Maquins Sewe

Profile: The KEMRI/CDC Health and Demographic Surveillance System—Western Kenya

The KEMRI/Centers for Disease Control and Prevention (CDC) Health and Demographic Surveillance System (HDSS) is located in Rarieda, Siaya and Gem Districts (Siaya County), lying northeast of Lake Victoria in Nyanza Province, western Kenya. The KEMRI/CDC HDSS, with approximately 220 000 inhabitants, has been the foundation for a variety of studies, including evaluations of insecticide-treated bed nets, burden of diarrhoeal disease and tuberculosis, malaria parasitaemia and anaemia, treatment strategies and immunological correlates of malaria infection, and numerous HIV, tuberculosis, malaria and diarrhoeal disease treatment and vaccine efficacy and effectiveness trials for more than a decade. Current studies include operations research to measure the uptake and effectiveness of the programmatic implementation of integrated malaria control strategies, HIV services, newly introduced vaccines and clinical trials. The HDSS provides general demographic and health information (such as population age structure and density, fertility rates, birth and death rates, in- and out-migrations, patterns of health care access and utilization and the local economics of health care) as well as disease- or intervention-specific information. The HDSS also collects verbal autopsy information on all deaths. Studies take advantage of the sampling frame inherent in the HDSS, whether at individual, household/compound or neighbourhood level.

A reversal in reductions of child mortality in Western Kenya, 2003-2009

We report and explore changes in child mortality in a rural area of Kenya during 2003-2009, when major public health interventions were scaled-up. Mortality ratios and rates were calculated by using the Kenya Medical Research Institute/Centers for Disease Control and Prevention Demographic Surveillance System. Inpatient and outpatient morbidity and mortality, and verbal autopsy data were analyzed. Mortality ratios for children less than five years of age decreased from 241 to 137 deaths/1,000 live-births in 2003 and 2007 respectively. In 2008, they increased to 212 deaths/1,000 live-births. Mortality remained elevated during the first 8 months of 2009 compared with 2006 and 2007. Malaria and/or anemia accounted for the greatest increases in child mortality. Stock-outs of essential antimalarial drugs during a time of increased malaria transmission and disruption of services during civil unrest may have contributed to increased mortality in 2008-2009. To maintain gains in child survival, implementation of good policies and effective interventions must be complemented by reliable supply and access to clinical services and essential drugs.

Mortality trends in the era of antiretroviral therapy: evidence from the Network for Analysing Longitudinal Population based HIV/AIDS data on Africa (ALPHA)

Background:The rollout of antiretroviral therapy (ART) is one of the largest public health interventions in Eastern and Southern Africa of recent years. Its impact is well described in clinical cohort studies, but population-based evidence is rare. Methods:We use data from seven demographic surveillance sites that also conduct community-based HIV testing and collect information on the uptake of HIV services. We present crude death rates of adults (aged 15–64) for the period 2000–2011 by sex, HIV status, and treatment status. Parametric survival models are used to estimate age-adjusted trends in the mortality rates of people living with HIV (PLHIV) before and after the introduction of ART. Results:The pooled ALPHA Network dataset contains 2.4 million person-years of follow-up time, and 39114 deaths (6893 to PLHIV). The mortality rates of PLHIV have been relatively static before the availability of ART. Mortality declined rapidly thereafter, with typical declines between 10 and 20% per annum. Compared with the pre-ART era, the total decline in mortality rates of PLHIV exceeds 58% in all study sites with available data, and amounts to 84% for women in Masaka (Uganda). Mortality declines have been larger for women than for men; a result that is statistically significant in five sites. Apart from the early phase of treatment scale up, when the mortality of PLHIV on ART was often very high, mortality declines have been observed in PLHIV both on and off ART. Conclusion:The expansion of treatment has had a large and pervasive effect on adult mortality. Mortality declines have been more pronounced for women, a factor that is often attributed to womens greater engagement with HIV services. Improvements in the timing of ART initiation have contributed to mortality reductions in PLHIV on ART, but also among those who have not (yet) started treatment because they are increasingly selected for early stage disease.

