Cardiovascular risk factors in 2011 and secular trends since 2007: The Cardiovascular Risk in Young Finns Study

Abstract

Aims: Cardiovascular risk factor levels in 2011 and 4-year changes between 2007 and 2011 were examined using data collected in follow-ups of the Cardiovascular Risk in Young Finns Study. Methods: The study population comprised 2063 Finnish adults aged 34–49 years (45% male). Lipid and blood pressure levels, glucose and anthropometry were measured and life style risk factors examined with questionnaires. Results: Mean total cholesterol level in 2011 was 5.19 mmol/l, low density lipoprotein (LDL)-cholesterol 3.27 mmol/l, high density lipoprotein (HDL)-cholesterol 1.33 mmol/l, and triglycerides 1.34 mmol/l. Using American Diabetes Association criteria, Type 2 diabetes (T2D) was observed in 4.1% and prediabetes (fasting glucose 5.6–6.9 mmol/l or glycated hemoglobin 5.7–6.4%) diagnosed for 33.8% of the participants. Significant changes (P < 0.05) between 2007 and 2011 included an increase in waist circumference (3.3%) in women. In both sexes, systolic (−3.0% in women, −4.0% in men) and diastolic (−3.0% in women, −3.3% in men) blood pressure and triglycerides (−3.4% in women, −6.5% in men) decreased during follow-up. Conclusions: Previously observed favorable trends in LDL-cholesterol levels have leveled off among a sample of young and middle-aged adults in Finland. Triglyceride and blood pressure levels have decreased. Over one-third of the study population had prediabetes and may be at increased risk for T2D.

Keywords

Cardiovascular risk factors secular trend

Introduction

Finland had very high coronary heart disease (CHD) mortality in the 1960s [1]. Since then mortality has decreased and cardiovascular risk factor levels have improved, especially in the working-age population [2,3]. The declining prevalence of CHD has been mostly attributed to lower cholesterol and blood pressure levels and decreased smoking prevalence; thus, Finnish experiences have provided a worldwide example of successful cardiovascular preventive work [4].

In recent years, reports on cardiovascular risk factor levels in adults have shown that a reversal in the favorable trend of cholesterol levels has been occurring in Finland and Sweden [5,6]. Concurrently, the prevalence of obesity has reached epidemic proportions in Finland [7], as it has worldwide [8]. Partly attributable to this, the incidence of type 2 diabetes (T2D) in Finland increased year on year by 4.3% from 1992 to 2001 [9] and increased around the world [10]. However, there are few reports on risk factor trends in younger populations.

This report describes cardiovascular risk factor data from the latest follow-up of the Cardiovascular Risk in Young Finns Study in 2011 among 34–49-year-old men and women. To estimate future trends in cardiovascular health, the main focus has been on examining 4-year changes in risk factor levels between 2007 and 2011.

Materials and methods

Population

The study population comprised participants of the Cardiovascular Risk in Young Finns Study (YFS), a population-based follow-up study on cardiovascular risk factors in Finland [11]. The study was carried out in all five Finnish university cities with medical schools and their rural surroundings. The first cross-sectional study was conducted in 1980. Altogether 4320 children and adolescents aged 3, 6, 9, 12, 15 and 18 years were randomly chosen from the population register of these areas to produce a representative sample of Finnish children. Of these individuals, 3596 (83%) participated in the original study. Since then, regular follow-ups have been performed (Figure 1). In the 2007 follow-up, 2202 subjects participated in the clinical examination. Subsequently, 412 of these participants did not participate in the follow-up in 2011. Concurrently, 273 subjects who had dropped out from the follow-ups before year 2007 re-participated in the 2011 follow-up. So far 104 participants have died. The present study is primarily based on 2063 participants (45% men, mean age 41.8 years in 2011) who participated in the 2011 follow-up. The study has been approved by the Joint Commission on Ethics of the Turku University and the Turku University Central Hospital. The study has been conducted according to the guidelines of the Declaration of Helsinki, and informed consent was obtained from all participants.

Anthropometry, blood pressure and lifestyle risk factors

Weight was measured with weighing scales to the nearest 0.1 kg and height with anthropometer to the nearest centimeter. Body mass index (BMI) was calculated as weight(kg)/height(m²). Waist circumference was measured using an anthropometric tape at the midpoint between the iliac crest and the lowest rib to the nearest 0.1 cm. The average of two measurements was used. Blood pressure was measured in sitting position after a 5-minute rest with a random zero sphygmomanometer, and the average of three measurements was used. Cigarette smoking, pregnancy, diabetes and medications were examined with questionnaires. Those smoking daily were classified as smokers.

