Estimation of population denominators for public health studies at the tract, gender, and age-specific level

Trends in epidemiology: the role of denominator fluctuation in population based estimates

Background

Population estimates are of paramount importance for calculating occurrence and association measures although they can be affected by problems of accuracy and completeness. This study has performed a simulation of the impact of Italian population size variability on incidence rates.

Methods

Data have been obtained by the Italian National Institute of Statistics. For each year expected cases were calculated at increasing fixed rates (up to 1,000/100,000) and were considered constant in the “following year”, calculating statistical differences (P < 0.05).

Results

In Italy and in other regions, statistically significant higher RRs were found in 2012 vs. 2011 whereas statistically significant lower RRs were found in 2013 vs. 2012 and in 2014 vs. 2013.

Contribution

The simulation confirms that significant differences due to population fluctuation could be found between consecutive years when investigating diseases with medium-high rates. Researchers should be encouraged to implement actions for reducing the risk of biased population denominators.

Increasing myocardial infarction mortality trends in a middle-income country

Background

Developed countries continue to show a decrease in cardiovascular disease (CVD) mortality. Little is known about CVD mortality trends in low and middle-income countries. The aim of our study is to describe myocardial infarction (MI) mortality trends and evaluate if differences between ethnic groups and geographic regions are present among the Ecuadorians with acute MI.

Methods

We conducted a cross sectional analysis mortality national registry and included deaths related to MI between 2012 and 2016 that had complete demographic data. To describe the general population, we used the 2010 census and applied estimates as population projections. We calculated age and sex standardized MI mortality rates per 100,000. We compared trends in MI mortality rate for every ethnic group and geographic region and used linear regression to estimate predictors of the changing mortality rates.

Results

We included 18,277 MI deaths between the years 2012 and 2016. The mean age of death was 73.6±19.5, 59% were male and 33% were illiterate. From 2012 to 2016, the standardized MI mortality rate increased from 51 to 157 deaths per 100,000. The most significant predictors of the increasing mortality rate were living in the coast (β=0.10), belonging to a mixed race (β=-0.033) and the year of death (β=0.013).

Conclusions

Our study found a worrisome increase in MI mortality between 2012-2016 in Ecuador, a middle-income country in South America. This rapid increase seems to be driven by geographic and racial differences. A thorough evaluation of the causes of this increase has to be undertaken by the Ecuadorian health authorities.

Spatial clustering of occupational injuries in communities

OBJECTIVES

Using the social-ecological model, we hypothesized that the home residences of injured workers would be clustered predictably and geographically.

METHODS

We linked health care and publicly available datasets by home zip code for traumatically injured workers in Illinois from 2000 to 2009. We calculated numbers and rates of injuries, determined the spatial relationships, and developed 3 models.

RESULTS

Among the 23 200 occupational injuries, 80% of cases were located in 20% of zip codes and clustered in 10 locations. After component analysis, numbers and clusters of injuries correlated directly with immigrants; injury rates inversely correlated with urban poverty.

CONCLUSIONS

Traumatic occupational injuries were clustered spatially by home location of the affected workers and in a predictable way. This put an inequitable burden on communities and provided evidence for the possible value of community-based interventions for prevention of occupational injuries. Work should be included in health disparities research. Stakeholders should determine whether and how to intervene at the community level to prevent occupational injuries.