Cause-specific childhood mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

Background Because most deaths in Africa and Asia are not well documented, estimates of mortality are often made using scanty data. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering all deaths over time and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available. Objective To build a large standardised mortality database from African and Asian sites, detailing the relevant methods, and use it to describe cause-specific mortality patterns. Design Individual demographic and verbal autopsy (VA) data from 22 INDEPTH sites were collated into a standardised database. The INDEPTH 2013 population was used for standardisation. The WHO 2012 VA standard and the InterVA-4 model were used for assigning cause of death. Results A total of 111,910 deaths occurring over 12,204,043 person-years (accumulated between 1992 and 2012) were registered across the 22 sites, and for 98,429 of these deaths (88.0%) verbal autopsies were successfully completed. There was considerable variation in all-cause mortality between sites, with most of the differences being accounted for by variations in infectious causes as a proportion of all deaths. Conclusions This dataset documents individual deaths across Africa and Asia in a standardised way, and on an unprecedented scale. While INDEPTH sites are not constructed to constitute a representative sample, and VA may not be the ideal method of determining cause of death, nevertheless these findings represent detailed mortality patterns for parts of the world that are severely under-served in terms of measuring mortality. Further papers explore details of mortality patterns among children and specifically for NCDs, external causes, pregnancy-related mortality, malaria, and HIV/AIDS. Comparisons will also be made where possible with other findings on mortality in the same regions. Findings presented here and in accompanying papers support the need for continued work towards much wider implementation of universal civil registration of deaths by cause on a worldwide basis.Background Because most deaths in Africa and Asia are not well documented, estimates of mortality are often made using scanty data. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering all deaths over time and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available. Objective To build a large standardised mortality database from African and Asian sites, detailing the relevant methods, and use it to describe cause-specific mortality patterns. Design Individual demographic and verbal autopsy (VA) data from 22 INDEPTH sites were collated into a standardised database. The INDEPTH 2013 population was used for standardisation. The WHO 2012 VA standard and the InterVA-4 model were used for assigning cause of death. Results A total of 111,910 deaths occurring over 12,204,043 person-years (accumulated between 1992 and 2012) were registered across the 22 sites, and for 98,429 of these deaths (88.0%) verbal autopsies were successfully completed. There was considerable variation in all-cause mortality between sites, with most of the differences being accounted for by variations in infectious causes as a proportion of all deaths. Conclusions This dataset documents individual deaths across Africa and Asia in a standardised way, and on an unprecedented scale. While INDEPTH sites are not constructed to constitute a representative sample, and VA may not be the ideal method of determining cause of death, nevertheless these findings represent detailed mortality patterns for parts of the world that are severely under-served in terms of measuring mortality. Further papers explore details of mortality patterns among children and specifically for NCDs, external causes, pregnancy-related mortality, malaria, and HIV/AIDS. Comparisons will also be made where possible with other findings on mortality in the same regions. Findings presented here and in accompanying papers support the need for continued work towards much wider implementation of universal civil registration of deaths by cause on a worldwide basis.

The adult population impact of HIV care and antiretroviral therapy in a resource poor setting 2003-2008.

Objective:To describe the population uptake of HIV care including antiretroviral therapy (ART) and its impact on adult mortality in a rural area of western Kenya with high HIV prevalence during a period of rapid HIV services scale-up. Design:Adult medical chart data were abstracted at health facilities providing HIV care/ART to residents of a Health and Demographic Surveillance System (HDSS) and linked with HDSS demographic and mortality data. Methods:We evaluated secular trends in patient characteristics across enrollment years and estimated proportions of HIV-positive adult residents receiving care. We evaluated adult (18–64 years) population mortality trends using verbal autopsy findings. Results:From 2003 to 2008, 5421 HDSS-resident adults enrolled in HIV care; 61.4% (nu200a=u200a3331) were linked to HDSS follow-up data. As the number of facilities expanded from 1 (2003) to 17 (2008), receipt of HIV services by HIV-positive residents increased from less than 1 to 29.5%, and ART coverage reached 64.0% of adults with CD4 cell count less than 250u200acells/&mgr;l. The proportion of patients with WHO stage 4 at enrollment decreased from 20.4 to 1.9%, and CD4 cell count testing at enrollment increased from 1.0 to 53.4%. Population-level mortality rates for adults declined 34% for all causes, 26% for AIDS/tuberculosis, and 47% for other infectious diseases; noninfectious disease mortality rates remained constant. Conclusion:The initial years of rapid HIV service expansion coincided with a drop in adult mortality by a third. Continued expansion of population access to HIV clinical services, including ART, and program quality improvements will be necessary to achieve further progress in reducing HIV-related morbidity and mortality.

