
Lipids, Nutrition and Cardiovascular Prevention Clinic of the Montreal Clinical
Research Institute (Québec, Canada). b Department of Medicine, Division of Endocrinology, Université de Montreal (Québec, Canada). c Genetic Molecular Epidemiology Lab, Population Health Research Institute (Ontario, Canada). d Department of Medicine, Divisions of Experimental Medicine and Medical Biochemistry, McGill University (Québec, Canada).
*To whom correspondence should be addressed: Alexis Baass, Lipids, Nutrition and Cardiovascular Prevention Clinic of the Montreal Clinical Research Institute, 110 avenue des Pins Ouest, Montreal, (Québec, Canada) H2W 1R7. Phone: 1-514-987-5650, Fax: 514-987-5689, E-mail: [email protected]
Number of Tables: 3 Number of Figures: 2 Number of Supplemental Material: 0
SHORT TITLE: Predicting CVD in DBL
ABSTRACT 1
Background: Dysbetalipoproteinemia (DBL) is an autosomal recessive lipid disorder
2
associated with a reduced clearance of remnant lipoproteins and is associated with an
3
increased cardiovascular disease (CVD) risk. The genetic cause of DBL is apoE2
4
homozygosity in 90% of cases. However, a second metabolic hit must be present to
5
precipitate the disease. However, no study has investigated the predictors of CVD,
6
peripheral artery disease (PAD) and coronary artery disease (CAD) in a large cohort of
7
DBL patients.
8
Objective: The objectives of this study were to describe the clinical characteristics of a
9
DBL cohort and to identify the predictors of CVD, PAD and CAD in this population.
10
Methods: The inclusion criteria included age ≥ 18 years, apoE2/E2, triglycerides (TG) >
11
135 mg/dL and VLDL-C/ plasma TG ratio > 0.30.
12
Results: We studied 221 adult DBL patients, of which 51 (23%) had a history of CVD.
13
We identified three independent predictors of CVD, namely hypertension (OR 5.68, 95%
14
CI 2.13-15.16, p=0.001), pack year of smoking (OR 1.03, 95% CI 1.01-1.05, p=0.01) and
15
TG tertile (OR 1.82, 95% CI 1.09-3.05, p=0.02). The CVD prevalence was 51% in
16
patients with hypertension and 18% in those without hypertension (p=0.00001), and 30%
17
in the highest TG tertile vs 15% in the lowest tertile (p=0.04). Similarly, the CVD
18
prevalence was higher in heavy smokers compared to non-smokers (36% vs 13%,
19
p=0.006).
20
Conclusion: Hypertension, smoking and triglycerides are independently associated with
21
CVD risk in DBL patients. Aggressive treatment should be initiated in DBL patients due
22
to the increased risk of CVD.
2
1 2
KEYWORDS: Dysbetalipoproteinemia; cardiovascular disease; hypertension; smoking;
3
triglycerides; risk stratification; type III hyperlipoproteinemia.
3
1
INTRODUCTION
2
Dysbetalipoproteinemia (DBL), traditionally known as type III hyperlipoproteinemia
3
according to the Fredrickson classification (OMIM# 617347), is a lipid disorder
4
associated with an altered metabolism of remnant lipoproteins resulting in the
5
accumulation of chylomicron remnants and intermediate-density lipoproteins (IDLs) in
6
the circulation. The prevalence of DBL is estimated to be approximately 0.12 to 0.40%,
7
but varies substantially according to the definition of DBL [1]. The most common genetic
8
defect underlying DBL is the apolipoprotein (apo) E2 homozygosity (90% of cases). In
9
the remaining 10% of cases, DBL is rather caused by an autosomal dominant mutation in
10
APOE gene [1,2]. However, the majority of E2/E2 individuals are not affected by DBL.
