Familial Hypercholesterolemia and Risk of Peripheral Arterial Disease

CLINICAL RESEARCH ARTICLE

Familial Hypercholesterolemia and Risk of Peripheral Arterial Disease and Chronic Kidney Disease Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019

Frida Emanuelsson,1,2 Børge G. Nordestgaard,2,3,4 and Marianne Benn1,2,4

1Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark; 2Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; 3Department of Clinical Biochemistry, Copenhagen University Hospital, 2730 Herlev, Denmark; and 4The Copenhagen General Population Study, Herlev and Gentofte Hospital, Copenhagen University Hospital, 2730 Herlev, Denmark

Context: Individuals with familial hypercholesterolemia (FH) have a high risk of coronary artery disease, but their risk of peripheral arterial disease (PAD) and chronic kidney disease (CKD) is unknown.

Objective: In individuals with clinical FH, we tested the hypotheses (1) that the risks of PAD and CKD are elevated and (2) that low ankle-brachial index (ABI) and estimated glomerular filtration rate (eGFR) are associated with a high risk of myocardial infarction.

Design and Setting: Prospective cohort study of the general population.

Participants: A total of 106,172 individuals, of whom 7109 were diagnosed with FH.

Main Outcome Measures: PAD, CKD, and myocardial infarction.

Results: Compared with individuals with unlikely FH, multivariable adjusted ORs (95% CIs) of PAD were 1.84 (1.70 to 2.00) in those with possible FH and 1.36 (1.00 to 1.84) in individuals with probable/ definite FH. For CKD, the corresponding ORs (95% CIs) were 1.92 (1.78 to 2.07) and 2.42 (1.86 to 3.26). Compared with individuals with unlikely FH and ABI .0.9, the multivariable adjusted hazard ratio (95% CI) of myocardial infarction was 4.60 (2.36 to 8.97) in those with possible/probable/ definite FH and ABI #0.9. Compared with individuals with unlikely FH and eGFR $60 mL/min/ 1.73 m2, the corresponding value was 2.19 (1.71 to 2.82) in those with possible/probable/definite FH and eGFR ,60 mL/min/1.73 m2.

Conclusions: Individuals with clinical FH have increased risks of PAD and CKD, and low ABI and eGFR are associated with high risk of myocardial infarction. Consequently, individuals with FH should be screened for PAD and CKD, and ABI and eGFR may be used as prognostic tools in the management and treatment of FH to identify those at very high risk of myocardial infarction. (J Clin Endocrinol Metab 103: 4491–4500, 2018)

eterozygous familial hypercholesterolemia (FH) is LDL cholesterol from plasma and consequently substan- Han autosomal dominant disorder of lipoprotein tially increased total and LDL cholesterol concentrations (3, metabolism, estimated to affect one out of 250 individ- 4). Pathogenic variants in the LDL receptor (LDLR), uals in Western populations (1, 2). Mutations in genes apolipoprotein B (APOB), and protein convertase subtilisin/ involved in the recycling pathways of the low-density kexin type 9 (PCSK9) genes account for the majority of lipoprotein (LDL) receptor lead to decreased clearance of known FH-causing mutations. Lifelong vascular exposure

ISSN Print 0021-972X ISSN Online 1945-7197 Abbreviations: ABI, ankle-brachial index; BMI, body mass index; CAD, coronary artery Printed in USA disease; CKD, chronic kidney disease; DLCN, Dutch Lipid Clinic Network; DM, diabetes Copyright © 2018 Endocrine Society mellitus; eGFR, estimated glomerular filtration rate; FH, familial hypercholesterolemia; Received 15 May 2018. Accepted 31 July 2018. ICD-8, International Classification of Diseases, Eighth Revision; ICD-10, International First Published Online 3 August 2018 Classification of Diseases, 10th Revision; LDL, low-density lipoprotein; PAD, peripheral arterial disease.

