Non-parametric analysis of seasonality in birth and multiple sclerosis risk in second generation of migrants in Kuwait.

Saeed Akhtar,Yasser Ayad,Ahmad Al-Shammari,Raed Alroughani,Jarrah Al-Abkal

doi:10.1186/s12883-014-0170-7

Abstract

BackgroundThere are inconsistent reports about multiple sclerosis (MS) risk among migrants from low to high MS risk geographical regions. This study assessed the overall MS incidence and evaluated seasonality in birth and subsequent MS risk later in the life in second generation of migrants born and lived in Kuwait.MethodsWe assessed the overall and gender-specific MS risk in second generation of migrants born and lived in Kuwait between January 1, 1950 and April 30, 2013. Data on migrants’ MS patients diagnosed and registered in Kuwait National MS Registry were used. Hewitt’s non-parametric test was carried out to evaluate the seasonality in migrants’ MS births in comparison with the second generation migrants’ births in general population.ResultsDuring the study period, an overall risk of migrants’ MS births (per 100,000 non-Kuwaiti births in general population) was 23.8 (95% CI: 20.8 – 27.0). Gender-specific MS risk showed that non-Kuwaiti female had statistically significant (p = 0.003) higher risk (28.6; 95% CI: 24.2 – 33.7) than non-Kuwaiti males (18.7; 95% CI: 15.1–23.0). The month-specific distribution of migrants’ MS births compared with migrants’ births in general population did not differ significantly (χ2 goodness-of-fit test statistic = 9.51, p = 0.575). Hewitt’s non-parametric test revealed an evidence of slight but statistically non-significant (p = 0.090) increased tendency of migrants’ MS births during September through February.ConclusionsThe proportion of migrants’ MS births (per 100,000 migrants’ births in general population) over the study period was 23.8 (95% CI: 20.8 – 27.0), which was statistically significantly higher than the previously reported Kuwaiti national MS births (16.2; 95% CI: 15.1–17.4) in Kuwait. Non-parametric analysis showed slight but statistically non-significant increased tendency of migrants’ MS births from September through February. Knowledge of MS risk factors and how and when they act among genetically vulnerable individuals from gestation to early adulthood will help design prevention strategies.

Highlights

There are inconsistent reports about multiple sclerosis (MS) risk among migrants from low to high MS risk geographical regions
Non-nationals born in Kuwait had an overall risk of MS births as 23.8
Gender-specific risk of MS births showed nonKuwaiti female had statistically significant (p = 0.003) increased risk (28.6; 95% confidence interval (CI): 24.2 – 33.7) than non-Kuwaiti males (18.7; 95% CI: 15.1–23.0) (Table 1)

Summary

Introduction

There are inconsistent reports about multiple sclerosis (MS) risk among migrants from low to high MS risk geographical regions. The contribution of each factor in MS etiology may vary in different geographic areas resulting into atypical spatial patterns of its incidence across the globe [2]. Studies on migratory populations have indicated that the MS risk among those migrating from a high to a low risk area exceeds that of the population into which they have immigrated. Children of Asian and West Indian immigrants born in England and Wales had MS prevalence similar to that in the general population of England and Wales [11,12]

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Conclusion