Jonathan Dykeman

An update on the prevalence of cerebral palsy: a systematic review and meta‐analysis

The aim of this study was to provide a comprehensive update on (1) the overall prevalence of cerebral palsy (CP); (2) the prevalence of CP in relation to birthweight; and (3) the prevalence of CP in relation to gestational age.

The incidence and prevalence of Huntington's disease: A systematic review and meta-analysis†‡§

Huntingtons disease (HD) is a rare, neurodegenerative disorder characterized by chorea, behavioral manifestations, and dementia. The aim of this study was to estimate the incidence and prevalence of HD through a systematic review of the literature. Medline and Embase databases were searched using terms specific to HD as well as studies of incidence, prevalence, and epidemiology. All studies reporting the incidence and/or prevalence of HD were included. Twenty original research articles were included. Eight studies examined incidence, and 17 studies examined prevalence. Meta‐analysis of data from four incidence studies revealed an incidence of 0.38 per 100,000 per year (95% confidence interval [CI]: 0.16, 0.94). Lower incidence was reported in the Asian studies (n = 2), compared to the studies performed in Europe, North America, and Australia (n = 6). The worldwide service‐based prevalence of HD, based on a meta‐analysis (n = 13 studies), was 2.71 per 100,000 (95% CI: 1.55–4.72). Eleven studies were conducted in Europe, North American, and Australia, with an overall prevalence of 5.70 per 100,000 (95% CI: 4.42–7.35). Three studies were conducted in Asia, with an overall prevalence of 0.40 per 100,000 (95% CI: 0.26–0.61). Metaregression revealed a significantly lower prevalence of HD in Asia, compared to European, North American, and Australian populations. HD is a devastating neurodegenerative disorder with a higher prevalence in Europe, North America, and Australia than in Asia. The difference in prevalence of this genetic disorder can be largely explained by huntingtin gene haplotypes.

Incidence and prevalence of multiple sclerosis in Europe: a systematic review.

BackgroundMultiple sclerosis (MS) is the most common cause of neurological disability in young adults worldwide and approximately half of those affected are in Europe. The assessment of differential incidence and prevalence across populations can reveal spatial, temporal and demographic patterns which are important for identifying genetic and environmental factors contributing to MS. However, study methodologies vary and the quality of the methods can influence the estimates. This study aimed to systematically review European studies of incidence and prevalence of MS and to provide a quantitative assessment of their methodological quality.MethodsA comprehensive literature search was performed to obtain all original population-based studies of MS incidence and prevalence in European populations conducted and published between January 1985 and January 2011. Only peer-reviewed full-text articles published in English or French were included. All abstracts were screened for eligibility and two trained reviewers abstracted the data and graded the quality of each study using a tool specifically designed for this study.ResultsThere were 123 studies that met the inclusion criteria. The study estimates were highly heterogeneous, even within regions or countries. Quality was generally higher in the more recent studies, which also tended to use current diagnostic criteria. Prevalence and incidence estimates tended to be higher in the more recent studies and were higher in the Nordic countries and in northern regions of the British Isles. With rare exceptions, prevalence and incidence estimates were higher in women with ratios as high as 3:1. Few studies examined ethnicity. Epidemiological data at the national level was uncommon and there were marked geographical disparities in available data, with large areas of Europe unrepresented and other regions well-represented in the literature. Only 37% of the studies provided standardized estimates.ConclusionsDespite the breadth of the literature on the epidemiology of MS in Europe, inter-study comparisons are hampered by the lack of standardization. Further research should focus on regions not yet studied and the evaluation of ethnic differences in MS prevalence and incidence. National-level studies using current diagnostic criteria, validated case definitions and similar age- and sex-standardization would allow better geographical comparisons.

Systematic review and meta-analysis of standard vs selective temporal lobe epilepsy surgery

Objective: To compare standard anterior temporal lobectomy (ATL) with selective amygdalohippocampectomy (SAH) for postoperative seizure control in temporal lobe epilepsy (TLE). Methods: We searched MEDLINE and Embase using Medical Subject Headings and keywords related to ATL and SAH. We included original research that directly compared seizure outcomes in patients undergoing SAH or ATL for TLE. A fixed-effect model was used to derive a pooled risk ratio (RR) for either an Engel Class I (free of disabling seizures) or a composite of an Engel Class I and II (rare disabling seizures) outcome. Results: Of 4,675 abstracts initially identified by the search, 65 were reviewed as full text. Thirteen studies containing data from 8 countries (5 continents) met our inclusion criteria. Eleven studies comprising 1,203 patients demonstrated that participants were statistically more likely to achieve an Engel Class I outcome after ATL compared with SAH (risk ratio 1.32, 95% confidence interval [CI] 1.12–1.57; p < 0.01). The summary risk difference of 8% (95% CI 3%–14%) translates to a number needed to treat of 13 (95% CI 7–33) for 1 additional patient to achieve an Engel Class I outcome after ATL. The result remained significant when 2 studies that contained fewer than 15 participants in at least 1 arm were excluded and in analyses restricted to hippocampal sclerosis. Conclusions: Standard ATL confers an improved chance of achieving freedom from disabling seizures in patients with TLE. Improved seizure freedom must be balanced against the neuropsychological impact of each procedure. A randomized controlled trial is justified.