doi: 10.1210/jc.2018-01058 J Clin Endocrinol Metab, December 2018, 103(12):4491–4500 https://academic.oup.com/jcem 4491 4492 Emanuelsson et al Familial Hypercholesterolemia and PAD and CKD Risk J Clin Endocrinol Metab, December 2018, 103(12):4491–4500 to elevated concentrations of LDL cholesterol leads to total T4 level ,50 nmol/L and/or a total T3 level ,0.9 nmol/L) atherosclerosis, the major clinical manifestation of FH. were excluded, leaving 106,172 individuals for the analyses. Accordingly, FH is a well-established cause of premature coronary artery disease (CAD) (4, 5). A similar involvement Diagnostic criteria for clinical FH FH was diagnosed by using the DLCN criteria, a set of Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 of the peripheral arteries seems likely but is largely unknown clinical criteria that are widely used and recommended by lipid for individuals with FH. and FH guidelines (3, 9, 10) The criteria were slightly modified, Lower extremity peripheral arterial disease (PAD) and as done previously (1, 11), because information on LDL cho- chronic kidney disease (CKD) are two manifestations of lesterol concentrations in children and family members and peripheral atherosclerotic disease that significantly con- personal details of tendon xanthoma or corneal arcus were tribute to morbidity and mortality (6, 7). Furthermore, lacking (Supplemental Table 1). A clinical FH diagnosis was considered definite when the both diseases constitute independent risk factors for total score was .8 points, probable when the score was 6 to 8 CAD in the general population (6, 7). Ankle-brachial points, possible when the score was 3 to 5 points, and unlikely index (ABI) and estimated glomerular filtration rate when the score was ,3 points. The score was calculated using (eGFR) are noninvasive, low-cost tools that are widely points assigned for (1) family history of a first-degree relative , , used in the diagnosis and management of PAD and CKD, with premature CAD ( 55 years of age for men and 60 years for women) and/or a first-degree relative with known hyper- respectively. Both have been shown to be markers of cholesterolemia (1 point); (2) personal history of premature cardiovascular risk in individuals in the general pop- CAD at baseline (ages as given previously, 2 points) or pre- ulation (7, 8) but hitherto not in individuals with FH. mature cerebral vascular disease (ages as given previously) or Consequently, signs and symptoms of PAD and CKD peripheral vascular disease at baseline (1 point if not already may not be routinely screened for as part of the FH 2 points for premature CAD); (3) LDL cholesterol $8.5 mmol/L diagnosis, and the results are not included in the overall (330 mg/dL, 8 points), 6.5 to 8.4 mmol/L (250 to 329 mg/dL, 5 points), 5.0 to 6.4 mmol/L (190 to 249 mg/dL, 3 points), and cardiovascular risk assessment in FH, thus influencing 4.0 to 4.9 mmol/L (155 to 189 mg/dL, 1 point); and (4) presence decisions on treatment, treatment intensity, and clinical of an LDLR W23X, W66G or W556S, or APOB R3500Q follow-up (3, 9). mutation (8 points). In individuals with clinical FH, we tested the hypotheses that (1) the risks of PAD and CKD are elevated and (2) that PAD, CKD, and MI ABI and eGFR, as markers of PAD and CKD, are associated Endpoints were based on the World Health Organization’s with high risk of myocardial infarction (MI), independent codes for International Classification of Diseases, Eighth Revision and 10th Revision (ICD-8 and ICD-10) and were of age, birth year, sex, current smoking, pack-years, body collected from 1 January 1977 through 9 March 2017 by mass index (BMI), lipoprotein(a) hypertension, diabetes reviewing all hospital admissions, including outpatient visits mellitus (DM), lipid-lowering medication use, and men- (because many PAD and CKD diagnoses do not require hospital opausal status. For these purposes, we used the Dutch admission), and diagnoses in the national Danish Patient Lipid Clinic Network (DLCN) criteria to diagnose clinical Registry and causes of death in the national Danish Registry of Causes of Death. The International Classification of Diseases, FH in individuals in the Copenhagen General Population Ninth Revision was not used because this version of the ICD Study. was never introduced in Denmark, and ICD-10 replaced ICD-8 as of 1 January 1994. PAD was defined as ICD-8 440 to 441, 443.99, and 445 and ICD-10 as I70 to I72 and I73.9; CKD as Materials and Methods ICD-8 582 to 584, 403 to 404, and 440.19 and ICD-10 as N18 to N19, I12 to I13, N28.0, and N70.1; and MI as ICD-8 410 The Copenhagen General Population Study and ICD-10 I21 to I22. The Copenhagen General Population Study is a prospective In all, 3736 individuals had a PAD diagnosis (2337 during cohort study initiated in 2003 with ongoing enrollment (1). White follow-up); 1993 individuals had a CKD diagnosis (1382 individuals of Danish descent (i.e., the person and both parents during follow-up), and 4365 individuals had an MI diagnosis were born in Denmark and were Danish citizens) were randomly (2157 during follow-up). Follow-up began at the first inclusion selected on the basis of the national Danish Civil Registration into the study and ended with censoring at the date of death, System to reflect the Danish population aged 20 to 100 years. Data occurrence of an event, or emigration or on 9 March 2017 were obtained from a self-administrated questionnaire that was (corresponding to the end of follow-up for the least updated reviewed together with an investigator on the day of attendance, a register), whichever came first. Follow-up was 100% complete, physical examination, and blood samples including DNA ex- as all individuals living in Denmark have a Danish Civil traction. The study was approved by local institutional review Registration System number that provides daily updated in- boards and a Danish ethical committee (H-KF-01-144/01) and formation on emigration and death. The follow-up time was up was conducted in accordance with the Declaration of Helsinki. to 13 years (median, 7.7 years). Written informed consent was obtained from all 106,506 in- In the cross-sectional analysis, PAD was defined as a dividuals available for the study. Because hypothyroidism may composite of the previously stated PAD ICD-8 and ICD-10 mimic FH in terms of elevated LDL cholesterol concentrations, diagnoses and/or self-reported intermittent claudication and/ 334 individuals with hypothyroidism (TSH level .5mIU/Landa or ABI #0.9, corresponding to the European Society of doi: 10.1210/jc.2018-01058 https://academic.oup.com/jcem 4493

Cardiology definition of lower extremity PAD (7), yielding composite of self-reported diabetes, use of antidiabetic med- 6705 individuals with an event. Likewise, CKD was defined as a ication, nonfasting plasma glucose level .11.0 mmol/L, and/ composite of the previously stated CKD ICD-8 and ICD-10 or hospitalization or death due to diabetes (ICD-8: 249 to diagnoses and/or a calculated eGFR,60 mL/min/1.73 m2, 250; ICD-10: E10 to E11, E13 to E14). Smoking was defined

coinciding with the Kidney Disease: Improving Global Out- as current smoking at baseline. Information on current and Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 comes definition of mildly to moderately decreased (stage G3) former smoking, type and amount of tobacco smoked, and kidney function or worse (12), yielding 11,283 individuals with menopausal status for women was self-reported. One pack- an event. Blood pressure measurements were performed in both year was defined as 20 cigarettes or equivalent (smoking ci- arms and legs by a trained technician (medical student), with the gars, cheroots, pipe) smoked daily for 1 year. participant resting in a supine position. Systolic blood pressure of the posterior tibial artery or the dorsalis pedis artery was Statistical analyses obtained by a handheld Doppler. ABI was calculated as the Data were analyzed using Stata SE/14.2. We used x2 analysis lowest ankle systolic blood pressure level divided by the right to test for distribution of dichotomous variables between the arm brachial systolic blood pressure level. Ankle blood pres- categories of clinical FH. The Cuzick nonparametric test for sure was measured in all patients who entered the study from trend was used to assess differences in continuous variables March 2009 onward (i.e., ABI could be calculated in 50,092 between categories of clinical FH. For cross-sectional analyses individuals). eGFR was calculated from plasma creatinine, of risks of PAD and CKD by categories of clinical FH, we used using the Chronic Kidney Disease Epidemiology Collaboration logistic regression to estimate ORs. For prospective analyses of (CKD-EPI) creatinine equation (12). Plasma creatinine mea- risks of PAD, CKD, and MI by categories of clinical FH, we surements were missing in 336 individuals (i.e., eGFR was used Cox proportional hazards regression with age as time scale available in 105,836 individuals). (or follow-up time for risks of MI) to estimate hazard ratios. Both regression models were adjusted for age, birth year, sex, Biochemical analyses current smoking, pack-years, BMI, lipoprotein(a), hyperten- Nonfasting plasma concentrations of total cholesterol, high- sion, DM, lipid-lowering medication use, and menopausal density lipoprotein cholesterol, triglycerides, and glucose were status. Birth year was adjusted to accommodate diagnostic and measured using standard enzymatic assays (Thermo Fisher therapeutic changes, including changes in lipid-lowering med- Scientific/Konelab, Helsinki, Finland) and performed in a ication use, over calendar time. Lipoprotein(a) was measured laboratory with internal (daily) and external (10 times per sequentially in 57,522 individuals entering the Copenhagen year) quality assessment and assurance. The plasma creatinine General Population Study; in addition, because lipoprotein(a) is enzymatic assay was isotope dilution mass spectrometry highly genetically determined, for adjustment only we imputed traceable. Lipoprotein(a) total mass was measured using apolipoprotein(a) levels to extend analyses to the complete data set, lipoprotein A isoform‒insensitive turbidimetric assays, either as done previously (13). Imputation was done using KIV-2, four an in-house assay as described elsewhere (13), an assay from genetic variants (rs10455872, rs74617384, rs641990, and DiaSys (DiaSys Diagnostic Systems, Holzheim, Germany) or an rs12194138) known to affect lipoprotein(a) levels, age, sex, and assay from Denka Seiken (Denka Seiken, Tokyo, Japan). diabetes using multivariable chained imputation (mi impute LDL cholesterol concentration was calculated using the Frie- chained in Stata) with fully conditional specification. Because dewald equation when plasma triglycerides were #4.0 mmol/L lipoprotein(a) levels were not normally distributed, levels were (352 mg/dL) and was measured by a direct enzymatic method at log-transformed in all analyses. higher triglyceride concentrations. Total and LDL cholesterol To test whether results were different for individuals with a was multiplied by 1.43 in individuals receiving lipid-lowering confirmed FH mutation compared with those with clinically medication, corresponding to a mean 30% reduction in LDL diagnosed FH, we also performed separate analyses for those cholesterol concentrations (14), as done previously (11, 15). with a confirmed mutation. Cumulative incidences of PAD, Lipid-lowering medication use was self-reported, with more CKD, and MI were plotted, and differences across ordered than 97% accounted for by statins. Statin type and dose were categories of clinical FH and ordered categories of clinical FH not reported. and ABI or eGFR were examined using the log-rank test. The definite and probable categories of FH (or definite, probable, Genotyping and possible categories for risk estimates of MI) were combined LDLR W23X, W66G, W556S, and APOB R3500Q muta- to maximize statistical power. Because PAD is part of the tions were genotyped by TaqMan assays (Applied Biosystems, DLCN criteria, a sensitivity analysis was performed with PAD Foster City, CA). These four variants account for 39% of FH excluded from the criteria. mutations in the Copenhagen population, and other previously reported mutations have low prevalence (1). Sequencing of ran- Results domly selected individuals with each variant was used to verify the TaqMan results. Baseline characteristics by categories of clinical FH are shown in Table 1. In all, 6623 individuals (6.2%) had possible FH Covariates and 488 (0.5%) had probable/definite FH. In the probable/ Hypertension was defined as systolic blood pressure level definite clinical FH category, 169 individuals (0.16% of total $ $ 140 mm Hg ( 135 mm Hg for individuals with diabetes), di- and 35% of those with probable/definite FH) had a con- astolic blood pressure level $90 mm Hg ($85 mm Hg for individuals with diabetes), and/or self-reported use of antihypertensive firmed LDLR W23X, W66G, W556S, or APOB R3500Q drugs specifically prescribed for hypertension. BMI was weight in mutation. Individuals with possible and probable/definite FH kilograms divided by height in meters squared. DM was defined as a were slightly older; had a higher BMI; and were more likely 4494 Emanuelsson et al Familial Hypercholesterolemia and PAD and CKD Risk J Clin Endocrinol Metab, December 2018, 103(12):4491–4500

