Sample sizes of studies on diagnostic accuracy: Literature survey

Lucas M. Bachmann, Milo A. Puhan, Gerben Ter Riet, Patrick M. Bossuyt

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


Objectives: To determine sample sizes in studies on diagnostic accuracy and the proportion of studies that report calculations of sample size. Design: Literature survey. Data sources: All issues of eight leading journals published in 2002. Methods: Sample sizes, number of subgroup analyses, and how often studies reported calculations of sample size were extracted. Results: 43 of 8999 articles were non-screening studies on diagnostic accuracy. The median sample size was 118 (interquartile range 71-350) and the median prevalence of the target condition was 43% (27-61%). The median number of patients with the target condition-needed to calculate a test's sensitivity-was 49 (28-91). The median number of patients without the target condition-needed to determine a test's specificity-was 76 (27-209). Two of the 43 studies (5%) reported a priori calculations of sample size. Twenty articles (47%) reported results for patient subgroups. The number of subgroups ranged from two to 19 (median four). No studies reported that sample size was calculated on the basis of preplanned analyses of subgroups. Conclusion: Few studies on diagnostic accuracy report considerations of sample size. The number of participants in most studies on diagnostic accuracy is probably too small to analyse variability of measures of accuracy across patient subgroups.

Original languageEnglish (US)
Pages (from-to)1127-1129
Number of pages3
JournalBMJ (Online)
Issue number7550
StatePublished - May 13 2006
Externally publishedYes

ASJC Scopus subject areas

  • General Medicine


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