Epidemiology for public health practice:The application of spatial epidemiology

Spatial epidemiology is the description and analysis of geographic patterns and variations in disease risk factors,morbidity and mortality with respect to their distributions associated with demographic,socioeconomic,environmental,health behavior,and genetic risk factors,and time-varying changes.In the Letter to Editor,we had a brief description of the practice for the mortality and the spacetime patterns of John Snow's map of cholera epidemic in London,United Kingdom in 1854.This map is one of the earliest public heath practices of developing and applying spatial epidemiology.In the early history,spatial epidemiology was predominantly applied in infectious disease and risk factor studies.However,since the recent decades,noncommunicable diseases have become the leading cause of death in both developing and developed countries,spatial epidemiology has been used in the study of noncommunicable disease.In the Letter,we addressed two examples that applied spatial epidemiology to cluster and identify stroke belt and diabetes belt across the states and counties in the United States.Similar to any other epidemiological study design and analysis approaches,spatial epidemiology has its limitations.We should keep in mind when applying spatial epidemiology in research and in public health practice.

Impact of diabetes mellitus on risk of cardiovascular disease and all-cause mortality: Evidence on health outcomes and antidiabetic treatment in United States adults

AIMTo examine the epidemic of diabetes mellitus (DM) and its impact on mortality from all-cause and cardiovascular disease (CVD), and to test the effect of antidiabetic therapy on the mortality in United States adults. METHODS The analysis included a randomized population sample of 272149 subjects ages ≥ 18 years who participated in the National Health Interview Surveys (NHIS) in2000-2009. Chronic conditions (hypertension, DM and CVD) were classified by participants’ self-reports of physician diagnosis. NHIS-Mortality Linked Files, and NHIS-Medical Expenditure Panel Survey Linkage Fileson prescribed medicines for patients with DM were used to test the research questions. χ 2, Poisson and Cox’s regression models were applied in data analysis.RESULTS Of all participants, 22305 (8.2%) had DM. The prevalence of DM significantly increased from 2000 to 2009 in all age groups (P < 0.001). Within an average 7.39 (SD= 3) years of follow-up, male DM patients had 1.56 times higher risk of death from all-cause (HR = 1.56, 95%CI:1.49-1.64), 1.72 times higher from heart disease [1.72 (1.53-1.93)], 1.48 times higher from cerebrovascular disease [1.48 (1.18-1.85)], and 1.67 times higher from CVD [1.67 (1.51-1.86)] than subjects without DM,respectively. Similar results were observed in females. In males, 10% of DM patients did not use any antidiabetic medications, 38.1% used antidiabetic monotherapy, and 51.9% used ≥ 2 antidiabetic medications. These corresponding values were 10.3%, 40.4% and 49.4% in females. A significant protective effect of metformin monotherapy or combination therapy (except for insulin) on all-cause mortality and a protective but non-significant effect on CVD mortality were observed. CONCLUSION This is the first study using data from multiple linkage files to confirm a significant increased prevalence of DM in the last decade in the United States. Patients with DM have significantly higher risk of death from all-cause and CVD than those without DM. Antidiabetic mediations,specifically for metformin use, show a protective effect against all-cause and CVD mortalities.

Climate Change, Air Quality and Urban Health: Evidence from Urban Air Quality Surveillance System in 161 Cities of China 2014

Air pollution has posed a serious public health issue in China. In the study, we aimed to examine the burden of air pollution and its association with climate factors and total mortality. City-level daily air quality index (AQI) data in 161 cities of China in 2014, and meteorological factors, socioeconomic status and total morality were obtained from China environmental, meteor-ology and healthcare agencies. Linear regression, spatial autocorrelation analysis and panel fixed models were applied in data analysis. Among 161 cities, monthly average AQI was significantly different by seasons and regions. The highest average AQI was in winter, and the lowest in summer. A significant clustering distribution of AQI by cities was observed, with the highest AQI in north China (22 cities, mean = 117.36). Among the 161 cities, 5 cities (3%) had AQI > 150 (e.g., moderate polluted reference value), and 50 cities (31.1%) had AQI between 100 and 150 (slightly polluted value). Daily heat index, precipitation and sunshine hours were negatively and significantly, but air pressure was positively correlated with AQI. Cities with higher AQI concentrations had higher total mortality than those with lower AQI. This AQI-mortality association remained significant after adjustment for socioeconomic status. In conclusion, the study highlights the burden and seasonal, regional and areas variations in air pollution across the nation. Air pollution is estimated to account for more than 4% of the urban health inequality in total mortality in China.

