Journal Club

Alcohol, Other Drugs, and Health: Current Evidence May–June 2011 1

Featured Article

Association of Alcohol Intake With Pancreatic Cancer Mortality in Never Smokers

Gapstur SM, et al. Arch Intern Med. 2011;171(5):444–451.

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Study Objective

• To examine the relationship between alcohol consumption and pancreatic cancer and to assess whether the association varied by beverage type or as a result of tobacco smoking.

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Study Design

• Analysis of cancer mortality data from the Cancer Prevention Study II, a prospective study of 1,030,467 US adults aged ≥30 years followed from 1982–2006.

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Assessing Validity of an Article About Harm

• Are the results valid?

• What are the results?

• How can I apply the results to patient care?

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Are the Results Valid?

• Did the investigators demonstrate similarity in all known determinants of outcomes? Did they adjust for differences in the analysis?

• Were exposed patients equally likely to be identified in the two groups?

• Were the outcomes measured in the same way in the groups being compared?

• Was follow-up sufficiently complete?

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Did the investigators demonstrate similarity in all known determinants of outcomes? Did they adjust for differences in the analysis?

• Yes.

– Multivariable-adjusted relative risks (RRs) and 95% confidence intervals (CIs) were computed using Cox proportional hazards regression analysis controlling for age, sex, race/ethnicity, education, marital status, body mass index, family history of pancreatic cancer, and personal history of gallstones, diabetes mellitus, or smoking.

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Were exposed patients equally likely to be identified in the groups?

 Yes.

– All participants completed a baseline survey including the question, “How many cups, glasses, or drinks of these beverages do you usually drink a day, and for how many years?” Intake amounts of beer, wine, and liquor were assessed separately.

– Participants who wrote “0” or left the alcohol consumption section blank* were classified as nondrinkers.

– Participants who did not provide interpretable alcohol-intake information, who reported past but not current alcohol intake, or who reported implausibly high alcohol intake (≥30 drinks per day) were excluded from this analysis.

*A total of 394,032 participants left the alcohol section blank.

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Were the outcomes measured in the same way in the groups being compared?

 Yes.

− Mortality outcomes were assessed via personal inquiry from 1982–1988 then through linkage to the National Death Registry through 2006.

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Was follow-up sufficiently complete?

• Yes.

– Death certificates and cause-of-death codes were obtained for >99% of known deaths in the sample.

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What are the Results?

• How strong is the association between exposure and outcomes?

• How precise is the estimate of the risk?

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How strong is the association between exposure and outcome? How precise is the estimate of the risk?

Drinks per Day No. of Deaths Beer Only Relative Risk (95% CI) No. of Deaths Wine Only Relative Risk (95% CI) No. of Deaths Liquor Only Relative Risk (95% CI) Never Smokers*

Nondrinker Occasional 1 ≥2

Ever Smokers†

Nondrinker Occasional 1 ≥2

Total Cohort†

Nondrinker Occasional 1 ≥2 ≥3 1792 59 19 25 1789 172 60 177 3581 231 79 77 125 1.00 (reference) 1.03 (0.79–1.33) 0.91 (0.58–1.44) 1.09 (0.73–1.63) 1.00 (reference) 1.02 (0.87–1.20) 0.86 (0.66–1.11) 1.08 (0.92–1.26) 1.00 (reference) 1.02 (0.89–1.17) 0.87 (0.70–1.09) 1.08 (0.86–1.35) 1.08 (0.90–1.30) 1792 131 41 24 1789 155 58 65 3581 286 99 50 39 1.00 (reference) 1.01 (0.84–1.21) 1.05 (0.77–1.44) 0.94 (0.63–1.40) 1.00 (reference) 1.03 (0.87–1.22) 0.90 (0.69–1.18) 0.98 (0.76–1.26) 1.00 (reference) 1.02 (0.90–1.15) 0.96 (0.79–1.18) 0.91 (0.68–1.20) 1.09 (0.79–1.49) 1792 76 23 41 1789 191 104 247 3581 267 127 156 132 1.00 (reference) 1.20 (0.96–1.52) 0.87 (0.58–1.32) 1.47 (1.08–2.01) 1.00 (reference) 0.97 (0.84–1.13) 0.94 (0.77–1.15) 1.18 (1.03–1.35) 1.00 (reference) 1.03 (0.91–1.17) 0.94 (0.78–1.12) 1.15 (0.98–1.35) 1.32 (1.10–1.57) *Adjusted for age, sex, race/ethnicity, education, marital status, body mass index, family history of pancreatic cancer, and history of gallstones or diabetes mellitus. †Adjusted for age, sex, race/ethnicity, education, marital status, body mass index, family history of pancreatic cancer, and history of gallstones, diabetes mellitus, or smoking.

How Can I Apply the Results to Patient Care?

• Were the study patients similar to the patients in my practice?

• Was the duration of follow-up adequate?

• What was the magnitude of the risk?

• Should I attempt to stop the exposure?

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Were the study patients similar to the patients in my practice?

• The sample included 576,697 women and 453,770 men aged ≥30 years from across the US and including the District of Columbia and Puerto Rico.

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Was the duration of follow-up adequate?

• Follow-up was 14 years.

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What was the magnitude of the risk?

• Never smokers had a 36% higher risk of pancreatic cancer mortality associated with consumption of 3 or more drinks per day (largely confined to those who drank liquor) compared with nondrinkers.

• Ever smokers had a 16% higher risk after adjustment for smoking history and other covariates.

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Should I attempt to stop the exposure?

• Patients should be counseled that consumption of 3 or more drinks per day of liquor is associated with an increased risk of pancreatic cancer compared to not consuming alcohol.

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