Parks and physical activity: why are some parks used more than others?

OBJECTIVE

To assess how park characteristics and demographic factors are associated with park use.

METHODS

We studied a diverse sample of parks in a Southern California metropolitan area in 2006-2008 representing a variety of racial and ethnic communities of different socioeconomic strata. We surveyed 51 park directors, 4257 park users and local residents, and observed 30 parks. We explored relationships among the number of people observed, the number of park programs offered, number of organized activities observed, park size, existence of park advisory board, perceptions of safety, and population density and characteristics.

RESULTS

The strongest correlates of the number of people using the park were the park size and the number of organized activities observed. Neighborhood population density, neighborhood poverty levels, perceptions of park safety, and the presence of a park advisory board were not associated with park use.

CONCLUSION

While perceptions of low safety have been considered a barrier to park use, perceptions of high safety do not appear to facilitate park use. Having events at the park, including sports competitions and other attractions, appears to be the strongest correlate of park use and community-level physical activity.

Statistics without tears: Populations and samples

Research studies are usually carried out on sample of subjects rather than whole populations. The most challenging aspect of fieldwork is drawing a random sample from the target population to which the results of the study would be generalized. In actual practice, the task is so difficult that some sampling bias occurs in almost all studies to a lesser or greater degree. In order to assess the degree of this bias, the informed reader of medical literature should have some understanding of the population from which the sample was drawn. The ultimate decision on whether the results of a particular study can be generalized to a larger population depends on this understanding. The subsequent deliberations dwell on sampling strategies for different types of research and also a brief description of different sampling methods.

Panel discussion on energy efficiency

The session on energy efficiency had no formal presentations and was organized as a panel discussion with four panelists. It was concluded that energy efficiency and saving measures on the short term is the most effective way to contribute to a sustainable energy system. Measures to improve and encourage energy efficiency should be implemented at all levels; municipal/local, national and super-national. Prices can be an effective instrument but need to be combined with systemic level measures. The transport sector was identified as the one with largest near future potential for increased energy efficiency. Agriculture and food is also an area with very large energy consumption and large potential for increased energy efficiency. The global population issue is yet another relevant, challenging and complex issue. It was noted that energy audits for end users in business and society increase awareness and insights into what they pay for, and they are likely to promote actions to save energy. Many measures are believed to suffer from Jevin's paradox, i.e., that more efficient use of energy just leads to more energy consumption somewhere else. Many examples were given, however, where this does not happen. Another point put forward was that measures to make the energy system more efficient do not only mean constraints and regulations but also create great opportunities for market actors and societies.

APOE and ACE polymorphisms and dementia risk in the older population over prolonged follow-up: 10 years of incidence in the MRC CFA Study

BACKGROUND

dementia risk conferred by apolipoprotein-E (APOE) and angiotensin-1-converting enzyme (ACE) polymorphisms have been reported for the MRC Cognitive Function and Ageing Study (CFAS) at 6-year follow-up. We concentrate on incident dementia risk over 10 years.

METHODS

participants come from MRC CFAS, a multi-centre longitudinal population-based study of ageing in England and Wales. Three follow-up waves of data collection were used: 2, 6 and 10 years. Logistic regressions were undertaken to investigate associations between APOE (n = 955) and ACE (n = 856) alleles/genotypes and incident dementia. Two types of control groups were used: non-demented and highly functioning non-demented. Results were back-weighted.

RESULTS

compared to APOE epsilon3, epsilon2 conferred protection of odds ratio (OR) = 0.3 (95% confidence interval, CI = 0.1-0.6) and epsilon4 risk of OR = 2.9 (95% CI = 1.7-4.9) for incident dementia. Compared to epsilon3/epsilon3, the epsilon3/epsilon4 and epsilon4/epsilon4 genotypes conferred risks of OR = 3.6 (95% CI = 1.8-7.3) and OR = 7.9 (95% CI = 1.6-39.2), respectively. The epsilon3/epsilon2 genotype protected against dementia (OR = 0.2, 95% CI = 0.1-0.7), and epsilon2/epsilon2 had a similar protective effect but with wide CIs (OR = 0.3, 95% CI = 0.1-1.7). Restricting the control group accentuated these differentials. The effects of ACE alleles/genotypes on incident dementia risk were small.

