Observational studies: practical tips for avoiding common statistical pitfalls.

This Personal View is intended for early-career researchers who are not yet experts in statistics. The Personal View focuses on common but usually avoidable flaws in the context of observational studies. I point out how study design, data collection, and statistical methods impact statistical results and research conclusions.

Short-Term Nitrogen Dioxide Exposure and Emergency Hospital Admissions for Asthma in Children: A Case-Crossover Analysis in England.

Background: There is an increasing body of evidence associating short-term ambient nitrogen dioxide (NO) exposure with asthma-related hospital admissions in children. However, most studies have relied on temporally resolved exposure information, potentially ignoring the spatial variability of NO. We aimed to investigate how daily NO estimates from a highly resolved spatio-temporal model are associated with the risk of emergency hospital admission for asthma in children in England.

Association between work characteristics and epigenetic age acceleration: cross-sectional results from UK - Understanding Society study.

Occupation-related stress and work characteristics are possible determinants of social inequalities in epigenetic aging but have been little investigated. Here, we investigate the association of several work characteristics with epigenetic age acceleration (AA) biomarkers. The study population included employed and unemployed men and women ( = 631) from the UK Understanding Society study.

Work-related stress and well-being in association with epigenetic age acceleration: A Northern Finland Birth Cohort 1966 Study.

Recent evidence indicates consistent association of low socioeconomic status with epigenetic age acceleration, measured from DNA methylation. As work characteristics and job stressors are crucial components of socioeconomic status, we investigated their association with various measures of epigenetic age acceleration. The study population included employed and unemployed men and women (n=604) from the Northern Finland Birth Cohort 1966.

A Novel Sample Selection Approach to Aid the Identification of Factors That Correlate With the Control of HIV-1 Infection.

Individuals infected with HIV display varying rates of viral control and disease progression, with a small percentage of individuals being able to spontaneously control infection in the absence of treatment. In attempting to define the correlates associated with natural protection against HIV, extreme heterogeneity in the datasets generated from systems methodologies can be further complicated by the inherent variability encountered at the population, individual, cellular and molecular levels. Furthermore, such studies have been limited by the paucity of well-characterised samples and linked epidemiological data, including duration of infection and clinical outcomes.

Development and transferability of ultrafine particle land use regression models in London.

Due to a lack of routine monitoring, bespoke measurements are required to develop ultrafine particle (UFP) land use regression (LUR) models, which is especially challenging in megacities due to their large area. As an alternative, for London, we developed separate models for three urban residential areas, models combining two areas, and models using all three areas. Models were developed against annual mean ultrafine particle count cm estimated from repeated 30-min fixed-site measurements, in different seasons (2016-2018), at forty sites per area, that were subsequently temporally adjusted using continuous measurements from a single reference site within or close to each area.

A spatial joint analysis of metal constituents of ambient particulate matter and mortality in England.

Few studies have investigated associations between metal components of particulate matter on mortality due to well-known issues of multicollinearity. Here, we analyze these exposures jointly to evaluate their associations with mortality on small area data. We fit a Bayesian profile regression (BPR) to account for the multicollinearity in the elemental components (iron, copper, and zinc) of PM and PM The models are developed in relation to mortality from cardiovascular and respiratory disease and lung cancer incidence in 2008-2011 at a small area level, for a population of 13.

Temporal trends and demographic risk factors for hospital admissions due to carbon monoxide poisoning in England.

Unintentional non-fire related (UNFR) carbon monoxide (CO) poisoning is a preventable cause of morbidity and mortality. Epidemiological data on UNFR CO poisoning can help monitor changes in the magnitude of this burden, particularly through comparisons of multiple countries, and to identify vulnerable sub-groups of the population which may be more at risk. Here, we collected data on age- and sex- specific number of hospital admissions with a primary diagnosis of UNFR CO poisoning in England (2002-2016), aggregated to small areas, alongside area-level characteristics (i.

Electric field and air ion exposures near high voltage overhead power lines and adult cancers: a case control study across England and Wales.

Background: Various mechanisms have been postulated to explain how electric fields emitted by high voltage overhead power lines, and the charged ions they produce, might be associated with possible adult cancer risk, but this has not previously been systematically explored in large scale epidemiological research.

Methods: We investigated risks of adult cancers in relation to modelled air ion density (per cm3) within 600 m (focusing analysis on mouth, lung, respiratory), and calculated electric field within 25 m (focusing analysis on non-melanoma skin), of high voltage overhead power lines in England and Wales, 1974-2008.

Results: With adjustment for age, sex, deprivation and rurality, odds ratios (OR) in the highest fifth of net air ion density (0.

Childhood type 1 diabetes: an environment-wide association study across England.

Aims/hypothesis: Type 1 diabetes is an autoimmune disease affecting ~400,000 people across the UK. It is likely that environmental factors trigger the disease process in genetically susceptible individuals. We assessed the associations between a wide range of environmental factors and childhood type 1 diabetes incidence in England, using an agnostic, ecological environment-wide association study (EnWAS) approach, to generate hypotheses about environmental triggers.

Risk of respiratory hospital admission associated with modelled concentrations of Aspergillus fumigatus from composting facilities in England.

Bioaerosols have been associated with adverse respiratory-related health effects and are emitted in elevated concentrations from composting facilities. We used modelled Aspergillus fumigatus concentrations, a good indicator for bioaerosol emissions, to assess associations with respiratory-related hospital admissions. Mean daily Aspergillus fumigatus concentrations were estimated for each composting site for first full year of permit issue from 2005 onwards to 2014 for Census Output Areas (COAs) within 4 km of 76 composting facilities in England, as previously described (Williams et al.

