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PubMed1981

Demography and computer simulation in historic village population reconstruction.

"Demographic anthropology has given rise to methodological advances in the analysis of single community populations. However, the obstacles of small data bases and incomplete vital-event registration remain. This paper details one approach to these problems; the principles of community demography are incorporated with computer simulation methodology, with the goals of validating the internal consistency of and determining demographic secular trends from data commonly utilized in anthropological investigations." The approach is tested on data for the 250 inhabitants of Old Crow Village, Yukon Territory, Canada, in 1978.

Americas↗
PubMed1996

Demonstrating programme impact on maternal mortality.

Reducing maternal mortality if one of the primary goals of safe mother hood programmes in developing countries. Maternal mortality is not, however, a feasible outcome indicator with which to judge the success of these programmes. This is due to an unfortunate combination of obstacles to measurement--some general to assessing the mortality impact of health programmes and some peculiar to estimating maternal mortality. There is a need to promote alternative views and measures of programme success, and alternative uses for information on maternal deaths.

Developing Countries↗
PubMed1989

Societies in transition: mortality patterns in Pacific Island populations.

The 22 Pacific Island countries and territories are in a state of demographic and epidemiological transition. Mortality data for the period around 1980 were collected from various sources and are presented in this comparative study. Because death registration in many Pacific countries is deficient some data have been adjusted for underenumeration; and some mortality estimates have been calculated by indirect means, using data from censuses or surveys. Cause of death information is affected by diagnostic inaccuracy and often tabulated in broad categories only; in some Pacific countries cause of death data are only available on hospital deaths. The less developed Melanesian malarious countries and the less developed dispersed atoll nations manifest higher mortality, and higher proportional mortality from infectious disease compared with other states. The more developed US-associated states, two New Zealand-associated states, and New Caledonian Europeans all have reasonably low mortality, and relatively high proportional mortality from cardiovascular disease (CVD). Females have longer life expectancy at birth than males in all countries except Vanuatu and the Solomon Islands. The phosphate-rich island of Nauru presents an atypical picture with considerable adult male mortality from diseases associated with modernization.

Adolescent↗
PubMed1991

Validation of the diagnosis of childhood morbidity using maternal health interviews.

The diagnosis of childhood illness by maternal health interview surveys is widely used to estimate the prevalence of childhood morbidity in developing countries. To determine the validity of interview-based diagnoses, and to define simple, sensitive and specific diagnostic algorithms, we compared symptoms and signs reported by mothers during structured interviews with physicians' diagnoses for 271 children on the Philippine island of Cebu. The 271 children had 318 physician diagnosed illnesses: 105 acute lower respiratory infections (ALRI), 121 diarrhoeas, 36 measles, 50 upper respiratory infections (URTI), 5 roseola infantums and one milaria rubria. An algorithm for measles (age greater than or equal to 120 days, rash and fever greater than or equal to 3 days and fading of rash) had a sensitivity and specificity of 94%. For ALRI an algorithm of cough, dysponea and fever had a sensitivity of 82%, but specificity was lower in comparison with URTI (58%) than with children who had no respiratory illness (79%). Inclusion of signs of respiratory distress (flaring of nostrils, intercostal retraction) raised the specificity to 83-84%, but reduced sensitivity to 68%. Diagnosis of diarrhoea based on frequent loose or liquid stools had a sensitivity of 95-97% and specificity of 80% in children with or without concomitant non-diarrhoeal illnesses. Addition of questions on numbers of stools (greater than or equal to 6 per day), and no signs of dehydration increased specificity to 95% but reduced the sensitivity to 84-86%. However, specific signs of dehydration were not well reported by the mothers.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1991

Specificity of association in analysis of mortality and inference on causality.

Specificity of association between putative risk factor and disease under study is important to inference on causality. Nevertheless many studies investigate mortality of a single disease without comparison with a control. Age-standardized proportional mortality ratios make single disease studies into case-control studies and thus demonstrate whether or not associations are disease specific. Comparison of disease-specific with all-cause mortality experiences of whole populations classified by exposure, clearly distinguishes between exposures associated with more death and with earlier/younger death, thereby overcoming an important limitation of the familiar standardized mortality ratio (SMR). Smoking is associated with more death from lung cancer (lifetime cause-specific proportions, never 1%, light 6%, moderate 8% and heavy 12%) and with earlier/younger death from ischaemic heart disease (never 35%, light 34%, moderate 32% and heavy 29%).

Adult↗
PubMed1993

Incidence of HIV-1 infection among adults in the Kagera region of Tanzania.