Biochemistry

Venous blood samples were drawn from the antecubital vein after an overnight fast and serum was separated, aliquoted and stored at −70°C until analysis. The serum triglyceride concentration was determined using the enzymatic glycerol kinase–glycerol phosphate oxidase method (Triglyceride reagent, Beckman Coulter Biomedical, Ireland). Serum total cholesterol levels were measured by the enzymatic cholesterol esterase–cholesterol oxidase method (Cholesterol reagent, Beckman Coulter Biomedical). The same reagent was used for estimating high density lipoprotein (HDL)-cholesterol levels after precipitation of low density lipoprotein (LDL) and very low density lipoprotein with dextran sulfate–Mg²⁺ [12]. Serum glucose concentration was determined by the enzymatic hexokinase method (Glucose reagent, Beckman Coulter Biomedical). All the above assays were performed on an AU400 instrument (Olympus, Japan) and the same methods were used both in 2007 and in 2011. The concentration of glycated hemoglobin A1c (GHbA1c) was assayed with an immunoturbidimetric method (Hemoglobin A1c assay, Abbott, USA) on an Architect ci8200 analyzer (Abbott) in 2011. LDL-cholesterol was estimated by the Friedewald formula in participants with triglyceride levels <4.0 mmol/l. The methods for total cholesterol, triglycerides, glucose and GHbA1c are accredited by the Finnish Accreditation Service according to standard ISO/IEC17025.

Definition of the metabolic syndrome, hypertension, prediabetes and type 2 diabetes

The metabolic syndrome was defined according to the Harmonized criteria [13]. The definition included the following criteria: waist circumference ≥102 cm in men and ≥88 cm in women, fasting glucose ≥ 5.6 mmol/l or treatment, hypertriglyceridemia ≥ 1.7 mmol/l, HDL-cholesterol ≤ 1.0 mmol/l in men and ≤ 1.3 in women, and systolic blood pressure ≥ 130mmHg or diastolic blood pressure ≥ 85 mmHg. The use of anti-hypertensive medication was considered as an indication of hypertension. A diagnosis required that any three of the five criteria be present. Pregnant women were excluded from analyses involving the metabolic syndrome (in 2007, n = 37 and in 2011, n = 13).

Participants were classified as having increased risk for diabetes (prediabetes) if they had fasting glucose from 5.6 mmol/l to 6.9 mmol/l or GHbA1c from 5.7% to 6.4%. The diagnosis of T2D included participants with fasting glucose ≥ 7mmol/l or GHbA1c ≥ 6.5% or self-reported diabetes or use of medication [14].

Statistical methods

The values of serum triglycerides were log10-transformed before all analyses, and values of serum glucose were transformed before analyses concerning change between 2007 and 2011 due to skewed distributions. An attrition analysis of characteristics from the baseline (1980) and the 2007 follow-up between participants and non-participants at the 2011 follow-up was undertaken to determine whether loss to follow-up was differential. Differences in age were examined using t-test, and differences in risk factor levels between participants and non-participants were examined with regression analyses adjusted for age.

The effect of age on risk factors was examined using linear regression analysis for continuous variables and logistic regression analysis for categorical variables. Multivariable linear and logistic regression models were used to examine whether the associations between age and risk factor were similar between men and women. The models included each risk factor as the dependent variable and age and age * sex as independent variables. The differences in risk factor level means between men and women in all age groups were examined by applying t-test for continuous variables and chi-squared test for categorical variables. Changes in cardiovascular risk factor levels were assessed from the examinations performed in 2007 and 2011 using t-test for continuous variables and Fisher’s exact test for categorical variables. To compare groups of the same age, we compared the 33–45-year-old participants in 2007 (mean age for women 39.2 years (n=860) and for men 39.3 years (n=680)) with the 34–43-year-old participants in 2011 (average age among women 38.9 years (n=637), and men 38.7 years (n=512)). Participants who had not participated in both 2007 and 2011 follow-ups were excluded from analyses concerning change between 2007 and 2011.

All statistical analyses were performed using SAS version 9.3 and statistical significance was inferred at a two-tailed P-value < 0.05.

Results

Attrition analysis

The representativeness of participants of the 2011 follow-up was examined by age-adjusted comparison of their baseline characteristics (1980) and characteristics in the 2007 follow-up with those who did not attend the 2011 follow-up (Supplemental Table I). In both comparisons, participants were older than non-participants. In the 2007 follow-up, non-participants had statistically significantly greater systolic and diastolic blood pressure and prevalence of smoking than participants. In the baseline comparison, for women, participants had statistically significantly greater BMI and lower diastolic blood pressure than non-participants.