CONCLUSIONS

APOE but not ACE is associated with late-onset incident dementia in the population. Using longer term follow-up with proper adjustment for attrition and incident cases increases estimates of risk.

Natural environment suitability of China and its relationship with population distributions

The natural environment factor is one of the main indexes for evaluating human habitats, sustained economic growth and ecological health status. Based on Geographic Information System (GIS) technology and an analytic hierarchy process method, this article presents the construction of the Natural Environment Suitability Index (NESI) model of China by using natural environment data including climate, hydrology, surface configuration and ecological conditions. The NESI value is calculated in grids of 1 km by 1 km through ArcGIS. The spatial regularity of NESI is analyzed according to its spatial distribution and proportional structure. The relationship of NESI with population distribution and economic growth is also discussed by analyzing NESI results with population distribution data and GDP data in 1 km by 1 km grids. The study shows that: (1) the value of NESI is higher in the East and lower in the West in China; The best natural environment area is the Yangtze River Delta region and the worst are the northwest of Tibet and southwest of Xinjiang. (2) There is a close correlation among natural environment, population distribution and economic growth; the best natural environment area, the Yangtze River Delta region, is also the region with higher population density and richer economy. The worst natural environment areas, Northwest and Tibetan Plateau, are also regions with lower population density and poorer economies.

Vaginal self-swab specimen collection in a home-based survey of older women: methods and applications

OBJECTIVES

To describe the methods used for, cooperation with, assays conducted on, and applications of vaginal specimens collected by older women in their homes.

METHODS

Community-residing women (N = 1,550), ages 57-85 years, participated in a nationally representative probability survey. Vaginal self-swab specimen collection and in-home interviews were conducted between 2005 and 2006. Specimens were analyzed for bacterial vaginosis (BV), vaginal candidiasis (VC), high-risk human papillomavirus (HR-HPV), and cytological characteristics. Field methods, consent procedures, the swab protocol, laboratory procedures, and results reporting are described.

RESULTS

One thousand twenty-eight respondents (67.5% weighted) agreed to provide a vaginal specimen; 99.1% were successful. The specimen adequacy rates were BV and VC, 94.1%; HR-HPV, 99.7%; and cytology, 85.5%. The most common recorded reason for nonparticipation was a physical or health problem (38% of nonresponders). Responders were significantly more likely than nonresponders to be younger and more educated, and were more likely to report a recent pelvic examination, menopausal hormone use, and recent sexual activity.

DISCUSSION

Collection of vaginal self-swab specimens from older women in a population-based study is feasible and provides novel data on microenvironmental characteristics of the female genital tract relevant to analyses of gynecologic health, sexual activity and problems, and immune and inflammatory function.

Population, poverty and economic development

Economists, demographers and other social scientists have long debated the relationship between demographic change and economic outcomes. In recent years, general agreement has emerged to the effect that improving economic conditions for individuals generally lead to lower birth rates. But, there is much less agreement about the proposition that lower birth rates contribute to economic development and help individuals and families to escape from poverty. The paper examines recent evidence on this aspect of the debate, concludes that the burden of evidence now increasingly supports a positive conclusion, examines recent trends in demographic change and economic development and argues that the countries representing the last development frontier, those of Sub-Saharan Africa, would be well advised to incorporate policies and programmes to reduce high fertility in their economic development strategies.