Table 1. Baseline Characteristics by Categories of Clinical Familial Hypercholesterolemia

Dutch Lipid Clinic Network Criteria P Unlikely Possible Probable/Definite for Trend Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 N (%) 99,063 (93.3) 6621 (6.2) 488 (0.5) Sex, women (%) 54,412 (55) 3625 (55) 294 (60) 0.06 Age, y 58 (48–67) 60 (53–67) 59 (51–66) ,0.001 BMI, kg/m2 25.5 (23.1–28.3) 27.1 (24.7–29.9) 26.3 (23.8–29.6) ,0.001 Current smoking, n (%) 16,490 (17) 1503 (23) 97 (20) ,0.001 Pack-years (current or former smokers) 15 (6–30) 21 (9–35) 16 (6–32) ,0.001 LDL cholesterol, mmol/L 3.2 (2.7–3.8) 5.2 (5.0–5.6) 6.6 (5.3–7.1) ,0.001 mg/dL 124 (104–147) 201 (193–215) 256 (205–277) ,0.001 Total cholesterol, mmol/L 5.6 (4.9–6.3) 7.4 (6.4–7.9) 7.4 (6.6–8.8) ,0.001 mg/dL 216 (189–242) 293 (271–313) 336 (290–372) ,0.001 Triglycerides, mmol/L 1.4 (0.9–2.0) 1.8 (1.3–2.6) 1.7 (1.1–2.5) ,0.001 mg/dL 123 (79–176) 158 (114–229) 150 (97–220) ,0.001 HDL cholesterol, mmol/L 1.6 (1.3–2.0) 1.4 (1.2–1.7) 1.4 (1.2–1.8) ,0.001 mg/dL 62 (50–77) 54 (46–66) 54 (46–69) ,0.001 Lipoprotein(a), mg/dL 9.5 (6.6–27.2) 13.8 (8.6–49.3) 17.6 (7.8–43.0) ,0.001 Lipid-lowering medication, n (%) 10,781 (11) 1674 (25) 294 (60) ,0.001 DM, n (%) 4671 (5) 429 (6) 34 (7) ,0.001 Hypertension, n (%) 52,623 (53) 4402 (67) 316 (65) ,0.001 PAD, n (%) 5825 (6) 826 (12) 54 (11) ,0.001 CKD, n (%) 9987 (10) 1207 (18) 89 (18) ,0.001 Myocardial infarction, n (%) 3581 (4) 728 (11) 56 (11) ,0.001 ABI 1.2 (1.1–1.2) 1.1 (1.1–1.2) 1.1 (1.1–1.2) ,0.001 eGFR, mL/min/1.73 m2 81 (70–91) 74 (64–85) 75 (64–87) ,0.001

