Mean fried fish/fish sandwich and tuna/other fish consumption were 0.7 and 2.2 servings per week, respectively. Tuna/other fish consumption was associated with younger age, female gender, and higher education, whereas fried fish/fish sandwich consumption was associated with male gender, nonwhite race, and lower education (). Tuna/other fish consumption was generally associated with a more favorable cardiovascular risk profile, although tuna/other fish intake was also associated with higher LDL cholesterol. Tuna/other fish consumption was inversely associated with saturated fat intake and positively associated with intake of alcohol, fruits, vegetables, and cereal fiber; fried fish/fish sandwich consumption was positively associated with intake of saturated fat, beef/pork, and vegetables. As noted previously, in a subsample of participants, greater tuna/other fish intake but not fried fish/fish sandwich intake was associated with higher plasma phospholipid EPA+DHA.
Baseline Characteristics According to Fish Consumption
During 12 years’ follow-up, 980 participants developed incident AF. Of these, 739 persons (75%) were diagnosed by hospital records, 54 (6%) by annual ECG, and 187 (19%) by both methods. presents AF-free survival according to fish consumption. Among persons consuming tuna/other fish ≥5 times per week, AF incidence was 19 per 1000 person-years, compared with 33 per 1000 person-years with intake <1 time per month (P<0.0001). Among persons consuming fried fish/fish sandwich ≥1 time per week, AF incidence was 27 per 1000 person-years, compared with 22 per 1000 person-years with intake <1 time per month (P=0.0009).
AF-free survival according to fish consumption.
Age- and multivariate-adjusted risks are presented in . After adjustment for potential confounders (Model 1), there was 24% lower risk with tuna/other fish intake 1 to 3 times per month (HR=0.76, 95% CI=0.61 to 0.95, P=0.02), 30% lower risk with intake 1 to 4 times per week (HR=0.70, 95% CI=0.57 to 0.87, P=0.001), and 35% lower risk with intake ≥5 times per week (HR=0.65, 95% CI=0.51 to 0.84, P=0.001), compared with <1 time per month (P trend=0.001). Results were not greatly altered by further adjustment for other dietary factors (Model 2) or other potential confounders/mediators (Model 3).
Risk of Incident AF According to Fish Consumption
In contrast, fried fish/fish sandwich consumption was not associated with lower AF risk (). After adjustment for potential confounders (Model 1), intake ≥1 time per week was associated with 24% higher risk (HR=1.24, 95% CI=1.03 to 1.49, P=0.03) compared with <1 time month. This positive association was attenuated by adjustment for other dietary factors (Model 2) and potential confounders/mediators (Model 3). Of potential mediators, adjustment for baseline left ventricular systolic function, treated hypertension, and C-reactive protein levels appeared to have the greatest effect (not shown).
Exclusion of participants taking fish oil supplements (n=183) or with prevalent coronary heart disease, stroke, or transient ischemic attack at baseline (n=1018) did not materially alter results (not shown). There was little evidence for interaction between tuna/other fish and fried fish/fish sandwich consumption (P for interaction >0.05) (). There was also little evidence that findings varied according to age, gender, education, prevalent coronary heart disease, treated hypertension, systolic blood pressure, or study site (P>0.05 for each interaction).
Figure 2 AF incidence according to both tuna/other fish and fried fish/fish sandwich consumption. For groups consuming tuna/other fish ≥1/week, AF cases/numbers at risk were 161/781, 213/1031, and 234/1362 for fried fish/fish sandwich intake ≥1/week, (more ...)
Because AF may occur as a result of preceding MI or CHF, we also evaluated the extent to which observed relationships between fish intake and AF might be mediated by MI or CHF (). After adjustment for MI or CHF as time-varying covariates, relationships between tuna/other fish intake and AF incidence were not greatly altered, with 29% lower risk with consumption 1 to 4 times per week (HR=0.71, 95% CI=0.55 to 0.88, P=0.001) and 31% lower risk with consumption ≥5 times per week (HR=0.69, 95% CI=0.54 to 0.89, P=0.004) compared with <1 time per month (P trend=0.003). Findings were similar among persons without MI or CHF or evaluating only persons with prevalent MI or CHF, although confidence intervals for intake ≥5 times per week included unity due to fewer numbers of events. In similar analyses, relationships between fried fish/fish sandwich intake and AF risk were not greatly altered by adjustment for preceding MI or CHF; however, associations appeared attenuated among persons without MI or CHF ().
Risk of Incident AF According to Fish Consumption, Adjusting for Preceding MI or CHF