Biomedical subjects

Elise Whitley

Publications and source records attributed to Elise Whitley.

16 recordsLinked to original sources

PubMed2006

Risk of schizophrenia and other non-affective psychosis among individuals exposed to head injury: case control study.

Studies of the risk of schizophrenia and related non-affective psychoses among individuals exposed to head injury have reported conflicting findings. The diagnostic specificity of reported associations remains unclear and the effects of sex, genetic vulnerability and timing of exposures are also uncertain. The authors used a comprehensive range of data derived from the linkage of several Swedish registers to investigate associations of head injury with schizophrenia and other non-affective psychoses. We carried out a nested case control study drawn from a cohort of 785,051 men and women born between 1973 and 1980. After head injury exposure, there was a small increase in the risk (OR 1.37 (CI 1.14-1.66)) of non-schizophrenic, non-affective psychoses but not schizophrenic disorder (OR 1.10 CI 0.82 to 1.47). There was no critical period effect for exposures in early childhood, the association with non-affective psychosis being observed only in those exposed to head injury after age 10. There was no evidence that associations differed in males and females or in those with, and those without, a family history of psychosis. We conclude that it is unlikely that head injury causes schizophrenia. There is a small but significant risk of non-schizophrenic psychotic disorders but this is not associated with early age of injury or family history of psychosis. Further research is needed to clarify the potential roles of social and biological intermediary factors.

Adult↗

PubMed2006

Residential radon and lung cancer--detailed results of a collaborative analysis of individual data on 7148 persons with lung cancer and 14,208 persons without lung cancer from 13 epidemiologic studies in Europe.

OBJECTIVES: Studies seeking direct estimates of the lung cancer risk associated with residential radon exposure lasting several decades have been conducted in many European countries. Individually these studies have not been large enough to assess moderate risks reliably. Therefore data from all 13 European studies of residential radon and lung cancer satisfying certain prespecified criteria have been brought together and analyzed. METHODS: Data were available for 7148 persons with lung cancer and 14,208 controls, all with individual smoking histories and residential radon histories determined by long-term radon gas measurements. RESULTS: The excess relative risk of lung cancer per 100 Bq/m3 increase in the observed radon concentration was 0.08 [95% confidence interval (95% CI) 0.03-0.16; P=0.0007] after control for confounding. The dose-response relationship was linear with no evidence of a threshold, and it remained significant when only persons with observed radon concentrations of <200 Bq/m3 were included. There was no evidence that the excess relative risk varied with age, sex, or smoking history. Removing the bias induced by random uncertainties related to radon exposure assessment increased the excess relative risk of lung cancer to 0.16 (95% CI 0.05-0.31) per 100 Bq/m3. With this correction, estimated risks at 0, 100, and 400 Bq/m3, relative to lifelong nonsmokers with no radon exposure, were 1.0, 1.2, and 1.6 for lifelong nonsmokers and 25.8, 29.9, and 42.3 for continuing smokers of 15-24 cigarettes/day. CONCLUSIONS: These data provide firm evidence that residential radon acts as a cause of lung cancer in the general population. They provide a solid basis for the formulation of policies with which to manage risk from radon and reduce deaths from the most common fatal cancer in Europe.

Case-Control Studies↗

PubMed2005

Folic acid supplements in pregnancy and birth outcome: re-analysis of a large randomised controlled trial and update of Cochrane review.

Periconceptual folic acid prevents neural tube defects. The effect of folic acid taken throughout pregnancy is unclear, however. We re-analysed data from a large randomised controlled trial performed between 1966 and 1967 and combined the results with those from trials included in a Cochrane review. A total of 2928 women were randomised: 1977 were allocated to placebo, 466 to folic acid 200 microg/day and 485 to folic acid 5 mg/day. Folic acid supplementation was not associated with any difference in mean birthweight, placental weight or gestational age. When combined with trials in the Cochrane review folic acid at high doses was associated with reduced risk of low birthweight (pooled relative risk 0.73 [95% CI 0.53, 0.99]). We found no conclusive evidence of benefit for folic acid supplementation in pregnant women given from time of booking onwards.

Adult↗

PubMed2004

Suicide risk in small areas in England and Wales, 1991-1993.

