Stephen Bremner

Association between ambient air pollution and birth weight in São Paulo, Brazil

Objectives: Previous studies have implicated air pollution in increased mortality and morbidity, especially in the elderly population and children. More recently, associations with mortality in infants and with some reproductive outcomes have also been reported. The aim of this study is to explore the association between exposure to outdoor air pollution during pregnancy and birth weight. Design: Cross sectional study using data on all singleton full term live births during a one year period. For each individual birth, information on gestational age, type of delivery, birth weight, sex, maternal education, maternal age, place of residence, and parity was available. Daily mean levels of PM10, sulphur dioxide, nitrogen dioxide, carbon monoxide, and ozone were also gathered. The association between birth weight and air pollution was assessed in regression models with exposure averaged over each trimester of pregnancy. Setting: São Paulo city, Brazil. Results: Birth weight was shown to be associated with length of gestation, maternal age and instruction, infant gender, number of antenatal care visits, parity, and type of delivery. On adjusting for these variables negative effects of exposure to PM10 and carbon monoxide during the first trimester were observed. This effect seemed to be more robust for carbon monoxide. For a 1 ppm increase in mean exposure to carbon monoxide during the first trimester a reduction of 23 g in birth weight was estimated. Conclusions: The results are consistent in revealing that exposure to air pollution during pregnancy may interfere with weight gain in the fetus. Given the poorer outlook for low birthweight babies on a number of health outcomes, this finding is important from the public health perspective.

Particulate matter and daily mortality and hospital admissions in the west midlands conurbation of the United Kingdom: associations with fine and coarse particles, black smoke and sulphate

OBJECTIVES There is considerable evidence linking ambient particles measured as particulate matter with aerodynamic diameter <10 μm (PM10) to daily mortality and hospital admissions but it is not clear which physical or chemical components of the particle mixture are responsible. The relative effects of fine particles (PM2.5), coarse particles (PM2.5–10), black smoke (mainly fine particles of primary origin) and sulphate (mainly fine particles of secondary origin) were investigated, together with ozone, SO2, NO2, and CO, on daily mortality and hospital admissions in the west Midlands conurbation of the United Kingdom. METHODS Time series of health outcome and environmental data were obtained for the period 1994–6. The relative risk of death or hospital admission was estimated with regression techniques, controlling for long term time trends, seasonal patterns, influenza epidemics, effects of day of the week, and temperature and humidity. Models were adjusted for any remaining residual serial correlation and overdispersion. The sensitivities of the estimates for the effects of pollution to the inclusion of a second pollutant and seasonal interactions (warm or cool) were also examined. RESULTS Daily all cause mortality was not associated with any gaseous or particulate air pollutant in the all year analysis, although all measures of particles apart from PM2.5–10 showed significant positive effects of the warm season. Neither respiratory nor cardiovascular admissions (all ages) were associated with any air pollutant, and there were no important seasonal interactions. However, analysis of admissions by age found evidence for various associations—notably between PM10, PM2.5, black smoke, SO2, and ozone (negative) and respiratory admissions in the 0–14 age group. The coarse fraction, PM2.5-10 differed from PM2.5in having smaller and less consistent associations (including several large significant negative associations) and a different lag distribution. The results for black smoke, an indicator of fine primary carbonaceous particles, were very similar to those for PM2.5, and tended to be more robust in two pollutant models. The effects of sulphate, an indicator of secondary particles, also showed some similarities to those of PM2.5. CONCLUSIONS Clear effects of air pollution on mortality and hospital admissions were difficult to discern except in certain age or diagnostic subgroups and seasonal analyses. It was also difficult to distinguish between different measures of particles. Within these limitations the results suggest that the active component of PM10 resides mostly in the fine fraction and that this is due mainly to primary particles from combustion (mainly vehicle) sources with a contribution from secondary particles. Effects of the coarse fraction cannot be excluded.

Short-Term Associations between Emergency Hospital Admissions for Respiratory and Cardiovascular Disease and Outdoor Air Pollution in London

There are concerns about the possible short-term effects of outdoor air pollution on health in the United Kingdom. In a study conducted during the time period between 1987 and 1992, investigators determined that ozone had small, but significant effects on emergency respiratory admissions. In the current study, the authors investigated associations between emergency admissions and outdoor air pollution for the time period from 1992 to 1994, inclusive, and compared the results with those obtained in the earlier study. The authors also examined particulate matter less than 10 microm in diameter (PM10) and carbon monoxide in the current study. Appropriate confounding factors, such as seasonal patterns, temperature, and humidity, were controlled for, and the authors used Poisson regression to estimate the association between daily emergency admissions for respiratory and cardiovascular diseases and ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, particles measured as Black Smoke, and PM10. Significant positive associations were found between emergency hospital admissions for respiratory disease and PM10 and sulfur dioxide, but such an association did not exist for ozone. The results were not significantly different from earlier results from London and were comparable with those determined in North America and Europe. Cardiovascular disease was associated with carbon monoxide and Black Smoke, but weaker associations existed with the other pollutants studied.

