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Canning, David

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Canning

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Canning, David
Author's Publications: search.filters.isAuthorOfPublication.4ee38e8d-5be3-4d68-aee2-3f657133d91f

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    Vaccination and All-Cause Child Mortality From 1985 to 2011: Global Evidence From the Demographic and Health Surveys
    (Oxford University Press (OUP), 2015-10-08) McGovern, Mark E.; Canning, David
    Based on models with calibrated parameters for infection, case fatality rates, and vaccine efficacy, basic childhood vaccinations have been estimated to be highly cost effective. We estimated the association of vaccination with mortality directly from survey data. Using 149 cross-sectional Demographic and Health Surveys, we determined the relationship between vaccination coverage and the probability of dying between birth and 5 years of age at the survey cluster level. Our data included approximately 1 million children in 68,490 clusters from 62 countries. We considered the childhood measles, bacillus Calmette-Guerin, diphtheria-pertussis-tetanus, polio, and maternal tetanus vaccinations. Using modified Poisson regression to estimate the relative risk of child mortality in each cluster, we also adjusted for selection bias that resulted from the vaccination status of dead children not being reported. Childhood vaccination, and in particular measles and tetanus vaccination, is associated with substantial reductions in childhood mortality. We estimated that children in clusters with complete vaccination coverage have a relative risk of mortality that is 0.73 (95% confidence interval: 0.68, 0.77) times that of children in a cluster with no vaccinations. Although widely used, basic vaccines still have coverage rates well below 100% in many countries, and our results emphasize the effectiveness of increasing coverage rates in order to reduce child mortality.
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    Exposure to Ambient Fine Particulate Air Pollution in Utero as a Risk Factor for Child Stunting in Bangladesh
    (MDPI, 2017) Goyal, Nihit; Canning, David
    Pregnant mothers in Bangladesh are exposed to very high and worsening levels of ambient air pollution. Maternal exposure to fine particulate matter has been associated with low birth weight at much lower levels of exposure, leading us to suspect the potentially large effects of air pollution on stunting in children in Bangladesh. We estimate the relationship between exposure to air pollution in utero and child stunting by pooling outcome data from four waves of the nationally representative Bangladesh Demographic and Health Survey conducted between 2004 and 2014, and calculating children’s exposure to ambient fine particulate matter in utero using high resolution satellite data. We find significant increases in the relative risk of child stunting, wasting, and underweight with higher levels of in utero exposure to air pollution, after controlling for other factors that have been found to contribute to child anthropometric failure. We estimate the relative risk of stunting in the second, third, and fourth quartiles of exposure as 1.074 (95% confidence interval: 1.014–1.138), 1.150 (95% confidence interval: 1.069–1.237, and 1.132 (95% confidence interval: 1.031–1.243), respectively. Over half of all children in Bangladesh in our sample were exposed to an annual ambient fine particulate matter level in excess of 46 µg/m3; these children had a relative risk of stunting over 1.13 times that of children in the lowest quartile of exposure. Reducing air pollution in Bangladesh could significantly contribute to the Sustainable Development Goal of reducing child stunting.
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    Access to healthcare and financial risk protection for older adults in Mexico: secondary data analysis of a national survey
    (BMJ Publishing Group, 2015) Doubova, Svetlana V; Pérez-Cuevas, Ricardo; Canning, David; Reich, Michael
    Objectives: While the benefits of Seguro Popular health insurance in Mexico relative to no insurance have been widely documented, little has been reported on its effects relative to the pre-existing Social Security health insurance. We analyse the effects of Social Security and Seguro Popular health insurances in Mexico on access to healthcare of older adults, and on financial risk protection to their households, compared with older adults without health insurance. Setting: Secondary data analysis was performed using the 2012 Mexican Survey of Health and Nutrition (ENSANUT). Participants: The study population comprised 18 847 older adults and 13 180 households that have an elderly member. Outcome measures The dependent variables were access to healthcare given the reported need, the financial burden imposed by health expenditures measured through catastrophic health-related expenditures, and using savings for health-related expenditures. Separate propensity score matching analyses were conducted for each comparison. The analysis for access was performed at the individual level, and the analysis for financial burden at the household level. In each case, matching on a wide set of relevant characteristics was achieved. Results: Seguro Popular showed a protective effect against lack of access to healthcare for older adults compared with those with no insurance. The average treatment effect on the treated (ATET) was ascertained through using the nearest-neighbour matching (−8.1%, t-stat −2.305) analysis. However, Seguro Popular did not show a protective effect against catastrophic expenditures in a household where an older adult lived. Social Security showed increased access to healthcare (ATET −11.3%, t-stat −3.138), and protective effect against catastrophic expenditures for households with an elderly member (ATET −1.9%, t-stat −2.178). Conclusions: Seguro Popular increased access to healthcare for Mexican older adults. Social Security showed a significant protective effect against lack of access and catastrophic expenditures compared with those without health insurance.
