Sample size issues in time series regressions of counts on environmental exposures.

BACKGROUND: Regression analyses of time series of disease counts on environmental determinants are a prominent component of environmental epidemiology. For planning such studies, it can be useful to predict the precision of estimated coefficients and power to detect associations of given magnitude. Existing generic approaches for this have been found somewhat complex to apply and do not easily extend to multiple series studies analysed in two stages. We have sought a simpler approximate approach which can easily extend to multiple series and give insight into factors determining precision. METHODS: We derive approximate expressions for precision and hence power in single and multiple time series studies of counts from basic statistical theory, compare the precision predicted by these with that estimated by analysis in real data from 51 cities of varying size, and illustrate the use of these estimators in a realistic planning scenario. RESULTS: In single series studies with Poisson outcome distribution, precision and power depend only on the usable variation of exposure (i.e. that conditional on covariates) and the total number of disease events, regardless of how many days those are spread over. In multiple time series (eg multi-city) studies focusing on the meta-analytic mean coefficient, the usable exposure variation and the total number of events (in all series) are again the sole determinants if there is no between-series heterogeneity or within-series overdispersion. With heterogeneity, its extent and the number of series becomes important. For all but the crudest approximation the estimates of standard errors were on average within + 20% of those estimated in full analysis of actual data. CONCLUSIONS: Predicting precision in coefficients from a planned time series study is possible simply and given limited information. The total number of disease events and usable exposure variation are the dominant factors when overdispersion and between-series heterogeneity are low

Methods to estimate acclimatization to urban heat island effects on heat- and cold-related mortality

Background: Investigators have examined whether heat mortality risk is increased in neighborhoods subject to the urban heat island (UHI) effect but have not identified degrees of difference in susceptibility to heat and cold between cool and hot areas, which we call acclimatization to the UHI. Objectives: We developed methods to examine and quantify the degree of acclimatization to heat- and cold-related mortality in relation to UHI anomalies and applied these methods to London, UK. Methods: Case–crossover analyses were undertaken on 1993–2006 mortality data from London UHI decile groups defined by anomalies from the London average of modeled air temperature at a 1-km grid resolution. We estimated how UHI anomalies modified excess mortality on cold and hot days for London overall and displaced a fixed-shape temperature-mortality function (“shifted spline” model). We also compared the observed associations with those expected under no or full acclimatization to the UHI. Results: The relative risk of death on hot versus normal days differed very little across UHI decile groups. A 1°C UHI anomaly multiplied the risk of heat death by 1.004 (95% CI: 0.950, 1.061) (interaction rate ratio) compared with the expected value of 1.070 (1.057, 1.082) if there were no acclimatization. The corresponding UHI interaction for cold was 1.020 (0.979, 1.063) versus 1.030 (1.026, 1.034) (actual versus expected under no acclimatization, respectively). Fitted splines for heat shifted little across UHI decile groups, again suggesting acclimatization. For cold, the splines shifted somewhat in the direction of no acclimatization, but did not exclude acclimatization. Conclusions: We have proposed two analytical methods for estimating the degree of acclimatization to the heat- and cold-related mortality burdens associated with UHIs. The results for London suggest relatively complete acclimatization to the UHI effect on summer heat–related mortality, but less clear evidence for cold–related mortality