Data are absolute numbers (n, %) for categorical variables and median (interquartile range) for continuous variables. One pack-year was defined as 20 cigarettes or equivalent (cigars, cheroots, pipe) smoked daily for 1 y. Total and LDL cholesterol concentrations were multiplied by 1.43 in individuals receiving lipid-lowering medication, corresponding to a mean 30% reduction in LDL cholesterol concentrations (14). ABI was measured in 50,092 individuals. PAD was defined as an ICD-8 or ICD-10 diagnosis of PAD and/or ABI #0.9 and/or intermittent claudication. CKD was defined as an ICD-8 or ICD-10 diagnosis of CKD and/or eGFR ,60 mL/min/1.73 m2. Abbreviation: HDL, high-density lipoprotein. to be smokers, have hypertension and DM, and use lipid- W23X, W66G, W556S, or APOB R3500Q mutation lowering medication than were those with unlikely FH. In- had risk estimates similar to those for individuals with dividuals with possible and probable/definite FH had higher clinical FH, with ORs of 1.32 (95% CI, 0.75 to 2.33) for concentrations of LDL cholesterol, total cholesterol, tri- PAD and 1.99 (95% CI, 1.22 to 3.26) for CKD compared glycerides, and lipoprotein(a) and lower concentrations of with those with unlikely FH. high-density lipoprotein cholesterol than those with unlikely In prospective analyses excluding individuals with FH. The prevalence of PAD and CKD, including diagnoses endpoints before and at study entry and compared with before, at, and after study entry, was higher in individuals individuals with unlikely FH, the hazard ratio of PAD with possible and probable/definite FH than in those with was 1.47 (95% CI, 1.28 to 1.69) for those with possi- unlikely FH, and individuals with possible and probable/ ble FH and 1.64 (95% CI, 1.0 to 2.56) for individuals definite FH had lower ABI and eGFR than those with with probable/definite FH (Fig. 1, lower panel). Corre- unlikely FH. sponding hazard ratios of CKD were 1.04 (95% CI, 0.84 to 1.28) for possible FH and 0.79 (95% CI, 0.33 to 1.90) Clinical FH and risk of PAD and CKD for probable/definite FH. Individuals with a confirmed In cross-sectional analyses including diagnoses before, mutation had risk estimates similar to those of in- at, and after study entry, risk of PAD was higher for dividuals with clinical FH, with hazard ratios of 1.56 individuals with possible and probable/definite FH than (95% CI, 0.70 to 3.48) for PAD and 0.93 (95% CI, 0.23 with those with unlikely FH, with ORs of 1.84 (95% CI, to 3.73) for CKD compared with those with unlikely FH. 1.70 to 2.00) and 1.36 (95% CI, 1.00 to 1.84), re- Exclusion of information on peripheral vascular disease spectively (Fig. 1, upper panel). For CKD, stepwise higher from the diagnostic criteria of clinical FH showed similar risks were seen by categories of clinical FH, with ORs of results (compare Supplemental Fig. 1 with Fig. 1). 1.92 (95% CI, 1.78 to 2.07) in possible FH and 2.42 The cumulative incidence of PAD as a function of age (95% CI, 1.86 to 3.15) in probable/definite FH compared increased from individuals with unlikely FH through those with unlikely FH. Individuals with a confirmed LDLR with possible FH to individuals with probable/definite FH doi: 10.1210/jc.2018-01058 https://academic.oup.com/jcem 4495 Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019

Figure 1. Cross-sectional (upper panel) and prospective (lower panel) risks of PAD and CKD as a function of categories of clinical FH based on modified DLCN criteria and for individuals with a confirmed FH mutation. Cross-sectional endpoints before, at, and after study entry for PAD were a composite of ICD-8 and ICD-10 diagnoses and/or intermittent claudication and/or ABI #0.9 and for CKD were ICD-8 and ICD-10 diagnoses and/or eGFR ,60 mL/min/1.73 m2. Prospective endpoints were based on ICD-8 and ICD-10 diagnoses only because information on ABI, intermittent claudication, and eGFR was obtained only at baseline. Individuals with an ICD-8 or ICD-10 diagnosis at baseline were excluded from the prospective analyses. ORs and hazard ratios were adjusted for sex, age, birth year, menopause, current smoking, pack-years, BMI, lipoprotein(a), hypertension, DM, and lipid-lowering medication use. N, number.

(P across ordered categories ,0.001) (Fig. 2, upper panel). with possible/probable/definite FH and eGFR ,60 mL/ At age 80 years, the cumulative incidences of PAD were min/1.73 m2. 10% for unlikely FH, 15% for possible FH, and 24% for The cumulative incidence of MI as a function of follow- probable/definite FH. The cumulative incidences of CKD up time increased from individuals with unlikely FH and as a function of age were similar for categories of clinical ABI .0.9, through possible/probable/definite FH and FH and unlikely FH (P = 0.80) (Fig. 2, lower panel). ABI .0.9 and unlikely FH and ABI #0.9, to possible/ At age 80 years, the cumulative incidences of CKD were probable/definite FH and ABI #0.9 (P across ordered 5% for unlikely FH, 6% for possible FH, and 5% for categories ,0.001) (Fig. 4, upper panel). After 5 years of probable/definite FH. follow-up, the cumulative incidence of MI was 1% in those with unlikely FH and ABI .0.9; 2% in those with possible/ ABI and eGFR associate with high risk of MI in probable/definite FH and ABI .0.9; 4% in those with clinical FH unlikely FH and ABI #0.9; and 9% in those with possible/ The risk of MI increased stepwise by categories of clinical probable/definite FH and ABI #0.9. FH and ABI or eGFR (P for trend ,0.001) (Fig. 3). For eGFR, the cumulative incidences of MI as a function of Compared with individuals with unlikely FH and ABI .0.9, follow-up time increased from individuals with unlikely FH the multivariable adjusted hazard ratios of MI were 4.60 and eGFR $60 mL/min/1.73 m2, through possible/probable/ (95% CI, 2.36 to 8.97) in those with possible/probable/ definite FH and eGFR $60 mL/min/1.73 m2 and un- definite FH and ABI #0.9. Compared with individuals with likely FH and eGFR ,60 mL/min/1.73 m2, to possible/ unlikely FH and eGFR $60 mL/min/1.73 m2, the corre- probable/definite FH and eGFR ,60 mL/min/1.73 m2 (P , sponding value was 2.19 (95% CI, 1.71 to 2.82) in those 0.001) (Fig. 4, lower panel). After 5 years of follow-up, the 4496 Emanuelsson et al Familial Hypercholesterolemia and PAD and CKD Risk J Clin Endocrinol Metab, December 2018, 103(12):4491–4500

