title: Variation in worldwide incidence of amyotrophic lateral sclerosis: a meta-analysis.
abstract: To assess the worldwide variation of amyotrophic lateral sclerosis (ALS) incidence, we performed a systematic review and meta-analysis of population-based data published to date.
  
  
  
  We reviewed Medline and Embase up to June 2015 and included all population-based studies of newly diagnosed ALS cases, using multiple sources for case ascertainment. ALS crude and standardized incidence (on age and sex using the US 2010 population) were calculated. Random effect meta-analysis and meta-regression were performed using the subcontinent as the main study level covariate. Sources of heterogeneity related to the characteristics of the study population and the study methodology were investigated.
  
  
  
  Among 3216 records, 44 studies were selected, covering 45 geographical areas in 11 sub-continents. A total of 13 146 ALS cases and 825 million person-years of follow-up (PYFU) were co-nsidered. The overall pooled worldwide crude ALS incidence was at 1.75 (1.55-1.96)/100 000 PYFU; 1.68 (1.50-1.85)/100 000 PYFU after standardization. Heterogeneity was identified in ALS standardized incidence between North Europe [1.89 (1.46-2.32)/100 000 PYFU] and East Asia [0.83 (0.42-1.24)/100 000 PYFU, China and Japan P = 0.001] or South Asia [0.73 (0.58-0.89)/100 000/PYFU Iran, P = 0.02]. Conversely, homogeneous rates have been reported in populations from Europe, North America and New Zealand [pooled ALS standardized incidence of 1.81 (1.66-1.97)/100 000 PYFU for those areas].
  
  
  
  This review confirms a heterogeneous distribution worldwide of ALS, and sets the scene to sustain a collaborative study involving a wide international consortium to investigate the link between ancestry, environment and ALS incidence.
authors.affiliation: INSERM, U1094, Tropical Neuroepidemiology, Limoges, France.|Univ. Limoges, UMR_S 1094, Tropical Neuroepidemiology, Institute of Neuroepidemiology and Tropical Neurology, CNRS FR 3503 GEIST, F-87000 Limoges, France.|CHU Limoges, Centre d'Epidémiologie de Biostatistique et de Méthodologie de la Recherche, Limoges, France.|Laboratorio di Malattie Neurologiche, IRCCS Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.|Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy.|Unit of Neurodegenerative Diseases, University of Bari 'Aldo Moro', at 'Pia Fondazione Cardinale G. Panico', Lecce, Italy.
authors.forename: Benoît
authors.initials: B
authors.lastname: Marin
authors.affiliation: INSERM, U1094, Tropical Neuroepidemiology, Limoges, France.|Univ. Limoges, UMR_S 1094, Tropical Neuroepidemiology, Institute of Neuroepidemiology and Tropical Neurology, CNRS FR 3503 GEIST, F-87000 Limoges, France.|CHU Limoges, Centre d'Epidémiologie de Biostatistique et de Méthodologie de la Recherche, Limoges, France.
authors.forename: Farid
authors.initials: F
authors.lastname: Boumédiene
authors.affiliation: Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy.|Unit of Neurodegenerative Diseases, University of Bari 'Aldo Moro', at 'Pia Fondazione Cardinale G. Panico', Lecce, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Logroscino
authors.affiliation: INSERM, U1094, Tropical Neuroepidemiology, Limoges, France.|Univ. Limoges, UMR_S 1094, Tropical Neuroepidemiology, Institute of Neuroepidemiology and Tropical Neurology, CNRS FR 3503 GEIST, F-87000 Limoges, France.|CHU Limoges, Service de Neurologie, Limoges, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Couratier
authors.affiliation: INSERM UMR 946, Genetic Variability and Human Diseases, Paris, France.|University Paris Diderot, UMR 946, Paris, France.
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Babron
authors.affiliation: INSERM UMR 946, Genetic Variability and Human Diseases, Paris, France.|University Paris Diderot, UMR 946, Paris, France.
authors.forename: Anne Louise
authors.initials: AL
authors.lastname: Leutenegger
authors.affiliation: Unit of Biostatistics, IRCCS 'Casa Sollievo della Sofferenza', San Giovanni Rotondo, Italy.
authors.forename: Massimilano
authors.initials: M
authors.lastname: Copetti
authors.affiliation: INSERM, U1094, Tropical Neuroepidemiology, Limoges, France.|Univ. Limoges, UMR_S 1094, Tropical Neuroepidemiology, Institute of Neuroepidemiology and Tropical Neurology, CNRS FR 3503 GEIST, F-87000 Limoges, France.|CHU Limoges, Centre d'Epidémiologie de Biostatistique et de Méthodologie de la Recherche, Limoges, France.
authors.forename: Pierre-Marie
authors.initials: PM
authors.lastname: Preux
authors.affiliation: Laboratorio di Malattie Neurologiche, IRCCS Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Beghi
mesh_terms: D000367:Age Factors; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D001208:Asia / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D009520:New Zealand / Q000453:epidemiology; D009656:North America / Q000453:epidemiology; D012737:Sex Factors
keywords: Amyotrophic lateral sclerosis; epidemiology; ethnic groups; incidence