Population policies, programmes and the environment

Human consumption is depleting the Earth's natural resources and impairing the capacity of life-supporting ecosystems. Humans have changed ecosystems more rapidly and extensively over the past 50 years than during any other period, primarily to meet increasing demands for food, fresh water, timber, fibre and fuel. Such consumption, together with world population increasing from 2.6 billion in 1950 to 6.8 billion in 2009, are major contributors to environmental damage. Strengthening family-planning services is crucial to slowing population growth, now 78 million annually, and limiting population size to 9.2 billion by 2050. Otherwise, birth rates could remain unchanged, and world population would grow to 11 billion. Of particular concern are the 80 million annual pregnancies (38% of all pregnancies) that are unintended. More than 200 million women in developing countries prefer to delay their pregnancy, or stop bearing children altogether, but rely on traditional, less-effective methods of contraception or use no method because they lack access or face other barriers to using contraception. Family-planning programmes have a successful track record of reducing unintended pregnancies, thereby slowing population growth. An estimated $15 billion per year is needed for family-planning programmes in developing countries and donors should provide at least $5 billion of the total, however, current donor assistance is less than a quarter of this funding target.

Age- and gender-specific awareness, treatment, and control of cardiovascular risk factors and subclinical vascular lesions in a founder population: the SardiNIA Study

AIM

We investigated the gender-specific control of cardiovascular (CV) risk factors and subclinical vascular lesions in a founder population in Italy.

METHODS AND RESULTS

6148 subjects were enrolled (aged 14-102 years) from four towns. Hypertension (HT), diabetes mellitus (DM) and dyslipidemia (LIP) were defined in accordance with guidelines. A self-reported diagnosis defined awareness of these conditions, and the current use of specific medications as treatment. Prevalence was HT 29.2%, DM 4.8%, LIP 44.1% and was higher in men than in women. Disease prevalence increased with age for every CV risk factor. Men were less likely than women to take anti-HT drugs and to reach BP control (9.9% vs. 16%). Only 17.6% of HT > 65 years had a BP < or =140/90 mmHg, though 48.5% were treated. The use of statins was very low (<1/3 of eligible subjects > 65 years, those with the highest treatment rate). The ratio of control-to-treated HT was lower in subjects with, than in those without, thicker carotid arteries (31.5% vs. 38.8%, p < 0.05) or stiffer aortas (26.0% vs. 40.0%, p < 0.05) or carotid plaques (26.3% vs. 41.1%, p<0.05).

CONCLUSION

A large number of subjects at high CV risk are not treated and the management of subclinical vascular lesions is far from optimal.

Alcohol consumption and development of acute respiratory distress syndrome: a population-based study

This retrospective population-based study evaluated the effects of alcohol consumption on the development of acute respiratory distress syndrome (ARDS). Alcohol consumption was quantified based on patient and/or family provided information at the time of hospital admission. ARDS was defined according to American-European consensus conference (AECC). From 1,422 critically ill Olmsted county residents, 1,357 had information about alcohol use in their medical records, 77 (6%) of whom developed ARDS. A history of significant alcohol consumption (more than two drinks per day) was reported in 97 (7%) of patients. When adjusted for underlying ARDS risk factors (aspiration, chemotherapy, high-risk surgery, pancreatitis, sepsis, shock), smoking, cirrhosis and gender, history of significant alcohol consumption was associated with increased risk of ARDS development (odds ratio 2.9, 95% CI 1.3–6.2). This population-based study confirmed that excessive alcohol consumption is associated with higher risk of ARDS.

Real-time ozone detection based on a microfabricated quartz crystal tuning fork sensor

A chemical sensor for ozone based on an array of microfabricated tuning forks is described. The tuning forks are highly sensitive and stable, with low power consumption and cost. The selective detection is based on the specific reaction of the polymer with ozone. With a mass detection limit of ∼2 pg/mm² and response time of 1 second, the sensor coated with a polymer sensing material can detect ppb-level ozone in air. The sensor is integrated into a miniaturized wearable device containing a detection circuit, filtration, battery and wireless communication chip, which is ideal for personal and microenvironmental chemical exposure monitoring.