associated with high risk of MI even after adjusting for sex, age, birth year, menopause, current smoking, pack-years, BMI, lipoprotein(a), hypertension, DM, Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 and lipid-lowering treatment. Although it may be argued that this finding is not surprising, the risk of PAD and CKD and its association with risk of MI in individuals with clinical FH has not, to our knowledge, previously been shown. Previous cross-sectional studies have reported a prevalence of PAD between 1% and 31% in patients with FH (16–19). In an angiography study screening 117 heterozygous patients with FH for atherosclerotic lesions, 33% had renal artery atherosclerosis, 56% had iliac atherosclerosis, 68% had abdominal aortic sclerosis, and 60% had CAD (20). Our findings together with the previously mentioned reports and with randomized clinical trials showing that LDL cholesterol‒lowering therapy improved both coronary and peripheral vascular outcomes in individuals who have hyper- lipidemia with and without FH (21–24) support that FH is a systemic atherogenic disease. The reported variation in prevalence of PAD in FH may be due to a number of factors. First, the severity of atherosclerosis is proportional to cumulative LDL cholesterol exposure (3, 25). Accordingly, differences in median age between studies may be one explanation, together with methodological differences such as definitions of end points. Second, although our study included individ-

Figure 2. Cumulative incidences of PAD (upper panel) and CKD (lower panel) as a function uals from the general population, other of age and by categories of clinical FH. N, number. studies included cohorts of patients with FH, in whom the clinical phenotype may cumulative incidence of MI was 1% in individuals with be more severe because of ascertainment bias (26). Third, unlikely FH and eGFR $60 mL/min/1.73 m2;2%in severity, extent, and anatomical topography of ath- those with possible/probable/definite FH and eGFR erosclerotic lesions seem to vary between individuals $60 mL/min/1.73 m2; 3% in those with unlikely FH and despite similar LDL cholesterol exposure (3, 27). This eGFR ,60 mL/min/1.73 m2; and 4% in those with may be due to differences in genotype, as well as dif- possible/probable/definite FH and eGFR ,60 mL/min/ ferences in the presence of other major risk factors of 1.73 m2. atherosclerotic disease, such as sex, smoking, diabetes, hypertension, and high concentrations of triglyceride- Discussion rich lipoproteins (3, 7). Fourth, specific risk factors may be more important for the development of disease at specific In this prospective cohort from the general population, we anatomical sites. In epidemiological studies, smoking has have shown that individuals with clinical FH have increased been identified as an important risk factor for lower ex- risk of PAD and CKD and that low ABI and eGFR are tremity vascular disease, as has DM (7, 28). Differences in doi: 10.1210/jc.2018-01058 https://academic.oup.com/jcem 4497 Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019

Figure 3. Prospective risk of myocardial infarction as a function of categories of clinical FH and ABI above/at and below 0.9 or eGFR at and above/ below 60 mL/min/1.73 m2. A diagnosis of clinical FH included individuals with possible/probable/definite FH. No FH = unlikely FH. Hazard ratios were adjusted for sex, age, birth y, menopause, current smoking, pack-years, BMI, lipoprotein(a), hypertension, DM, and lipid-lowering medication use. ABI was available in 50,092 individuals. Individuals with an event at baseline were excluded from the prospective analysis. N, number. blood flow, mechanical load, and arterial microenviron- 10,221), but not in a prospective analysis based solely on ment may also contribute to anatomical differences in incident ICD-8 and ICD-10 diagnoses of CKD (n = atherosclerotic plaque formation. In a recent study that 1382). This may be due to clinical underdiagnosis of included partly the same individuals from the Copenhagen CKD and thus lack of power in the prospective analysis. general population, Beheshti et al. (29) found no association We could not include eGFR prospectively because plasma between clinical or genetic FH, or high LDL cholesterol per se, creatinine was measured only at baseline. and risk of ischemic stroke, even though LDL cholesterol Because PAD defines a pure vascular disease, with ABI traditionally has been seen as a risk factor for ischemic stroke as a diagnostic marker, our findings of an association and despite the fact that statins reduced ischemic stroke risk in between FH and high risk of PAD as well as low ABI as a clinical intervention trials (30). The risk of stroke instead predictor of cardiovascular risk in FH are in line with the seemed to be driven by the presence of previous ischemic heart present evidence of LDL cholesterol as a causal factor in disease, and the authors speculatedthathighLDLcholesterol the pathogenesis of atherosclerosis (25). In contrast, level leads to ischemic heart disease producing mural thrombi CKD covers a variety of kidney abnormalities of different from MI and heart failure—mural thrombi that will dislocate etiologies, with eGFR being the gold standard but un- and cause ischemic stroke (29). Alternatively, individuals with specific measure of decline in kidney function (12). DM ischemic heart disease may have a higher burden of other and hypertension are both risk factors and/or major major atherosclerotic risk factors in addition to FH, such as causes of CKD, and CKD is associated with dyslipidemia high concentrations of triglyceride-rich lipoproteins. and increased cardiovascular risk (31). The potential The prevalence of CKD has not previously been de- roles of LDL cholesterol and atherosclerosis as causal risk termined in a large FH population. In the current general factors of CKD have not been determined. In randomized population study, 18% of individuals with clinical FH clinical trials, statins reduced the risk of cardiovascular had CKD according to ICD-8 and ICD-10 diagnoses events in individuals with CKD but seemed to have no or and/or eGFR measurements compared with 10% of little effect on the progression of kidney disease (32). In those with unlikely FH. This is lower than the rate re- contrast, in a study of 4040 patients with renovascular ported in angiographically characterized patients with disease and reduced kidney function, statins were asso- FH, where mild to moderate renal artery stenosis was ciated with significant reductions in risk of dialysis and observed in 39 of 80 patients (33%), suggesting that hospitalization (33). In a study of 100 patients who had atherosclerotic lesions are present in the renal arteries FH without hypertension and with normal glucose tol- before any potential decline in renal function (20). erance, lowering of LDL cholesterol with a statin was In our study, we found an association between FH and associated with improved kidney function. Interestingly, CKD in a cross-sectional analysis, in which the endpoint improvement was observed not only in terms of creati- was a composite of CKD ICD-8 and ICD-10 diagnoses nine clearance but also for microalbuminuria, a marker (n = 1993) and/or an eGFR ,60 mL/min/1.73 m2 (n = of glomerular endothelial dysfunction (34). This suggests 4498 Emanuelsson et al Familial Hypercholesterolemia and PAD and CKD Risk J Clin Endocrinol Metab, December 2018, 103(12):4491–4500