11
Indeed, the overall prevalence of E2/E2 is 0.7-1.0% [3], but less than 20% of these
12
individuals develop DBL, although the estimated prevalence is highly discordant
13
throughout the literature [reviewed in 1-4]. The presence of secondary factors such as
14
insulin resistance, obesity, type 2 diabetes, diet, alcohol, hypothyroidism, pregnancy,
15
oestrogen therapy, menopause or high polygenic burden must also be present to
16
precipitate DBL [5]. These precipitating factors act by either decreasing remnants
17
clearance, increasing very-low-density lipoprotein (VLDL) production and/or decreasing
18
the lipoprotein lipase (LPL) activity [6]. In E2/E2 individuals, the DBL phenotype
19
generally does not occur until the third or fourth decade of life.
20
The clearance of remnant lipoproteins from the circulation is mediated through apoE.
21
ApoE is a ligand for the hepatic low-density lipoprotein (LDL) receptor (LDLR), but also
22
for the LDLR-related protein (LRP) and the HSPG receptor (HSPG-R) [1]. The apoE2
4
1
isoform possesses a low affinity for the LDLR, causing a delayed clearance of the
2
remnant lipoproteins only when a second metabolic hit occurs [7].
3
In terms of the basic lipid profile, DBL patients are characterized by elevated total
4
cholesterol and triglycerides (TG), and often present with reduced high-density
5
lipoprotein cholesterol (HDL-C) and LDL-C as well [3,8,9]. The gold standard to
6
diagnose DBL requires ultracentrifugation. In patients with triglycerides value between
7
150 and 1000 mg/dL (1.7 and 11.3 mmol/L), a VLDL-C/ plasma TG ratio > 0.30 (0.69 in
8
SI units) is considered to be the cut off to establish a DBL diagnosis [10-12].
9
Concerning the treatment of DBL patients, a combination treatment with statin and
10
fibrate is often used. However, fenofibrate is preferred over gemfibrozil due to risk of
11
myopathy when gemfibrozil-statin combination therapy is employed [13,14].
12
The clinical manifestations frequently seen in DBL include tuberous xanthomas and
13
pathognomonic palmar striated xanthomas, which are caused by subcutaneous ectopic
14
deposition of remnant lipoproteins [for pictures, see 11,15]. Furthermore, the coronary
15
artery disease (CAD) risk has been reported to be 5 to 10 fold higher in DBL than in the
16
general population [16]. The risk of peripheral artery disease (PAD) is also increased in
17
this population, with a reported prevalence of 11-19% [17,18] compared to 4% in the
18
general US population [19]. The E2/E2 genotype itself has been associated with a 2-fold
19
higher risk of PAD compared to the E3/E3 [20]. Hopefully, DBL patients generally
20
respond well to treatment and lifestyle changes [2,21].
21
However, to date, little is known about the cardiovascular risk factors in DBL patients.
22
The objectives of this study were to describe the clinical characteristics of a large DBL
5
1
cohort and to investigate what are the predictors of cardiovascular disease (CVD) in this
2
population.
3 4
MATERIALS AND METHODS
5
Study Population and Data Collection
6
We screened 17 109 patients from the Institut de recherches cliniques de Montreal
7
(IRCM) lipid clinic research database and identified 339 (2% of the 14 346 tested
8
patients) with apoE2/E2 and 335 of them were adults. In the present study, the criteria
9
used to establish a diagnosis of DBL among E2/E2 individuals is based on the gold
10
standard criteria of Fredrickson that require ultracentrifugation: triglycerides > 135
11
mg/dL (1.5 mmol/L) as well as VLDL-C/plasma TG > 0.30 (in mg/dL) [10-12]. As
12
presented in the Figure 1, a total of 221 DBL patients were included in the present
13
retrospective study according to these criteria. Baseline clinical data corresponding to the
14
first visit at the lipid clinic were collected over a thirty-five year period (from 1969 to
15
2004). Each patient underwent a 4-week washout of fibrate before the baseline lipid
16
profile. The statin therapy was also stopped, with the exception of patients in secondary
17
prevention. The main outcome of this study was the presence of prevalent cardiovascular
18
disease and included the following events: angina, myocardial infarction, coronary
19
angioplasty, coronary bypass surgery, claudication, peripheral angioplasty, peripheral
20
arterial surgery, transient ischemic attack, stroke, and carotid endarterectomy. The CVD
21
events were self-reported by the patients and validated in the majority of cases with
22
copies of relevant tests and progress notes of emergency visits and hospitalizations.
