Confounding in association studies: month of birth and multiple sclerosis

Month of Birth and the Incidence of Multiple Sclerosis in Southern Iran

Comment on: Month of birth and risk of multiple sclerosis: confounding and adjustments

We read the latest paper from Torkildsen et al. with great interest and agree with the authors that their data provide a convincing empirical demonstration of the extent to which failing to correct for year and place of birth can generate false-positive associations in studies considering the role of month of birth (MOB) in multiple sclerosis. However, regarding their suggestion that these data...

Month of birth and risk of multiple sclerosis: confounding and adjustments

A month of birth effect on multiple sclerosis (MS) risk has been reported from different countries. Recent critics have suggested that this finding is caused by confounding and that adequately adjusting for year and place of birth would markedly reduce this effect. All inhabitants in Norway are registered in the Norwegian Population Registry (Statistics Norway), making this an ideal area for pe...

Reply to comment: Month of birth and risk of multiple sclerosis: confounding and adjustments

Reply to comment: Month of birth and risk of multiple sclerosis: confounding and adjustments Øivind Torkildsen*, Jan Aarseth, Elisabeth Gulowsen Celius, Trygve Holmøy, Margitta T. Kampman, Kristin Ingeleiv Løken-Amsrud, Rune Midgard, Kjell-Morten Myhr, Trond Riise & Nina Grytten Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norwa...

Confounding Underlies the Apparent Month of Birth Effect in Multiple Sclerosis

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 a...