Subgroup analysis of large trials can guide further research: A case study of vitamin E and pneumonia

Clinical Epidemiology

Volumn 3, Issue 1, 2011, Pages 51-59

  Hemilä, Harri ^a   Kaprio, Jaakko ^a  

^a UNIVERSITY OF HELSINKI   (Finland)

Author keywords

Tocopherol; Carotene; Leisure time exercise; Pneumonia; Smoking; Subgroup analysis; Vitamin E

Indexed keywords

ALPHA TOCOPHEROL; BETA CAROTENE;

ADULT; AGED; ARTICLE; CANCER CHEMOTHERAPY; CIGARETTE SMOKING; CLINICAL RESEARCH; COMPARATIVE EFFECTIVENESS; CONTROLLED STUDY; DISEASE PREDISPOSITION; DRUG EFFECT; DRUG EFFICACY; EVIDENCE BASED MEDICINE; EXERCISE; FOLLOW UP; HUMAN; LUNG CANCER; MAJOR CLINICAL STUDY; MALE; OUTCOME ASSESSMENT; PLACEBO EFFECT; PNEUMONIA; RANDOMIZED CONTROLLED TRIAL; RISK ASSESSMENT; RISK REDUCTION; VITAMIN SUPPLEMENTATION;

EID: 79952918352     PISSN: None     EISSN: 11791349     Source Type: Journal    
DOI: 10.2147/CLEP.S16114     Document Type: Article

References (25)

1. Assmann SF, Pocock SJ, Enos LE, Kasten LE. Subgroup analysis and other (mis)uses of baseline data in clinical trials. Lancet. 2000; 355:1064-1069.
2. Altman DG. Within trial variation-a false trail? J Clin Epidemiol. 1998;51:301-303.
3. Freemantle N. Interpreting the results of secondary end points and subgroup analyses in clinical trials: should we lock the crazy aunt in the attic? BMJ. 2001;322:989-991.
4. Peto R, Pike MC, Armitage P, et al. Design and analysis of randomized clinical trials requiring prolonged observation of each patient. II. Analysis and examples. Br J Cancer. 1977;35:1-39.
5. Brookes ST, Whitely E, Egger M, Smith GD, Mulheran PA, Peters TJ. Subgroup analyses in randomized trials: risks of subgroup-specific analyses; power and sample size for the interaction test. J Clin Epidemiol. 2004;57:229-236.
6. Hemilä H, Virtamo J, Albanes D, Kaprio J. The effect of vitamin E on common cold incidence is modified by age, smoking, and residential neighborhood. J Am Coll Nutr. 2006;25:332-339.
7. The ATBC Cancer Prevention Study Group. The alpha-tocopherol, beta-carotene lung cancer prevention study: design, methods, participant characteristics, and compliance. Ann Epidemiol. 1994;4:1-10.
8. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study Group. The effect of vitamin E and beta-carotene on the incidence of lung cancer and other cancers in male smokers. N Engl J Med. 1994;330: 1029-1035.
9. Hemilä H, Virtamo J, Albanes D, Kaprio J. Vitamin E and beta-carotene supplementation and hospital-treated pneumonia incidence in male smokers. Chest. 2004;125:557-565.
10. Powers SK, Jackson MJ. Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production. Physiol Rev. 2008; 88:1243-1276.
11. Hemilä H, Kaprio J, Albanes D, Virtamo J. Physical activity and the risk of pneumonia in male smokers administered vitamin E and β-carotene. Int J Sports Med. 2006;27:336-341.
12. Pietinen P, Hartman AM, Haapa E, et al. Reproducibility and validity of dietary assessment instruments: a self-administered food use questionnaire with a portion size picture booklet. Am J Epidemiol. 1988;128: 655-666.
13. Saltin B, Grimby G. Physiological analysis of middle-aged and old former athletes. Circulation. 1968;38:1104-1115.
14. Hemilä H, Kaprio J. Vitamin E supplementation and pneumonia risk in males who initiated smoking at an early age: effect modification by body weight and vitamin C. Nutr J. 2008;7:33.
15. Hemilä H, Kaprio J. Vitamin E supplementation may transiently increase tuberculosis risk in males who smoke heavily and have high dietary vitamin C intake [Discussion: 2009;101:145-147]. Br J Nutr. 2008;100:896-902.
16. Hemilä H, Kaprio J. Modification of the effect of vitamin E supplementation on the mortality of male smokers by age and dietary vitamin C. Am J Epidemiol. 2009;169:946-953.
17. Hemilä H. Vitamin E is likely to affect mortality even at low doses. Clin Trials. 2009;6:392-393.
18. Feinstein AR. The problem of cogent subgroups: a clinicostatistical tragedy. J Clin Epidemiol. 1998;51:297-299.
19. Lagakos SW. The challenge of subgroup analyses-reporting without distorting. N Engl J Med. 2006;354:1667-1669.
20. Rothwell PM. Treating individuals. Subgroup analysis in randomized controlled trials: importance, indications, and interpretation. Lancet. 2005;365:176-186.
21. Bruno RS, Ramakrishnan R, Montine TJ, Bray TM, Traber MG. α-Tocopherol disappearance is faster in cigarette smokers and is inversely related to their ascorbic acid status. Am J Clin Nutr. 2005;81: 95-103.
22. Meydani SN, Leka LS, Fine BC, et al. Vitamin E and respiratory tract infections in elderly nursing home residents: a randomized controlled trial [Discussion: 2004;292:2834]. JAMA. 2004;292:828-836.
23. Graat JM, Schouten EG, Kok FJ. Effect of daily vitamin E and multivitamin- mineral supplementation on acute respiratory tract infections in elderly persons. JAMA. 2002;288:715-721.
24. Hathcock JN, Azzi A, Blumberg J, et al. Vitamins E and C are safe across a broad range of intakes [Discussion: 2005;82:1141-1143]. Am J Clin Nutr. 2005;81:736-745.
25. Vandenbroucke JP. Observational research, randomized trials, and two views of medical science. PLoS Med. 2008;5:e67.