To Match or Not to Match in Epidemiological Studies—Same Outcome but Less Power
Abstract
:1. Introduction
2. Methods
2.1. Study Design
2.2 Data Collection
2.3. Questionnaire
2.4. The Matching Techniques
2.5. Statistical Analyses
3. Results
4. Discussion
5. Methodological Considerations
6. Conclusions
References
- Rothman, KJ. Modern Epidemiology; Little Brown and Company: Boston/Toronto, USA/Canada, 1986. [Google Scholar]
- Rothman, KJ. Epidemiology An Introduction, 1st ed; Oxford University Press: New York, NY, USA, 2002. [Google Scholar]
- Dunlay, SM; Weston, SA; Jacobsen, SJ; Roger, VL. Risk factors for heart failure: a population-based case-control study. Am. J. Med 2009, 11, 1023–1028. [Google Scholar]
- Spector, LG; Ross, JA; Puumala, SE; Roesler, M; Olshan, AF; Bunin, GR. Feasibility of nationwide birth registry control selection in the United States. Am. J. Epidemiol 2007, 7, 852–856. [Google Scholar]
- Newton, R; Crouch, S; Ansell, P; Simpson, J; Willett, EV; Smith, A; Burton, C; Jack, A; Romas, E. Hodgkińs lymphoma and infection: findings from a UK case-control study. Br. J. Cancer 2007, 9, 1310–1314. [Google Scholar]
- Arslan, AA; Shore, RE; Afanasyeva, Y; Koenig, KL; Toniolo, P; Zeleniuch-Jacquotte, A. Circulating estrogen metabolites and risk for breast cancer in premenopausal women. Cancer Epidemiol. Biomarkers Prev 2009, 8, 2273–2279. [Google Scholar]
- Mell, LK; Davis, RL; Owens, D. Association between streptococcal infection and obsessive-compulsive disorder, Tourettés syndrome, and tic disorder. Pediatrics 2005, 1, 56–60. [Google Scholar]
- Farhat, MH; Barada, KA; Tawil, AN; Itani, DM; Hatoum, HA; Shamseddine, AI. Effect of mucin production on survival in colorectal cancer: a case-control study. World J. Gastroenterol 2008, 45, 6981–6985. [Google Scholar]
- Faresjö, Å; Foteini, A; Lionis, C; Johansson, S; Wallander, MA; Faresjö, T. Health-related quality of life of irritable bowel syndrome patients in different cultural settings. Health Qual. Life Outcomes 2006, 4, 21. [Google Scholar]
- Faresjö, A; Grodzinsky, W; Johansson, S; Wallander, MA; Timpka, T; Akerlind, I. Psychosocial factors at work and in everyday life are associated with irritable bowel syndrome. Eur. J. Epidemiol 2007, 7, 473–480. [Google Scholar]
- Rosenbaum, PR; Silber, JH. Matching and thick description in an observational study of mortality after surgery. Biostatistics 2001, 2, 217–232. [Google Scholar]
- Garay, KW. The role of matching in epidemiological studies. Am J. Pharm. Edu 2004, 3, 1–7. [Google Scholar]
- Klein-Geltink, JE; Rochon, PA; Dyer, S; Laxer, M; Anderson, GM. Readers should systematically assess methods used to identify, measure and analyze confounding in observational cohort studies. J. Clin. Epidemiol 2007, 8, 766–772. [Google Scholar]