Real-time estimation of small-area populations with human biomarkers in sewage

A new approach is conceptualized for measuring small-area human populations by using biomarkers in sewage. The basis for the concept (SCIM: Sewage Chemical-Information Mining) is supported by a comprehensive examination and synthesis of data published across several disciplines, including medicine, microbiology, clinical chemistry, and environmental science. Accurate measures of human populations are fundamental to numerous disciplines, including economics, marketing, politics, sociology, public health and safety (e.g., disease management; assessment of natural hazards; disaster prevention and response), quality of life, and the environment. Knowing the size, distribution, and flow of a small-area (local) population facilitates understanding the numerous and complex linkages and interactions between humans and the environment. Examples include material-flow (substance-flow) analysis, determining the magnitude of per capita contribution of pollutant loadings to watersheds, or forecasting future impacts of local populations on the environment or a population's demands on resources. While no definitive approach exists for measuring small-area populations, census-taking is a long-established convention. No approach exists, however, for gauging small-area populations in real-time, as none is able to capture population dynamics, which involve transient changes (e.g., daily influx and efflux) and lasting changes (e.g., births, deaths, change in residence). Accurate measurement of small-area populations in real time has never been possible but is essential for facilitating the design of more sustainable communities. Real-time measurement would provide communities the capability of testing what-if scenarios in design and policy decisions. After evaluation of a range of biomarkers (including the nitrogenous waste product creatinine, which has been long used in clinical chemistry as a parameter to normalize the concentrations of other urinary excretion products to account for urine dilution), the biomarker with the most potential for the SCIM concept for real-time measurement of population was determined to be coprostanol - the major sterol produced by microbial reduction of cholesterol in the colon.

Solid-tumor mortality in the vicinity of uranium cycle facilities and nuclear power plants in Spain

To ascertain solid tumor mortality in towns near Spain's four nuclear power plants and four nuclear fuel facilities from 1975 to 1993, we conducted a mortality study based on 12,245 cancer deaths in 283 towns situated within a 30-km radius of the above installations. As nonexposed areas, we used 275 towns lying within a 50- to 100-km radius of each installation, matched by population size and sociodemographic characteristics (income level, proportion of active population engaged in farming, proportion of unemployed, percentage of illiteracy, and province). Using log-linear models, we examined relative risk for each area and trends in risk with increasing proximity to an installation. The results reveal a pattern of solid-tumor mortality in the vicinity of uranium cycle facilities, basically characterized by excess lung [relative risk (RR) 1.12, 95% confidence interval (CI), 1.02-1.25] and renal cancer mortality (RR 1.37, 95% CI, 1.07-1.76). Besides the effects of natural radiation, these results could well be evincing the influence on public health exerted by the environmental impact of mining. No such well-defined pattern appeared in the vicinity of nuclear power plants. Monitoring of cancer incidence and mortality is recommended in areas surrounding nuclear fuel facilities and nuclear power plants, and more specific studies are called for in areas adjacent to installations that have been fully operational for longer periods. In this regard, it is important to use dosimetric information in all future studies.

Brain cancer incidence in the provinces of Zaragoza and Navarre (Spain): effect of age, period and birth cohort

Several studies have detected increases in malignant brain tumour incidence and mortality rates particularly among the elderly. We analyzed time trends in malignant brain tumors incidence in Zaragoza over the period 1973-1990 and Navarre over the period 1973-1991, two Spanish provinces that have been collecting data through their respective Cancer Registries for the last 20 years, using Poisson regression analysis of age, period of diagnosis and cohort. In general, age-adjusted rates showed a steady rise in both registries, except in the case of females in Navarre, for whom a decrease in risk was observed for the last period, 1988-1991. This increase is a reflection of the rise in incidence experienced by the elderly, since the cohorts successively register rates that are stable over time, and even downward in the case of females in Navarre. The risk run by generations born circa 1920-1930 was the highest encountered. Rates were higher in Navarre in both sexes and for all but the last period in females, when rates on the two registers stood level. Increasingly generalised use of CT scanning and magnetic resonance in the 1980s in Spain, coupled with better and more effective health care access for the elderly, are factors that may well have some bearing on these findings.

Malignant brain tumour mortality among children and adolescents: geographical distribution in Spain

Log-linear Poisson mixed models were used to study provincial malignant brain tumour (MBT) mortality among children and adolescents in Spain (1975-1992) in order to investigate the influence of specific socio-economic factors and to produce smoothed estimators of standardised mortality ratios (SMRs). Interdependence between geographical units was taken into account by including provinces as random effect terms nested with the corresponding Autonomous Region (Spain's administrative divisions). MBT mortality showed a positive association with three variables: non-cancer-related infant mortality; percentage of provincial land surface area devoted to agriculture; and industrial/construction activity. According to the final model, SMRs increased by 4% with every 10% rise in the area devoted to agriculture, with a 4% excess risk predicted for every increase in non-cancer-related infant mortality of 1 per 1000 person-years, and a 7% excess risk for contiguous categories of industrial/construction activity. By smoothing extreme values caused by random variability, the regression model yielded a reasonable estimation of SMRs. While infant mortality may be linked to the quality of medical care available, the relationship seen between MBT mortality and agricultural area accords with the excess risk reported for farmers' offspring. Finally, industrial activity might be regarded as a risk factor or as a marker of other conditions also associated with these tumours.