Cholera in Bangladesh: Climatic Components of Seasonal Variation

Background: The mechanisms underlying the seasonality of cholera are still not fully understood, despite long-standing recognition of clear bimodal seasonality in Bangladesh. We aimed to quantify the contribution of climatic factors to seasonal variations in cholera incidence. Methods: We investigated the association of seasonal and weather factors with the weekly number of cholera patients in Dhaka, Bangladesh, using Poisson regression models. The contribution of each weather factor (temperature and high and low rainfall) to seasonal variation was estimated as the mean over the study period (1983-2008) for each week of the year of each weather term. Fractions of the number of cholera patients attributed to each weather factor, assuming all values were constant at their minimum risk levels throughout the year, were estimated for spring and monsoon seasons separately. Results: Lower temperature predicted a lower incidence of cholera in the first 15 weeks of the year. Low rainfall predicted a peak in spring, and high rainfall predicted a peak at the end of the monsoon. The risk predicted from all the weather factors combined showed a broadly bi-modal pattern, as observed in the raw data. Low rainfall explained 18% of the spring peak, and high rainfall explained 25% of the peak at the end of the monsoon. Conclusions: Seasonal variation in temperature and rainfall contribute to cholera incidence in complex ways, presumably in interaction with unmeasured environmental or behavioral factors

Effect of evacuation and displacement on the association between flooding and mental health outcomes: a cross-sectional analysis of UK survey data.

BACKGROUND: Extensive flooding occurred during the winter of 2013-14 in England. Previous studies have shown that flooding affects mental health. Using data from the 2013-14 Public Health England National Study of Flooding and Health, we compared the prevalence of symptoms of depression, anxiety, and post-traumatic stress disorder between participants displaced by flooding and those flooded, but not displaced, 1 year after flooding. METHODS: In this multivariable ordinal regression analysis, we collected data from a cross-sectional survey collected 1 year after the flooding event from flood-affected postcodes in five counties in England. The analysis was restricted to individuals whose homes were flooded (n=622) to analyse displacement due to flooding. The primary outcome measures were depression (measured by the PHQ-2 depression scale) and anxiety (measured by the two-item Generalised Anxiety Disorder [GAD]-2 anxiety scale), and post-traumatic stress disorder (measured by the Post-Traumatic Stress Disorder Checklist [PCL]-6 scale). We adjusted analyses for recorded potential confounders. We also analysed duration of displacement and amount of warning received. FINDINGS: People who were displaced from their homes were significantly more likely to have higher scores on each scale; odds ratio (OR) for depression 1·95 (95% CI 1·30-2·93), for anxiety 1·66 (1·12-2·46), and for post-traumatic stress disorder 1·70 (1·17-2·48) than people who were not displaced. The increased risk of depression was significant even after adjustment for severity of flooding. Scores for depression and post-traumatic stress disorder were higher in people who were displaced and reported receiving no warning than those who had received a warning more than 12 h in advance of flooding (p=0·04 for depression, p=0·01 for post-traumatic stress disorder), although the difference in anxiety scores was not significant. INTERPRETATION: Displacement after flooding was associated with higher reported symptoms of depression, anxiety, and post-traumatic stress disorder 1 year after flooding. The amount of warning received showed evidence of being protective against symptoms of the three mental illnesses studied, and the severity of flooding might be the reason for some, but not all, of the differences between the groups. FUNDING: National Institute for Health Research Health Protection Research Units (HPRU) in Emergency Preparedness and Response at King's College London, Environmental Change and Health at the London School of Hygiene and Tropical Medicine, and Evaluation of Interventions at the University of Bristol, Public Health England

Impact of flooding on health-related quality of life in England: results from the National Study of Flooding and Health.