23
Diagnosis of hypertension was established according the Canadian Hypertension 6
1
Education Program (CHEP) criteria. Written informed consent was obtained from each
2
patient included in the study. The study protocol conforms to the ethical guidelines of the
3
1975 Declaration of Helsinki. The study protocol has been priorly approved by the IRCM
4
ethics institutional review board on research on humans.
5 6
Biochemical analysis
7
Blood samples were obtained after a 12-h overnight fast. Lipid measurements including
8
the ultracentrifugation and electrophoresis were performed according to standardized
9
methods and performed at the laboratory of the IRCM lipid clinic. LDL-C values were
10
measured using the gold standard beta quantification method. A commercial ELISA kit
11
(Macra EIA Kit; Strategic Diagnostics Industries, Inc, Newark) was used to measure
12
circulating lipoprotein (a) (Lp(a)), whereas apolipoprotein B concentration was measured
13
by electroimmunoassay (Behringwerke, Marburg, Germany). ApoE isoforms were
14
determined either by phenotyping or genotyping. Briefly, apoE phenotype was
15
determined by isoelectric focusing of delipidated VLDL, which is highly concordant with
16
APOE genotyping [22]. APOE genotype was determined by restriction enzyme analysis
17
as previously described [23].
18 19
Statistical Analyses
20
Statistical analyses were performed using both the SPSS statistical software version 25
21
(IBM Corp, Armonk, NY) and SAS 9.4 (SAS Institute, Cary NC). The p values are
22
considered statistically significant when < 0.05. All p values are two-sided. Continuous
23
normally distributed variables are expressed as mean ± standard deviation (SD), whereas
7
1
continuous abnormally distributed variables are presented as median (Q1-Q3). These
2
skewed variables were log-transformed prior the analysis. Categorical variables are
3
expressed as frequency (n (%)). Differences between the CVD and the non-CVD groups
4
were assessed by a Student’s t-test, the Chi2 test or the Fisher’s exact test. Univariate and
5
multivariate logistic regression models were used to study the predictors of CVD.
6
7
RESULTS
8
The general baseline characteristics of the 221 DBL patients are presented in Table 1.
9
The cohort comprised 59% of men and the mean age was 50 years. A total of 23 % of the
10
cohort had a previous history of CVD (n=51), with a prevalence of 14% for CAD, 12%
11
for PAD, and 5% for cerebrovascular disease (CeVD). The prevalence of hypertension,
12
smoking (both former and current), diabetes, statin use, fibrate use, tuberous xanthomas
13
and tuberoeruptive xanthomas was significantly higher in the CVD group than in the non-
14
CVD group (p< 0.05). The pack year of smoking was also significantly higher in the
15
CVD group (p=0.02). Total cholesterol and plasma TG were not statistically different
16
between groups (p=NS).
17
The univariate ORs for each significant predictors of CVD, PAD and CAD are presented
18
in Table 2. In the multivariate model where each predictors were entered in the model by
19
a forward stepwise method, only hypertension (OR 5.68, 95% CI 2.13-15.16, p=0.001),
20
pack year of smoking (OR 1.03, 95% CI 1.01-1.05, p=0.01) and TG tertile (OR 1.82,
21
95% CI 1.09-3.05, p=0.02) remained independent predictors of CVD (Table 3). The
22
multivariate predictors of PAD were pack year of smoking (OR 1.04, 95% CI 1.01-1.07,
8
1
p=0.006), tuberous xanthomas (OR 14.01, 95% CI 2.12-92.5, p=0.006) and VLDL-C/
2
plasma TG ratio (OR 18.85, 95% CI 1.18-300.21, p=0.04), whereas the multivariate
3
predictors of CAD were hypertension (OR 3.92, 95% CI 1.58-9.75, p=0.003) and TG
4
tertile (OR 2.13, 95% CI 1.24-3.67, p=0.006).