- Klungel, OH; Martens, EP; Patsy, BM; Grobbee, DE; Sullivan, SD; Stricker, BH; Leufkens, HG; de Boer, A. Methods to assess intended effects of drug treatment in observational studies are reviewed. J. Clin. Epidemiol 2004, 12, 1223–1231. [Google Scholar]
- McHorney, CA; Ware, JE, Jr; Raczek, AE. The MOS 36-item short form health survey (SF-36): psychosomatic and clinical tests of validity in measuring physical and mental constructs. Med. Care 1993, 31, 247–263. [Google Scholar]
- Miettinen, OS. Stratification by a multivariate confounder score. Am. J. Epidemiol 1976, 104, 609–620. [Google Scholar]
- Faresjö, A; Grodzinsky, E; Johansson, S; Wallander, MA; Timpka, T; Akerlind, I. A population-based case-control study of work and psychosocial problems in patients with irritable bowel syndrome-women are more seriously affected than men. Am. J. Gastroenterol 2007, 2, 371–379. [Google Scholar]
- Adeyemo, MA; Chang, L. New treatments for irritable bowel syndrome in women. Women Health (London Engl.) 2008, 6, 605–622. [Google Scholar]
- Heitkemper, MM; Jarrett, ME. Update on irritable bowel syndrome and gender differences. Nutr. Clin. Pract 2008, 3, 275–283. [Google Scholar]
IBS cases n = 347 | Matched control group n = 1,041 | All controls n = 2,727 | ||||
---|---|---|---|---|---|---|
n | % | n | % | n | % | |
Sex: Male Female | 96 251 | 27.7 72.3 | 288 753 | 27.7 72.3 | 1,309 1,418 | 48.0 52.0*** |
Age groups: 15 to 24 25 to 44 45 to 64 | 36 147 164 | 10.4 42.4 47.3 | 108 441 492 | 10.4 42.4 47.3 | 428 1,167 1,132 | 15.7 42.8 41.5 |
Civil status: Living alone Married/cohabitant Divorced Widow/widower | 56 258 26 4 | 16.3 75.0 7.6 1.2 | 160 787 65 18 | 15.5 76.4 6.3 1.7 | 528 1,989 153 31 | 19.5 73.6 5.7 1.1 |
Educational level: Primary school (low) Secondary school Upper secondary school University college or university (high) | 57 60 80 146 | 16.6 17.5 23.3 42.6 | 149 200 229 453 | 14.5 19.4 22.2 43.9 | 362 524 701 1,115 | 13.4 19.4 25.9 41.3 |
Female | Male | Total | ||||
---|---|---|---|---|---|---|
SF-36 scale: | IBS cases (n = 251) | Matched controls (n = 753) | IBS cases (n = 96) | Matched controls (n = 288) | IBS cases (n = 347) | Matched controls (n = 1,041) |
Physical functioning | 84.2 (81.6 to 86.4) | 89.0 ** (87.7 to 90.3) | 89.3 (86.1 to 93.0) | 92.1 n.s (90.4 to 94.0) | 86.0 (83.5 to 88.1) | 90.0 *** (89.0 to 91.0) |
Physical role | 71.0 (66.3 to 75.6) | 84.0 *** (81.3 to 86.0) | 82.1 (76.0 to 89.0) | 88.0 n.s (85.0 to 91.1) | 74.1 (70.0 to 78.0) | 85.1 *** (83.0 to 87.0) |
Bodily pain | 68.0 (65.0 to 71.0) | 80.0 *** (78.4 to 81.5) | 74.2 (69.3 to 79.1) | 83.0 ** (80.5 to 85.1) | 69.4 (67.1 to 72.1) | 81.1 *** (79.5 to 82.0) |
General health | 62.0 (59.0 to 65.1) | 75.0 *** (73.4 to 76.4) | 67.4 (63.0 to 72.1) | 75.0 ** (73.0 to 77.2) | 63.5 (61.1 to 66.1) | 75.0 *** (74.1 to 76.2) |
