A simple sample size formula for analysis of covariance in randomized clinical trials

Journal of Clinical Epidemiology

Volumn 60, Issue 12, 2007, Pages 1234-1238

  Borm, George F ^a   Fransen, Jaap ^a   Lemmens, Wim A J G ^a  

^a RADBOUD UNIVERSITY MEDICAL CENTER   (Netherlands)

Author keywords

Analysis of covariance; Clinical trial; Power; Precision; Sample size; Statistical test

Indexed keywords

LEFLUNOMIDE; PLACEBO; SALAZOSULFAPYRIDINE;

ACCURACY; ANALYSIS OF COVARIANCE; ARTICLE; CALCULATION; CLINICAL TRIAL; CONFIDENCE INTERVAL; CORRELATION ANALYSIS; DATA ANALYSIS; DISEASE ACTIVITY; FOLLOW UP; HUMAN; PRIORITY JOURNAL; RHEUMATOID ARTHRITIS; SAMPLE SIZE; SIMULATION; STUDENT T TEST;

ANALYSIS OF VARIANCE; ANTIRHEUMATIC AGENTS; ARTHRITIS, RHEUMATOID; DRUG THERAPY, COMBINATION; HUMANS; ISOXAZOLES; RANDOMIZED CONTROLLED TRIALS AS TOPIC; RESEARCH DESIGN; SAMPLE SIZE; SULFASALAZINE; TREATMENT OUTCOME;

EID: 35948987547     PISSN: 08954356     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.jclinepi.2007.02.006     Document Type: Article

References (16)

1. Vickers A.J., and Altman D.G. Statistics notes: analysing controlled trials with baseline and follow up measurements. BMJ 323 (2001) 1123-1124
2. Venter A., Maxwell S.E., and Bolig E. Power in randomized group comparisons: the value of adding a single intermediate time point to a traditional pretest-posttest design. Psychol Methods 7 (2002) 194-209
3. Van Breukelen G.J. ANCOVA versus change from baseline had more power in randomized studies and more bias in nonrandomized studies. J Clin Epidemiol 59 (2006) 920-925
4. Armitage P., and Berry G. Statistical methods in medical research. 3rd edition (1994), Blackwell Science, Oxford
5. Dougados M., Emery P., Lemmel E.M., Zerbini C.A., Brin S., and Van Riel P. When a DMARD fails, should patients switch to sulfasalazine or add sulfasalazine to continuing leflunomide?. Ann Rheum Dis 64 (2005) 44-51
6. Prevoo M.L.L., Van 't Hof M.A., Kuper H.H., Van Leeuwen M.A., Vande Putte L.B., and Van Riel P.L. Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum 38 (1995) 44-48
7. Van Gestel A.M., Haagsma C.J., and Van Riel P.L.C.M. Validation of rheumatoid arthritis improvement criteria that include simplified joint counts. Arthritis Rheum 41 (1998) 1845-1850
8. VandePutte L.B., Atkins C., Malaise M., Sany J., Russell A.S., Van Riel P.L., et al. Efficacy and safety of adalimumab as monotherapy in patients with rheumatoid arthritis for whom previous disease modifying antirheumatic drug treatment has failed. Ann Rheum Dis 63 (2004) 508-516
9. Welsing P.M., and Van Riel P.L. The Nijmegen inception cohort of early rheumatoid arthritis. J Rheumatol Suppl 69 (2004) 14-21
10. Hernandez A.V., Steyerberg E.W., and Habbema D.F. Covariate adjustment in randomized controlled trials with dichotomous outcomes increases statistical power and reduces sample size requirements. J Clin Epidemiol 57 (2004) 454-460
11. Hernandez A.V., Eijkemans M.J.C., and Steyerberg E.W. Randomized controlled trials with time-to-event outcomes: how much does prespecified covariate adjustment increase power?. Ann Epidemiol 16 (2006) 41-48
12. Twisk J., and Proper K. Evaluation of the results of a randomized controlled trial: how to define changes between baseline and follow-up. J Clin Epidemiol 57 (2004) 223-228
13. European Agency for the Evaluation of Medicinal products (EMEA), Committee for Proprietary Medicinal Products (CPMP). Points to consider on adjustment for baseline covariates (2001), EMEA, London
14. Raab G.M., Day S., and Sales J. How to select covariates to include in the analysis of a clinical trial. Control Clin Trials 21 (2000) 330-342
15. Bland J.M. Sample size in guidelines trials. Fam Pract 17 Suppl 1 (2000) S17-S20
16. Mood A.M., Graybill F.A., and Boes D.C. Introduction to the theory of statistics (1974), McGraw-Hill, London 167 p.