Modelling asthma epidemics on the relationship between air pollution and asthma emergency visits in Barcelona, Spain

We have investigated different methods of controlling for asthma epidemics in the time series regression of the relationship between air pollution and asthma emergency visits in Barcelona, Spain. The relationship between air pollution and asthma emergency room visits was modelled using autoregressive Poisson models. We examined the effect of using no control by epidemics, and modelling asthma epidemics with a single dummy variable, six dummy variables, and a dummy variable for each epidemic day. Air pollution coefficients increased when controlling asthma epidemics with six dummy variables instead of a single variable. They further increased when autocorrelation was allowed for. Standard errors were relatively unaffected when either the epidemics or the autocorrelation were included in the model. Black smoke, nitrogen dioxide and ozone were statistically significant associated to asthma emergency visits after using six dummy variables to control for asthma epidemics. We have shown that different models, including different confounding variables, give markedly different estimates of the effect of a pollutant on health. Care is needed in the interpretation of such models, and careful reporting so it is clear how the confounding variables have been modelled.     

Temperature and Daily Mortality in Shanghai： A Time-series Study

Objective To investigate the association between temperature and daily mortality in Shanghai from June 1, 2000 to December 31,2001. Methods Time-series approach was used to estimate the effect of temperature on daily total and cause-specific mortality. We fitted generalized additive Poisson regression using non-parametric smooth functions to control for long-term time trend, season and other variables. We also controlled for day of the week. Results A gently sloping V-like relationship between total mortality and temperature was found, with an optimum temperature (e.g.temperature with lowest mortality risk) value of 26.7℃ in Shanghai. For temperatures above the optimum value, total mortality increased by 0.73% for each degree Celsius increase; while for temperature below the optimum value, total mortality decreased by 1.21% for each degree Celsius increase. Conclusions Our findings indicate that temperature has an effect on daily mortality in Shanghai, and the time-series approach is a useful tool for studying the temperature-mortality association.     

大气颗粒物质量浓度与四川大学华西医院非意外创伤急诊人次的时间序列研究

目的 分析大气颗粒物（PM_2.5和PM₁₀）质量浓度对医院非意外创伤急诊人次的短期效应,探讨大气颗粒物对人群健康的急性危害。方法 采用广义相加模型分析2014～2016年成都市区大气污染物质量浓度对四川大学华西医院非意外创伤急诊人次的短期效应,并在不同年龄组（<65岁组和≥65岁组）中进行分层分析。结果 2014年1月1日至2016年11月30日期间成都市区大气颗粒物PM_2.5和PM₁₀的年平均质量浓度分别为66.47 μg/m3和109.35 μg/m3。在非意外创伤急诊全人群中,大气颗粒物的健康效应在滞后1 d时最大,PM_2.5和PM₁₀的日均质量浓度每增加10 μg/m3,急诊人次数分别增加0.634%（95%CI: 0.273%~0.997%）和0.413%（95%CI: 0.166%~0.660%）。在≥65岁组中,调整全部气态污染物（SO₂+NO₂+CO+O3）的影响后, PM_2.5和PM₁₀的日均质量浓度每增加10 μg/m3,滞后1 d的急诊人次数分别增加1.439%（95%CI:0.599%~2.287%）和 1.150%（95%CI:0.566%~1.738%）。结论 大气颗粒物质量浓度升高与非意外创伤急诊人次数呈正相关,且存在滞后效应,对65岁以上老年人群健康的急性损害较大。     

The effects of foot orthosis and low-dye tape on lower limb joint angles and moments during running in individuals with pes planus

BackgroundPes Planus or Flat feet is one of the most common lower limb abnormalities. When runners with this abnormality participate in recreational running, interventional therapies could help in pain alleviation and enhance performance. To determine the most effective treatment, however, a biomechanical examination of the effects of each treatment modality is required.Research questionThe aim of the present study was to investigate the effects of Foot Orthoses (FOs) and Low-Dye Tape (LDT) on lower limb joint angles and moments during running in individuals with pes planus.Methodskinematic and kinetic data of 20 young people with pes planus were measured during running in three conditions: (1) SHOD (2) with shoes and FOs (3) with shoes and LDT. One-way repeated measure ANOVA was used to investigate the impacts of the FOs and LDT on the lower limb joint angles and moments throughout the stance phase of the running cycle.ResultsThe results showed that FOs reduced ankle eversion compared to SHOD and LDT (P < 0.001) and decreased the dorsiflexion angle (P = 0.005) and the plantarflexor moment compared to the SHOD (P < 0.001). FOs increased knee adduction angle (P = 0.021) and knee external rotator moment (P < 0.001) compared to both conditions and increased knee extensor and abductor moments compared to SHOD (P < 0.001). At the hip joint, FOs only increased hip external rotation compared with the LDT condition (P = 0.031); and LDT increased hip extensor moment compared to SHOD and FOs (P = 0.037) and also increased hip adduction angle compared to SHOD (P = 0.037).SignificanceFOs with a medial wedge appears to increase the external knee adduction moment and knee adduction angles, which are risk factors for the development and progression of knee osteoarthritis. Further, usage of FOs seems to reduce the ankle joint role in propulsion as it impacts the ankle sagittal angles and moments.     

