Methods: Two investigators used two hierarchical classification schemes to independently assess 290 articles published in 1996-2009 in the HNI sections of AJR and Radiology. One scheme classified articles by study design using the traditional epidemiological hierarchy; the second by diagnostic efficacy using the criteria presented by Fryback and Thornbury (Med Decis Making, 1991). The country of origin and number of authors were noted.
Results: Among the 202 clinical research studies the distribution in hierarchical order was 19% case reports/case series, 72% cross-sectional, 2% case-control, 5% cohort, and 3% experimental studies. The distribution was not significantly different across time (Fisher's exact test, p=0.10), but was significantly different across geographic regions (p<0.01). Among the 97 diagnostic efficacy studies the distribution in hierarchical order was 3% technical, 87% diagnostic accuracy, 2% diagnostic thinking, 4% therapeutic, and 4% patient outcome efficacy studies. The distribution was not significantly different across time (Fisher's exact test, p=0.14) or geographic regions (p=0.33).
Conclusions: The HNI literature in AJR and Radiology consists mostly of cross-sectional and diagnostic accuracy studies, a trend that did not vary over time. While these types of studies are necessary, they are not sufficient to guide clinical practice or health policy. Studies that are higher on the epidemiological and efficacy hierarchies are needed to provide greater strength of evidence and relevance to patient outcomes, respectively.