Associations between metal constituents of ambient particulate matter and mortality in England: an ecological study.

Objectives: To investigate long-term associations between metal components of particulate matter (PM) and mortality and lung cancer incidence.

Design: Small area (ecological) study.

Setting: Population living in all wards (~9000 individuals per ward) in the London and Oxford area of England, comprising 13.

Birth weight centiles and small for gestational age by sex and ethnicity for England and Wales.

Objectives: To construct UK ethnicity birth weight centiles (UK-EBWC) for gestational age and cut-offs for small for gestational age (SGA) for England and Wales and to evaluate the SGA misclassification using the UK centiles.

Design: Analysis of national birth data.

Participants: All live singleton births in England and Wales in 2006-2012, as recorded by the Office for National Statistics and birth registrations, linked with National Health Service into numbers for babies.

Fetal growth, stillbirth, infant mortality and other birth outcomes near UK municipal waste incinerators; retrospective population based cohort and case-control study.

Background: Some studies have reported associations between municipal waste incinerator (MWI) exposures and adverse birth outcomes but there are few studies of modern MWIs operating to current European Union (EU) Industrial Emissions Directive standards.

Methods: Associations between modelled ground-level particulate matter ≤10 μm in diameter (PM) from MWI emissions (as a proxy for MWI emissions) within 10 km of each MWI, and selected birth and infant mortality outcomes were examined for all 22 MWIs operating in Great Britain 2003-10. We also investigated associations with proximity of residence to a MWI.

A note on intrinsic conditional autoregressive models for disconnected graphs.

In this note we discuss (Gaussian) intrinsic conditional autoregressive (CAR) models for disconnected graphs, with the aim of providing practical guidelines for how these models should be defined, scaled and implemented. We show how these suggestions can be implemented in two examples, on disease mapping.

Birth weight trends in England and Wales (1986-2012): babies are getting heavier.

Introduction: Birth weight is a strong predictor of infant mortality, morbidity and later disease risk. Previous work from the 1980s indicated a shift in the UK towards heavier births; this descriptive analysis looks at more recent trends.

Methods: Office for National Statistics (ONS) registration data on 17.

Estimating Particulate Exposure from Modern Municipal Waste Incinerators in Great Britain.

Municipal Waste Incineration (MWI) is regulated through the European Union Directive on Industrial Emissions (IED), but there is ongoing public concern regarding potential hazards to health. Using dispersion modeling, we estimated spatial variability in PM concentrations arising from MWIs at postcodes (average 12 households) within 10 km of MWIs in Great Britain (GB) in 2003-2010. We also investigated change points in PM emissions in relation to introduction of EU Waste Incineration Directive (EU-WID) (subsequently transposed into IED) and correlations of PM with SO, NOx, heavy metals, polychlorinated dibenzo-p-dioxins/furan (PCDD/F), polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions.

[The perception of the relationship between environment and health according to data from Italian Behavioural Risk Factor Surveillance System (PASSI)].

Unlabelled: "OBJECTIVES: to identify groups of people in relation to the perception of environmental risk and to assess the main characteristics using data collected in the environmental module of the surveillance network Italian Behavioral Risk Factor Surveillance System (PASSI).

Methods: perceptive profiles were identified using a latent class analysis; later they were included as outcome in multinomial logistic regression models to assess the association between environmental risk perception and demographic, health, socio-economic and behavioural variables.

Results: the latent class analysis allowed to split the sample in "worried", "indifferent", and "positive" people.

Asthmatic symptoms and air pollution: a panel study on children living in the Italian Po Valley.

The Po Valley (Northern Italy) has elevated levels of air-pollution due to various sources of pollution and adverse weather conditions. This study evaluates the short-term effects of exposure to particulate matter with a diameter of 10 microns or less (PM10) on asthma symptoms in school-aged children. An initial cross-sectional survey was conducted in the area to estimate asthma prevalence in children.

Air pollution from incinerators and reproductive outcomes: a multisite study.

Background: The few studies that have investigated the relationship between emissions from municipal solid-waste incinerators and adverse pregnancy outcomes have had conflicting results. We conducted a study to assess the effects of air emissions from the eight incinerators currently in operation in the Emilia-Romagna Region of Italy on reproductive outcomes (sex ratio, multiple births, preterm births, and small for gestational age [SGA] births).

Methods: We considered all births (n = 21,517) to women residing within a 4-km radius of an incinerator at the time of delivery during the period 2003-2010 who were successfully linked to the Delivery Certificate database.

Volume reduction of cystic lesions after surgical decompression: a computerised three-dimensional computed tomographic evaluation.

Objectives: This study was performed to evaluate the three-dimensional radiographic variation in mandibular odontogenic cystic lesions after decompression.

Materials And Methods: Pre- and post-decompression computed tomography (CT) evaluations in 20 patients affected by keratocysts (n = 10), dentigerous cysts (n = 9) and ameloblastoma (n = 1) were analysed using software designed for three-dimensional measurement of volumes; the results were correlated with treatment duration, age, sex and histological type.

Results: The mean (range) decompression time was 5.

Prospective evaluation of ultrasound and biochemical-based multivariable models for the prediction of late pre-eclampsia.

Objective: Prospective assignment at 11 + 0 to 13 + 6  weeks of risk for late pre-eclampsia (PE) using eight logistic regression-based statistical models.

Methods: Five hundred and fifty-four pregnancies. Uterine artery pulsatility index, parity, body mass index, mean arterial pressure, pregnancy-associated plasma protein-A, free β-human chorionic gonadotrophin and maternal age, were combined to obtain 'a posteriori risk of PE'.