Common errors in statistics and methods.

As statistical reviewers and editors for BMJ Paediatrics Open (BMJPO), we frequently see methodological and statistical errors in articles submitted to our journal. To make a list of these common errors and propose suitable corrections, and inspired by similar efforts at other leading journals, we surveyed the statistical reviewers and editors at BMJPO to collect their 'pet peeves' and examples of best practices.(1, 2) We have divided these into seven sections: graphics; statistical significance and related issues; presentation, vocabulary, textual and tabular presentation; causality; model building, regression and choice of methods; meta-analysis; and miscellaneous.

Effect of a Low-Calorie Dietary Intervention on Liver Health and Body Weight in Adults with Metabolic-Dysfunction Associated Steatotic Liver Disease (MASLD) and Overweight/Obesity: A Systematic Review and Meta-Analysis.

Introduction: Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD) is a common cause of chronic liver disease. This review assessed the efficacy of a Low-Calorie Diet (LCD) on liver health and body weight in people living with MASLD and obesity.

Methods: The study was registered with PROSPERO (CRD42021296501), and a literature search was conducted using multiple databases.

Corrector therapies (with or without potentiators) for people with cystic fibrosis with class II CFTR gene variants (most commonly F508del).

Background: Cystic fibrosis (CF) is a common life-shortening genetic condition caused by a variant in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. A class II CFTR variant F508del is the commonest CF-causing variant (found in up to 90% of people with CF (pwCF)). The F508del variant lacks meaningful CFTR function - faulty protein is degraded before reaching the cell membrane, where it needs to be to effect transepithelial salt transport.

Prebiotics for people with cystic fibrosis.

Background: Cystic fibrosis (CF) is a multisystem disease; the importance of growth and nutritional status is well established given their implications for lung function and overall survivability. Furthermore, it has been established that intestinal microbial imbalance and inflammation are present in people with CF. Oral prebiotics are commercially available substrates that are selectively utilised by host intestinal micro-organisms and may improve both intestinal and overall health.

Prognosis of adults and children following a first unprovoked seizure.

Background: Epilepsy is clinically defined as two or more unprovoked epileptic seizures more than 24 hours apart. Given that, a diagnosis of epilepsy can be associated with significant morbidity and mortality, it is imperative that clinicians (and people with seizures and their relatives) have access to accurate and reliable prognostic estimates, to guide clinical practice on the risks of developing further unprovoked seizures (and by definition, a diagnosis of epilepsy) following single unprovoked epileptic seizure.

Objectives: 1.

Hydroxyurea (hydroxycarbamide) for sickle cell disease.

Background: Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and a reduced life expectancy. Hydroxyurea (hydroxycarbamide), an oral chemotherapeutic drug, ameliorates some of the clinical problems of SCD, in particular that of pain, by raising foetal haemoglobin (HbF).

Physical activity and exercise training in cystic fibrosis.

Background: Physical activity (including exercise) may form an important part of regular care for people with cystic fibrosis (CF). This is an update of a previously published review.

Objectives: To assess the effects of physical activity interventions on exercise capacity by peak oxygen uptake, lung function by forced expiratory volume in one second (FEV), health-related quality of life (HRQoL) and further important patient-relevant outcomes in people with cystic fibrosis (CF).

Statistical methods used to combine the effective reproduction number, [Formula: see text], and other related measures of COVID-19 in the UK.

In the recent COVID-19 pandemic, a wide range of epidemiological modelling approaches were used to predict the effective reproduction number, R(t), and other COVID-19-related measures such as the daily rate of exponential growth, r(t). These candidate models use different modelling approaches or differing assumptions about spatial or age-mixing, and some capture genuine uncertainty in scientific understanding of disease dynamics. Combining estimates using appropriate statistical methodology from multiple candidate models is important to better understand the variation of these outcome measures to help inform decision-making.