Significant genetic differentiation among populations of Anomalocardia brasiliana (Gmelin, 1791): A bivalve with planktonic larval dispersion

Four Brazilian populations of Anomalocardia brasiliana were tested for mutual genetic homogeneity, using data from 123 sequences of the mtDNA cytochrome oxidase c subunit I gene. A total of 36 haplotypes were identified, those shared being H3 (Canela Island, Prainha and Acupe) and both H5 and H9 (Prainha and Acupe). Haplotype diversity values were high, except for the Camurupim population, whereas nucleotide values were low in all the populations, except for that of Acupe. Only the Prainha population showed a deviation from neutrality and the SSD test did not reject the demographic expansion hypothesis. Fst values showed that the Prainha and Acupe populations represent a single stock, whereas in both the Canela Island and Camurupim stocks, population structures are different and independent. The observed structure at Canela Island may be due to the geographic distance between this population and the remainder. The Camurupim population does not share any haplotype with the remaining populations in northeastern Brazil. The apparent isolation could be due to the rocky barrier located facing the mouth of the Mamanguape River. The results highlight the importance of wide-scale studies to identify and conserve local genetic diversity, especially where migration is restricted.

Estimating the effects of potential public health interventions on population disease burden: a step-by-step illustration of causal inference methods

Causal inference methods allow estimation of the effects of potential public health interventions on the population burden of disease. Motivated by calls for epidemiologic research to be presented in ways that are more informative for intervention, the authors present a didactic discussion of the steps required to estimate the population effect of a potential intervention using an imputation-based causal inference method and discuss the assumptions of and limitations to its use. An analysis of neighborhood smoking norms and individual smoking behavior is used as an illustration. The implementation steps include the following: 1) modeling the adjusted exposure and outcome association, 2) imputing the outcome probability for each individual while manipulating the exposure by "setting" it to different values, 3) averaging these probabilities across the population, and 4) bootstrapping confidence intervals. Imputed probabilities represent counterfactual estimates of the population smoking prevalence if neighborhood smoking norms could be manipulated through intervention. The degree to which temporal ordering, randomization, stability, and experimental treatment assignment assumptions are met in the illustrative example is discussed, along with ways that future studies could be designed to better meet the assumptions. With this approach, the potential effects of an intervention targeting neighborhoods, individuals, or other units can be estimated.

Using genetics to understand the dynamics of wild primate populations

While much can be learned about primates by means of observation, the slow life history of many primates means that even decades of dedicated effort cannot illuminate long-term evolutionary processes. For example, while the size of a contemporary population can be estimated from field censuses, it is often desirable to know whether a population has been constant or changing in size over a time frame of hundreds or thousands of years. Even the nature of "a population" is open to question, and the extent to which individuals successfully disperse among defined populations is also difficult to estimate by using observational methods alone. Researchers have thus turned to genetic methods to examine the size, structure, and evolutionary histories of primate populations. Many results have been gained by study of sequence variation of maternally inherited mitochondrial DNA, but in recent years researchers have been increasingly focusing on analysis of short, highly variable microsatellite segments in the autosomal genome for a high-resolution view of evolutionary processes involving both sexes. In this review we describe some of the insights thus gained, and discuss the likely impact on this field of new technologies such as high-throughput DNA sequencing.

RICHEST--a web server for richness estimation in biological data

Richness is defined as the number of distinct species or classes in a sample or population. Although richness estimation is an important practice, it requires mathematical and computational methods that are challenging to understand and implement. We have developed a web server, RICHness ESTimator (RICHEST), which implements three non-parametric statistical methods for richness estimation. Its user-friendly web interface allows users to analyze and compare their data conveniently over the web.

Prevalence and awareness of CKD among African Americans: the Jackson Heart Study

BACKGROUND

Chronic kidney disease (CKD) leads to end-stage renal disease and is a growing epidemic throughout the world. In the United States, African Americans have an incidence of end-stage renal disease 4 times that of whites.

STUDY DESIGN

Cross-sectional to examine the prevalence and awareness of CKD in African Americans.

SETTING & PARTICIPANTS

Observational cohort in the Jackson Heart Study (JHS).

PREDICTOR

CKD was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2), the presence of albuminuria, or dialysis therapy.