Cardiovascular risk factors

The levels of cardiovascular risk factors in 34–49-year-old men and women are shown in Table I. Men had higher (P <0.0001) total cholesterol, LDL-cholesterol, triglycerides, blood pressure, BMI and waist circumference compared with women, whereas women had higher HDL-cholesterol. In both sexes total cholesterol, LDL-cholesterol, triglycerides, blood pressure, BMI and waist circumference increased with age (P <0.05). In men HDL-cholesterol also increased with age. As indicated by a statistically significant interaction, the association between systolic blood pressure and age was greater in women than in men.

Table I.

Cardiovascular risk factor levels in 2011 in 2051 Finnish women and men aged 34–49 years and stratified by age.

Age group (years)	N ^a	Total cholesterol (mmol/l)Mean (SD)	LDL- cholesterol (mmol/l)Mean (SD)		HDL- cholesterol (mmol/l)Mean (SD)	Triglycerides (mmol/l)Mean (SD)	Systolic blood pressure (mmHg)Mean (SD)	Diastolic blood pressure (mmHg)Mean (SD)	BMI (kg/m²)Mean (SD)	Waist (cm)Mean (SD)	Daily smoking (%)
Women
34	151	4.95 (1.05)	2.97	(0.74)	1.43 (0.34)	1.32 (2.85)	111 (11)	69 (9)	25.0 (4.8)	84.7 (12.9)	13.7
37	177	4.91 (0.82)	3.02	(0.70)	1.43 (0.32)	1.00 (0.52)	111 (10)	70 (8)	25.1 (4.3)	84.4 (10.6)	14.4
40	187	4.96 (0.80)	3.06	(0.71)	1.42 (0.30)	1.10 (0.64)	114 (12)	71 (10)	26.1 (6.1)	87.4 (15.5)	14.1
43	211	5.03 (0.86)	3.15	(0.74)	1.42 (0.33)	1.04 (0.45)	116 (14)	74 (10)	26.6 (5.5)	89.3 (14.5)	14.9
46	202	5.20 (0.90)	3.25	(0.76)	1.44 (0.32)	1.21 (0.97)	119 (14)	74 (9)	26.7 (6.1)	89.1 (14.0)	9.5
49	194	5.33 (0.86)	3.36	(0.79)	1.45 (0.34)	1.16 (0.59)	122 (16)	75 (9)	25.9 (4.0)	89.8 (15.1)	14.7
Men
34	138	4.95 (0.92)	3.16	(0.8)	1.19 (0.25)	1.38 (1.27)	120 (12)	74 (10)	25.9 (4.0)	93.0 (11.9)	20.0
37	141	5.24 (1.03)	3.40	(0.9)	1.15 (0.28)	1.55 (0.99)	120 (13)	74 (11)	26.2 (4.4)	94.8 (12.7)	20.7
40	170	5.28 (0.95)	3.45	(0.85)	1.18 (0.29)	1.54 (1.10)	122 (12)	78 (9)	27.1 (4.4)	96.3 (12.1)	15.6
43	158	5.42 (1.06)	3.48	(0.95)	1.20 (0.30)	1.81 (1.83)	125 (14)	80 (12)	27.6 (4.4)	99.1 (12.0)	18.0
46	165	5.48 (1.03)	3.53	(0.93)	1.20 (0.30)	1.66 (0.90)	125 (14)	80 (11)	27.2 (3.8)	97.6 (11.6)	14.2
49	162	5.48 (0.98)	3.52	(0.88)	1.29 (0.34)	1.53 (0.88)	125 (14)	79 (10)	27.8 (5.1)	99.9 (14.7)	17.5
All women	1120	5.07 (0.89)	3.14	(0.75)	1.43 (0.33)	1.13 (1.21)	116 (14)	72 (10)	26.1 (5.5)	87.6 (14.1)	13.5
All men	931	5.32 (1.01)	3.43	(0.90)	1.20 (0.30)	1.58 (1.21)	123 (13)	78 (11)	27.0 (4.4)	96.9 (12.7)	17.6
	N ^a	Total cholesterol (mmol/l)	LDL- cholesterol (mmol/l)		HDL- cholesterol (mmol/l)	Triglycerides (mmol/l)	Systolic blood pressure (mmHg)	Diastolic blood pressure (mmHg)	BMI (kg/m²)	Waist (cm)	Daily smoking (%)
P-value (between sexes)		<0.001	<0.001		<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.01
All	2051	5.19 (0.95)	3.27 (0.83)		1.33 (0.33)	1.34 (1.23)	119 (14)	75 (10)	26.5 (5.1)	91.0 (14.3)	15.3
Effect of age
β (women)^b		0.030	0.026		<0.001	0.008	0.78	0.44	0.13	0.39
P-value (women)		<0.001	<0.001		0.724	0.005	<0.001	<0.001	<0.001	<0.001	0.653
β (men)^b		0.030	0.022		0.006	0.01	0.42	0.42	0.12	0.43
P-value (men)		<0.001	0.021		0.002	0.006	<0.001	<0.001	<0.001	<0.001	0.284
P-value for interaction^c		0.580	0.433		0.053	0.662	0.002	0.792	0.856	0.764	0.661

N varied between 1106 and 1120 in women and between 893 and 931 in men.

values are regression coefficients (expressed in mmol/l, mmHg, kg/m² or cm) for a 1-unit change in age.