BACKGROUND: There is growing evidence that areas characterised by high levels of social fragmentation have higher suicide rates. Previous ecological studies have focused on relatively large geographic areas and/or examined associations in all age groups combined. METHODS: Negative binominal regression was used to assess age- and sex-specific suicide rate ratios for a range of census-derived indicators of the social, health and economic characteristics of small areas (mean population aged > or = 15: 4500) in England and Wales. RESULTS: Indicators of social fragmentation (e. g. proportion of people living alone or population mobility) were most consistently associated with suicide risk. For example, across quartiles of wards ranked according to increasing proportions of single-person households, age- and sex-adjusted suicide rate ratios were: 1.00, 1.05 (1.00, 1.11), 1.14 (1.08, 1.19) and 1.42 (1.36, 1.49). Associations were strongest in 15 to 44 and 45 to 64 year-olds. Associations with social fragmentation persisted after controlling for the effect of other area characteristics. CONCLUSIONS: Targeted mental health promotion and social policy initiatives to reduce area-health inequalities in suicide might usefully focus on areas with high levels of social fragmentation.

Adolescent↗

PubMed2003

Why are suicide rates rising in young men but falling in the elderly?-- a time-series analysis of trends in England and Wales 1950-1998.

Suicide rates doubled in males aged <45 in England and Wales between 1950 and 1998, in contrast rates declined in older males and females of all ages. Explanations for these divergent trends are largely speculative, but social changes are likely to have played an important role. We undertook a time-series analysis using routinely available age- and sex-specific suicide, social, economic and health data, focussing on the two age groups in which trends have diverged most-25-34 and 60+ year olds. Between 1950 and 1998 there were unfavourable trends in many of the risk factors for suicide: rises in divorce, unemployment and substance misuse and declines in births and marriage. Whilst economic prosperity has increased, so too has income inequality. Trends in suicide risk factors were generally similar in both age-sex groups, although the rises in divorce and markers of substance misuse were most marked in 25-34 year olds and young males experienced the lowest rise in antidepressant prescribing. Statistical modelling indicates that no single factor can be identified as underlying recent trends. The factors most consistently associated with the rises in young male suicide are increases in divorce, declines in marriage and increases in income inequality. These changes have had little effect on suicide in young females. This may be because the drugs commonly used in overdose-their favoured method of suicide-have become less toxic or because they are less affected by the factors underlying the rise in male suicide. In older people declines in suicide were associated with increases in gross domestic product, the size of the female workforce, marriage and the prescribing of antidepressants. Recent population trends in suicide appear to be associated with by a range of social and health related factors. It is possible that some of the patterns observed are due to declining levels of social integration, but such effects do not appear to have adversely influenced patterns in older generations.

Adolescent↗

PubMed2003

Urban-rural differences in suicide trends in young adults: England and Wales, 1981-1998.

Suicide rates amongst young people, particularly males, have increased in many industrialised countries since the 1960s. There is evidence from some countries that the steepest rises have occurred in rural areas. We have investigated whether similar geographical differences in trends in suicide exist in England and Wales by examining patterns of suicide between 1981 and 1998 in relation to rurality. We used two complementary population-based indices of rurality: (1) population density and (2) population potential (a measure of geographic remoteness from large concentrations of population). We used the electoral ward (n=9264, median population aged 15-44: 1829) as the unit of analysis. To assess whether social and economic factors underlie rural-urban differences in trends we used negative binomial regression models to investigate changes in suicide rates between the years for which detailed national census data were available (1981 and 1991). Over the years studied, the most unfavourable trends in suicide in 15-44-year olds generally occurred in areas remote from the main centres of population; this effect was most marked in 15-24-year-old females. Observed patterns were not explained by changes in age- and sex-specific unemployment, socio-economic deprivation or social fragmentation. The mental health of young adults or other factors influencing suicide risk may have deteriorated more in rural than urban areas in recent years. Explanations for these trends require further investigation.

Adolescent↗

PubMed2003

Influence of cohort effects on patterns of suicide in England and Wales, 1950-1999.

BACKGROUND: Age- and gender-specific suicide rates in England and Wales have changed considerably since 1950. AIMS: To assess whether cohort effects underlie some of these changes. METHOD: Graphical displays to assess age-period-cohort effects on suicide for the period 1950-1999. RESULTS: Successive male birth cohorts born after 1940 carried with them, as they aged, a greater risk of suicide than their predecessors although this effect diminished for the 1975 and 1980 birth cohorts. There was less clear evidence of any increased risk of suicide in post-war female birth cohorts. CONCLUSIONS: Succeeding generations of males born in the post-war years have experienced increasing rates of suicide at all ages, an observation in keeping with patterns seen in other countries. If these trends continue into middle- and old-age they will lead to a great increase in overall male suicide rates.

Adolescent↗

PubMed2002

Statistics review 6: Nonparametric methods.