OUTCOMES & MEASUREMENTS

Data from the JHS were analyzed. Medical history, including disease awareness and drug therapy, anthropometric measurements, and serum and urine samples, were obtained from JHS participants at the baseline visit. Associations between CKD prevalence and awareness and selected demographic, socioeconomic, health care access, and disease status parameters were assessed by using logistic regression models.

RESULTS

The prevalence of CKD in the JHS was 20%; CKD awareness was only 15.8%. Older participants had a greater prevalence, but also were more aware of CKD. Hypertension, diabetes, cardiovascular disease, hypercholesterolemia, hypertriglyceridemia, increasing age and waist circumference, and being single or less physically active were associated with CKD. Only advancing CKD stage was associated with awareness.

LIMITATIONS

Cross-sectional assessment, single urine measurement.

CONCLUSIONS

The JHS has a high prevalence and low awareness of CKD, especially in those with less severe disease status. This emphasizes the need for earlier diagnosis and increased education of health care providers and the general population.

Population attributable fraction of mortality associated with tobacco smoking in Japan: a pooled analysis of three large-scale cohort studies

BACKGROUND

Quantitative measures of the burden of tobacco smoking in Asian countries are limited. We estimated the population attributable fraction (PAF) of mortality associated with smoking in Japan, using pooled data from three large-scale cohort studies.

METHODS

In total, 296,836 participants (140,026 males and 156,810 females) aged 40-79 years underwent baseline surveys during the 1980s and early 1990s. The average follow-up period was 9.6 years. PAFs for all-cause mortality and individual tobacco-related diseases were estimated from smoking prevalence and relative risks.

RESULTS

The prevalence of current and former smokers was 54.4% and 25.1% for males, and 8.1% and 2.4% for females. The PAF of all-cause mortality was 27.8% [95% confidence interval (CI): 25.2-30.4] for males and 6.7% (95% CI: 5.9-7.5) for females. The PAF of all-cause mortality calculated by summing the disease-specific PAFs was 19.1% (95% CI: 16.0-22.2) for males and 3.6% (95% CI: 3.0-4.2) for females. The estimated number of deaths attributable to smoking in Japan in 2005 was 163,000 for males and 33,000 for females based on the former set of PAFs, and 112,000 for males and 19,000 for females based on the latter set. The leading causes of smoking-attributable deaths were cancer (61% for males and 31% for females), ischemic heart diseases and stroke (23% for males and 51% for females), and chronic obstructive pulmonary diseases and pneumonia (11% for males and 13% for females).

CONCLUSION

The health burden due to smoking remains heavy among Japanese males. Considering the high prevalence of male current smokers and increasing prevalence of young female current smokers, effective tobacco controls and quantitative assessments of the health burden of smoking need to be continuously implemented in Japan.

Managing wildlife populations with uncertainty: cormorants Phalacrocorax carbo

Managing wildlife populations for conservation, control or harvesting involves uncertainty. Nevertheless, decisions need to be made based on the available evidence. The two main sources of uncertainty in population modelling are parameter estimates and structural uncertainty. Structural uncertainty in models is not included as often as parameter uncertainty.We present an approach where parameter and structural uncertainty (strength of density dependence) is included within a model, using the over-wintering English population of cormorants Phalacrocorax carbo L. Because of the damage caused to inland fishery interests by cormorants, there was a change in UK government policy in autumn 2004, increasing the numbers of birds that can be shot under licence.A stochastic Monte Carlo annual population model was produced to examine the effect of changes to the numbers of birds shot each year. Indices of annual population size were converted to population estimates and used to determine annual growth rates and strength of density dependence.There is strong evidence for density dependence in the data, which suggests the population is currently slightly above carrying capacity, with a mean growth rate of 4-6% per annum. The 1300 birds shot under licence in 2004/05 represent about 4.5% of the English population, and if this level of culling continues, the population would be expected to decline by 9% by 2007, compared to the long-term average. The a priori preferred model, which included all uncertainty, gave predictions for 2004/05 and 2005/06 in close agreement with field data.The model was used to produce short-term population projections, with the understanding that Adaptive Resource Management (ARM) will be adopted to iteratively update the parameters and model each year, feeding back into the numbers of available licences.Synthesis and applications. We recommend the approach used in this study of including parameter and structural uncertainty within a single model, where possible, with the proportion of iterations that utilize a particular structure dependent on the weight of evidence for that structure. This will produce results with wider confidence intervals, but ensures that the evidence for any particular model is not over-interpreted.

