Maternal Coffee and Alcohol Consumption During Pregnancy and Childhood Leukemia Risk

1. Journal Club Alcohol and Health: Current Evidence May-June 2006 www.alcoholandhealth.org

2. Featured Article Maternal coffee and alcohol consumption during pregnancy, parental smoking and risk of childhood acute leukemia Menegaux F, et al. Cancer Detect and Prev. 2005;29:487–493. www.alcoholandhealth.org

3. Study Objective To examine the association between… • alcohol use, coffee drinking, and smoking during pregnancy and • childhood acute lymphoid leukemia (ALL) and acute nonlymphoid leukemia (ANLL) www.alcoholandhealth.org

4. Study Design • Case-control study of children hospitalized with… • newly diagnosed acute leukemia (n=280) or • for a disease other than cancer/birth defect (n=288) • All subjects from the same hospitals; controls mainly from orthopedic departments • Interviews of mothers that covered alcohol use during pregnancy and other topics (e.g., medical history) • Analyses adjusted for potential confounders www.alcoholandhealth.org

5. Assessing Validity of an Article About Harm • Are the results valid? • What are the results? • How can I apply the results to patient care? www.alcoholandhealth.org

6. 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? www.alcoholandhealth.org

7. Did the investigators demonstrate similarity in all known determinants of outcomes? Did they adjust for differences in the analysis? • Cases and controls were compared on demographic factors (they were similar). • Analyses were adjusted for these factors while examining effects of alcohol use, smoking, and coffee drinking separately. • Other risk factors for leukemia were not reported. www.alcoholandhealth.org

8. Were exposed patients equally likely to be identified in the two groups? • Researchers described use of standardized questionnaires and similar interviewing conditions for both groups. • But, recall bias may have made identifying the exposure more likely in mothers of children with leukemia. • When asked about exposures during pregnancy, a mother with a child with newly diagnosed leukemia may be more likely to recall the exposures than would a mother of a child with an acute injury. www.alcoholandhealth.org

9. Were the outcomes measured in the same way in the groups being compared? • Cases and controls were drawn from the same hospitals. www.alcoholandhealth.org

10. Was follow-up sufficiently complete? • There was no follow-up. • This was a retrospective case-control study. www.alcoholandhealth.org

11. What are the Results? • How strong is the association between exposure and outcomes? • How precise is the estimate of the risk? www.alcoholandhealth.org

12. How strong is the association between exposure and outcomes? *Compared with no useand in analyses adjusted for age, sex, hospital, and ethnicity www.alcoholandhealth.org

13. How strong is the association between exposure and outcome? (cont.) • Results did not differ when analyses were adjusted for… • any of the substances examined, • profession, • education, • early infection history, • breast-feeding, • maternal history of fetal loss, or • familial history of cancer. www.alcoholandhealth.org

14. How precise is the estimate of the risk? • Confidence intervals: • for any alcohol use and ALL: 1.4–3.0 • for any alcohol use and ANLL: 1.2–5.8 • for drinking 4–8 cups of coffee per day and ALL: 1.3–4.7 • These intervals do not include 1, indicating statistical significance. • However, they are wide, particularly in the cases of alcohol and ANLL and coffee and ALL. www.alcoholandhealth.org

15. 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? www.alcoholandhealth.org

16. Were the study patients similar to the patients in my practice? • The children were identified in 4 hospitals in France. • How they might differ from other children with leukemia, aside from geography, is not known. • Most of the children were Caucasian. www.alcoholandhealth.org

17. Was the duration of follow-up adequate? • There was no follow-up. • Children with leukemia were younger than controls. Although unlikely, it is possible that… • results might have been different if follow-up (time since pregnancy and prenatal exposure) had been similar. www.alcoholandhealth.org

18. What was the magnitude of the risk? • The risk of leukemia was 2–3 times greater for children of women who… • drank alcohol or 4–8 cups of coffee per day during pregnancy. www.alcoholandhealth.org

19. Should I attempt to stop the exposure? • Pregnant women should not drink alcohol. • This recommendation is primarily because of the risk of fetal alcohol effects and syndrome. • Leukemia may represent an additional, but rarer, risk of alcohol consumption. www.alcoholandhealth.org

20. Should I attempt to stop the exposure (cont.)? • Both the alcohol and coffee findings should be considered hypothesis generating. • This study alone should not determine choices around coffee consumption. • Data are sparse in this area, and further study is needed. www.alcoholandhealth.org