June 2007

Objective To describe and analyse the reporting of methodology relating to reliability in caries epidemiological studies conducted in the Nordic countries between 1990 and 2001. Basic research design. Basic research design Literature searches were conducted in the Medline database, and reference lists of all obtained publications were scrutinised for additional studies. Publications fulfilling the inclusion criteria were assessed for study design, and methodological aspects relating to reliability were assessed according to recommendations for evidence-based medicine (EBM). The frequency of endorsement of the assessed items was analysed. Moreover, the type and strength of evidence was evaluated. Main outcome measures Reporting of predetermined methodological items relating to reliability and the frequency of endorsement of the assessed items were of primary interest. Results Initially, 724 publications were located in the literature searches. Of 133 eligible publications obtained, 32 fulfilled the inclusion criteria and remained throughout the analyses. The majority of the studies reported the reliability methodology, which was generally inadequate. The frequencies of endorsement ranged from 0% to 69 %. All publications contributed to a low strength of evidence. In this context, it was proposed that prospective longitudinal studies with a random sample selection be classified as type-2 (2b) level of evidence. Conclusion There seems to be a need to improve the reporting and the methodology relating to reliability in caries epidemiological publications. Reporting of random sample selection and at least two of the items assessed seems to discriminate between high and low quality with respect to the reported methodology relating to reliability. Key words: dental caries, dentistry, epidemiology, evidence-based medicine, public health, reliability, validity