5
As illustrated in the Figure 2A, the prevalence of CVD was 51 % in the patients with
6
hypertension compared to 18% in patients without hypertension (p=0.00001). When
7
patients were stratified into TG tertiles, the prevalence of CVD was 15% in the lowest
8
tertile, 24% in the second tertile and 30% in the highest tertile (p=0.04) (Figure 2B).
9
Finally, the CVD prevalence according to the smoking status is illustrated in Figure 2C.
10
The smoking status has been divided in non-smokers (pack year = 0), mild-smokers (pack
11
year ≤ 15) and heavy-smokers (pack year > 15). The CVD prevalence is 13% in the non-
12
smokers group, 27% in the mild-smokers group and 36% in the heavy smokers group
13
(p=0.006).
14
15
DISCUSSION
16
DBL patients are characterized by accumulation of remnant lipoproteins in circulation,
17
which consists of triglyceride-rich lipoproteins that are enriched in cholesterol. These
18
remnant particles are highly atherogenic [24,25] and are associated with an increased risk
19
of CVD [16]. The present study is the first to identify independent clinical predictors of
20
total CVD, PAD and CAD in a cohort of well characterized DBL patients. Specific
21
strengths of this study include the fact that the gold standard diagnostic criteria were used
9
1
to confirm DBL diagnosis. Furthermore, this cohort of 221 patients represents the largest
2
cohort for which a strict definition of DBL was used.
3
We identified hypertension, pack year of smoking and elevated triglycerides as
4
independent predictors of cardiovascular disease in DBL.
5
Among all the patients attending our lipid clinic, 2% (339 /14 346) of them were found to
6
be E2/E2. This prevalence is twice the prevalence observed in the general population
7
(0.7-1%). Furthermore, 66% of the E2/E2 patients (221/335) had DBL, which is
8
dramatically higher than the estimated rate of less than 20%. The referral bias probably
9
explains these differences. Indeed, only the worst cases of dyslipidemia are referred to
10
our specialized lipid clinic.
11
In the present cohort of DBL patients, the prevalence of PAD is 12%, whereas the
12
prevalence of CAD is 14%. These prevalences of PAD and CAD seem similar or slightly
13
lower than the reported prevalences, even though it remains difficult to make inter-
14
studies comparisons due to the differences in the criteria used for the diagnosis of DBL.
15
Indeed, while some studies use criteria based on ultracentrifugation results [8], others rely
16
mainly on the presence of E2/E2 genotype [17] or criteria based on apoB value [26]. The
17
reported prevalence of PAD among DBL patients varies between 11%-27%, whereas the
18
reported prevalence of CAD is between 19%-28% [6,8,17]. Furthermore, the prevalence
19
of tuberous and tuberoeruptive xanthomas in the whole DBL cohort is only 4% for each
20
type of xanthoma. This prevalence is surprisingly low compared to the prevalence found
21
in other cohorts. Indeed, some studies found that up to 51 to 64% of DBL patients had
22
tuberous and tuberoeruptive xanthomas [1,27]. Similarly, the prevalence of striated
23
palmar xanthomas found in our cohort is only 8%, compared to the reported prevalence 10
1
of 55 to 64% [1,27]. However, data on the prevalence of xanthomas in DBL are very
2
scarce. Furthermore, the presence of xanthomas in E2/E2 patients is not systematically
3
screened in the clinical context, even in specialized lipid clinics. Therefore any
4
comparison between DBL cohorts is difficult to establish.
5
Previously, the only other study investigating cardiovascular risk in a small DBL cohort
6
(n=67) identified sex as a CVD risk predictor [28]. It is interesting to note that in our
7
cohort, there was a higher proportion of men in the CVD group than in the non-CVD
8
group, but this difference was not statistically significant. Surprisingly, both age and sex,
9
which are considered traditional CVD risk factors, were not significant predictors of
10
CVD in our DBL cohort. This could be due to the fact that the mean age in our cohort is
11
only 50 years, which limits the detrimental effect of age on the CVD risk, or simply due
12
to the referral bias. In a previous study, the authors found a 30.6% higher Lp(a) value
13
among DBL individuals with atherosclerosis, but the difference was not significant [28].