Evolution of statin prescribing 1994–2001: a case of agism but not of sexism?

Objective: To study trends in the use of lipid lowering drugs in the UK, and to assess which patient factors influence prescribing. Methods: Routinely collected computerised medical data were analysed from 142 general practices across England and Wales that provide data for the Doctors’ Independent Network database. Subjects included were people aged 35 years or more with treated ischaemic heart disease, averaging annually over 30 000. The temporal trend from 1994 to 2001 in prescription of lipid lowering drugs and daily statin dose and the odds ratios (ORs) for receiving a statin prescription in 1998 were examined. Results: Lipid lowering drug prescribing increased greatly over time, entirely because of statins, so that in 2001 56.3% of men and 41.1% of women with ischaemic heart disease received lipid lowering drugs. However, 33% of these patients were on a < 20 mg simvastatin daily equivalent. In 1998 the OR for receiving a statin fell from 1 at age 55–64 to 0.64 at 65–74 and 0.16 at 75–84 years. The age effect was similar in those without major comorbidity. Revascularised patients were much more likely to receive a statin than those with angina (OR 3.92, 95% confidence interval (CI) 3.57 to 4.31). Men were more likely to receive a statin than women (OR 1.62, 95% CI 1.54 to 1.71) but this difference disappeared after adjustment for age and severity of disease (OR 1.06). Geographical region had little effect but there was a very weak socioeconomic gradient. Conclusions: Although prescribing has increased, many patients who may benefit from lipid lowering drugs either do not receive it or are undertreated, possibly because of lack of awareness of the relative potency of the different statins. Patients with angina and the elderly are less likely to receive treatment that may prevent a coronary event.

Outdoor air pollution and respiratory health in patients with COPD

Objectives Time series studies have shown adverse effects of outdoor air pollution on mortality and hospital admissions in patients with chronic obstructive pulmonary disease (COPD) but panel studies have been inconsistent. This study investigates short-term effects of outdoor nitrogen dioxide, ozone, sulfur dioxide, particulate matter (PM10) and black smoke on exacerbations, respiratory symptoms and lung function in 94 patients with COPD in east London. Methods Patients were recruited from an outpatient clinic and were asked to complete daily diary cards (median follow-up 518 days) recording exacerbations, symptoms and lung function, and the amount of time spent outdoors. Outdoor air pollution exposure (lag 1 day) was obtained from local background monitoring stations. Results Symptoms but not lung function showed associations with raised pollution levels. Dyspnoea was significantly associated with PM10 (increase in odds for an IQR change in pollutant: 13% (95% CI 4% to 23%)) and this association remained after adjustment for other the pollutants measured. An IQR increase in nitrogen dioxide was associated with a 6% (0–13%) increase in the odds of a symptomatic fall in peak flow rate. The corresponding effect sizes for PM10 and black smoke were 12% (2–25%) and 7% (1–13%), respectively. Conclusion It is concluded that outdoor air pollution is associated with important adverse effects on symptoms in patients with COPD living in London.

Short-term associations between outdoor air pollution and mortality in London 1992-4.

OBJECTIVES: A previous study of the short term effects of air pollution in London from April 1987 to March 1992 found associations between all cause mortality and black smoke and ozone, but no clear evidence of specificity for cardiorespiratory deaths. London data from 1992 to 1994 were analysed to examine the consistency of results over time and to include particles with a mean aerodynamic diameter of 10 microns (PM10) and carbon monoxide. METHODS: Poisson regression was used of daily mortality counts grouped by age and diagnosis, adjusting for trend, seasonality, calendar effects, deaths from influenza, meteorology, and serial correlation. The pollutants examined were particles (PM10 and black smoke), nitrogen dioxide, ozone, sulphur dioxide, and carbon monoxide with single and cumulative lags up to 3 days. RESULTS: No significant associations were found between any pollutant and all cause mortality, but, with the exception of ozone, all estimates were positive. Each pollutant apart from ozone was significantly associated with respiratory mortality; PM10 showed the largest effect (4% increase in deaths of all ages for a 10th-90th percentile increment). The pollutants significantly associated with cardiovascular deaths were nitrogen dioxide, ozone, and black smoke but there was no evidence of an association with PM10. In two pollutant models of respiratory deaths, the effect of black smoke, which in London indicates fine particles of diesel origin, was independent of that of PM10, but not vice versa. CONCLUSION: These results from a new data set confirm a previous report that there are associations between various air pollutants and daily mortality in London. This new study found greater specificity for associations with respiratory and cardiovascular deaths, and this increases the plausibility of a causal explanation. However, the effects of ozone found in the earlier study were not replicated. The fraction of PM10 which comprises black smoke accounted for much of the effect of PM10.