Our study has some limitations. In- formation regarding LDL cholesterol concentrations in children and family members and the presence of tendon Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 xanthomas and corneal arcus was not recorded and could not be included in the diagnostic criteria. This may have led to a slight underdiagnosis of FH in our population. Also, because peripheral vascular disease is part of the DLCN criteria for FH, the cross-sectional risk of PAD may rather be seen as a measure of the prevalence of PAD by DLCN criteria at baseline. However, we observed results similar to the main analyses when peripheral vascular disease was excluded from the criteria. In the prospective analysis, individuals with PAD diagnoses at baseline were excluded. Lipid- lowering medication use was recorded in all individuals, with 97% accounted for by statins. However, we did not have information regarding type or dose of lipid-lowering therapy or changes in lipid-lowering therapy over time. To account for diagnostic and therapeutic changes over time, including changes in lipid-lowering therapy, all prospective analyses were adjusted for birth year. To our knowledge, this adjustment is the best method available, but it may not be sufficient. Another limitation of the study is that eGFR was calculated from a single measurement of plasma creatinine, which may lead to some misclassification of kidney disease. Un- fortunately, we did not have access to albuminuria or proteinuria measure-

Figure 4. Cumulative incidences of myocardial infarction as a function of follow-up time ments. Genetic FH diagnosis was con- (corresponding to a screening setting) and by categories of clinical FH and ABI above/at and below firmed in 169 individuals (0.16%) in the 0.9 (upper panel) or eGFR at and above/below 60 mL/min/1.73 m2 (lower panel). A diagnosis of studied population. Separate analyses clinical FH included individuals with possible/probable/definite FH. No FH = unlikely FH. N, number. for this group showed results similar to those for individuals with clinical FH compared with individuals with unlikely that high LDL cholesterol concentration is a contribut- FH. However, these analyses were underpowered because ing factor in the progression of kidney disease, even in of the low number of individuals and events. In contrast, the the absence of hypertension and DM, which might be large number of individuals with unlikely and possible FH due to renal atherosclerosis. Whether the improvement were likely responsible for the low P values, even for in microalbuminuria represents a direct effect of LDL covariates for which the differences in frequency or medians cholesterol on glomerular function or is a secondary between the clinical FH categories were small, such as age. effect of improved renal microvascular circulation is The strengths of our study include showing that ABI unclear. Further studies are needed to elucidate the po- and eGFR are associated with high risk of MI in in- tential causal effects of LDL cholesterol in kidney disease. dividuals with clinical FH, independent of sex, age, birth doi: 10.1210/jc.2018-01058 https://academic.oup.com/jcem 4499 year, menopause, current smoking, pack-years, BMI, 2. Wald DS, Bestwick JP, Morris JK, Whyte K, Jenkins L, Wald NJ. lipoprotein(a), hypertension, DM, and lipid-lowering Child-parent familial hypercholesterolemia screening in primary care. N Engl J Med. 2016;375(17):1628–1637. treatment. In addition, the study is based on a well- 3. Nordestgaard BG, Chapman MJ, Humphries SE, Ginsberg HN, characterized population with complete follow-up, in- Masana L, Descamps OS, Wiklund O, Hegele RA, Raal FJ, Downloaded from https://academic.oup.com/jcem/article-abstract/103/12/4491/5063925 by Endocrine Society Member Access 1 user on 09 February 2019 cluding .7000 individuals with clinical FH. The current Defesche JC, Wiegman A, Santos RD, Watts GF, Parhofer KG, Hovingh GK, Kovanen PT, Boileau C, Averna M, Bor´en J, findings have a number of clinical implications, which are Bruckert E, Catapano AL, Kuivenhoven JA, Pajukanta P, Ray currently not reflected in guidelines for the management K, Stalenhoef AF, Stroes E, Taskinen M-R, Tybjærg-Hansen A; and treatment of FH (3, 9). European Atherosclerosis Society Consensus Panel. Famil- ial hypercholesterolaemia is underdiagnosed and undertreated 1. Diagnosis of clinical FH should include screening in the general population: guidance