Confounding underlies the apparent month of birth effect in multiple sclerosis.

ABSTRACT:

Objective

Several groups have reported apparent association between month of birth and multiple sclerosis. We sought to test the extent to which such studies might be confounded by extraneous variables such as year and place of birth.

Methods

Using national birth statistics from 2 continents, we assessed the evidence for seasonal variations in birth rate and tested the extent to which these are subject to regional and temporal variation. We then established the age and regional origin distribution for a typical multiple sclerosis case collection and determined the false-positive rate expected when comparing such a collection with birth rates estimated by averaging population-specific national statistics.

Results

We confirm that seasonality in birth rate is ubiquitous

SUBMITTER: Fiddes B 

PROVIDER: S-EPMC3748787 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature