Does gender confound risk factors for acute myocardial infarction in those under 40 years of age? : a case control study

Abstract EN

Background : Studies have shown that gender has an effect on acute myocardial infarction (AMI).

The current study concentrated on those under 40 years of age.

Little research has been done on this age group in Iraq.

The effect of gender on fatality due to AMI was studied.

In addition, the confounding effect of gender on known risk factors was studied.

Objectives: To assess the effect of gender on risk factors for AMI in patients under 40 years of age.

Methods : A case control study was conducted in Ibn Al Nafis Cardiology Hospital in Baghdad during the period from May to December 2000.

All cases of AMI 40 years of age and under were studied.

A total of 48 cases, 40 males and 8 females were admitted to the hospital and included in the study.

Cases were diagnosed as AMI only with ECG changes and/or enzyme changes suggestive of the disease.

Both typical and atypical histories were included.

A control group was selected from the outpatient department of the same hospital.

The controls were matched with the cases as closely as possible in terms of age and sex.

AMI was excluded in the controls using the same criteria.

An interview of all cases and controls using a validated questionnaire was carried out.

Main Outcome Measures included distribution of cases compared to controls in terms of age and gender.

Case fatality by gender was studied.

The effect of gender was measured on the risk factors studied.

Results: Males were more affected in the younger age group than females.

Increasing age, in general, was found to have a positive correlation with the number of cases admitted (Pearson's rho=0.943, p=0.057).

Younger age group seemed to have a protective effect against fatal outcome of the disease.

Current smoking was found to have a significant effect unconfounded by gender (adjusted Mantel- Haenszel weighted OR=3.3 with a 95% confidence limits of 1.16-9.63).

High serum cholesterbl (>250 mg/dl) showed a significant effect unconfounded by gender (OR=7.93, 95% confidence interval 1.73-62.04).

Low density lipoproteins (LDL) showed significantly higher values in cases compared to controls (F=11.29, p=0.0001), and high density lipoproteins (HDL) showed significantly lower values in cases (F value=2.67, p=0.023).

In both LDL/HDL and the total cholesterol TC / HDL ratios, the cases showed significantly higher values than the controls (F value = 8.51 and 4.91 respectively, p value=<0.0001 for both).

Family history was unconfounded by gender.

(Adjusted OR = 3.76, 95% CI 1.18-12.86).

Conclusions: Fatality associated with AMI in those under 40 years of age affected males more than females.

Gender did not appear to confound risk factors for AMI including current smoking, high cholesterol levels, high levels of LDL, low levels of HDL, and family history.

These are important risk factors in patients under 40 years of age irrespective of gender.