The present review introduces nonparametric methods. Three of the more common nonparametric methods are described in detail, and the advantages and disadvantages of nonparametric versus parametric methods in general are discussed.

Humans↗

PubMed2002

Statistics review 5: Comparison of means.

The present review introduces the commonly used t-test, used to compare a single mean with a hypothesized value, two means arising from paired data, or two means arising from unpaired data. The assumptions underlying these tests are also discussed.

Adult↗

PubMed2002

Statistics review 4: sample size calculations.

The present review introduces the notion of statistical power and the hazard of under-powered studies. The problem of how to calculate an ideal sample size is also discussed within the context of factors that affect power, and specific methods for the calculation of sample size are presented for two common scenarios, along with extensions to the simplest case.

Clinical Trials as Topic↗

PubMed2002

Statistics review 3: hypothesis testing and P values.

The present review introduces the general philosophy behind hypothesis (significance) testing and calculation of P values. Guidelines for the interpretation of P values are also provided in the context of a published example, along with some of the common pitfalls. Examples of specific statistical tests will be covered in future reviews.

Clinical Trials as Topic↗

PubMed2002

Recruitment strategies in a cluster randomized trial--cost implications.

The presence of a non-zero intracluster correlation coefficient in cluster randomized trial data has well-known statistical implications for trial design, in particular, inflating the required sample size for given specifications. However, problems in recruitment are common in such trials and there may be different costs of recruitment resulting from different recruitment strategies. Examples of how such differences arise are taken from cluster randomized trials and more intuitive methods of describing clustering are summarized which, in conjunction with such cost issues, may provide a framework that enables triallists to consider explicitly the trade-off between power and cost that is often inherent in such trials.

Adolescent↗

PubMed2002

Statistics review 2: samples and populations.

The previous review in this series introduced the notion of data description and outlined some of the more common summary measures used to describe a dataset. However, a dataset is typically only of interest for the information it provides regarding the population from which it was drawn. The present review focuses on estimation of population values from a sample.

Confidence Intervals↗

PubMed2002

What determines the use of home care services by elderly people?

The objective of the present study was to investigate the determinants of use of statutory and private home care services by older people living in the community. A questionnaire was distributed to a stratified random sample of 2,000 elderly people living in the community registered with 11 general practices in a British city (equal numbers of men and women, aged 65-74 years, and 75 years or over). The outcome measures were the use of statutory or private home care services in the previous 3 months. Logistic regression was used to explore potential determinants of the use of these services. The response rate was 79%. Increasing age, not owning a car and being a widow(er) were associated with greater use of both statutory and private home care services, as was worse self-reported overall health. Worse physical functioning, worse emotional health, problems with cognition, foot problems and a greater number of falls were determinants of use of statutory and private services. Older age on leaving full-time education was associated with increased use of private home care services. Problems with eyesight were determinants for both types of home care services for women, but only private services for men. For women, leakage of urine was associated with greater use of private services. Social networks and social support were not generally associated with use of these services after controlling for demographic factors. Understanding the determinants for the use of both statutory and private home care services is important because of the increasing numbers of elderly people in the population and the policy to maintain older people in their own homes. Purchasers and providers should be able to address at least some of the modifiable predictors.

Aged↗

PubMed2002

Falls and the use of health services in community-living elderly people.

Falls are common and often preventable in older people. This short report describes substantial unmet need in relation to falls. Although falling, nearly falling, fear of falling, and activity restriction are common, many people do not seek assistance from healthcare professionals. Only 2% of those who had attended their general practioner (GP), a casualty department, or had been admitted to hospital after a fall were taking drugs to protect against osteoporosis. People who have fallen or are at a risk of falling need to be identified, and local policies and information regarding treatment for osteoporosis are needed.

Accidental Falls↗

PubMed2001

Statistics review 1: presenting and summarising data.

The present review is the first in an ongoing guide to medical statistics, using specific examples from intensive care. The first step in any analysis is to describe and summarize the data. As well as becoming familiar with the data, this is also an opportunity to look for unusually high or low values (outliers), to check the assumptions required for statistical tests, and to decide the best way to categorize the data if this is necessary. In addition to tables and graphs, summary values are a convenient way to summarize large amounts of information. This review introduces some of these measures. It describes and gives examples of qualitative data (unordered and ordered) and quantitative data (discrete and continuous); how these types of data can be represented figuratively; the two important features of a quantitative dataset (location and variability); the measures of location (mean, median and mode); the measures of variability (range, interquartile range, standard deviation and variance); common distributions of clinical data; and simple transformations of positively skewed data.

Analysis of Variance↗