Global epidemiology of amyotrophic lateral sclerosis: a systematic review of the published literature

Abstract

Background: Amyotrophic lateral sclerosis (ALS) is relatively rare, yet the economic and social burden is substantial. Having accurate incidence and prevalence estimates would facilitate efficient allocation of healthcare resources.

Objective: To provide a comprehensive and critical review of the epidemiological literature on ALS.

Methods: MEDLINE and EMBASE (1995-2011) databases of population-based studies on ALS incidence and prevalence reporting quantitative data were analyzed. Data extracted included study location and time, design and data sources, case ascertainment methods and incidence and/or prevalence rates. Medians and interquartile ranges (IQRs) were calculated, and ALS case estimates were derived using 2010 population estimates.

Results: In all, 37 articles met the inclusion criteria. In Europe, the median incidence rate (/100,000 population) was 2.08 (IQR 1.47-2.43), corresponding to an estimated 15,355 (10,852-17,938) cases. Median prevalence (/100,000 population) was 5.40 (IQR 4.06-7.89), or 39,863 (29,971-58,244) prevalent cases.

Conclusions: Disparity in rates among ALS incidence and prevalence studies may be due to differences in study design or true variations in population demographics such as age and geography, including environmental factors and genetic predisposition. Additional large-scale studies that use standardized case ascertainment methods are needed to more accurately assess the true global burden of ALS.

Copyright © 2013 S. Karger AG, Basel.

Figures

Fig. 1

Flow diagram. I/P = incident/prevalence.

Fig. 2

Country-specific crude incidence rate of ALS. *Logroscino et al. [49] not included in this figure (latest year of data collection during study); †Rates are adjusted.

Fig. 3

Country-specific crude prevalence rate of ALS. Text inside bars represents point prevalence estimate date.

Fig. 4

Summary statistics for all studies and by region. *Lighter shaded areas indicate the lowest and highest reported rate; darker shaded area represent the inter-quartile (IQ) range.

Fig. 5

Temporal trends in incidence and prevalence. Panel A does not include 2 study outliers: Govoni et al. (1964–1998; 34 years) [38] and Sorenson et al. (1925–1998; 74 years) [46].

Fig. 6

Age-related trends in incidence and prevalence.

Fig. 7

Distribution of age cohorts evaluated for peaked ALS incidence rates. n = number of studies reporting for the cohort.