BACKGROUND: Flooding can have extensive effects on the health and wellbeing of affected communities. The impact of flooding on psychological morbidity has been established; however, the wider impacts of flooding exposure, including on health-related quality of life (HRQoL), have not been described. METHODS: Using data from the English National Study of Flooding and Health cohort, HRQoL 2 and 3 years post-flooding was assessed with the EuroQol Group EQ-5D-5L tool. Associations between exposure groups (flooding and disruption from flooding) and HRQoL were assessed, using ordinal and linear regression, adjusting for a priori confounders. RESULTS: For both 2 and 3 years post-flooding, the median HRQoL scores were lower in the flooded and disrupted groups, compared with unaffected respondents. A higher proportion of flooded and disrupted respondents reported HRQoL problems in most dimensions of the EQ-5D-5L, compared with unaffected respondents. In year 2, independent associations between exposure to flooding and experiencing anxiety/depression [adjusted odds ratio (aOR) 7.7; 95% CI 4.6-13.5], problems with usual activities (aOR 5.3; 95% CI 2.5-11.9) and pain/discomfort (aOR 2.4; 95% CI 1.5-3.9) were identified. These problems persisted 3 years post-flooding; associations between exposure to flooding and experiencing anxiety/depression (aOR 4.3; 95% CI 2.5-7.7), problems with usual activities (aOR 2.9; 95% CI 1.5-6.1) and pain/discomfort (aOR 2.5; 95% CI 1.5-4.2) were identified. CONCLUSIONS: Exposure to flooding and disruption from flooding significantly reduces HRQoL. These findings extend our knowledge of the impacts of flooding on health, with implications for multi-agency emergency response and recovery plans

Fire History from Life-History: Determining the Fire Regime that a Plant Community Is Adapted Using Life-Histories

Wildfire is a fundamental disturbance process in many ecological communities, and is critical in maintaining the structure of some plant communities. In the past century, changes in global land use practices have led to changes in fire regimes that have radically altered the composition of many plant communities. As the severe biodiversity impacts of inappropriate fire management regimes are recognized, attempts are being made to manage fires within a more ‘natural’ regime. In this aim, the focus has typically been on determining the fire regime to which the community has adapted. Here we take a subtly different approach and focus on the probability of a patch being burnt. We hypothesize that competing sympatric taxa from different plant functional groups are able to coexist due to the stochasticity of the fire regime, which creates opportunities in both time and space that are exploited differentially by each group. We exploit this situation to find the fire probability at which three sympatric grasses, from different functional groups, are able to co-exist. We do this by parameterizing a spatio-temporal simulation model with the life-history strategies of the three species and then search for the fire frequency and scale at which they are able to coexist when in competition. The simulation gives a clear result that these species only coexist across a very narrow range of fire probabilities centred at 0.2. Conversely, fire scale was found only to be important at very large scales. Our work demonstrates the efficacy of using competing sympatric species with different regeneration niches to determine the probability of fire in any given patch. Estimating this probability allows us to construct an expected historical distribution of fire return intervals for the community; a critical resource for managing fire-driven biodiversity in the face of a growing carbon economy and ongoing climate change

Ursinus College Alumni Journal, November 1961

The president\u27s wife writes • Mater Ursini • The Ursinus College European tour • Admiral Moreell looks at a philosopher • Zucker looks at Moreell • A woman\u27s approach to peace • Founders\u27 Day • 1962 Forum programs • Cutting campus • From Alaska to Greenland • Faith and freedom in Taiwan • Reginald Helfferich honored • Poet King • Henry P. Laughlin, \u2738 • Robert Pease, \u2733 • Ursinus student at White House conference • Harleston R. Wood • Football • Soccer • Hockey • Basketball • Wrestling • 53.5% contribute to Loyalty Fund in 1961 • Progress report 1962 campaign • 1961 campaign results • The Century Club • Loyalty Fund all-stars • Loyalty Fund kick-off dinner • Matching gifts • Results of the 1961 Loyalty Fund campaign • Contributors to the 1961 Loyalty Fund campaign • Class notes • Weddings • Births • Necrology • Sing along with us • New faculty membershttps://digitalcommons.ursinus.edu/alumnijournal/1072/thumbnail.jp

Impact of repeat flooding on mental health and health-related quality of life:a cross-sectional analysis of the English National Study of Flooding and Health

