Association of coffee drinking with total and cause-specific mortality

Abstract

Background: Coffee is one of the most widely consumed beverages, but the association between coffee consumption and the risk of death remains unclear.

Methods: We examined the 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.

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.

Conclusions: In this large prospective study, coffee consumption was inversely associated with total and cause-specific mortality. Whether this was a causal or associational finding cannot be determined from our data. (Funded by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.).

Figure 1. Subgroup Analysis of Associations between the Consumption of 4 or More Cups of Coffee per Day and Total and Cause-Specific Mortality

Hazard ratios for death from all causes and from specific causes are for the comparison of men and women who drank 4 or more cups of coffee per day with those who did not drink coffee. Participants were classified as drinking caffeinated or decaffeinated coffee according to whether they reported drinking caffeinated or decaffeinated coffee more than half the time. Risk estimates for other categories of coffee consumption are shown in Tables 2 and 3 in the Supplementary Appendix. Risk estimates were adjusted for the following factors at baseline: age; body-mass index; race or ethnic group; level of education; alcohol consumption; the number of cigarettes smoked per day, use or non-use 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; diabetes (yes vs. no); marital status; physical activity; total energy intake; consumption of fruits, vegetables, red meat, white meat, and saturated fat; and use or nonuse of vitamin supplements. 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). In women, risk estimates were also adjusted for use or nonuse of postmenopausal hormone therapy. Horizontal lines represent 95% confidence intervals.

Figure 2. Subgroup Analysis of Associations between the Consumption of 4 or More Cups of Coffee per Day and Total Mortality

Hazard ratios for death from any cause are for the comparison of men and women who drank 4 or more cups of coffee per day with those who did not drink coffee. The multivariate model was adjusted for the following factors at baseline: age; body-mass index (BMI; the weight in kilograms divided by the square of the height in meters); 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; diabetes (yes vs. no); marital status; physical activity; total energy intake; consumption of fruits, vegetables, red meat, white meat, and saturated fat; use or nonuse of vitamin supplements; and, in women, use or non-use of postmenopausal hormone therapy. Risk estimates for other categories of coffee consumption are shown in Tables 4 and 5 in the Supplementary Appendix. High and low dietary-intake categories are split at the median. Horizontal lines represent 95% confidence intervals. P values for interactions were computed with the use of likelihood-ratio tests comparing Cox proportional-hazards models with and without cross-product terms for each level of baseline stratifying variables, with coffee consumption as an ordinal variable. P values for the years of follow-up were derived from testing the addition of a cross-product term for follow-up with coffee consumption.