Table 1.
Study and patient characteristics of the included studies.
| S. No. | Study (Year) | Study Design | Settings | Study Interval | Type of ACS | Age Cut-off (Years) | Arm | No. of Patients | Age (Years) | Risk Factors Assessed |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Beckowski et al. (2018) | Case control | Multicenter Registry (Polish Registry of Acute Coronary Syndrome), WOBASZ, and NATPOL, Poland | 2007 - 2014 | UA, NSTEMI, STEMI | ≤45 | Case | 1941 | 42 (39-44) | Major ACS risk factors (HT, obesity, hypercholesterolemia, DM, and smoking), family history of CAD, kidney disease, lung disease, ischemic stroke, PAD, anthroprometric |
| Control | 1170 | 42 (39-44) | ||||||||
| 2 | Friedlander (2001) | Case control | Washington State, USA | July 1991 - February 1995 | Acute myocardial infarction | 18-44 | Case | 107 | 39.5 ± 4.5 | Race, education, marital status, DM, HT, hypercholesterolemia, current smoking, sedentary lifestyle, coffee, BMI, laboratory parameter, genetic |
| Control | 526 | 37.7 ± 5.3 | ||||||||
| 3 | La Vecchia et al. (1987) | Case control | 34 Hospitals in Northern Italia | January 1983 - December 1984 | Acute myocardial infarction | <45 | Case | 52 | N/A | Smoking, DM, HT, HT in pregnancy, hyperlipidemia, obesity, parity, age at first birth, menopausal status, coffee, alcohol, OC, hormonal replacement treatment, family history of coronary heart disease, marital status, education, social class |
| Control | 91 | |||||||||
| 4 | Lewis et al. (1997) | Case control | 16 centers in Germany, the United Kingdom, France, Austria, and Switzerland | August 1993 - June 1996 | Acute myocardial infarction | 16-44 | Case | 182 | N/A | Country, age, smoking, HT, aspirin, DM, high lipids, family history of MI, high alcohol, parity, current OC, first user of OC, BMI, preeclampsia history |
| Control | 635 | |||||||||
| 5 | Liu et al. (2020) | Case control | Beijing Anzhen Hospital, China | January 2010 - August 2016 | UA, NSTEMI, STEMI | 19-44 | Case | 415 | 40.77 ± 4.02 | Overweight, HT, hyperlipidemia, DM, depression or anxiety, gynecological disease, hyperuricemia, family history of CHD, hyperhomocysteinemia, hypothyroidism, hypercholesterolemia, high CRP, anemia, cardiac insufficiency, smoking, history of PCI, autoimmune disease, postmenopausal, OC, renal insufficiency, renal artery stenosis |
| 6 | Oliveira et al. (2007) | Case control | Department of Cardiology in 4 Hospitals in Porto, Portugal | 2001 - 2003 | NSTEMI, STEMI | 18-45 | Case | 42 | 40.7 ± 3.4 | Age, education, BMI, waist circumference, leisure-time physical activity, total energy intake, ethanol, caffeine, family history of CAD, angina, dyslipidemia, HT, DM, smoking |
| Control | 486 | 35.0 ± 7.7 | ||||||||
| 7 | Tanis et al. (2003) | Case control | 8 University Hospitals and 8 General Hospitals in Netherlands | January 1990 - October 1995 | Acute myocardial infarction | 18-49 | Case | 217 | 42.8 ± 6.1 | Age, obese, caucasian ethnicity, OC, education level, HT, hypercholesterolemia, DM, smoking, family history of cardiovascular disease |
| Control | 763 | 38.7 ± 8.0 |
Abbreviations: ACS, acute coronary syndrome; BMI, body mass index; CAD, coronary artery disease; CRP, C-reactive protein; DM, diabetes mellitus; HT, hypertension, N/A, not available; NSTEMI, nonST-elevation myocardial infarction; OC, oral contraceptive; PAD, peripheral artery disease; PCI, primary coronary intervention; STEMI, ST-elevation myocardial infarction; UA, unstable angina.