The results of a population-based follow-up study are presented. The baseline study which started in August 1987, was carried out to determine the prevalence of human immunodeficiency virus (HIV-1) infection in the Kagera region of Tanzania. A multistage cluster sampling technique was adopted in the selection of the study population. In the follow-up survey which started in June 1988, members of the same study population were revisited and studied in order to determine the incidence of HIV-1 infection among those who were HIV seronegative in the initial survey. HIV serology was conducted by using enzyme-linked immunosorbent assay and all positive sera were confirmed by the Western blot technique. A total population of 1316 adults aged 15-54 years was studied, constituting an average follow-up response rate of 69% in the rural areas and of 59% in the urban area. The overall incidence of HIV-1 infection among the adult population sample was 13.7 per 1000 person-years at risk with the highest incidence in the urban zone (47.5 per 1000 person-years at risk) and the lowest incidence in one of the three rural zones (4.9 per 1000 person-years at risk). The age-specific annual incidence was highest in the age group 25-34 years for males and in the age group 15-24 for females. From these results it was estimated that the number of newly infected adults in the region each year is about 8200 with a range between 5400 and 11,000 corresponding to the 95% confidence limits on the overall incidence.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1995

United States mortality from ill-defined causes, 1968-1988: potential effects on heart disease mortality trends.

BACKGROUND: Deaths are coded to the International Classification of Diseases (ICD) category, 'Symptoms, Signs, and ill-defined Conditions' when there is insufficient information for cause of death determination. Due to difficulties of diagnosis of coronary heart disease (CHD) death and since CHD is the leading cause of death among US adults, CHD is the most likely cause of ill-defined deaths. METHODS: Vital statistics and census data were used to create annual age-adjusted ill-defined rates, unrevised CHD rates, and CHD rates revised to include ill-defined deaths for US African Americans and whites, ages 35-74 years, during 1968-1988. Ill-defined and CHD mortality trend analyses were conducted. RESULTS: In 1968, African American/white ratios of ill-defined mortality were 5 among men and 7 among women; following steep declines in ill-defined mortality among African Americans, ratios were 3 among men and 2 among women in 1988. In 1968, approximately 3% and 1% of all deaths among African Americans and whites, respectively, were certified to ill-defined causes; in 1988, approximately 1.5% of deaths among African Americans were coded ill-defined, with no change among whites. Revised CHD rates showed substantially higher excess CHD mortality among African Americans than whites compared to unrevised CHD rates. Declines in revised CHD mortality steepened throughout the study period among men, and among women began to decelerate after 1978. CONCLUSIONS: Ill-defined mortality was of sufficient magnitude to potentially contribute to substantial underestimation of racial disparities in CHD mortality. Also, temporal changes in ill-defined mortality may have affected CHD trends which are used to evaluate the efficacy of public health interventions.

Adult↗
PubMed1995

Life table analysis of the United States' Year 2000 mortality objectives.

BACKGROUND: The US Year 2000 mortality objectives are model standards cast as targeted changes in age-adjusted cause-specific death rates. This research centred on the projected impact of such changes on life expectancy and the mortality toll for each sex. METHODS: A computer simulation was conducted using single decrement, multiple decrement and cause-elimination life table techniques, together with a decomposition procedure. RESULTS: Male and female life expectancy at birth was projected to increase by 1.71 and 1.51 years, respectively, between the designated 1987 baseline and 2000. The leading beneficiaries would be those aged 65 and older, followed by those aged 45-64, and infants. Declines in coronary heart disease, stroke and injury death rates would most influence the projected life expectancy changes, irrespective of sex. Approximately 782,000 male deaths and 730,000 female deaths would be averted under Year 2000 assumptions. CONCLUSIONS: Life expectancy would be a useful summary measure to incorporate into official evaluations of the Year 2000 mortality objectives. Targeting of excess male mortality in the US and other highly industrialized nations is recommended.

Adolescent↗
PubMed1995

A comparison of sisterhood information on causes of maternal death with the registration causes of maternal death in Matlab, Bangladesh.

BACKGROUND: To explore whether causes of maternal death can be investigated using the sisterhood method, an indirect method for providing a community-based estimate of the level of maternal mortality, this study compares the sisterhood causes of maternal death with the Matlab Demographic Surveillance System's (DSS) causes of maternal death. METHODS: Data for this study came from the Matlab DSS, which has been in operation since 1966 as a field site of the International Centre for Diarrhoeal Disease Research, Bangladesh. The maternal deaths that occurred during the 15-year period from 1976 to 1990 in the Matlab DSS area are the basis of this study. A sisterhood survey was conducted in Matlab in November and December 1991 to collect information on conditions, events and symptoms that preceded death. The collected information was evaluated to assign a most likely cause of maternal death. The sisterhood survey cause of maternal death was then compared with the DSS cause of maternal death. RESULTS: Cause of death could not be assigned with reasonable confidence for 34 (11%) of the 305 maternal deaths for which information was collected. For the remaining deaths, the agreement between the two classification systems was generally high for most cause-of-death categories considered. CONCLUSIONS: Though cause-of-death information obtained by the sisterhood method will always be subject to some error, it can provide an indication of an overall distribution of causes of maternal deaths. This data can be used for the planning of programmes aimed at reducing maternal mortality and for the evaluation of such programmes over time.

