Trends in nested case- control studies as compared to case- control and cohort designs, 1996- 2005

ABSTRACT

This investigation was prompted by the growing importance of nested case-control studies and the increasing frequency with which they are done in epidemiologic research. After a brief explanation of nested case-control studies, we evaluate the trends in research methodology over the last decade, especially with regard to cohort, case-control, and nested case-control designs. Data for this study were extracted from the PubMed database, using these keywords Nested Case-Control, Risk-Set Sampling and Density Sampling. The search was confined to the 10-year period from 1996 to the end of 2005. As for other methodologies, we used keywords Cohort and Case-Control for a search over the same time period. The search itself was performed on April 25, 2006. We found 201 1 articles reporting nested case-control studies. There were 95 such articles in 1996; the number had increased to 289 in 2005. Case-control and cohort designs accounted for 68456 and 60479 articles, respectively. The number of case-control articles rose from 4378 in 1996 to 10270 in 2005, while that of cohort articles increased from 2981 to 9771 over the same period. The number of cohort and nested case-control articles followed similar upward trends over the last decade and their rate of increase was greater than that of simple case-control articles