‡

Significant interaction means that the association between a risk factor and age is different in men than in women.

The average serum total cholesterol in the study participants was 5.19 mmol/l, with 51.3% (57.3% of men and 46.3% of women) of participants having serum cholesterol over 5.0 mmol/l and 58% having serum LDL cholesterol level over 3.0 mmol/l. The prevalence of overweight (BMI 25–30 kg/m²) was 29.8% in women and 43.5% in men. The prevalence of obesity (BMI >30 kg/m²) was 20.2% in women and 21.0% in men. Daily smoking prevalence was higher in men (17.6%) than in women (13.5%), and was highest in the age group of 37-year-old men (20.7%) and 43-year-old women (14.9%) in 2011.

Type 2 diabetes and metabolic syndrome in 2011

As shown in Table II, T2D was observed in 4.1% of the participants. Prediabetes was observed among 33.8% of the participants. Men had higher levels of glucose and GHbA1c, as well as higher prevalence of prediabetes and metabolic syndrome, than women. There was no significant difference between sexes in the prevalence of T2D. Glucose, GHbA1c and prevalence of prediabetes, T2D and metabolic syndrome increased with age in both sexes. The association of glucose and GHbA1c with age was stronger in men than in women. Over half (54%) of the T2D diagnoses were self-reported or based on the use of medication for T2D. Fasting glucose was over 7.0 mmol/l in 15% of the T2D cases, 15% had elevated GHbA1c levels (>6.5%) and 15% had both elevated fasting glucose and GHbA1c levels.

Table II.

Glucose levels, type 2 diabetes and metabolic syndrome prevalence in 2011 in 2064 Finnish women and men aged 34–49 years.

Age (years)	N ^a	Glucose (mmol/l)Mean (SD)	Prediabetes (%)^b	Glycated hemoglobin (%)Mean (SD)	Type 2 diabetes mellitus (%)^c	Metabolic syndrome (%)^d
Women
34	147	5.01 (0.44)	16.5	5.40 (0.30)	2.0	8.7
37	177	5.15 (1.07)	17.8	5.45 (0.42)	2.2	8.1
40	187	5.28 (1.34)	24.5	5.44 (0.38)	3.7	15.5
43	210	5.31 (0.86)	31.3	5.54 (0.54)	4.3	20.7
46	200	5.38 (1.18)	27.2	5.53 (0.50)	5.5	19.1
49	194	5.32 (0.71)	35.4	5.55 (0.47)	5.1	26.9
Men
34	137	5.39 (0.75)	29.5	5.46 (0.76)	3.6	10.4
37	140	5.39 (0.47)	38.3	5.45 (0.24)	1.4	23.0
40	169	5.46 (0.51)	40.0	5.46 (0.28)	1.8	22.5
43	158	5.59 (0.77)	47.8	5.57 (0.54)	6.3	32.7
46	165	5.67 (1.10)	52.4	5.59 (0.53)	4.9	30.0
49	162	5.74 (1.03)	50.6	5.65 (0.58)	8.0	31.9
All women	1129	5.25 (1.00)	26.0	5.49 (0.45)	3.9	17.6
All men	935	5.55 (0.82)	43.5	5.53 (0.52)	4.4	25.9
P-value		<0.001	<0.001	0.050	0.580	<0.001
All	2064	5.13 (0.88)	33.8	5.51 (0.47)	4.1	21.39
Effect of age
β (women)^e		0.021		0.010
P-value (women)	<0.001	<0.001	<0.001	0.030		<0.001
β (men)^e		0.026		0.015
P-value (men)		<0.001	0.026	<0.001	0.008	<0.001
P-value for interaction^f		<0.001	0.805	0.031	0.636	0.237

N varied between 1091 and 1129 in women and between 919 and 935 in men.

Fasting glucose 5.6–6.9 mmol/l or glycated hemoglobin (GHbA1c) 5.7–6.4%.

Participants with fasting glucose ≥ 7 mmol/l or GHbA1c ≥ 6.5% or self-reported diabetes or use of medication.

Defined by Harmonized criteria [13].