Vitality | 50.0 (47.0 to 53.8) | 62.0 *** (60.0 to 63.2) | 59.0 (54.2 to 63.4) | 66.5 * (64.1 to 69.1) | 52.3 (50.0 to 55.1) | 63.1 *** (62.0 to 64.3) |
Social functioning | 75.1 (72.0 to 78.4) | 87.0 *** (85.0 to 88.1) | 83.0 (77.5 to 87.8) | 89.0 * (86.5 to 91.1) | 77.0 (74.2 to 80.0) | 87.3 *** (86.1 to 89.0) |
Emotional role | 69.5 (65.0 to 75.0) | 84.2 *** (82.0 to 86.3) | 86.0 (76.1 to 90.1) | 87.0 n.s (86.1 to 92.1) | 73.2 (69.1 to 77.2) | 85.4 *** (84.0 to 87.2) |
Mental health | 67.0 (64.3 to 69.5) | 77.0 *** (76.1 to 78.2) | 74.3 (71.1 to 78.1) | 79.0 * (76.4 to 81.0) | 69.0 (67.1 to 71.0) | 77.4 *** (76.4 to 79.0) |
Female | Male | Total | ||||
---|---|---|---|---|---|---|
SF-36 scale: | IBS cases (n = 251) | Un-matched controls (n = 1,418) | IBS cases (n = 96) | Un-matched controls (n = 1,309) | IBS cases (n = 347) | Un-matched controls (n = 2,727) |
Physical functioning | 84.2 (81.6 to 86.4) | 89.7 ** (88.8 to 90.5) | 89.3 (86.1 to 93.0) | 93.0 n.s (92.3 to 94.0) | 86.0 (83.5 to 88.1) | 91.3*** (91.0 to 92.0) |
Physical role | 71.0 (66.3 to 75.6) | 84.0 *** (82.5 to 86.0) | 82.1 (76.0 to 89.0) | 88.1 n.s (87.1 to 90.0) | 74.1 (70.0 to 78.0) | 86.1*** (85.0 to 87.1) |
Bodily pain | 68.0 (65.0 to 71.0) | 80.6 *** (79.5 to 81.7) | 74.2 (69.3 to 79.1) | 84.4*** (83.3 to 85.5) | 69.4 (67.1 to 72.1) | 82.4*** (82.1 to 83.2) |
General health | 62.0 (59.0 to 65.1) | 75.0 *** (74.0 to 76.1) | 67.4 (63.0 to 72.1) | 77.1 *** (76.1 to 78.1) | 63.5 (61.1 to 66.1) | 76.1*** (75.2 to 77.0) |
Vitality | 50.0 (47.0 to 53.8) | 62.0 *** (61.0 to 63.0) | 59.0 (54.2 to 63.3) | 67.2** (66.1 to 68.4) | 52.3 (50.0 to 55.1) | 64.4*** (64.0 to 65.2) |
Social functioning | 75.1 (72.0 to 78.4) | 87.0 *** (86.0 to 88.1) | 83.0 (77.5 to 87.8) | 90.1** (89.0 to 91.0) | 77.0 (74.2 to 80.0) | 88.3*** (87.5 to 89.0) |
Emotional role | 69.5 (65.0 to 75.0) | 83.0 *** (81.1 to 84.5) | 83.0 (76.1 to 90.1) | 87.0 n.s (85.1 to 88.2) | 73.2 (69.1 to 77.2) | 85.0*** (84.0 to 86.0) |
Mental health | 67.0 (64.3 to 69.5) | 76.0 *** (75.1 to 77.0) | 74.3 (71.1 to 78.1) | 79.4** (78.5 to 80.4) | 69.0 (67.0 to 71.0) | 78.0*** (77.0 to78.3) |
© 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
Share and Cite
Faresjö, T.; Faresjö, Å. To Match or Not to Match in Epidemiological Studies—Same Outcome but Less Power. Int. J. Environ. Res. Public Health 2010, 7, 325-332. https://doi.org/10.3390/ijerph7010325
Faresjö T, Faresjö Å. To Match or Not to Match in Epidemiological Studies—Same Outcome but Less Power. International Journal of Environmental Research and Public Health. 2010; 7(1):325-332. https://doi.org/10.3390/ijerph7010325
Chicago/Turabian StyleFaresjö, Tomas, and Åshild Faresjö. 2010. "To Match or Not to Match in Epidemiological Studies—Same Outcome but Less Power" International Journal of Environmental Research and Public Health 7, no. 1: 325-332. https://doi.org/10.3390/ijerph7010325