A systematic review and meta-analysis on the epidemiology of Duchenne and Becker muscular dystrophy.

The muscular dystrophies are a broad group of hereditary muscle diseases with variable severity. Population-based prevalence estimates have been reported but pooled estimates are not available. We performed a systematic review of worldwide population-based studies reporting muscular dystrophies prevalence and/or incidence using MEDLINE and EMBASE databases. The search strategy included key terms related to muscular dystrophies, incidence, prevalence and epidemiology. Two reviewers independently reviewed all abstracts, full text articles and abstracted data using standardized forms. Pooling of prevalence estimates was performed using random effect models. 1104 abstracts and 167 full text articles were reviewed. Thirty-one studies met all eligibility criteria and were included in the final analysis. The studies differed widely in their approaches to case ascertainment, resulting in significant methodological heterogeneity and varied data quality. The pooled prevalence of DMD and BMD was 4.78 (95% CI 1.94-11.81) and 1.53 (95% CI 0.26-8.94) per 100,000 males respectively. The incidence of DMD ranged from 10.71 to 27.78 per 100,000. This is the first meta-analysis of worldwide prevalence estimates for muscular dystrophies. There is a need for more epidemiological studies addressing global estimates on incidence and prevalence of muscular dystrophies, utilizing standardized diagnostic criteria as well as multiple sources of case ascertainment.

Depression in epilepsy: A systematic review and meta-analysis

Objective: To estimate the prevalence of depression in persons with epilepsy (PWE) and the strength of association between these 2 conditions. Methods: The MEDLINE (1948–2012), EMBASE (1980–2012), and PsycINFO (1806–2012) databases, reference lists of retrieved articles, and conference abstracts were searched. Content experts were also consulted. Two independent reviewers screened abstracts and extracted data. For inclusion, studies were population-based, original research, and reported on epilepsy and depression. Estimates of depression prevalence among PWE and of the association between epilepsy and depression (estimated with reported odds ratios [ORs]) are provided. Results: Of 7,106 abstracts screened, 23 articles reported on 14 unique data sources. Nine studies reported on 29,891 PWE who had an overall prevalence of active (current or past-year) depression of 23.1% (95% confidence interval [CI] 20.6%–28.31%). Five of the 14 studies reported on 1,217,024 participants with an overall OR of active depression of 2.77 (95% CI 2.09–3.67) in PWE. For lifetime depression, 4 studies reported on 5,454 PWE, with an overall prevalence of 13.0% (95% CI 5.1–33.1), and 3 studies reported on 4,195 participants with an overall OR of 2.20 (95% CI 1.07–4.51) for PWE. Conclusions: Epilepsy was significantly associated with depression and depression was observed to be highly prevalent in PWE. These findings highlight the importance of proper identification and management of depression in PWE.

Incidence and Prevalence of Multiple Sclerosis in the Americas: A Systematic Review

Background: The incidence and prevalence of multiple sclerosis (MS) varies considerably around the world. No previous study has performed a comprehensive review examining the incidence and prevalence of MS across the Americas. The purpose of this study was to systematically review and assess the quality of studies estimating the incidence and/or prevalence of MS in North, Central and South American regions. Methods: A comprehensive literature search was performed using MEDLINE and EMBASE from January 1985 to January 2011. Search terms included ‘multiple sclerosis’, ‘incidence’, ‘prevalence’ and ‘epidemiology’. Only full-text articles published in English or French were included. Study quality was assessed using an assessment tool based on recognized guidelines and designed specifically for this study. Results: A total of 3,925 studies were initially identified, with 31 meeting the inclusion criteria. The majority of studies examined North American regions (n = 25). Heterogeneity was high among all studies, even when stratified by country. Only half of the studies reported standardized rates, making comparisons difficult. Quality scores ranged from 3/8 to 8/8. Conclusion: This review highlights the gaps that still exist in the epidemiological knowledge of MS in the Americas, and the inconsistencies in methodologies and quality among the published studies. There is a need for future studies of MS prevalence and incidence to include uniform case definitions, employ comparable methods of ascertainment, report standardized results, and be performed on a national level. Other factors such as sex distribution, ethnic make-up and population lifestyle habits should also be considered.