Values are regression coefficients (expressed in mmol/l or %) for a 1-unit change in age.

Significant interaction means that the association between a risk factor and age is different in men than in women.

Secular trends between 2007 and 2011

Four-year comparisons in cardiovascular risk factor levels between comparable age groups are shown in Table III. There was a significant increase in waist circumference among women. Significant decreases were observed in triglycerides and in systolic and diastolic blood pressure in both sexes. Analysis of changes in components of metabolic syndrome separately is shown in Table IV. The prevalence of elevated blood pressure, hyperglycemia and hypertriglyceridemia decreased in both men and women, while the prevalence of decreased HDL-cholesterol and elevated waist circumference increased in both men and women. Changes in the prevalence of elevated blood pressure and hypertriglyceridemia were significant in both sexes, and change in the prevalence of elevated waist circumference was significant in women.

Table III.

Changes in cardiovascular risk factor levels in 1583 participants (mean age 39 years) in 2007, and in 1149 participants (mean age 39 years) in 2011.

	Risk factor			Change between 2007 and 2011
		2007	2011	%	P-value
Women	Total cholesterol (mmol/l)	4.94	4.95	0.2	0.804
	LDL-cholesterol (mmol/l)	2.97	3.04	2.4	0.079
	HDL-cholesterol (mmol/l)	1.44	1.42	−1.4	0.274
	Triglycerides (mmol/l)	1.16	1.12	−3.4	<0.001
	Systolic blood pressure (mmHg)	117	113	−3.0	<0.001
	Diastolic blood pressure (mmHg)	73	71	−3.0	<0.001
	Body mass index (kg/m²)	25.5	25.8	1.4	0.186
	Waist (cm)	84.0	87.0	3.6	<0.001
	Glucose (mmol/l)	5.19	5.2	0.2	0.852
	Metabolic syndrome (%)	15.7	14.1	−10	0.413
	Daily smoking (%)	12.6	13.2	4.9	0.751
Men	Total cholesterol (mmol/l)	5.28	5.21	−1.3	0.216
	LDL-cholesterol (mmol/l)	3.36	3.37	0.3	0.830
	HDL-cholesterol (mmol/l)	1.21	1.18	−2.5	0.094
	Triglycerides (mmol/l)	1.68	1.57	−6.5	<0.001
	Systolic blood pressure (mmHg)	126	121	−4.0	<0.001
	Diastolic blood pressure (mmHg)	79	77	−3.3	<0.001
	Body mass index (kg/m²)	26.9	26.6	−1.0	0.294
	Waist (cm)	95.1	96.5	1.5	0.402
	Glucose (mmol/l)	5.51	5.46	−0.9	0.217
	Metabolic syndrome (%)	23.5	21.3	−9.3	0.399
	Daily smoking (%)	19.7	17.8	−9.5	0.447

N varied in 2007 between 834 and 858 in women and 652 and 680 in men, and in 2011 between 605 and 633 in women and between 483 and 512 in men.

Table IV.

Components of metabolic syndrome by the Harmonized criteria in 2007 in 1540 participants (mean age 39) and in 2011 in 1149 participants (mean age 39 years).

Year	Women			P-value for change^a	Men			P-value for change
	2007	2011	Change (%)	P-value for change^a	2007	2011	Change (%)	P-value for change
N	860	637	2007–2011		680	512	2007–2011
Elevated blood pressure	23.0	12.4	−46.1	<0.001	45.6	28.9	−36.6	<0.001
Hyperglycemia	15.6	12.4	−20.4	0.082	32.1	31.3	−2.5	0.766
Hypertriglyceridemia	13.0	9.3	−28.9	0.024	35.0	26.2	−25.2	0.001
Decreased HDL-cholesterol	34.9	38.3	9.8	0.174	24.7	26.4	6.7	0.514
Elevated waist circumference	31.1	37.5	20.8	0.009	22.9	25.6	11.6	0.290

Chi-squared test was applied to examine the differences between 2007 and 2011.

In 2007, according to self-administrated questionnaires among 1527 participants aged 33–45 years, 115 (7.5%) were using anti-hypertensive medication, 37 (2.4%) were using medication for hypercholesterolemia and 5 (0.3%) were using any treatment for diabetes. In 2011, among 1079 participants aged 34–43 years, 68 (6.3%) were using anti-hypertensive medication, 27 (2.5%) were using medication for hypercholesterolemia and 9 (0.8%) were using any treatment for diabetes. The trends in lipid levels, glucose and blood pressure changes were examined in study participants, excluding those with reported use of relevant medication. Trends in lipid levels, blood pressure and glucose were essentially similar when compared with the trends observed in the whole cohort.