for clinicians to pre- for signs and symptoms of PAD and CKD. vent coronary heart disease: consensus statement of the Eu- ropean Atherosclerosis Society. Eur Heart J. 2013;34(45): 2. Assessment of total cardiovascular risk in in- 3478–3490. dividuals with FH should include evaluation of ABI 4. Goldstein JK, Hobbs H, Brown M. Familial hypercholesterolaemia. and eGFR, also in the absence of symptoms of PAD In: Scriver CR, Beaudet AL, Sly WS, Valle D, eds. The Metabolic & or CKD. As for preexisting coronary heart disease Molecular Bases of Inherited Disease.8thed.NewYork,NY: McGraw-Hill; 2001: 2863–2913. and diabetes (risk factors that are included in 5. Benn M, Watts GF, Tybjaerg-Hansen A, Nordestgaard BG. Fa- present guidelines), abnormal ABI or eGFR values milial hypercholesterolemia in the Danish general population: may be used to identify those at very high risk of MI prevalence, coronary artery disease, and cholesterol-lowering medication. J Clin Endocrinol Metab. 2012;97(11):3956–3964. who should receive high-intensity lipid-lowering 6. Fowkes FG, Rudan D, Rudan I, Aboyans V, Denenberg JO, treatment, aiming at LDL cholesterol concentra- McDermott MM, Norman PE, Sampson UKA, Williams LJ, tions below 1.8 mmol/L (70 mg/dL). Mensah GA, Criqui MH. Comparison of global estimates of 3. Risk factors of CKD (i.e., hypertension and DM) prevalence and risk factors for peripheral artery disease in 2000 and 2010: a systematic review and analysis. Lancet. 2013; should be treated, and use of potentially nephro- 382(9901):1329–1340. toxic drugs should be limited in patients with FH. 7. Aboyans V, Ricco J-B, Bartelink M-LEL, Bjorck ¨ M, Brodmann M, Cohnert T, Collet J-P, Czerny M, De Carlo M, Debus S, Espinola- In conclusion, the current study shows that a clinical Klein C, Kahan T, Kownator S, Mazzolai L, Naylor AR, Roffi M, diagnosis of possible and probable/definite FH based on R¨other J, Sprynger M, Tendera M, Tepe G, Venermo M, the DLCN criteria is associated with an increased risk of Vlachopoulos C, Desormais I. 2017 ESC Guidelines on the Di- agnosis and Treatment of Peripheral Arterial Diseases, in collab- PAD and CKD. Furthermore, reduced ABI and eGFR oration with the European Society for Vascular Surgery (ESVS). values are associated with increased risk of MI in in- Eur Heart J. 2018;39(9):763–816. dividuals with clinical FH in the general population. This 8. Matsushita K, van der Velde M, Astor BC, Woodward M, Levey AS, de Jong PE, Coresh J, Gansevoort RT; Chronic Kidney Disease suggests that individuals with FH should be routinely Prognosis Consortium. Association of estimated glomerular fil- screened for PAD and CKD and that ABI and eGFR may tration rate and albuminuria with all-cause and cardiovascular be used as prognostic tools in the management and mortality in general population cohorts: a collaborative meta- 375 – treatment of FH. analysis. Lancet. 2010; (9731):2073 2081. 9.CatapanoAL,GrahamI,DeBackerG,WiklundO,ChapmanMJ, Drexel H, Hoes AW, Jennings CS, Landmesser U, Pedersen TR, Reiner ˇ Acknowledgments Z, Riccardi G, Taskinen M-R, Tokgozoglu L, Verschuren WMM, Vlachopoulos C, Wood DA, Zamorano JL, Cooney MT; ESC Sci- We thank the participants and staff of the Copenhagen General entific Document Group. 2016 ESC/EAS guidelines for the management of dyslipidaemias. Eur Heart J. 2016;37(39):2999–3058. Population Study for their important contributions. 10. Defesche JC, Lansberg PJ, Umans-Eckenhausen MAW, Kastelein Financial Support: This work was supported by the Danish JJP. Advanced method for the identification of patients with Council of Independent Research (to F. E.). inherited hypercholesterolemia. Semin Vasc Med. 2004;4(1): Correspondence and Reprint Requests: Marianne Benn, 59–65. MD, Department of Clinical Biochemistry, Rigshospitalet, 11. Langsted A, Kamstrup PR, Benn M, Tybjærg-Hansen A, Nordestgaard BG. High lipoprotein(a) as a possible cause of clinical familial hyper- Copenhagen University Hospital, Blegdamsvej 3, 2100 cholesterolaemia: a prospective cohort study. Lancet Diabetes Endo- Copenhagen, Denmark. E-mail: [email protected]. crinol. 2016;4(7):577–587. Disclosure Summary: The authors have nothing to 12. Kidney Disease: Improving Global Outcomes (KDIGO) CKD disclose. Work Group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl. 2013;3:1–150. References 13. Langsted A, Nordestgaard BG, Benn M, Tybjaerg-Hansen A, Kamstrup PR. 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