Coffee, bean, roasted, ext.

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

other: prospective study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

publication

Title:

Association of coffee drinking with total and cause-specific mortality

Year:

2012

Bibliographic source:

The New England Journal of Medicine, 366, 20: 1891-1904

Materials and methods

Study type:

cohort study (prospective)

Endpoint addressed:

other: Total and cause-specific mortality

GLP compliance:

no

Test material

Specific details on test material used for the study:

Caffeinated and decaffeinated coffee

Method

Type of population:

general

Ethical approval:

confirmed and informed consent free of coercion received

Details on study design:

METHOD OF DATA COLLECTION
- Type: Questionnaire
- Details: Between 1995 and 1996, 617,119 American Association of Retired Persons (AARP) members, 50 to 71 years of age, returned a comprehensive questionnaire assessing diet and lifestyle. Participants resided in six states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and two metropolitan areas (Atlanta and Detroit). Of the respondents, 566,401 completed the questionnaire satisfactorily. Completion of the self-administered questionnaire was considered to imply informed consent to participate in the study.

STUDY PERIOD: Participants were followed from baseline (1995–1996) until the date of death or December 31, 2008, whichever came first.

STUDY POPULATION
- Total population (Total no. of persons in cohort from which the subjects were drawn): 566,401
- Selection criteria: questionnaires completed by the person itself (not a spouse or other surrogate correspondent); no cancer, heart disease or stroke history; detailed information on coffee and/or cigarette consumption; subjects with extremely low or high caloric consumption were rejected.
- Total number of subjects participating in study: 402,260
- Sex/age/race: 229,119 men and 173,141 women, 50 to 71 years of age at baseline
- Smoker/nonsmoker: both
- Total number of subjects at end of study: 349,745

HEALTH EFFECTS STUDIED:
Mortality

OTHER DESCRIPTIVE INFORMATION ABOUT STUDY:
Participants completed a baseline questionnaire that assessed demographic and lifestyle characteristics and 124 dietary items. Consumption of fruits, vegetables, red meat, white meat, and saturated fat were adjusted for total energy intake with the use of the nutrient density approach (i.e., measured per 1000 kcal per day for food groups and as a percentage of total energy for saturated fat).
Coffee consumption was assessed according to 10 frequency categories, ranging from 0 to 6 or more cups per day. In addition, 96.5% of coffee drinkers provided information on whether they drank caffeinated or decaffeinated coffee more than half the time, and this was used to categorize coffee drinkers.
Vital status was assessed by periodic linkage of the cohort to the Social Security Administration Death Master File, linkage with cancer registries, questionnaire responses, and responses to other mailings.

Statistical methods:

Hazard ratio sand 95% confidence intervals for mortality associated with coffee consumption were estimated with the use of Cox proportional-hazards regression models, with person-years as the underlying time metric; results calculated with age as the underlying time metric were similar. We tested the proportional-hazards assumption by modeling the interaction of follow-up time with coffee consumption and observed no significant deviations. Analyses were conducted with the use of SAS software, version 9.1. Statistical tests were two-sided, and P values of less than 0.05 were considered to indicate statistical significance.
Multivariate models were adjusted for the following baseline factors: age; body-mass index (BMI); race or ethnic group; level of education; alcohol consumption; the number of cigarettes smoked per day, use or nonuse of pipes or cigars, and time of smoking cessation (<1 year, 1 to <5 years, 5 to <10 years, or =10 years before baseline); health status; presence or absence of diabetes; marital status; level of physical activity; total energy intake; consumption of fruits, vegetables, red meat, white meat, and saturated fat; and use of any vitamin supplement (yes vs. no). In addition, risk estimates for death from cancer were adjusted for history of cancer (other than nonmelanoma skin cancer) in a first-degree relative (yes vs. no). For women, status with respect to postmenopausal hormone therapy was also included in multivariate models.
Hazard ratios for death associated with categories of coffee consumption (<1, 1, 2 or 3, 4 or 5, and =6 cups per day), as compared with no coffee consumption, were estimated from a single model. Tests of linear trend across categories of coffee consumption were performed by assigning participants the midpoint of their coffee-consumption category and entering this new variable into a separate Cox proportional-hazards regression model.

Results and discussion

Results:

During 5,148,760 person-years of follow-up between 1995 and 2008, a total of 33,731 men and 18,784 women died. In age-adjusted models, the risk of death was increased among coffee drinkers. However, coffee drinkers were also more likely to smoke, and, after adjustment for tobacco-smoking status and other potential confounders, there was a significant inverse association between coffee consumption and mortality. Adjusted hazard ratios for death among men who drank coffee as compared with those who did not were as follows: 0.99 (95% confidence interval [CI], 0.95 to 1.04) for drinking less than 1 cup per day, 0.94 (95% CI, 0.90 to 0.99) for 1 cup, 0.90 (95% CI, 0.86 to 0.93) for 2 or 3 cups, 0.88 (95% CI, 0.84 to 0.93) for 4 or 5 cups, and 0.90 (95% CI, 0.85 to 0.96) for 6 or more cups of coffee per day (P<0.001 for trend); the respective hazard ratios among women were 1.01 (95% CI, 0.96 to 1.07), 0.95 (95% CI, 0.90 to 1.01), 0.87 (95% CI, 0.83 to 0.92), 0.84 (95% CI, 0.79 to 0.90), and 0.85 (95% CI, 0.78 to 0.93) (P<0.001 for trend). Inverse associations were observed for deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections, but not for deaths due to cancer. Results were similar in subgroups, including persons who had never smoked and persons who reported very good to excellent health at baseline.

Confounding factors:

Tobacco smoking, consumption of more than three alcoholic drinks per day, consumption of more red meat, less physical activity.

Strengths and weaknesses:

Limitations:
Coffee consumption was assessed by self-report at a single time point and may not reflect long-term patterns of consumption. The distinction between persons who drank caffeinated coffee and those who drank decaffeinated coffee was subject to misclassification, since these categories were defined on the basis of consumption of either beverage more than half the time. Data lacked on how coffee was prepared (espresso, boiled, or filtered), and the constituents of coffee may have differed according to the method of preparation.

Applicant's summary and conclusion

Conclusions:

In a large prospective study, coffee consumption was inversely associated with total and cause-specific mortality.

Executive summary:

A large prospective study examined an association of coffee drinking with subsequent total and cause specific mortality among 229,119 men and 173,141 women in the National Institutes of Health–AARP Diet and Health Study who were 50 to 71 years of age at baseline. Participants with cancer, heart disease, and stroke were excluded. Coffee consumption was assessed once at baseline. During 5,148,760 person-years of follow-up between 1995 and 2008, a total of 33,731 men and 18,784 women died. In age-adjusted models, the risk of death was increased among coffee drinkers. However, coffee drinkers were also more likely to smoke, and, after adjustment for tobacco-smoking status and other potential confounders, there was a significant inverse association between coffee consumption and mortality. Whether this was a causal or associational finding it could not be determined from the data.