TY - JOUR
T1 - Geographical Variations in Sex Ratio Trends over Time in Multiple Sclerosis
AU - New Zealand MS Prevalence Study Group co-investigators
AU - Trojano, Maria
AU - Lucchese, Guglielmo
AU - Graziano, Giusi
AU - Taylor, Bruce V.
AU - Simpson, Steve
AU - Lepore, Vito
AU - Grand'Maison, Francois
AU - Duquette, Pierre
AU - Izquierdo, Guillermo
AU - Grammond, Pierre
AU - Amato, Maria Pia
AU - Bergamaschi, Roberto
AU - Giuliani, Giorgio
AU - Boz, Cavit
AU - Hupperts, Raymond
AU - Van Pesch, Vincent
AU - Lechner-Scott, Jeannette
AU - Cristiano, Edgardo
AU - Fiol, Marcela
AU - Oreja-Guevara, Celia
AU - Saladino, Maria Laura
AU - Verheul, Freek
AU - Slee, Mark
AU - Paolicelli, Damiano
AU - Tortorella, Carla
AU - D'Onghia, Mariangela
AU - Iaffaldano, Pietro
AU - Direnzo, Vita
AU - Butzkueven, Helmut
AU - Pearson, John F.
AU - Clarke, Glynnis F.
AU - Abernathy, David A.
AU - Mason, Deborah F.
AU - Willoughby, Ernie
AU - Sabel, Clive
PY - 2012/10/25
Y1 - 2012/10/25
N2 - Background: A female/male (F/M) ratio increase over time in multiple sclerosis (MS) patients was demonstrated in many countries around the world. So far, a direct comparison of sex ratio time-trends among MS populations from different geographical areas was not carried out. Objective: In this paper we assessed and compared sex ratio trends, over a 60-year span, in MS populations belonging to different latitudinal areas. Methods: Data of a cohort of 15,996 (F = 11,290; M = 4,706) definite MS with birth years ranging from 1930 to 1989 were extracted from the international MSBase registry and the New Zealand MS database. Gender ratios were calculated by six decades based on year of birth and were adjusted for the F/M born-alive ratio derived from the respective national registries of births. Results: Adjusted sex ratios showed a significant increase from the first to the last decade in the whole MS sample (from 2.35 to 2.73; p = 0.03) and in the subgroups belonging to the areas between 83° N and 45° N (from 1.93 to 4.55; p<0.0001) and between 45° N to 35° N (from 1.46 to 2.30; p<0.05) latitude, while a sex ratio stability over time was found in the subgroup from areas between 12° S and 55° S latitude. The sex ratio increase mainly affected relapsing-remitting (RR) MS. Conclusions: Our results confirm a general sex ratio increase over time in RRMS and also demonstrate a latitudinal gradient of this increase. These findings add useful information for planning case-control studies aimed to explore sex-related factors responsible for MS development.
AB - Background: A female/male (F/M) ratio increase over time in multiple sclerosis (MS) patients was demonstrated in many countries around the world. So far, a direct comparison of sex ratio time-trends among MS populations from different geographical areas was not carried out. Objective: In this paper we assessed and compared sex ratio trends, over a 60-year span, in MS populations belonging to different latitudinal areas. Methods: Data of a cohort of 15,996 (F = 11,290; M = 4,706) definite MS with birth years ranging from 1930 to 1989 were extracted from the international MSBase registry and the New Zealand MS database. Gender ratios were calculated by six decades based on year of birth and were adjusted for the F/M born-alive ratio derived from the respective national registries of births. Results: Adjusted sex ratios showed a significant increase from the first to the last decade in the whole MS sample (from 2.35 to 2.73; p = 0.03) and in the subgroups belonging to the areas between 83° N and 45° N (from 1.93 to 4.55; p<0.0001) and between 45° N to 35° N (from 1.46 to 2.30; p<0.05) latitude, while a sex ratio stability over time was found in the subgroup from areas between 12° S and 55° S latitude. The sex ratio increase mainly affected relapsing-remitting (RR) MS. Conclusions: Our results confirm a general sex ratio increase over time in RRMS and also demonstrate a latitudinal gradient of this increase. These findings add useful information for planning case-control studies aimed to explore sex-related factors responsible for MS development.
UR - http://www.scopus.com/inward/record.url?scp=84868131395&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0048078
DO - 10.1371/journal.pone.0048078
M3 - Article
C2 - 23133550
AN - SCOPUS:84868131395
SN - 1932-6203
VL - 7
JO - PLoS ONE
JF - PLoS ONE
IS - 10
M1 - e48078
ER -