Discussion

This study shows that the previously observed favorable trends in cholesterol levels have leveled off. More than half of the participants had a total cholesterol level greater than 5.0 mmol/l. Moreover, significant increase in waist circumference in women was observed. On the other hand, levels of systolic and diastolic blood pressure decreased significantly in both sexes. Prevalence of T2D was 4.1% in the study population.

Cardiovascular risk factor levels began to improve in the 1970s in Finland [2]. This was followed by a remarkable reduction in CHD risk. From the 1960s to the 1990s the mortality from CHD in Finland among working-age men decreased by over 70%, and in the whole population by around 60% [1]. The decrease in mortality has been estimated to be mainly due to favorable dietary and lifestyle changes (effect of over 70%), though improvements in treatment have also had an impact (effect of approximately 25%) [4]. Earlier observations in Australasia, North America and Europe have suggested that total cholesterol levels decreased between 1980 and 2008 [15]. Results from the FINRISK (The National FINRISK Study) study in 2002 show that serum cholesterol levels, blood pressure and smoking declined in Finland from 1972 to 1997 [2]. However, between 1997 and 2002 the changes in risk factor levels were not as remarkable [16]. Our earlier studies in the YFS cohort have shown that total cholesterol (in men −6.6%, in women −4.1%), LDL-cholesterol (in women −3.6%, in men −4.2%) and systolic (in women −4.2%, in men −7.7%) and diastolic blood pressure (in women −4.6%, in men −8.0%) decreased between 1986 and 2001 in 24–30-year-old Finnish adults, while BMI (in women 7.3%, in men 3.9%) and triglyceride levels increased (in women 27%, in men 24.5%) [17]. Between 2001 and 2007 total cholesterol (in women −6.6%, in men −5.8%) and LDL−cholesterol (in women −11.6%, in men −10.2%) decreased, but at the same time waist circumference (in women 3.2%, in men 1.8%), systolic (in women 1.8%, in men 1.9%) and diastolic blood pressure (in women 3.9%, in men 3.5%), and glucose levels (in women 3.7%, in men 3.1%) increased in 30–39-year-old participants [18].

The present study shows that favorable trends in cholesterol levels ceased between 2007 and 2011 among the YFS cohort. Our results are in line with the findings from the Swedish Västerbotten County population, in which blood cholesterol levels had increased among men and women from 2007 after an initial decrease since 1990 [5]. Furthermore, the results of the FINRISK survey in 2012 among 7,921 Finnish men and women aged 25–74 years suggest that serum cholesterol levels have begun to rise after decades of favorable development [6]. Among the 35–44-year-old participants of the FINRISK survey, total cholesterol was above 5.0 mmol/l in 62.9% of men and 47.3% of women. In the present study, there were no significant changes in cholesterol levels between 2007 and 2011, though LDL-cholesterol levels increased and HDL-cholesterol levels decreased in both sexes. Total cholesterol was above 5.0 mmol/l in 57.3% of men and 46.3% of women. Use of medication for hypercholesterolemia was reported by 77 participants (3.9% of the study population). The trends in cholesterol levels were essentially similar to the whole study cohort when participants with relevant medication were excluded. Low-carbohydrate diets may have affected adherence to the national nutrition recommendations: the overall consumption of saturated fat (butter) has increased and the consumption of skim milk has decreased in Finland since 2009 [19], which could have modified especially LDL-cholesterol levels in our study. A lowering in HDL levels normally results in rising triglyceride levels [20], but we have no plausible explanation for the decline in levels of both HDL and triglycerides observed in this study. Though we are only able to speculate on the reasons for this observation, one putative explanation is an altered diet.

Increased levels of LDL-cholesterol and decreased levels of HDL-cholesterol have been associated with higher cardiovascular mortality [21]. In a previous study among adults aged between 25 and 54 years, women had a CVD risk similar to men, while women received preventive medications less often than men of similar age [22]. In our study, significant differences between men and women aged 34–49 were seen in levels of all risk factors except T2D.

Results from the FINRISK study in 2012 [23] suggest that the decrease in age-adjusted blood pressure levels has not continued in the Finnish adult population. In contrast, both systolic and diastolic blood pressure decreased (P always <0.001) during follow-up in our study. Systolic blood pressure decreased by 4.0% in men and 3.0% in women, and diastolic blood pressure decreased by 3.3% in men and 3.0% in women. When participants using anti-hypertensive medication were excluded, the trends remained similar (P always <0.001). Changes in blood pressure levels and decrease of glucose levels in both sexes induced a decrease in the prevalence of metabolic syndrome. However, the secular trend findings concerning blood pressure levels, as well as favorable trends in smoking prevalence among men, must be interpreted cautiously, as non-participants in the 2011 study had higher blood pressure levels and smoking prevalence in 2007, possibly causing selection bias.

