[Use of multilevel models in health research].
OBJECTIVE
The aim of this study was to analyze the use of multilevel methodology in health sciences.


METHODS
A literature search was performed in Medline for articles published between 1995 and 2001. Fifteen search words were used, some of which were "multilevel model", "multilevel analysis", "hierarchical linear model", "mixed model", and "random effects model". A total of 1288 abstracts were retrieved. Two hundred twenty-two of the articles on theoretical and/or applied issues related to multilevel methods were examined to determine their current use, the type of model, the number of levels, the units of analysis and the outcome variables related to health sciences.


RESULTS
66.7% of the articles studied was found with the keywords: "multilevel analysis", "multilevel modelling" and "multilevel model". Fifty-six percent of the articles were multilevel applications in different health sciences. However, in 10% of the articles, the main objective was to present and disseminate the methodology in a language comprehensible to non-specialists.


CONCLUSIONS
The use of multilevel modelling in health has increased with time and is being applied in different health areas and specialties. However, it is still not considered a commonly used technique.
Catalán-Reyes
M J
MJ
Departamento de Estadística, Instituto de Matemáticas y Física, Universidad de Valparaíso, Chile. monica.catalan@uv.cl
Galindo-Villardón
M P
MP
D035843:Biomedical Research / Q000379:methods*; D015233:Models, Statistical