Error bounds for data-driven models of dynamical systems

This work provides a technique for estimating error bounds about the predictions of data-driven models of dynamical systems. The bootstrap technique is applied to predictions from a set of dynamical system models, rather than from the time-series data, to estimate the reliability (in the form of prediction intervals) for each prediction. The technique is illustrated using human core temperature data, modeled by a hybrid (autoregressive plus first principles) approach. The temperature prediction intervals obtained are in agreement with those from the Camp-Meidell inequality. Moreover, as expected, the prediction intervals increase with the prediction horizon, time-series data variability, and model inaccuracy.     

A multilevel time-series model for the incidence of AIDS cases in Spain

OBJECTIVE: The main aim of this research is to study the quantitative evolution of the incidence of AIDS in the 19 Spanish Communities. The hypothesis is that incidence follows a multilevel autoregressive model, where each Community shows random variability around a general process. METHOD: On the basis of official data on the number of existing AIDS cases, an autorregressive multilevel time-series model was developed. RESULTS AND CONCLUSIONS: Analysis shows that the hypothesis is supported, indicating that overall AIDS incidence in Spain has already reached a maximum and has a tendency to remain stable or to decline in future. Long term expected values have become stable in most Communities; a slight increase is expected only in Extremadura. However, this Community has a relatively sparse population, and its contribution on the overall Spanish incidence is small.Long term expected values are estimated to be around 152.99 new cases per million inhabitants per year. This value is slightly smaller than the maximum incidence, observed in 1994 (179.4 cases).     

Ozone air pollution and daily mortality in Genoa, Italy between 1993 and 1996

The association between ozone (O3) and daily mortality was investigated in Genoa, an Italian city characterized by a Mediterranean climate and a high prevalence of elderly inhabitants. The O3 effect, adjusted for long time trend, seasonality and weather, was assessed using Poisson regression modelling, allowing for overdispersion and autocorrelation, and expressed as mean variation percent of daily mortality per 50 microg/m3 increase (MV). Significant MVs for overall (+4.0%) and cardiovascular (+7.2%) mortality were detected at 1-day lag. The effects were stronger in the warmer season (May-October). Similar estimates were found after restricting the analyses to the elderly (>or=75 years). Furthermore, in this group, higher MVs were observed for total mortality at 2-day lag. A statistically significant synergistic effect between O3 and temperature was observed for cardiovascular mortality, particularly in elderly people, with an evident increase in mortality risk above 26 degrees C (MV +30.0% for the whole population and +40.0% for the elderly, respectively). This investigation highlights the importance of taking local climatic and demographic features into account when comparing different time-series studies, and substantiates the influence of photochemical pollution on mortality trends in small urban areas.     

Air pollution, weather, and respiratory emergency room visits in two northern New England cities: an ecological time-series study

Daily emergency room (ER) visits for all respiratory (ICD-9 460-519) and asthma (ICD-9 493) were compared with daily sulfur dioxide (SO2), ozone (O3), and weather variables over the period 1998-2000 in Portland, Maine (population 248,000), and 1996-2000 in Manchester, New Hampshire (population 176,000). Seasonal variability was removed from all variables using nonparametric smoothed function (LOESS) of day of study. Generalized additive models were used to estimate the effect of elevated levels of pollutants on ER visits. Relative risks of pollutants are reported over their interquartile range (IQR, the 75th -25th percentile pollutant values). In Portland, an IQR increase in SO2 was associated with a 5% (95% CI 2-7%) increase in all respiratory ER visits and a 6% (95% CI 1-12%) increase in asthma visits. An IQR increase in O3 was associated with a 5% (95% CI 1-10%) increase in Portland asthmatic ER visits. No significant associations were found in Manchester, New Hampshire, possibly due to statistical limitations of analyzing a smaller population. The absence of statistical evidence for a relationship should not be used as evidence of no relationship. This analysis reveals that, on a daily basis, elevated SO2 and O3 have a significant impact on public health in Portland, Maine.     

Use of poisson regression and box-jenkins models to evaluate the short-term effects of environmental noise levels on daily emergency admissions in Madrid,Spain

The relationship between environmental factors and hospital admissions has usually been analysed without taking into account the influence of a factor closely related to traffic in big cities, that is, environmental noise levels. We analysed the relationship between environmental noise and emergency admissions, for all causes and specific causes in Madrid (Spain), for the study period 1995–1997, using two statistical methods for the analysis of epidemiological time series data: Poisson autoregressive models and Box–Jenkins (ARIMA) methodology. Both methods produce a clear association between emergency admissions for all and specific causes and environmental noise levels. We found very similar results from both methods for all and circulatory causes, but slightly different for respiratory causes. Around 5% of all emergency admissions can be attributed to high noise levels, with a lower figure for specific causes. Current levels of environmental noise have a considerable epidemiological impact on emergency admissions in Madrid. A reduction of environmental noise levels could be accompanied by a possible reduction in the number of emergency admissions.