Antiepileptic drug monotherapy for epilepsy: a network meta-analysis of individual participant data.

Background: This is an updated version of the original Cochrane Review published in 2017. Epilepsy is a common neurological condition with a worldwide prevalence of around 1%. Approximately 60% to 70% of people with epilepsy will achieve a longer-term remission from seizures, and most achieve that remission shortly after starting antiepileptic drug treatment.

Interventions to prevent spontaneous preterm birth in women with singleton pregnancy who are at high risk: systematic review and network meta-analysis.

Objectives: To compare the efficacy of bed rest, cervical cerclage (McDonald, Shirodkar, or unspecified type of cerclage), cervical pessary, fish oils or omega fatty acids, nutritional supplements (zinc), progesterone (intramuscular, oral, or vaginal), prophylactic antibiotics, prophylactic tocolytics, combinations of interventions, placebo or no treatment (control) to prevent spontaneous preterm birth in women with a singleton pregnancy and a history of spontaneous preterm birth or short cervical length.

Design: Systematic review with bayesian network meta-analysis.

Data Sources: The Cochrane Pregnancy and Childbirth Group's Database of Trials, the Cochrane Central Register of Controlled Trials, Medline, Embase, CINAHL, relevant journals, conference proceedings, and registries of ongoing trials.

Cochrane systematic review and meta-analysis of the impact of psychological treatment on health-related quality of life in people with epilepsy: an update by the ILAE Psychology Task Force, highlighting methodological changes.

Clinical interest in using psychological interventions for people with epilepsy (PWE) aiming at decreasing mental health difficulties, improving health-related quality of life (HRQOL) and seizure-related outcomes, continues to grow. This article summarizes the 2020 update of the 2017 Cochrane Review and meta-analysis of psychological interventions for PWE, highlighting the reasons for major methodological modifications such as the recategorization of interventions and expanded risk of bias assessment. A 2020 literature search yielded 36 RCTs (n=3526) investigating psychological treatments for PWE with a validated HRQOL measure as an outcome.

Practical Considerations and Challenges When Conducting an Individual Participant Data (IPD) Meta-Analysis.

This chapter provides a broad overview of the use of individual participant (sometimes referred to as patient) data (IPD ) within meta-analyses, the associated advantages of using IPD in meta-analysis compared to aggregate data, and when IPD should be used in meta-analysis.This chapter also outlines the steps of conducting an IPD meta-analysis, with practical guidance relating to requesting and obtaining IPD for meta-analysis. Challenges that can be associated with conducting an IPD meta-analysis are also discussed, including consideration of availability bias, when a subset of the relevant IPD is not available for meta-analysis.

Treatments for seizures in catamenial (menstrual-related) epilepsy.

Background: This is an updated version of a Cochrane Review previously published in 2019. Catamenial epilepsy describes worsening seizures in relation to the menstrual cycle and may affect around 40% of women with epilepsy. Vulnerable days of the menstrual cycle for seizures are perimenstrually (C1 pattern), at ovulation (C2 pattern), and during the luteal phase (C3 pattern).

Ectopic fat deposition in populations of black African ancestry: A systematic review and meta-analysis.

Aims: In populations of black African ancestry (BA), a paradox exists whereby lower visceral adipose tissue is found despite their high risk for type 2 diabetes (T2D). This systematic review investigates ethnic differences in other ectopic fat depots (intrahepatic lipid: IHL; intramyocellular lipid: IMCL and intrapancreatic lipid; IPL) to help contextualise their potential contribution to T2D risk.

Methods: A systematic literature search was performed in December 2020 to identify studies reporting at least one ectopic fat comparison between BA and one/more other ethnicity.

Prophylactic drug management for febrile seizures in children.

Background: Febrile seizures occurring in a child older than one month during an episode of fever affect 2-4% of children in Great Britain and the United States and recur in 30%. Rapid-acting antiepileptics and antipyretics given during subsequent fever episodes have been used to avoid the adverse effects of continuous antiepileptic drugs. This is an updated version of a Cochrane Review previously published in 2017.