14
Similarly, in our study we did not find any difference in Lp(a) values between the CVD
15
and the non-CVD groups. Interestingly, the CVD, PAD and CAD risk in DBL patients
16
does not seem to be mainly predicted by lipid parameters. The sole exception is
17
triglycerides which in DBL patients are carried in atherogenic remnant lipoproteins.
18
Indeed, other non-lipidic clinical risk factors including smoking (for CVD and PAD),
19
hypertension (for CVD and CAD), as well as tuberous xanthomas and diabetes (for PAD
20
only) represent independent predictors in the present study.
21
Contrarily to what is observed in the general population, LDL-C is not a risk factor for
22
cardiovascular disease in our DBL cohort [29]. Indeed, due to several mechanisms related
23
to the presence of apoE2 such as an upregulation of the LDLR, a preferential binding of 11
1
LDL to LDLR or a decreased conversion of VLDL to LDL, DBL patients usually have
2
lower LDL-C values than the general population [24,30]. Therefore, LDL-C is not the
3
most appropriate target of treatment in DBL patients, in which the accumulation of
4
remnant lipoproteins is the main driver of the increased CVD risk.
5
The major limitation of this study is the retrospective nature of the cardiovascular events
6
reporting. Indeed, the prospective CVD events that occurred during the follow-up at the
7
lipid clinic have not been documented in the research database. Furthermore, our study
8
did not include non-E2/E2 DBL patients who carry an autosomal dominant mutation in
9
APOE gene. Therefore, the results of the present study can not be generalized to all DBL
10
patients.
11
12
CONCLUSIONS
13
In conclusion, this study reported cardiovascular risk factors among DBL patients using
14
data from the largest cohort of DBL patients for which a strict definition was used for the
15
diagnosis. In this cohort, hypertension, smoking and triglycerides were independent
16
predictors of CVD events. Therefore, not all DBL patients are at the same risk of
17
developing CVD and this risk can be stratify. Treatment that focus on lifestyle changes
18
should be initiated in all DBL patients, but more aggressive treatment should be initiated
19
in those at higher CVD risk. In particular, smoking cessation and adequate blood pressure
20
control beside hypolipidemic drugs are of major importance for these patients.
21 22
CONFLICT OF INTEREST 12
1
A.B. received research grants from Akcea, Amgen, Astra Zeneca, the Fondation Leducq,
2
Merck Frosst and Sanofi. He has participated in clinical research protocols from Acasti
3
Pharma Inc., Akcea, Amgen, Astra Zeneca, Ionis Pharmaceuticals, Inc., The Medicines
4
Company, Merck Frosst, Novartis, Pfizer, Regeneron Pharmaceuticals Inc. and Sanofi.
5
He has served on advisory boards and received honoraria for symposia from Akcea,
6
Amgen and Sanofi.
7
S.B. has participated in clinical research protocols from Akcea, Amgen, The Medicines
8
Company and Sanofi. She has served on advisory boards for Akcea, Amgen, Eli Lilly,
9
Merck Frosst, Novo Nordisk, Sanofi and Valeant Pharmaceuticals, and received
10
honoraria for symposia from Akcea, Amgen, Boehringer Ingelheim, Merck Frosst, Novo
11
Nordisk and Sanofi-Aventis.
12
G.P. Received research funding from Sanofi and received honoraria from Akcea, Amgen
13
and Sanofi.
14
M.P. has nothing to declare.
15 16
FINANCIAL SUPPORT
17
This work was supported by The Fondation Leducq Transatlantic Networks of
18
Excellence [grant number 13CVD03]. The study funders had no role in the study design,
19
in the collection, analysis and interpretation of data, in the writing of the report and in the
20
decision to submit the article for publication.
21 22
AUTHOR CONTRIBUTIONS
13
1
The authors' contributions were as follows: All authors contributed to the discussion,
2
analysis and interpretation of data and have reviewed the article for the intellectual
3
content. M.P performed statistical analysis and has drafted the manuscript. All authors
4
have approved the final article. A.B. had primary responsibility for final content.