Particulate air pollution and hospital admissions for cardiorespiratory diseases: are the elderly at greater risk?

A systematic literature review suggests that particulate air pollution is associated with daily admissions for both respiratory and cardiac diseases in people aged >65 yrs. A model of acute effects is proposed which shows how admissions can be brought forward by a relatively short period of time as well as events being added that would not have happened at all except for air pollution. A model of the effects of air pollution on chronic disease is proposed that provides the background of long-term vulnerability upon which the increased short-term vulnerability is superimposed. A study of daily hospital admissions in London shows that for respiratory disease the relative risks of admission associated with particles reduce with increasing age, while for cardiac disease, there is no trend. When the attributable risk is estimated using baseline admission rates for respiratory disease, it is children who have the highest attributable risk, followed by the elderly. For cardiac disease there is a steep increase in attributable risk with age, reflecting the dominant influence of baseline risks. The attributable risk for cardiovascular disease in the elderly is considerably greater than for respiratory disease, due to higher baseline admission rates.

Association between Gc genotype and susceptibility to TB is dependent on vitamin D status

Group-specific component (Gc) variants of vitamin D binding protein differ in their affinity for vitamin D metabolites that modulate antimycobacterial immunity. We conducted studies to determine whether Gc genotype associates with susceptibility to tuberculosis (TB). The following subjects were recruited into case–control studies: in the UK, 123 adult TB patients and 140 controls, all of Gujarati Asian ethnic origin; in Brazil, 130 adult TB patients and 78 controls; and in South Africa, 281 children with TB and 182 controls. Gc genotypes were determined and their frequency was compared between cases versus controls. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were obtained retrospectively for 139 Gujarati Asians, and case-control analysis was stratified by vitamin D status. Interferon (IFN)-γ release assays were also performed on 36 Gujarati Asian TB contacts. The Gc2/2 genotype was strongly associated with susceptibility to active TB in Gujarati Asians, compared with Gc1/1 genotype (OR 2.81, 95% CI 1.19–6.66; p = 0.009). This association was preserved if serum 25(OH)D was <20 nmol·L−1 (p = 0.01) but not if serum 25(OH)D was ≥20 nmol·L−1 (p = 0.36). Carriage of the Gc2 allele was associated with increased PPD of tuberculin-stimulated IFN-γ release in Gujarati Asian TB contacts (p = 0.02). No association between Gc genotype and susceptibility to TB was observed in other ethnic groups studied.

Factors associated with mental disorders in long-settled war refugees: refugees from the former Yugoslavia in Germany, Italy and the UK

BACKGROUND Prevalence rates of mental disorders are frequently increased in long-settled war refugees. However, substantial variation in prevalence rates across studies and countries remain unexplained. AIMS To test whether the same sociodemographic characteristics, war experiences and post-migration stressors are associated with mental disorders in similar refugee groups resettled in different countries. METHOD Mental disorders were assessed in war-affected refugees from the former Yugoslavia in Germany, Italy and the UK. Sociodemographic, war-related and post-migration characteristics were tested for their association with different disorders. RESULTS A total of 854 war refugees were assessed (≥ 255 per country). Prevalence rates of mental disorders varied substantially across countries. A lower level of education, more traumatic experiences during and after the war, more migration-related stress, a temporary residence permit and not feeling accepted were independently associated with higher rates of mood and anxiety disorders. Mood disorders were also associated with older age, female gender and being unemployed, and anxiety disorders with the absence of combat experience. Higher rates of post-traumatic stress disorder (PTSD) were associated with older age, a lower level of education, more traumatic experiences during and after the war, absence of combat experience, more migration-related stress, and a temporary residence permit. Only younger age, male gender and not living with a partner were associated with substance use disorders. The associations did not differ significantly across the countries. War-related factors explained more variance in rates of PTSD, and post-migration factors in the rates of mood, anxiety and substance use disorder. CONCLUSIONS Sociodemographic characteristics, war experiences and post-migration stressors are independently associated with mental disorders in long-settled war refugees. The risk factors vary for different disorders, but are consistent across host countries for the same disorders.

Can we identify how programmes aimed at promoting self-management in musculoskeletal pain work and who benefits? A systematic review of sub-group analysis within RCTs

Background: There are now several systematic reviews of RCTs testing self‐management for those with chronic musculoskeletal pain. Evidence for the effectiveness of self‐management interventions in chronic musculoskeletal pain is equivocal and it is not clear for which sub‐groups of patients SM is optimally effective.