Non-communicable diseases in low- and middle-income countries: context, determinants and health policy

The rise of non-communicable diseases and their impact in low- and middle-income countries has gained increased attention in recent years. However, the explanation for this rise is mostly an extrapolation from the history of high-income countries whose experience differed from the development processes affecting today's low- and middle-income countries. This review appraises these differences in context to gain a better understanding of the epidemic of non-communicable diseases in low- and middle-income countries. Theories of developmental and degenerative determinants of non-communicable diseases are discussed to provide strong evidence for a causally informed approach to prevention. Health policies for non-communicable diseases are considered in terms of interventions to reduce population risk and individual susceptibility and the research needs for low- and middle-income countries are discussed. Finally, the need for health system reform to strengthen primary care is highlighted as a major policy to reduce the toll of this rising epidemic.

Visceral adiposity and subclinical coronary artery disease in elderly adults: Rancho Bernardo Study

OBJECTIVE

Despite growing attention to central obesity as a predictor of clinical coronary heart disease (CHD), there are few reports about the association between directly measured visceral obesity and subclinical coronary atherosclerosis in elderly adults. We examined this association in elderly, community-dwelling adults without clinically recognized CHD.

METHODS AND PROCEDURES

Elderly adults (190 men, BMI 27.2 +/- 3.6 kg/m(2); 220 women, BMI 25.8 +/- 4.6) aged 55-88 years (median 69 years) with no history of CHD or coronary revascularization had an electron beam computed tomography (EBCT) to measure coronary artery calcification score (CACS), an estimate of coronary plaque burden. Visceral and subcutaneous adiposity were assessed by a triple-slice EBCT scan at the lumbar 4-5 disc level and height, weight, and waist and hip circumferences were measured.

RESULTS

In sex-specific ordinal logistic regression analyses, no measure of obesity or body fat distribution, including BMI, waist-to-hip ratio, waist girth, and visceral and subcutaneous fat by EBCT, was significantly associated with CACS before or after adjusting for multiple covariates of CACS (age, smoking, alcohol intake, exercise, pulse pressure, low-density lipoprotein (LDL)/high-density lipoprotein (HDL)-cholesterol ratio, and fasting plasma glucose).

DISCUSSION

In elderly adults without clinically recognized CHD, body weight and fat distribution do not predict coronary artery plaque burden. These results raise questions about the value of weight reduction diets for preventing heart disease in elderly survivors without clinical heart disease.

Adaptation, migration or extirpation: climate change outcomes for tree populations

Species distribution models predict a wholesale redistribution of trees in the next century, yet migratory responses necessary to spatially track climates far exceed maximum post-glacial rates. The extent to which populations will adapt will depend upon phenotypic variation, strength of selection, fecundity, interspecific competition, and biotic interactions. Populations of temperate and boreal trees show moderate to strong clines in phenology and growth along temperature gradients, indicating substantial local adaptation. Traits involved in local adaptation appear to be the product of small effects of many genes, and the resulting genotypic redundancy combined with high fecundity may facilitate rapid local adaptation despite high gene flow. Gene flow with preadapted alleles from warmer climates may promote adaptation and migration at the leading edge, while populations at the rear will likely face extirpation. Widespread species with large populations and high fecundity are likely to persist and adapt, but will likely suffer adaptational lag for a few generations. As all tree species will be suffering lags, interspecific competition may weaken, facilitating persistence under suboptimal conditions. Species with small populations, fragmented ranges, low fecundity, or suffering declines due to introduced insects or diseases should be candidates for facilitated migration.

