Power and sample size calculations for clinical trials of myofascial pain of jaw muscles.
When a clinical trial is planned, the approximate number of subjects needed for significant differences between/among groups to be detected must be estimated. Sample-size calculations provide the investigator with this information. This paper discusses the choice of outcome measures and describes the steps used to estimate the numbers of subjects necessary for a study that compares treatments for patients with chronic myofascial pain of jaw muscles. Within- and between-subject variances were estimated for the chosen variables, the subjects' pain ratings on visual analogue scales. Sample sizes were then calculated for theoretical differences between groups by pre-treatment means and overall standard deviations (Cohen, 1977). The results of this analysis can be used by other researchers when planning studies involving these types of patients.
Dao
T T
TT
Faculté de médecine dentaire, Université de Montréal, Canada.
Lavigne
G J
GJ
Feine
J S
JS
Tanguay
R
R
Lund
J P
JP
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002986:Clinical Trials as Topic / Q000379:methods*; D005157:Facial Pain / Q000175:diagnosis; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000706:statistics & numerical data*; D012107:Research Design; D012494:Sampling Studies; D015983:Selection Bias; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000628:therapy*