BACKGROUND AND OBJECTIVES: Guidelines for conducting studies and reading medical literature on diagnostic tests have been published: Requirements for the selection of cases and controls, and for ensuring a correct reference standard are now clarified. Our objective was to provide tables for sample size determination in this context. STUDY DESIGN AND SETTING: In the usual situation, where the prevalence Prev of the disease of interest is <0.50, one first determines the minimal number Ncases of cases required to ensure a given precision of the sensitivity estimate. Computations are based on the binomial distribution, for user-specified type I and type II error levels. The minimal number N(controls) of controls is then derived so as to allow for representativeness of the study population, according to Ncontrols=Ncases [(1-Prev)/Prev]. RESULTS: Tables give the values of Ncases corresponding to expected sensitivities from 0.60 to 0.99, acceptable lower 95% confidence limits from 0.50 to 0.98, and 5% probability of the estimated lower confidence limit being lower than the acceptable level. CONCLUSION: When designing diagnostic test studies, sample size calculations should be performed in order to guarantee the design accuracy.
BACKGROUND AND OBJECTIVES: Guidelines for conducting studies and reading medical literature on diagnostic tests have been published: Requirements for the selection of cases and controls, and for ensuring a correct reference standard are now clarified. Our objective was to provide tables for sample size determination in this context. STUDY DESIGN AND SETTING: In the usual situation, where the prevalence Prev of the disease of interest is <0.50, one first determines the minimal number Ncases of cases required to ensure a given precision of the sensitivity estimate. Computations are based on the binomial distribution, for user-specified type I and type II error levels. The minimal number N(controls) of controls is then derived so as to allow for representativeness of the study population, according to Ncontrols=Ncases [(1-Prev)/Prev]. RESULTS: Tables give the values of Ncases corresponding to expected sensitivities from 0.60 to 0.99, acceptable lower 95% confidence limits from 0.50 to 0.98, and 5% probability of the estimated lower confidence limit being lower than the acceptable level. CONCLUSION: When designing diagnostic test studies, sample size calculations should be performed in order to guarantee the design accuracy.
Authors: Wesley H Self; Richard G Wunderink; Derek J Williams; Tyler W Barrett; Adrienne H Baughman; Carlos G Grijalva Journal: Acad Emerg Med Date: 2015-05-20 Impact factor: 3.451
Authors: Andrea S Gershon; Chengning Wang; Jun Guan; Jovonka Vasilevska-Ristovska; Lisa Cicutto; Teresa To Journal: Can Respir J Date: 2009 Nov-Dec Impact factor: 2.409