Immediate antiepileptic drug treatment, versus placebo, deferred, or no treatment for first unprovoked seizure.

Background: This is an updated version of the Cochrane review previously published in 2016. There is considerable disagreement about the risk of recurrence following a first unprovoked epileptic seizure. A decision about whether to start antiepileptic drug treatment following a first seizure should be informed by information on the size of any reduction in risk of future seizures, the impact on long-term seizure remission, and the risk of adverse effects.

Transcranial magnetic stimulation for the treatment of epilepsy.

Background: Epilepsy is a highly prevalent neurological condition characterised by repeated unprovoked seizures with various aetiologies. Although antiepileptic medications produce clinical improvement in many individuals, nearly a third of individuals have drug-resistant epilepsy that carries significant morbidity and mortality, and even individuals who have clinical improvement from antiepileptic medications often report iatrogenic symptoms. There remains a need for non-invasive and more effective therapies for this population.

Efficacy and safety of pharmacological, physical, and psychological interventions for the management of chronic pain in children: a WHO systematic review and meta-analysis.

Chronic pain in childhood is an international public health problem. We conducted a systematic review and meta-analysis to provide a summary of the published evidence of pharmacological, physical, and psychological therapies for children with chronic pain conditions. We searched CENTRAL, MEDLINE, EMBASE, and PsycINFO from inception to April 2020; clinical trial registries; and other sources for randomised controlled trials or comparative observational trials.

Antidepressants for people with epilepsy and depression.

Background: Depressive disorders are the most common psychiatric comorbidity in people with epilepsy, affecting around one-third, with a significant negative impact on quality of life. There is concern that people may not be receiving appropriate treatment for their depression because of uncertainty regarding which antidepressant or class works best, and the perceived risk of exacerbating seizures. This review aimed to address these issues, and inform clinical practice and future research.

Corrector therapies (with or without potentiators) for people with cystic fibrosis with class II CFTR gene variants (most commonly F508del).

Background: Cystic fibrosis (CF) is a common life-shortening genetic condition caused by a variant in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. A class II CFTR variant F508del (found in up to 90% of people with CF (pwCF)) is the commonest CF-causing variant. The faulty protein is degraded before reaching the cell membrane, where it needs to be to effect transepithelial salt transport.

Psychological treatments for people with epilepsy.

Background: Given the significant impact epilepsy may have on the health-related quality of life (HRQOL) of individuals with epilepsy and their families, there is increasing clinical interest in evidence-based psychological treatments, aimed at enhancing psychological and seizure-related outcomes for this group. This is an updated version of the original Cochrane Review published in Issue 10, 2017.

Objectives: To assess the impact of psychological treatments for people with epilepsy on HRQOL outcomes.

Levetiracetam add-on for drug-resistant focal epilepsy.

Background: Drug resistance is common in focal epilepsy. In this update, we summarised the current evidence regarding add-on levetiracetam in treating drug-resistant focal epilepsy. The original review was published in 2001 and last updated in 2012.

Inhaled mannitol for cystic fibrosis.

Background: Several agents are used to clear secretions from the airways of people with cystic fibrosis. Mannitol increases mucociliary clearance, but its exact mechanism of action is unknown. The dry powder formulation of mannitol may be more convenient and easier to use compared with established agents which require delivery via a nebuliser.

Antiepileptic drugs as prophylaxis for postcraniotomy seizures.

Background: This is an updated version of the Cochrane Review previously published in 2018. The incidence of seizures following supratentorial craniotomy for non-traumatic pathology has been estimated to be between 15% to 20%; however, the risk of experiencing a seizure appears to vary from 3% to 92% over a five-year period. Postoperative seizures can precipitate the development of epilepsy; seizures are most likely to occur within the first month of cranial surgery.