The prevalence of obesity has been increasing worldwide for decades [8]. Around 20% of the adult population in Finland are obese (BMI >30) [7]. Preliminary results from FINRISK 2012 suggest that the prevalence of obesity leveled off between 2007 and 2012 in the Finnish population [24]. Similar trends can be seen around the world, especially among those of high socioeconomic status [25]. In this study, significant changes in BMI were not observed. Waist circumference has increased in both sexes, though non-significantly in men. Increased waist circumference is associated with higher incidence of cardiovascular diseases [26] and T2D [27].

The incidence of T2D increased in the Finnish population by an average of 4.3% per year between 1992 and 2001 [9]. In a Finnish population aged 25 to 44 years in 2007 [28], 2.4% of the study population had T2D. In the present study, 4.1% of the participants had T2D. Our results suggest that over one-third of our study population had an increased risk for T2D. Very high T2D risk was observed in 4% of the study population with GHbA1c between 6.0% and 6.5% [29,30].

Limitations

A common limitation in longitudinal studies is non-participation at follow-up. Because baseline risk factor levels were similar among participants and non-participants and the study group has been dynamic, the present study population was probably representative of the original population. However, loss to follow-up was greater in cigarette smokers, who also had higher systolic and diastolic blood pressure in the 2007 and 2011 follow-ups in both sexes, which may have differentially affected secular trend analyses in blood pressure levels and the prevalence of smoking and the metabolic syndrome. To minimize the bias caused by non-participation, only participants who had participated in both follow-ups in 2007 and 2011 were included in the analyses concerning change in cardiovascular risk factors between 2007 and 2011.

Follow-up examinations in the YFS were designed to retain 3-year differences between the age groups [11]. However, the most recent follow-up in 2011 was performed 4 years after the 2007 follow-up, so that studying 4-year changes between 2007 and 2011 was only possible by merging groups to achieve similar mean ages.

Conclusions

A significant increase was observed in waist circumference among women during the 4-year follow-up. Moreover, over one-third of our study population had an increased risk for T2D. Although favorable trends were observed in blood pressure levels and smoking prevalence, these data suggest that monitoring and intervention in cardiovascular risk factor levels is needed among Finnish adults.

Footnotes

Conflict of interest

None declared.

Funding

The Young Finns Study has been financially supported by the Academy of Finland: grants 126925, 121584, 124282, 129378 (Salve), 117787 (Gendi), and 41071 (Skidi), the Social Insurance Institution of Finland, Kuopio, Tampere and Turku University Hospital Medical Funds (grant 9M048 and 9N035 for Terho Lehtimäki), Orion-Farmos Research Foundation, Juho Vainio Foundation, Paavo Nurmi Foundation, Finnish Foundation of Cardiovascular Research and Finnish Cultural Foundation, Tampere Tuberculosis Foundation and Emil Aaltonen Foundation.

Dr Magnussen is supported by a National Health and Medical Research Council Early Career Fellowship (APP1037559).

References

Puska

Vartiainen

Tuomilehto

. Changes in premature deaths in Finland: successful long-term prevention of cardiovascular diseases. Bull World Health Organ 1998;76:419–25.

Vartiainen

Laatikainen

Peltonen

. Thirty-five-year trends in cardiovascular risk factors in Finland. Int J Epidemiol 2010;39:504–18.

Vartiainen

Jousilahti

Alfthan

. Cardiovascular risk factor changes in Finland, 1972–1997. Int J Epidemiol 2000;29:49–56.

Valsta

Tapanainen

Sundvall

. Explaining the 25-year decline of serum cholesterol by dietary changes and use of lipid-lowering medication in Finland. Public Health Nutr 2010;13:932–8.

Johnson

Lindahl

. A reversal of decreasing trends in population cholesterol levels in Vasterbotten County, Sweden. Glob Health Action 2012;5. doi:10.3402/gha.v5i0.10367. Epub 23 March 2012.

Vartiainen

Borodulin

Sundvall

. FINRISKI-tutkimus: Väestön kolesterolitaso on vuosikymmenien laskun jälkeen kääntynyt nousuun. [Cholesterol levels in the Finnish population have increased after decades of decline]. Finnish. Suom Lääkäril 2012;67:2365–8.

Lahti-Koski

Seppänen-Nuijten

Männistö

. Twenty-year changes in the prevalence of obesity among Finnish adults. Obes Rev 2010 Mar;11:171–6.

Lobstein

Baur

Uauy

, IASO International Obesity TaskForce. Obesity in children and young people: a crisis in public health. Obes Rev 2004;5 (Suppl 1):4–104.