Adaptation, migration or extirpation: climate change outcomes for tree populations

Species distribution models predict a wholesale redistribution of trees in the next century, yet migratory responses necessary to spatially track climates far exceed maximum post-glacial rates. The extent to which populations will adapt will depend upon phenotypic variation, strength of selection, fecundity, interspecific competition, and biotic interactions. Populations of temperate and boreal trees show moderate to strong clines in phenology and growth along temperature gradients, indicating substantial local adaptation. Traits involved in local adaptation appear to be the product of small effects of many genes, and the resulting genotypic redundancy combined with high fecundity may facilitate rapid local adaptation despite high gene flow. Gene flow with preadapted alleles from warmer climates may promote adaptation and migration at the leading edge, while populations at the rear will likely face extirpation. Widespread species with large populations and high fecundity are likely to persist and adapt, but will likely suffer adaptational lag for a few generations. As all tree species will be suffering lags, interspecific competition may weaken, facilitating persistence under suboptimal conditions. Species with small populations, fragmented ranges, low fecundity, or suffering declines due to introduced insects or diseases should be candidates for facilitated migration.

Migration to the Maya Biosphere Reserve, Guatemala: Why place matters

Virtually all migration research examines international migration or urbanization. Yet understudied rural migrants are of critical concern for environmental conservation and rural sustainable development. Despite the fact that a relatively small number of all migrants settle remote rural frontiers, these are the agents responsible for perhaps most of the tropical deforestation on the planet. Further, rural migrants are among the most destitute people worldwide in terms of economic and human development. While a host of research has investigated deforestation resulting from frontier migration, and a modest literature has emerged on frontier development, this article explores the necessary antecedent to tropical deforestation and poverty along agricultural frontiers: out-migration from origin areas. The data come from a 2000 survey with community leaders and key informants in 16 municipios of migrant origin to the Maya Biosphere Reserve (MBR), Petén, Guatemala. A common denominator among communities of migration origin to the Petén frontier was unequal resource access, usually land. Nevertheless, the factors driving resource scarcity were widely variable. Land degradation, land consolidation, and population growth prevailed in some communities but not in others. Despite similar exposure to community and regional level push factors, most people in the sampled communities did not out-migrate, suggesting that any one or combination of factors is not necessarily sufficient for out-migration.

A community-based evaluation of sudden death associated with therapeutic levels of methadone

BACKGROUND

Published case reports have associated the therapeutic use of methadone with the occasional occurrence of sudden cardiac death. Because of the established utility of this drug and with the eventual goal of enhancing safety of use, we performed a community-based study to evaluate this association.

METHODS

During a 4-year period, we prospectively evaluated all patients who consecutively had sudden cardiac death and underwent investigation by the medical examiner in the metropolitan area of Portland, Ore. Case subjects of interest were those with a therapeutic blood level of methadone (<1 mg/L), and case comparison subjects were those with no methadone identified. Patients with recreational drug use or any drug overdose were excluded from either group. Detailed autopsies were conducted, including the detection and quantification of all substances in the blood.

RESULTS

A total of 22 sudden cardiac death cases with therapeutic levels of methadone (mean 0.48+/-0.22 mg/L; range 0.1-0.9 mg/L) were identified (mean age 37.0+/-10 years, 68% were male) and compared with 106 consecutive sudden cardiac death cases without evidence of methadone (mean age 42+/-13 years, 69% were male). The most common indication for methadone use was pain control (n=12, 55%). Among cases receiving methadone therapy, sudden death-associated cardiac abnormalities were identified in only 23% (n=5), with no clear cause of sudden cardiac death in the remaining 77% (n=17). Among cases with no methadone, sudden death-associated cardiac abnormalities were identified in 60% (n=64, P=.002).

CONCLUSION

The significantly lower prevalence of cardiac disease in the case group implicates methadone, even at therapeutic levels, as a likely cause of sudden death. These findings point toward an association between methadone and occurrence of sudden death in the community. Clinical safeguards and further prospective studies specifically designed to enhance safety of methadone use are warranted.