Abortion, Induced↗
PubMed1998

Provisional country estimates of prevalent adult human immunodeficiency virus infections as of end 1994: a description of the methods.

BACKGROUND: A country-by-country review of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) data was undertaken by the World Health Organization. This paper describes the methods used to make estimates of HIV prevalence. RESULTS: It is estimated that, globally, approximately 16.9 million adults were living with HIV infections at the end of 1994. The majority (66%) of the infections were in sub-Saharan Africa (over 11000000), followed by South and South East Asia (over 3000000). Estimated prevalence rates for HIV infection ranged from less than 1 per 100000 sexually active adult population to 18 per 100 (18%), with a median prevalence of 14 per 10000. In 50 countries the estimated HIV prevalence rate was less than 5 per 10000 sexually active adults. In 15 countries (all in sub-Saharan Africa) the prevalence rate was above 5%. The lowest estimated prevalence rates were seen in Central and East Asia and the highest in Central and Southern Africa. CONCLUSIONS: Estimates of prevalent HIV infections are intended to give an indication of the magnitude of the HIV pandemic but, due to the difficulties in accurately assessing the levels of HIV infections in national populations, should be considered provisional.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Projected mortality from lung cancer in South Korea, 1980-2004.

BACKGROUND: In recent years, mortality from lung cancer has increased rapidly in Korea, a South East Asian country with a high prevalence of smoking. The objectives of this study are to examine how age, period, and birth cohort effects contributed to trends in lung cancer mortality in Korea 1980-1994, and to predict lung cancer mortality rates for 1995-2004. METHODS: Age- and sex-specific lung cancer mortality rates were obtained from annual reports of the National Office of Statistics in Korea. Poisson regression models were used to estimate age, period and cohort effects. RESULTS: Among men, age-adjusted annual mortality rates from lung cancer (per 100000) increased from 3.7 in 1980 to 17.8 in 1994; corresponding rates for women were 1.4 and 7.0. As age increased, mortality rates from lung cancer increased more rapidly in men than in women. Within the same age group, the mortality of younger cohorts was higher than older cohorts. The average annual number of lung cancer deaths projected for the years 2000-2004 among men and women will be 15441 and 3572 respectively, while the average annual age-adjusted mortality rates from lung cancer (per 100000) will be 65.4 for men and 15.1 for women. These rates correspond to 17.7- and 10.7-fold increases over the 1980 mortality rates in men and women, respectively. CONCLUSION: These results, in conjunction with trends in tobacco consumption, indicate that mortality from lung cancer in both men and women will increase substantially through the early part of the 21st century in Korea.

Adult↗
PubMed1998

Inappropriate use of daily mortality analyses to estimate longer-term mortality effects of air pollution.

BACKGROUND: To avoid the usual problems of multi-population correlation studies of air pollution and mortality, and for reasons of convenience, daily time-series mortality studies within single populations have recently become popular in air pollution epidemiology. Such studies describe how the short-term distribution of deaths relates to short-term fluctuations in air pollution levels. The regression-based risk coefficients from these acute-effects studies have been widely used to estimate the excess annual mortality within a population with a specified average level of air pollution. Such calculations are inappropriate. Since daily time-series data provide no simple direct information about the degree of life-shortening associated with the excess daily deaths (many of which are thought to be due to exacerbation of well-advanced disease, especially cardiovascular disease), such data cannot contribute to the estimation of the effects of air pollution upon chronic disease incidence and long-term death rates. Yet it is that category of effect that is of most public health importance. CONCLUSION: Such effects are best estimated from long-term cohort studies that incorporate good knowledge of local (or personal) exposure to air pollutants and of potential confounders. Time-series studies, properly evaluated, can identify the existence of acute toxic effects of transient peak levels of air pollution; they are thus useful for monitoring acute toxicity and for identifying the most noxious pollutants. However, to quantify the long-term health impacts of air pollution we cannot use acute-effects data.

Air Pollution↗
PubMed1998

Estimating deaths and injuries due to road traffic accidents in Karachi, Pakistan, through the capture-recapture method.