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    The effect of vaccination on children's physical and cognitive development in the Philippines
    (Informa UK Limited, 2012) Bloom, David; Canning, David; Seiguer Shenoy, Erica
    We use data from the Cebu Longitudinal Health and Nutrition Survey (CLHNS) in the Philippines to link vaccination in the first 2 years of life with later physical and cognitive development in children. We use propensity score matching to estimate the causal effect of vaccination on child development. We find no effect of vaccination on later height or weight, but full childhood vaccination for measles, polio, Tuberculosis (TB), Diphtheria, Pertussis and Tetanus (DPT) significantly increases cognitive test scores relative to matched children who received no vaccinations. The size of the effect is large, raising test scores, on average, by about half an SD.
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    The causes and consequences of demographic transition
    (Informa UK Limited, 2011) Canning, David
    The causes and consequences of the demographic transition are considered in light of the recent book by Dyson (2010) on demography and development. In the last 50 years the world has seen an exogenous decline in mortality that generated a decline in fertility and an increase in urbanization that has had profound economic, social and political consequences. However, historically, declines in mortality and fertility, and escape from the Malthusian trap, have required countries to have already undergone considerable economic and political development. We therefore argue for two way causality between the demographic transition and economic and political outcomes.
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    The Cost of Low Fertility in Europe
    (Springer Science + Business Media, 2009) Bloom, David; Canning, David; Fink, Gunther; Finlay, Jocelyn
    We analyze the effect of fertility on income per capita with a particular focus on the experience of Europe. For European countries with below-replacement fertility, the cost of continued low fertility will only be observed in the long run. We show that in the short run, a fall in the fertility rate will lower the youth dependency ratio and increase the working-age share, thus raising income per capita. In the long run, however, the burden of old-age dependency dominates the youth dependency decline, and continued low fertility will lead to small working-age shares in the absence of large migration inflows. We show that the currently very high working-age shares generated by the recent declines in fertility and migration inflows are not sustainable, and that significant drops in the relative size of the working-age population should be expected. Without substantial adjustments in labor force participation or migration policies, the potential negative repercussions on the European economy are large.
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    The association of maternal age with infant mortality, child anthropometric failure, diarrhoea and anaemia for first births: Evidence from 55 low- and middle-income countries
    (BMJ, 2011) Finlay, Jocelyn; Ozaltin, E.; Canning, David
    Objective: To examine the association between maternal age at first birth and infant mortality, stunting, underweight, wasting, diarrhoea and anaemia in children in low- and middle income countries. Design: Cross-sectional analysis of nationally representative household samples. A modified Poisson regression model is used to estimate unadjusted and adjusted RR ratios. Setting: Low- and middle-income countries. Population: First births to women aged 12-35 where this birth occurred 12-60 months prior to interview. The sample for analysing infant mortality is comprised of 176 583 children in 55 low- and middle-income countries across 118 Demographic and Health Surveys conducted between 1990 and 2008. Main outcome measures: Infant mortality in children under 12 months and stunting, underweight, wasting, diarrhoea and anaemia in children under 5 years. Results: The investigation reveals two salient findings. First, in the sample of women who had their first birth between the ages of 12 and 35, the risk of poor child health outcome is lowest for women who have their first birth between the ages of 27 and 29. Second, the results indicate that both biological and social mechanisms play a role in explaining why children of young mothers have poorer outcomes. Conclusions: The first-born children of adolescent mothers are the most vulnerable to infant mortality and poor child health outcomes. Additionally, first time mothers up to the age of 27 have a higher risk of having a child who has stunting, diarrhoea and moderate or severe anaemia. Maternal and child health programs should take account of this increased risk even for mothers in their early 20s. Increasing the age at first birth in developing countries may have large benefits in terms of child health.
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    Progress in Health around the World
    (Informa UK Limited, 2012) Canning, David
    Health is a key component of human development. This article looks at how health is measured, and the convergence of health across countries. We argue that health measures should account for illness as well as mortality, but in practice life expectancy is a reasonable proxy for population health. While health is improving we see two distinct groups of countries in the data, clustering around different long run steady states. Many countries have experienced large health gains without prior income gains and in countries not affected by HIV/AIDS the last 40 years have been a success story in terms of health.