Time trend and age-period-cohort effects on gastric cancer incidence in Zaragoza and Navarre, Spain

STUDY OBJECTIVE

To describe time trends in gastric cancer incidence in Zaragoza and Navarre, and to investigate time period and birth cohort as determinants of such trends.

DESIGN

Cases from two registries were grouped into five year intervals and the following were calculated: age specific and sex specific incidence rates, and the male to female ratio. Log linear models including age, period of diagnosis, and birth cohort were fitted.

SETTING

The Zaragoza Cancer Registry covers the province of Zaragoza, which has a population of 824,776 (403,755 men and 421,021 women). The Navarre Cancer Registry covers the province of Navarre which has 512,512 inhabitants (254,786 men and 257,726 women). In both cases population figures were based on the late census.

PATIENTS

These comprised incident cases of gastric cancer reported to the Zaragoza Cancer Registry in 1963-87 and to the Navarre Cancer Registry in 1973-87.

MAIN RESULTS

Navarre registered higher adjusted and cumulative rates than Zaragoza for both sexes. In both provinces, there were relative declines in the rates for men and women of 3% and 4% respectively per year. In Zaragoza, the risk of developing stomach cancer fell in generations born between 1888 and 1933, and rose in subsequent birth cohorts in both sexes, while in Navarre the cohort effect showed an approximately linear risk for both sexes. Both provinces recorded increases in risk associated with cohorts born between 1933 and 1943.

CONCLUSION

The incidence rates of gastric cancer fell in both Zaragoza and Navarre. The reason for the greater incidence of gastric cancer in Navarre remains unknown. Trends in rates seem to be mainly linked to birth cohort. Increases in risk in generations born after 1933 may be ascribable to nutritional deficiencies in the early years of life.

The AIDS epidemic among Spanish drug users: a birth cohort-associated phenomenon

OBJECTIVES

In Spain the number of new acquired immunodeficiency syndrome (AIDS) cases among injection drug users continues to rise. The time trend up to 1994 has been analyzed, with special attention paid to the different generations.

METHODS

The source for injection drug use-related cases was the Spanish AIDS Register. Independent analyses of annual specific rates were run for each sex with the use of an age-period-cohort log-linear model.

RESULTS

After adjustment for age and year of diagnosis, AIDS incidence related to injection drug use is associated with specific birth cohorts. Rising values are observed in the successive generations born during the 1950s, peaking in men born in 1962 and women born in 1964. In subsequent cohorts, there is a marked falloff in incidence for both sexes, but this decline is seen to halt in men from the 1972 birth cohort onwards. The overall period effect is upward, yet the trend flattens in the last years. There is a pronounced age effect with maximum values in men and women at ages 29 and 27, respectively.

CONCLUSIONS

It is essential to urge avoidance of risk behaviors in new generations.

Childhood cancer incidence in Zaragoza and Navarre (Spain): 1973-1987

Patterns and trends in childhood cancer incidence for Navarre and Zaragoza registries were studied over the 15-year period, 1973-1987. Overall cancer rates and rates for 10 specific types of cancer were analysed using a log-linear Poisson model or, alternatively, a gamma-Poisson model whenever overdispersion was present, with age, sex, registry and period being used as predictor variables. Childhood cancer was 30% more frequent in boys than in girls, and, except for lymphomas and bone tumours, incidence decreased remarkably with age. Adjusted rates were high in comparison with other European countries, particularly in the case of non-Hodgkin's lymphomas. Cancer rates proved somewhat higher in Navarre, but this difference attained statistical significance solely in the case of central nervous system tumours (rate ratio = 1.75; 95% confidence interval 1.21-2.54). A significant rise in overall incidence was observed (11% 5-yearly increase) due mainly to the upward trend in central nervous system tumours. While the rise in these tumours coincides with the period which witnessed the spread of computerised tomography in Spain, the trend nevertheless held steady over the last 5-year period, when access to this diagnostic technique had already become generalised nationwide.

