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Title: Fish consumption and the 30-year risk of fatal myocardial infarction

Authors: Daviglus ML, Stamler J, Orencia AJ, et al.

Reference:  The New England Journal of Medicine 1997;336:1046-53

Reviewer: Max A Luna

Problem addressed: Although most studies have shown a positive association between consumption of fish and a lower risk of coronary heart disease, recent studies have reported conflicting results.  This study reexamines this association in a large prospective cohort after 30 years of follow-up.

Purpose of study: To compare the risk of death from myocardial infarction (MI) between groups with different degrees of fish consumption

Methods: Slightly over 1800 men ages 44 to 55 years old were entered in a prospective cohort in 1957. The group underwent a first and second examination in 1957 and 1958 using standard questionnaires, laboratory data and physical exams. Annual examination was done yearly for the first 10 years and by mailed questionnaires or telephone interview for the next 15 years.  For the 31st year, survival data were obtained from the National Death Index.

Baseline information was gathered from each subject regarding cardiovascular risk factors and diet information about diet over the previous 20 years, detailing food consumption information over the previous 28 days.  Fish consumption categories were created based on the consumption of 120-g units per 28 days.  These were coded as follows: 0 for none, 1 for less than 4 units, 2 for 4 to 8 units, and 3 for more than 8 units, corresponding to the following average daily intakes: none, 1 to 17 g, 18 to 34 g, or 35 g or more.  The end points of the study were death from MI, death from coronary heart disease and death from cardiovascular disease.  MI was classified as sudden or not sudden according to the duration of the terminal illness and the place of death, as recorded on the death certificate.

Results: During the 30-year follow-up period, there were 293 deaths from myocardial infarction (196 sudden deaths, 94 nonsudden deaths, and three that were not classifiable), 430 deaths from any type of coronary disease, 573 from any type of cardiovascular disease and 1042 deaths from any cause.

There was a significant inverse relation between fish consumption and the risk of death from coronary artery disease and  fatal myocardial infarction.  For the subjects who consumed 35 g or more of fish daily as compared with the nonconsumers, the relative risk of death from coronary heart disease was .62 (95% CI .40-.94) and .56 (95% CI .33-.93) for death due to myocardial infarction.  The decreased risk of death from myocardial infarction was predominantly due to nonsudden death.

MULTIVARIATE-ADJUSTED RELATIVE RISK OF DEATH
CAUSE OF DEATH	FISH CONSUMPTION
	0g/day	1-17 g/day	18-34 g/day	35 g/day
Overall
MI	1.00	0.88	0.76	0.56*
ALL CHD	1.00	0.88	0.84	0.62**
All CVD	1.00	0.94	0.89	0.74**
All Causes	1.00	1.02	0.98	0.85
MI DEATH
Nonsudden	1.00	1.04	0.67	0.33**
Sudden	1.00	1.31	0.77	0.51*
Escliding MI
CHD	1.00	0.93	1.11	0.82
CVD	1.00	1.03	1.09	1.02
All Causes	1.00	1.10	1.10	1.00

*= P 0.05 **= P 0.01

Fish consumption was not related to any of the endpoints in the group younger than 47 years. The relative risk of fatal myocardial infarction for the group greater than 47 years old was of .41.

The relation between fish consumption and the risk of fatal myocardial infarction persisted throughout the 30 years of follow-up.

Discussion: Based on this data it appears that there is a significant, independent, inverse graded association between base-line fish consumption and the 30-year risk of death from coronary heart disease, particularly nonsudden death from myocardial infarction. There was a 42% and 67% relative risk reduction for MI deaths and nonsudden death respectively in the groups consuming 35 g/day of fish compared to the non-fish eaters.

An unexpected finding was the fact that most of the MI mortality reduction in this study was due to nonsudden deaths, which is opposite to what has been observed in the overall decline of MI deaths in the US. This may be due to a different definition of sudden death compared to other studies.

Thirty-five grams of fish is equal to 1.2 ounces and that an average size fish meal is between 6-8 ounces. Therefore to eat an average of 35 grams or more of fish a day you would need to eat about 6 (6 ounce) portions of fish every 28 days.