5 6
ACKNOWLEDGEMENTS
7
The authors want to thank the Montreal Clinical Research Institute (IRCM) research team
8
and the nursing staff for their everyday help, support and implication.
14
1
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18
1
TABLES
2
Table 1. Baseline characteristics of the DBL cohort. Variables
Reference
Total cohort
DBL Sex Age Hypertension Smoking prevalence Smoking Diabetes BMI Total cholesterol Triglycerides LDL-C HDL-C Non-HDL-C VLDL-C VLDL-TG VLDL-C/ plasmaTG ratio Apolipoprotein B Lipoprotein (a) Statin at baseline Fibrate at baseline Tuberous xanthoma Tuberoeruptive xanthoma Striated palmar xanthoma Eruptive xanthoma Broad-beta band on electrophoresis
Male (%) (year) n (%) former (%) current (%) Pack year n (%) (kg/m2) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (mg/dL) (g/L) (g/L) n (%) n (%) n (%) n (%) n (%) n (%) n (%)
N=221 120/202 (59%) 50 ± 14 35 (16%) 41/155 (26%) 59/155 (38%) 16 ± 18 16 (7%) 27.9 ± 3.7 333 ± 133 352 (244-597) 101 (81-134) 34 ± 9 299 ± 135 140 (94-247) 291 (197-532) 0.39 (0.35-0.46) 1.23 (0.98-1.68) 0.10 (0.04-0.26) 38 (17%) 73 (33%) 8 (4%) 9 (4%) 17 (8%) 7 (3%) 106/113 (94%)
n (%) 51 (23%) Retrospective CVD 32 (14%) CAD 26 (12%) PAD 11 (5%) CeVD 3 p values between CVD and non-CVD groups.
CVD N=51 33/48 (69%) 52 ± 13 18 (35%) 17/41 (41%) 17/41 (41%) 22 ± 19 8 (16%) 27.7 ± 3.9 353 ± 135 371 (282-617) 100 (84-142) 33 ± 9 320 ± 138 165 (107-279) 334 (219-564) 0.38 (0.35-0.44) 1.30 (0.99-1.83) 0.08 (0.04-0.26) 19 (37%) 28 (55%) 6 (12%) 5 (10%) 3 (6%) 3 (6%) 31/32 (97%)
Non-CVD N=170 87/154 (56%) 49 ± 14 17 (10%) 24/114 (21%) 42/114 (37%) 14 ± 18 8 (5%) 27.9 ± 3.7 327 ± 132 337 (233-555) 102 (80-133) 34 ± 9 293 ± 134 137 (91-243) 285 (185-469) 0.39 (0.34-0.46) 1.21 (0.98-1.65) 0.11 (0.03-0.53) 19 (11%) 45 (26%) 2 (1%) 4 (2%) 14 (8%) 4 (2%) 75/81 (93%)
51 (100%) 32 (63%) 26 (51%) 11 (22%)
-
p value 0.13 0.29 0.00001 0.006 0.02 0.008 0.75 0.21 0.14 0.47 0.71 0.21 0.18 0.11 0.90 0.43 0.88 0.00002 0.0002 0.002 0.03 0.77 0.20 0.67 -
19
1
BMI: body mass index; CAD: coronary artery disease; CeVD: cerebrovascular disease;
2
CVD: cardiovascular disease; DBL: dysbetalipoproteinemia; HDL-C: high-density
3
lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; PAD: peripheral
4
artery disease; TG: triglycerides; VLDL: very-low-density lipoprotein.