Childhood and adolescent cancer in Spain: mortality time trends 1956-1990

Using log-linear Poisson modelling, trends in childhood cancer mortality among the population under 20 years of age in Spain are described over the 35-year period from 1956 to 1990. Overall cancer mortality and seven specific sites were considered: all leukaemias, Hodgkin's disease, non-Hodgkin's lymphomas, malignant brain tumours, kidney cancer, malignant bone neoplasms, and a broad category of ill-defined tumours. An age-period-cohort model was used to analyse the influence of age, period of death and birth cohort. Recent trends were estimated by restricting analysis to the last three 5-year periods. In general, mortality began to decline at the beginning of the 1970s, with reductions of 36% in males and 45% in females being registered between 1966-1970 and 1986-1990. The use of age-period-cohort models revealed an initially rising period effect attributable to diagnostic advances. The decline in mortality in post-1965 generations and the final downturn in the period effect are both most certainly a consequence of the remarkable progress achieved in the treatment of such tumours. During the final 15 years, there was a relative decline in mortality of approximately 20% every 5 years. However, in the case of malignant renal tumours in males and malignant bone tumours and non-Hodgkin's lymphomas in both sexes the situation remained stable.

The epidemiology of tuberculosis among foreign-born persons in the United States, 1986 to 1993

BACKGROUND

One third of the world's population is infected with Mycobacterium tuberculosis, and in the developed countries immigration is a major force that sustains the incidence of tuberculosis. We studied the effects of immigration on the epidemiology of tuberculosis and its recent resurgence in the United States.

METHODS

We analyzed data from the national tuberculosis reporting system of the Centers for Disease Control and Prevention. Since 1986 reports of tuberculosis have included the patient's country of origin. Population estimates for foreign-born persons were derived from special samples from the 1980 and 1990 censuses.

RESULTS

The proportion of persons reported to have tuberculosis who were foreign-born increased from 21.6 percent (4925 cases) in 1986 to 29.6 percent (7346 cases) in 1993. For the entire eight-year period, most foreign-born patients with tuberculosis were from Latin America (43.9 percent; 21,115 cases) and Southeast Asia (34.6 percent; 16,643 cases). Among foreign-born persons the incidence rate was almost quadruple the rate for native residents of the United States (30.6 vs. 8.1 per 100,000 person-years), and 55 percent of immigrants with tuberculosis had the condition diagnosed in their first five years in the United States.

CONCLUSIONS

Immigration has had an increasingly important effect on the epidemiology of tuberculosis in the United States. It will be difficult to eliminate tuberculosis without better efforts to prevent and control it among immigrants and greater efforts to control it in the countries from which they come.

Approaches to disease cluster investigations in a state health department

Classical tests for clustering rarely have a major role in the investigation of disease clusters at the neighbourhood level performed by a health department. When examining a single cluster, the boundaries are often ill-defined, and the dimension (geographic, occupational, iatrogenic) is rarely obvious. Furthermore, using cluster tests to routinely scan disease registries looking for clusters is undesirable for several reasons. A better approach is to be vigilant for unusual environmental exposures, and to evaluate the impact they may have. In this context, cluster techniques may serve as part of a larger investigation that includes other epidemiologic approaches.

Characteristics of a random sample of emergency food program users in New York: II. Soup kitchens

A random sample of soup kitchen clients in New York City was studied and specific comparisons made on various parameters including homelessness. Compared with the general population of low income persons, soup kitchen users were overwhelmingly male, disproportionately African-American, and more likely to live alone. The homeless (41 percent of the sample) were less likely to receive food stamps or free food, or to use food pantries. Fewer of them received Medicaid or had health insurance. Forty-seven percent had no income in contrast to 29 percent of the total sample.