Assessment of cerebral oxygenation response to hemodialysis using near-infrared spectroscopy (NIRS):Challenges and solutions

To date,the clinical use of functional near-infrared spectroscopy(NIRS)to detect cerebral ischemia has been largely limited to surgical settings,where motion artifacts are minimal.In this study,we present novel techniques to address the challenges of using NIRS to monitor ambu-latory patients with kidney disease during approximately eight hours of hemodialysis(HD)treatment.People with end-stage kidney disease who require HD are at higher risk for cognitive impairment and dementia than age-matched controls.Recent studies have suggested that HD-related declines in cerebral blood flow might explain some of the adverse outcomes of HD treatment.However,there are currently no established paradigms for monitoring cerebral per-fusion in real-time during HD treatment.In this study,we used NIRS to assess cerebral hemo-dynamic responses among 95 prevalent HD patients during two consecutive HD treatments.We observed substantial signal attenuation in our predominantly Black patient cohort that required probe modifications.We also observed consistent motion artifacts that we addressed by devel-oping a novel NIRS methodology,called the HD cerebral oxygen demand algorithm(HD-CODA),to identify episodes when cerebral oxygen demand might be outpacing supply during HD treatment.We then examined the association between a summary measure of time spent in cerebral deoxygenation,derived using the HD-CODA,and hemodynamic and treatment-related variables.We found that this summary measure was associated with intradialytic mean arterial pressure,heart rate,and volume removal.Future studies should use the HD-CODA to implement studies of real-time NIRS monitoring for incident dialysis patients,over longer time frames,and in other dialysis modalities.

Family Planning Awareness, Perceptions and Practice among Community Members in the Kintampo Districts of Ghana

Family planning is known to prevent maternal deaths, but some social norms, limited supplies and inconsistent use makes this difficult to achieve in most low- and middle-income countries. In spite of the high fertility levels in most sub-Saharan African countries and the potential economic benefits of family planning, its patronage remains very low in the sub-region. This study was with the objective of identifying the levels of awareness, utilization, access to and perceptions about family planning and contraception. A cross-sectional study design was used for the study, with data collected from multiple sources using both quantitative and qualitative approaches. Relevant findings included a marked disconnect between family planning/contraceptive knowledge and use. The pills and injectables were the most frequently used, but females in the study population poorly patronised emergency contraception. Supplies of most family planning methods were found to be health facility based, requiring clients to have to necessarily go there for services. Some respondents harboured perceptions that family planning was the responsibility of females alone and that it fuelled promiscuity among female users. Recommendations made include ensuring that health facilities had adequate staff and expertise to provide facility-based family planning services and also to disabuse the minds of community members of the negative perceptions towards family planning.

Making Family Planning Services Relevant to Adolescents: Perspectives from Rural Communities in Central Ghana

In lower middle-income countries like Ghana, it is common to find low contraceptive use among adolescents with corresponding high pregnancy outcomes. Evidence points to the fact that the use of contraceptives prevents maternal, neonatal and infant deaths, but in most lower middle-income countries, socio-cultural practices inhibit adolescents’ use. Ensuring the uptake of family planning among adolescents is deemed a necessary means of reducing maternal, neonatal and infant mor-tality. This manuscript seeks to provide contextually relevant approaches to satisfying family planning needs of adolescents in a population lacking it. We employed a qualitative study design from an interpretive paradigm with phenomenology as the methodology to understand societal attitudes towards family planning delivery to adolescents, so as to arrive at contextually appro-priate ways of providing family planning to this needy group. Focused group discussions and in-depth interviews techniques were used in data collection among adolescents, relevant commu-nity opinion leaders and family planning & health services providers. Themes that emerged from data analysis with respect to “perspectives on family planning care delivery to adolescents” and “best ways in addressing adolescents’ family planning needs” are presented, followed by discussion of the issues emerging. A significant and encouraging finding of the study was that opinion leaders and healthcare providers viewed family planning as a means of protecting adolescents against pregnancies and their complications. A key recommendation is for policy makers and political leaders to enact legislations that enable adolescents to have friendly family planning service delivery in all places and at all times.