20
1
Table 2. Univariate predictors of CVD, PAD and CAD among DBL individuals. Predictors
OR (95%CI)
Univariate p value
CVD Hypertension
4.91 (2.29-10.52)
0.00004
Smoking pack year
1.02 (1.00-1.04)
0.02
Diabetes
3.77 (1.34-10.62)
0.01
Tuberous xanthoma
11.20 (2.19-57.38)
0.004
Tuberoeruptive xanthoma
4.51 (1.16-17.48)
0.03
TG tertile †
1.51 (1.02-2.25)
0.04
PAD Smoking pack year
1.03 (1.00-1.05)
0.03
Diabetes
7.61 (2.55-22.75)
0.0003
LDL-C
3.43 (1.14-10.30)
0.03
VLDL-C/ plasma TG ratio
9.55 (1.52-59.89)
0.02
28.95 (5.48-153.05)
0.00008
6.91 (1.73-27.65)
0.006
Tuberous xanthoma Tuberoeruptive xanthoma
CAD Hypertension
5.19 (2.26-11.96)
0.0001
Triglycerides
2.06 (1.11-3.82)
0.02
VLDL-TG
2.12 (1.17-3.84)
0.01
TG tertile †
1.86 (1.14-3.06)
0.01
2
† OR for third vs first tertile.
3
CAD:
4
dysbetalipoproteinemia; LDL-C: low-density lipoprotein cholesterol; PAD: peripheral
5
artery disease; TG: triglycerides; VLDL: very-low-density lipoprotein.
coronary
artery
disease;
CVD:
cardiovascular
disease;
DBL:
21
1
Table 3. Independent multivariate predictors of CVD, CAD and PAD among DBL
2
individuals. Predictors
OR (95%CI)
Multivariate p value
CVD Hypertension
5.68 (2.13-15.16)
0.001
Smoking pack year
1.03 (1.01-1.05)
0.01
TG tertile †
1.82 (1.09-3.05)
0.02
PAD Tuberous xanthomas VLDL-C/ plasma TG ratio Smoking pack year
14.01 (2.12-92.5)
0.006
18.85 (1.18-300.21)
0.04
1.04 (1.01-1.07)
0.006
CAD Hypertension
3.92 (1.58-9.75)
0.003
TG tertile †
2.13 (1.24-3.67)
0.006
3
† OR for third vs first tertile.
4
CAD:
5
dysbetalipoproteinemia; PAD: peripheral artery disease; TG: triglycerides; VLDL: very-
6
low-density lipoprotein.
coronary
artery
disease;
CVD:
cardiovascular
disease;
DBL:
22
1
FIGURE LEGENDS
2
Figure 1. Flowchart of patients’ selection. IRCM: Montreal Clinical Research Institute;
3
TG: triglycerides; VLDL: very-low-density lipoprotein.
4
Figure 2. CVD prevalence according to category of independent predictors.
5
A. CVD prevalence according to the presence or absence of hypertension.
6
B. CVD prevalence according to TG tertile. OR and p value for third vs first tertile.
7
C. CVD prevalence according to pack year group of smoking. OR and p value between
8
groups 0 and > 15.
9
CVD: cardiovascular disease; HTN: hypertension; TG: triglycerides.
23
Patients in the IRCM lipid clinic research database N=17109 Patients with E2/E2 N=339 (2%) Patients with E2/E2 ≥ 18 years N=335 Triglycerides > 135 mg/dL N=284 VLDL-C/TG > 0.30 N=221
Figure 1.
Total included N=221
A 100 p=0.00001 OR 4.91 (2.29-10.52)
90 CVD prevalence (%)
80 70 60
51
50 40 30 18
20 10 0 HTN
Figure 2A.
non-HTN
B
35
p=0.04 OR 1.51 (1.02-2.25)
CVD prevalence (%)
30
30
24
25 20 15
15
10 5 0 tertile 1 (0-274)
tertile 2 (275-462) TG tertiles
Figure 2B.
tertile 3 (≥ 463)
C
40
p=0.006 OR 1.95 (1.21-3.13)
CVD prevalence (%)
35 30
36
27
25 20 15
13
10 5 0 0
Figure 2C.
≤ 15 Pack year
> 15
HIGHLIGHTS 1. Dysbetalipoproteinemia (DBL) is a rare autosomal recessive lipid disorder. 2. DBL is associated with an increased cardiovascular disease (CVD) risk. 3. Triglycerides, hypertension and smoking are independent predictors of CVD in DBL.