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    Adjusting HIV prevalence estimates for non-participation: an application to demographic surveillance
    (International AIDS Society, 2015) McGovern, Mark E.; Marra, Giampiero; Radice, Rosalba; Canning, David; Newell, Marie-Louise; Bärnighausen, Till
    Introduction: HIV testing is a cornerstone of efforts to combat the HIV epidemic, and testing conducted as part of surveillance provides invaluable data on the spread of infection and the effectiveness of campaigns to reduce the transmission of HIV. However, participation in HIV testing can be low, and if respondents systematically select not to be tested because they know or suspect they are HIV positive (and fear disclosure), standard approaches to deal with missing data will fail to remove selection bias. We implemented Heckman-type selection models, which can be used to adjust for missing data that are not missing at random, and established the extent of selection bias in a population-based HIV survey in an HIV hyperendemic community in rural South Africa. Methods: We used data from a population-based HIV survey carried out in 2009 in rural KwaZulu-Natal, South Africa. In this survey, 5565 women (35%) and 2567 men (27%) provided blood for an HIV test. We accounted for missing data using interviewer identity as a selection variable which predicted consent to HIV testing but was unlikely to be independently associated with HIV status. Our approach involved using this selection variable to examine the HIV status of residents who would ordinarily refuse to test, except that they were allocated a persuasive interviewer. Our copula model allows for flexibility when modelling the dependence structure between HIV survey participation and HIV status. Results: For women, our selection model generated an HIV prevalence estimate of 33% (95% CI 27–40) for all people eligible to consent to HIV testing in the survey. This estimate is higher than the estimate of 24% generated when only information from respondents who participated in testing is used in the analysis, and the estimate of 27% when imputation analysis is used to predict missing data on HIV status. For men, we found an HIV prevalence of 25% (95% CI 15–35) using the selection model, compared to 16% among those who participated in testing, and 18% estimated with imputation. We provide new confidence intervals that correct for the fact that the relationship between testing and HIV status is unknown and requires estimation. Conclusions: We confirm the feasibility and value of adopting selection models to account for missing data in population-based HIV surveys and surveillance systems. Elements of survey design, such as interviewer identity, present the opportunity to adopt this approach in routine applications. Where non-participation is high, true confidence intervals are much wider than those generated by standard approaches to dealing with missing data suggest.
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    Using interviewer random effects to remove selection bias from HIV prevalence estimates
    (Springer Science + Business Media, 2015) McGovern, Mark; Bärnighausen, Till; Salomon, Joshua; Canning, David
    Background Selection bias in HIV prevalence estimates occurs if non-participation in testing is correlated with HIV status. Longitudinal data suggests that individuals who know or suspect they are HIV positive are less likely to participate in testing in HIV surveys, in which case methods to correct for missing data which are based on imputation and observed characteristics will produce biased results. Methods The identity of the HIV survey interviewer is typically associated with HIV testing participation, but is unlikely to be correlated with HIV status. Interviewer identity can thus be used as a selection variable allowing estimation of Heckman-type selection models. These models produce asymptotically unbiased HIV prevalence estimates, even when non-participation is correlated with unobserved characteristics, such as knowledge of HIV status. We introduce a new random effects method to these selection models which overcomes non-convergence caused by collinearity, small sample bias, and incorrect inference in existing approaches. Our method is easy to implement in standard statistical software, and allows the construction of bootstrapped standard errors which adjust for the fact that the relationship between testing and HIV status is uncertain and needs to be estimated. Results Using nationally representative data from the Demographic and Health Surveys, we illustrate our approach with new point estimates and confidence intervals (CI) for HIV prevalence among men in Ghana (2003) and Zambia (2007). In Ghana, we find little evidence of selection bias as our selection model gives an HIV prevalence estimate of 1.4% (95% CI 1.2% – 1.6%), compared to 1.6% among those with a valid HIV test. In Zambia, our selection model gives an HIV prevalence estimate of 16.3% (95% CI 11.0% - 18.4%), compared to 12.1% among those with a valid HIV test. Therefore, those who decline to test in Zambia are found to be more likely to be HIV positive. Conclusions Our approach corrects for selection bias in HIV prevalence estimates, is possible to implement even when HIV prevalence or non-participation is very high or very low, and provides a practical solution to account for both sampling and parameter uncertainty in the estimation of confidence intervals. The wide confidence intervals estimated in an example with high HIV prevalence indicate that it is difficult to correct statistically for the bias that may occur when a large proportion of people refuse to test.