OBJECTIVE: To assess the association between flooding/repeat flooding and: (1) psychological morbidity (anxiety, depression, post-traumatic stress disorder (PTSD)) and (2) health-related quality of life (HRQoL) at 6 months post-flooding. DESIGN: Cross-sectional analysis of data from the English National Study of Flooding and Health. SETTING: Cumbria, England. PARTICIPANTS: Questionnaires were sent to 2500 residential addresses at 6 months post-flooding; 590 people responded. OUTCOMES: Probable depression was assessed using the Patient Health Questionnaire, probable anxiety using the Generalised Anxiety Disorder scale and probable PTSD using the short-form PTSD checklist (PCL-6). HRQoL was assessed using the EQ-5D-5L. Mental health outcomes were analysed using logistic regression; HRQoL dimensions using ordinal regression; and summary index/Visual Analogue Scale scores using linear regression. RESULTS: One hundred and nineteen participants had been flooded, over half of whom were experiencing a repeat flooding event (54%; n=64). Mental health outcomes were elevated among flooded compared with unaffected participants (adjusted OR for probable depression: 7.77, 95% CI: 1.51 to 40.13; anxiety: 4.16, 95% CI: 1.18 to 14.70; PTSD: 14.41, 95% CI: 3.91 to 53.13). The prevalence of depression was higher among repeat compared with single flooded participants, but this was not significant after adjustment. There was no difference in levels of anxiety or PTSD. Compared with unaffected participants, those flooded had lower EQ-5D-5L index scores (adjusted coefficient: -0.06, 95% CI: -0.12 to -0.01) and lower self-rated health scores (adjusted coefficient: -6.99, 95% CI: -11.96 to -2.02). There was, however, little difference in HRQoL overall between repeat and single flooded participants. CONCLUSIONS: Interventions are needed to help minimise the impact of flooding on people's mental health and HRQoL

The English National Cohort Study of Flooding and Health: the change in the prevalence of psychological morbidity at year two.

BACKGROUND: The longer term impact of flooding on health is poorly understood. In 2015, following widespread flooding in the UK during winter 2013/14, Public Health England launched the English National Study of Flooding and Health. The study identified a higher prevalence of probable psychological morbidity one year after exposure to flooding. We now report findings after two years. METHODS: In year two (2016), a self-assessment questionnaire including flooding-related exposures and validated instruments to screen for probable anxiety, depression and post-traumatic stress disorder (PTSD) was sent to all participants who consented to further follow-up. Participants exposure status was categorised according to responses in year one; we assessed for exposure to new episodes of flooding and continuing flood-related problems in respondents homes. We calculated the prevalence and odds ratio for each outcome by exposure group relative to unaffected participants, adjusting for confounders. We used the McNemar test to assess change in outcomes between year one and year two. RESULTS: In year two, 1064 (70%) people responded. The prevalence of probable psychological morbidity remained elevated amongst flooded participants [n = 339] (depression 10.6%, anxiety 13.6%, PTSD 24.5%) and disrupted participants [n = 512] (depression 4.1%, anxiety 6.4%, PTSD 8.9%), although these rates were reduced compared to year one. A greater reduction in anxiety 7.6% (95% confidence interval [CI] 4.6-9.9) was seen than depression 3.8% (95% CI 1.5-6.1) and PTSD: 6.6% (95% CI 3.9-9.2). Exposure to flooding was associated with a higher odds of anxiety (adjusted odds ratio [aOR] 5.2 95%, 95% CI 1.7-16.3) and depression (aOR 8.7, 95% CI 1.9-39.8) but not PTSD. Exposure to disruption caused by flooding was not significantly associated with probable psychological morbidity. Persistent damage in the home as a consequence of the original flooding event was reported by 119 participants (14%). The odds of probable psychological morbidity amongst flooded participants who reported persistent damage, compared with those who were unaffected, were significantly higher than the same comparison amongst flooded participants who did not report persistent damage. CONCLUSIONS: This study shows a continuance of probable psychological morbidity at least two years following exposure to flooding. Commissioners and providers of health and social care services should be aware that the increased need in populations may be prolonged. Efforts to resolve persistent damage to homes may reduce the risk of probable psychological morbidity