Non-traditional risk factors for myocardial infarction in adults under forty: A systematic review of emerging trends

Table 4 Subgroup and sensitivity analyses

Study ID	Subgroup (e.g., sex, age, region)	Effect estimates (OR/HR/RR with 95%CI)	Notes
1	Age (< 40 vs 40-55), sex	HIV: OR = 4.06 (3.48-4.71); SLE: OR = 2.12 (1.89-2.39); OSA: OR = 1.16 (1.12-1.20) for MI risk in young adults	No stratified data < 40; large administrative database; cross-sectional analysis of hospitalizations
2	Sex (women vs men), marital status (unpartnered vs partnered)	HR = 1.31 (1.15-1.49) unpartnered vs partnered for 1-year readmission; unpartnered women: 37.6% readmission vs unpartnered men: 26.8%	No significant sex-marital status interaction (P = 0.69); effect attenuated after psychosocial adjustment
3	Sex, marital status	HR = 1.28 (1.15-1.42) unpartnered vs partnered for 1-year readmission; unpartnered women had highest readmission	Significant sex-marital status interaction; psychosocial factors partially mediate risk
4	Age group (18-30 vs 31-45), sex	Telomere length shorter in MI patients aged 31-45 vs controls (P < 0.05); females with MI had shorter telomeres than female controls (P < 0.01)	No longitudinal MI risk data; small sample; case-control design
5	SES and depression combined	HR = 1.47 (1.36-1.60) for low SES + depression vs high SES, no depression (AMI risk)	Large population; no stratification < 40; depression by ICD codes; median 11.6 years follow-up
6	Time (≤ 1 year vs > 1 year), OSA status	HR for MACCE after 1 year in OSA: 3.87 (1.20-12.46); overall HR = 1.55 (0.94-2.57) for OSA vs non-OSA	Mean age 575; not exclusive to young adults; median 1-year follow-up
7	Sex (women vs men)	Adjusted OR for depressive symptoms at AMI: 1.64 (1.36-1.98) women vs men	Data collected at AMI admission only; no MI risk prediction; age up to 55; no follow-up
8	BMI (< 25 vs ≥ 25), hypertension status	Stronger inverse association of mediterranean diet with AMI in BMI < 25 and normotensive individuals	Case-control; median age 61; not restricted to young adults; no follow-up
9	Education level, sex	Men with high education had higher type A and work strain; women with low education had more type A behavior	Small sample; only men in main analysis; older data; case-control; no follow-up
10	Sleep duration categories (≤ 6 hours, 7 hours, 8 hours, ≥ 9 hours)	OR = 1.38 (1.15-1.67) for short sleep (≤ 6 hours) and non-ideal CVH	Cross-sectional; broad age range; outcome is CV health, not MI; no follow-up
11	Age (per year increase), high-risk subgroup vs low-risk	OR = 1.125 (1.063-1.190) per year age for high-growth atherosclerosis group	Cross-sectional autopsy study; subclinical outcome; no direct MI data; no follow-up
12	Sex, AMI subtype (type 1 vs others)	Women: Depression OR = 3.09 (2.37-4.04), men OR = 1.77 (1.15-2.73); family history stronger in men	Case-control; age 18-55; no exclusive < 40 data; robust adjustment; no follow-up
13	Sex	Non-traditional RFs rare (e.g., hypothyroidism, CTD, SCAD); no significant sex differences	Retrospective; in-hospital outcomes only; no effect estimates for non-traditional RFs; no follow-up

OR: Odds ratio; HR: Hazard ratio; HIV: Human immunodeficiency virus; RR: Relative risk; SLE: Systemic lupus erythematosus; OSA: Obstructive sleep apnea; MI: Myocardial infarction; AMI: Acute myocardial infarction; ICD: Implantable cardioverter-defibrillator; MACCE: Major adverse cardiac and cerebrovascular events; BMI: Body mass index; CV: Cardiovascular; RFs: Risk factors; CTD: Connective tissue disease; SCAD: Spontaneous coronary artery dissection.