The prevalence of primary dystonia: a systematic review and meta-analysis.

Dystonia is a hyperkinetic movement disorder characterized by sustained muscle contractions that produce repetitive movements and abnormal postures. Specific information on the prevalence of dystonia has been difficult to establish because the existing epidemiological studies of the condition have adopted different methodologies for case ascertainment, resulting in widely differing reported prevalence. Medline and Embase databases were searched using terms specific to dystonia for studies of incidence, prevalence, and epidemiology. All population‐based studies reporting an incidence and/or prevalence of primary dystonia were included. Sixteen original studies were included in our systematic review. Fifteen studies reported the prevalence of dystonia, including 12 service‐based and three population‐based studies. We performed a meta‐analysis on the results of the service‐based studies, and were able to combine data on the prevalence of several dystonia subtypes. From these studies, we calculated an overall prevalence of primary dystonia of 16.43 per 100,000 (95% confidence interval [CI]: 12.09–22.32). The prevalence of dystonia reported in the three population‐based studies appears higher than that reported in the service‐based studies. Only 1 of the 16 studies reported an incidence of cervical dystonia. This corresponded to a corrected incidence estimate of 1.07 per 100,000 person‐years (95% CI: 0.86–1.32). Despite numerous studies on the epidemiology of dystonia, attempting to determine an accurate prevalence of the condition for health services planning remains a significant challenge. Given the methodological limitations of the existing studies, our own prevalence estimate of primary dystonia likely underestimates the true prevalence of the condition.

Prevalence and incidence of epilepsy A systematic review and meta-analysis of international studies

Objective: To review population-based studies of the prevalence and incidence of epilepsy worldwide and use meta-analytic techniques to explore factors that may explain heterogeneity between estimates. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards were followed. We searched MEDLINE and EMBASE for articles published on the prevalence or incidence of epilepsy since 1985. Abstract, full-text review, and data abstraction were conducted in duplicate. Meta-analyses and meta-regressions were used to explore the association between prevalence or incidence, age group, sex, country level income, and study quality. Results: A total of 222 studies were included (197 on prevalence, 48 on incidence). The point prevalence of active epilepsy was 6.38 per 1,000 persons (95% confidence interval [95% CI] 5.57–7.30), while the lifetime prevalence was 7.60 per 1,000 persons (95% CI 6.17–9.38). The annual cumulative incidence of epilepsy was 67.77 per 100,000 persons (95% CI 56.69–81.03) while the incidence rate was 61.44 per 100,000 person-years (95% CI 50.75–74.38). The prevalence of epilepsy did not differ by age group, sex, or study quality. The active annual period prevalence, lifetime prevalence, and incidence rate of epilepsy were higher in low to middle income countries. Epilepsies of unknown etiology and those with generalized seizures had the highest prevalence. Conclusions: This study provides a comprehensive synthesis of the prevalence and incidence of epilepsy from published international studies and offers insight into factors that contribute to heterogeneity between estimates. Significant gaps (e.g., lack of incidence studies, stratification by age groups) were identified. Standardized reporting of future epidemiologic studies of epilepsy is needed.

Cumulative Incidence of Second Intestinal Resection in Crohn's Disease: A Systematic Review and Meta-Analysis of Population-Based Studies

OBJECTIVES:Approximately 50% of Crohn’s disease patients undergo an intestinal resection within 10 years of diagnosis. The risk of second surgery in Crohn’s disease and the influence of time are not well characterized. We performed a systematic review and meta-analysis to establish the risk of second abdominal surgery in patients with Crohn’s disease among patients who had a previous surgery.METHODS:We searched Medline, EMBASE, PubMed (March 2014), and conference proceedings for terms related to Crohn’s disease and intestinal surgery. We included population-based articles (n=11) and an abstract (n=1) reporting surgical risk for the overall study period and for 5 and 10 years after the first surgery for Crohn’s disease. We stratified studies by year (start year before vs. after 1980) to explore the role of time.RESULTS:For all population-based studies, the overall risk of second surgery was 28.7% (95% confidence interval (CI): 22.6–36.6%). The 5-year risk of second surgery was 24.2% (95% CI: 22.3–26.4%). The 10-year risk of second surgery was 35.0% (95% CI: 31.8–38.6%). A significant difference in the 10-year risk of second surgery was observed over time such that studies conducted after 1980 had a lower risk of second surgery (33.2%; 95% CI: 31.2–35.4%) compared with those that started before 1980 (44.6%; 95% CI: 37.7–52.7%).CONCLUSIONS:Approximately one-quarter of Crohn’s disease patients who have a first surgery also have a second, and the majority of these surgeries occur within 5 years of the first surgery. The 10-year risk of second surgery is significantly decreasing over time.