Lammi

Blomstedt

Moltchanova

. Marked temporal increase in the incidence of type 1 and type 2 diabetes among young adults in Finland. Diabetologia 2008;51:897–9.

10.

Danaei

Finucane

. National, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2.7 million participants. Lancet 2011;378:31–40.

11.

Raitakari

Juonala

Rönnemaa

. Cohort profile: the cardiovascular risk in Young Finns Study. Int J Epidemiol 2008;37:1220–6.

12.

Kostner

. Letter: Enzymatic determination of cholesterol in high-density lipoprotein fractions prepared by polyanion precipitation. Clin Chem 1976;22:695.

13.

Alberti

Eckel

Grundy

. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation 2009;120:1640–5.

14.

American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care 2013;36 Suppl 1:S67–74.

15.

Farzadfar

Finucane

Danaei

. National, regional, and global trends in serum total cholesterol since 1980: systematic analysis of health examination surveys and epidemiological studies with 321 country-years and 3.0 million participants. Lancet 2011;377:578–86.

16.

Vartiainen

Laatikainen

Tapanainen

. Suomalaisten sydän- ja verisuonitautien riskitekijät FINRISKI-tutkimuksessa 1982–2002. [Cardiovascular risk factor levels in the Finnish population between 1982–2002. FINRISKI-study.] Finnish. Suom Lääkäril 2003;58:4099–105.

17.

Juonala

Viikari

Hutri-Kähönen

. The 21-year follow-up of the Cardiovascular Risk in Young Finns Study: risk factor levels, secular trends and east-west difference. J Intern Med 2004;255:457–68.

18.

Raiko

Viikari

Ilmanen

. Follow-ups of the Cardiovascular Risk in Young Finns Study in 2001 and 2007: levels and 6-year changes in risk factors. J Intern Med 2010;267:370–84.

19.

Helakorpi

Holstila

Virtanen

. Suomalaisen aikuisväestön terveyskäyttäytyminen ja terveys, kevät 2011. [Health Behavior and Health among the Finnish Adult Population, Spring 2011]. Helsinki: Terveyden ja hyvinvoinnin laitos, 2012.

20.

Brewer

Jr.

Hypertriglyceridemia: changes in the plasma lipoproteins associated with an increased risk of cardiovascular disease. Am J Cardiol 1999 May;83:3F–12F.

21.

Pekkanen

Linn

Heiss

. Ten-year mortality from cardiovascular disease in relation to cholesterol level among men with and without preexisting cardiovascular disease. N Engl J Med 1990;322:1700–7.

22.

Lehto

Havulinna

. Gender differences in the prevalence, causes and treatment of high cardiovascular risk: findings from the FINRISK Survey. Eur J Prev Cardiol 2012;19:1153–60.

23.

Laatikainen

Jula

Kastarinen

. Verenpainetasot ja hoitotasapaino FINRISKI-tutkimusalueilla 1982–2012. [Blood pressure levels and therapeutic balance in FINRISK study areas in 1982–2012]. Finnish. Suom Lääkäril 2013;68:1803–9.

24.

Järvi

. Suomalaisten lihominen pysähtyi. [Weight gaining of Finnish people stopped]. Finnish. Suom Lääkäril 2013;68:292.

25.

Rokholm

Baker

Sørensen

. The levelling off of the obesity epidemic since the year 1999 – a review of evidence and perspectives. Obes Rev 2010;11:835–46.

26.

Flint

Rexrode

. Body mass index, waist circumference, and risk of coronary heart disease: a prospective study among men and women. Obes Res Clin Pract 2010;4:e171–e181.

27.

Siren

Eriksson

Vanhanen

. Waist circumference a good indicator of future risk for type 2 diabetes and cardiovascular disease. BMC Public Health 2012;12:631–2458–12–631.

28.

Pajunen

Keinänen-Kiukaanniemi

Korpi-Hyövälti

. Ylipainon ja lihavuuden esiintyvyys tyypin 2 diabetespotilailla. [Prevalence of overweight and obesity in patients with type 2 diabetes in Finland]. Finnish. Suom Lääkäril 2012;38:2621–6.

29.

Shimazaki

Kadowaki

Ohyama

. Hemoglobin A1c (HbA1c) predicts future drug treatment for diabetes mellitus: a follow-up study using routine clinical data in a Japanese university hospital. Transl Res 2007;149:196–204.

30.

Andersson

van Gaal

Caterson

. Relationship between HbA1c levels and risk of cardiovascular adverse outcomes and all-cause mortality in overweight and obese cardiovascular high-risk women and men with type 2 diabetes. Diabetologia 2012;55:2348–55.