BACKGROUND: Road traffic accidents (RTA) are an important yet preventable cause of death and disability in developing countries like Pakistan. Yet accurate epidemiological data on injuries in developing country injuries is often difficult to obtain. We applied the capture-recapture method to estimate the death and injury rates due to RTA in Karachi. METHODS: We applied the two-sample capture-recapture method using traffic police records as one source of capture and the logs of a non-government ambulance service as the second capture source for the same 10 months and 20 days for which 1994 data were available. We generated a conservative adjusted estimate of injuries and deaths by considering entries in the two sources as matched if they reported the same date, time, and place, and at least one of the other matching variables, of name, vehicle registration number, vehicle types or patient outcome. We then compared the estimated rates with the police rates. RESULTS: In 1994 police reported 544 deaths and 793 injuries due to RTA while ambulance records noted 343 deaths and 2048 injuries. The capture-recapture analysis estimated at least 972 (95% CI: 912-1031) deaths and 18,936 (95% CI: 15,507-22,342) injuries attributable to RTA during the study period. Official sources counted only 56% of deaths and 4% of serious injuries. The estimated rates for the year 1994 were 185 injuries and 11.2 deaths per 100,000 population. CONCLUSION: Road traffic injuries and deaths in Karachi are a much more substantial health problem than is evident from official statistics.

Accidents↗
PubMed1999

The comparison of mixed distribution analysis with a three-criteria model as a method for estimating the prevalence of iron deficiency anaemia in Costa Rican children aged 12-23 months.

BACKGROUND: A maximum likelihood method of mixed distribution analysis (MDA) is presented as a method to estimate the prevalence of iron deficiency anaemia (IDA) in Costa Rican infants 12-23 months old. MDA characterizes the parameters of the admixed distributions of iron deficient anaemics and non-iron-deficient-anaemics (NA) from the frequency distribution of haemoglobin concentration of the total sample population. METHODS: Data collected by Lozoff et al. (1986) from 345 Costa Rican infants 12-23 months old were used to estimate the parameters of the IDA and NA haemoglobin distributions determined by MDA and the widely used three-criteria model of iron deficiency. The estimates of the prevalence of IDA by each of the methods were compared. The sensitivity and specificity of MDA compared to diagnosis by the three-criteria method were assessed. Simulations were carried out to assess the comparability of MDA and the three-criteria method in low and high prevalence scenarios. RESULTS: The mean and standard deviation (SD) of the NA haemoglobin distribution determined by both methods was 12.1 +/- 1.0 g/dL. The IDA haemoglobin distribution determined by MDA had a mean and SD of 10.2 +/- 1.3 g/dL while the IDA distribution by the three-criteria method had a mean and SD of 10.4 +/- 1.3 g/dL. The prevalences of IDA as estimated by MDA and the three-criteria method were 24% and 29%, respectively. The sensitivity and specificity of MDA were 95% and 97%, respectively. The performance of MDA was similar to the three-criteria method at a simulated high prevalence of IDA and less similar at a low prevalence of IDA. CONCLUSIONS: Compared to the reference three-criteria method MDA provides a more accurate estimate of the true prevalence of IDA than the haemoglobin cutoff method in a population of children aged 12-23 months with a moderate to high prevalence of IDA. MDA is a less costly method for estimating the severity of IDA in populations with moderate to high prevalences of IDA, and for assisting in the design, monitoring and evaluation of iron intervention programmes.

Anemia, Iron-Deficiency↗
PubMed1986

Projection of mean and variance functions for population processes with time-homogeneous laws of evolution.

This paper provides algorithms for projection of mean and covariance functions for stochastic population processes governed by time-homogeneous laws of fertility and mortality. The theoretical foundation of the algorithms is general age-dependent branching processes in discrete time. The algorithms are employed in several illustrative projections, based on 1982 Chinese data, of a population experiencing an abrupt transition to below replacement fertility. Methods of constructing confidence limits for total population size are illustrated. Also developed are procedures for projecting mean and variance functions for populations which may be heterogeneous with respect to mortality or fertility. The projections performed yield two observations. First, the coefficient of variation in population size appears to be inversely related to the Malthusian parameter of population growth. Second, the coefficient of variation for population size is negligible for large homogeneous initial populations. But when the initial population is heterogeneous with respect to fertility or mortality, then substantial coefficients of variation, exceeding 0.4, are observed in some of the projections performed.

Analysis of Variance↗
PubMed1987

Demographic heterogeneity and uncertainty in population projections.

Recent developments in a class of stochastic population processes were used to study the impact of demographic heterogeneity on the uncertainty of population projections. Selected for study by computer simulation were population projections for East Africa designed to quantify opinions regarding expected fertility and mortality declines. Since both fertility and mortality declined in these projections, their laws of evolution may be described as time inhomogeneous. The computer simulation studies reported in this paper strongly suggest that randomized laws of evolution should be taken into account in further developments of population projection methodologies designed formally and computationally to accommodate uncertainty. Variability in fecundability, the kind of demographic heterogeneity studied in this paper, is only one aspect of these randomized laws.

Africa, Eastern↗