Clinical and metabolic characteristics of the studied groups
There was a statistically significant higher prevalence of smoking (86.4% vs 64.3%, p<0.001), BMI (28.6 kg/m2 vs 27.6 kg/m2, p=0.012), total cholesterol (210.0 mg% vs 197.7 mg%, p=0.006) and TG levels (145.5 mg% vs 1113.0 mg%, p<0.001) in the MI<50 group than in the MI≥50 group. Prevalence of hypertension (55.2% vs 68.1%, p<0.001), DM (15.9% vs 35.7%, p<0.001), HDL cholesterol (41.5 mg% vs 47.6 mg%, p<0.001) and fasting glucose (99.0 mg% vs 105.4 mg%, p=0.002) levels were significantly lower in the MI<50 group than in the MI≥50 group (Table 1).
Statistically significant differences between the MI<50 group and the no-MI<50 group included smoking (86.4% vs 43.1%, respectively, p<0.001), BMI (28.6 kg/m2 vs 27.0 kg/m2, p<0.001), prevalence of hypertension (55.2% vs 29.2%, p<0.001), DM (15.9% vs 0.8%, p<0.001) and depression (8.4% vs 3.3%, p=0.018) as well as LDL cholesterol (132.4 mg% vs 123.3 mg%, p=0.049), HDL (41.5 mg% vs 54.1 mg%, p<0.001), TG (145.5 mg% vs 120.0 mg%, p<0.001) and glucose (99.0 mg% vs 93.0 mg%, p<0.001) levels.
There were 16.7%, 26.2% and 0.8% participants on statin treatment at baseline in the MI<50, MI≥50 and no-MI<50 groups, respectively. There were no individuals using or addicted to cocaine, HIV infected or affected by other severe communicable diseases neither within the study group of MI<50 nor both control groups of MI≥50 and no-MI<50 individuals.
Socioeconomic characteristics of the studied groups
There were significant differences between the MI<50 group and the MI≥50 group in the level of education (percentage of people with primary education 5.7% vs 15.2% respectively, p=0.001), the type of job (blue-collar 48.4% vs 41.3%, respectively, p<0.001) and marital status (percentage of single people: 18.5% vs 8.68% respectively, p<0.001); Table 2.
Comparing the MI<50 group and the no-MI<50 group, there were statistically significant differences in the level of education (percentage of people with university degree 22.3% vs 41.7%, respectively, p<0.001) and the type of job (white-collar 38.5% vs 60.1%, respectively, p<0.001) but not in marital status
Family history
There were statistically significant differences among the MI<50, MI≥50, and no-MI<50 groups in the presence of a family history of premature CVD in the first-degree relatives: 32.9% vs 9.6% (p<0.0001) and 32.9% vs 11.7% (p<0.0001), respectively (Table 3). There were also statistically significant differences among the MI<50, MI≥50 and no-MI<50 groups in the presence of a family history of premature CVD age involving the first- and second-degree relatives: 35.9% in the MI<50 group vs 15.6% in the MI ≥50 group (p<0.0001) and 14.2% in the no-MI<50 group (p<0.0001). Moreover, there were statistically significant differences between the studied groups in the family history of CVD events at every age within family members (the first- and the second-degree relatives): 65.4% in the MI<50 group vs 47.6% in the MI ≥50 group (p<0.0001) and 41.7% in the no-MI<50 group (p<0.0001).
The statistically significant differences among the MI<50, MI≥50 and no-MI<50 groups also included the percentage of patients with ≥2 affected relatives, including parents, children, siblings, siblings of parents, and grandparents, with a history of premature CVD events: 10.8% vs 2.9% (p<0.0001) and 10.8% vs 3.7% (p<0.0001), respectively; Figure 1.
There were statistically significant differences in the age of the first episode of MI between patients without a family history of premature CVD and patients with 1 affected relative (56.6 vs 48.6 years, respectively, p<0.0001) and with ≥2 affected first-degree relatives (56.6 vs 41.8 years, respectively, p<0.0001); Table 4. These differences were also significant for first- and second-degree relatives with premature CVD: 56.5 years for patients without affected relatives vs 50.7 for patients with 1 affected relative (p=0.0003) and vs 47.0 years for patients with ≥2 affected relatives (p<0.0001). There were also statistically significant differences in the age of the first episode of MI among patients without a family history of CVD at any age and patients with 1 affected relative (57.9 vs 51.9 years, respectively, p<0.0001) and with ≥2 affected first-degree relatives (57.9 vs 47.9 years, respectively; p<0.0001). These differences were also significant for first- and second-degree relatives with CVD event at any age: 58.1 years for patients without affected relatives vs 52.5 for patients with 1 affected relative (p=0.0002) and vs 50.9 years for patients with ≥2 affected relatives (p=0.0005). There was a statistically significant reversal association between the age of the first episode MI and the number of first-degree relatives with a history of premature MI/stroke (Figure 2).
When only MI, without ischemic stroke, was included in the family history, there were similar statistically significant differences in the age of the first episode of MI among patients without a family history of MI, premature and at any age as well, with 1 affected relative and with ≥2 affected relatives (Table in Supplementary Materials). There was also a significant reversal association between the age of the first episode MI and the number of affected relatives, including first-degree and first- and second degree relatives with a history of premature MI and MI at any age as well.