Risk factors for excess mortality and death in adults with tuberculosis in Western Kenya.

OBJECTIVESnTo evaluate excess mortality and risk factors for death during anti-tuberculosis treatment in Western Kenya.nnnMETHODSnWe abstracted surveillance data and compared mortality rates during anti-tuberculosis treatment with all-cause mortality from a health and demographic surveillance population to obtain standardised mortality ratios (SMRs). Risk factors for excess mortality were obtained using a relative survival model, and for death during treatment using a proportional hazards regression model.nnnRESULTSnThe crude mortality rate during anti-tuberculosis treatment was 18.0 (95%CI 16.8-19.2) per 100 person-years. The age and sex SMR was 8.8 (95%CI 8.2-9.4). Excess mortality was greater in human immunodeficiency virus (HIV) positive TB patients (excess hazard ratio [eHR] 2.1, 95%CI 1.5-3.1), and lower in patients who were female or started treatment in a later year. Mortality was high in patients with unknown HIV status (HR 2.9, 95%CI 2.2-3.8) or, if HIV-positive, not on antiretroviral treatment (ART; HR 3.3, 95%CI 2.5-4.5) or not known to be on ART (HR 2.8, 95%CI 2.1-3.7). The attributable fraction of incomplete uptake of HIV testing and ART on mortality was 31% (95%CI 15-45) compared to HIV-positive patients on ART.nnnCONCLUSIONnIncreasing the uptake of HIV testing and ART would further reduce mortality during anti-tuberculosis treatment by an estimated 31%.

Remotely Sensed Environmental Conditions and Malaria Mortality in Three Malaria Endemic Regions in Western Kenya

Background Malaria is an important cause of morbidity and mortality in malaria endemic countries. The malaria mosquito vectors depend on environmental conditions, such as temperature and rainfall, for reproduction and survival. To investigate the potential for weather driven early warning systems to prevent disease occurrence, the disease relationship to weather conditions need to be carefully investigated. Where meteorological observations are scarce, satellite derived products provide new opportunities to study the disease patterns depending on remotely sensed variables. In this study, we explored the lagged association of Normalized Difference Vegetation Index (NVDI), day Land Surface Temperature (LST) and precipitation on malaria mortality in three areas in Western Kenya. Methodology and Findings The lagged effect of each environmental variable on weekly malaria mortality was modeled using a Distributed Lag Non Linear Modeling approach. For each variable we constructed a natural spline basis with 3 degrees of freedom for both the lag dimension and the variable. Lag periods up to 12 weeks were considered. The effect of day LST varied between the areas with longer lags. In all the three areas, malaria mortality was associated with precipitation. The risk increased with increasing weekly total precipitation above 20 mm and peaking at 80 mm. The NDVI threshold for increased mortality risk was between 0.3 and 0.4 at shorter lags. Conclusion This study identified lag patterns and association of remote- sensing environmental factors and malaria mortality in three malaria endemic regions in Western Kenya. Our results show that rainfall has the most consistent predictive pattern to malaria transmission in the endemic study area. Results highlight a potential for development of locally based early warning forecasts that could potentially reduce the disease burden by enabling timely control actions.

The Association of Weather Variability and Under Five Malaria Mortality in KEMRI/CDC HDSS in Western Kenya 2003 to 2008: A Time Series Analysis

Malaria is among the leading causes of mortality in the younger under-five group of children zero to four years of age. This study aims at describing the relationship between rainfall and temperature on under-five malaria or anaemia mortality in Kenya Medical Research Institute and United States Centers for Disease Control (KEMRI/CDC) Health and Demographic Surveillance System (HDSS). This study was conducted through the ongoing KEMRI and CDC collaboration. A general additive model with a Poisson link function was fit to model the weekly association of lagged cumulative rainfall and average temperature on malaria/anemia mortality in KEMRI/CDC HDSS for the period 2003 to 2008. A trend function was included in the model to control for time trends and seasonality not explained by weather fluctuations. 95% confidence intervals was presented with estimates. Malaria or anemia mortality was found to be associated with changes in temperature and rainfall in the KEMRI HDSS, with a delay up to 16 weeks. The empirical estimates of associations describe established biological relationships well. This information, and particularly, the strength of the relationships over longer lead times can highlight the possibility of developing a predictive forecast with lead times up to 16 weeks in order to enhance preparedness to high transmission episodes.

A Spatial Hierarchical Analysis of the Temporal Influences of the El Niño-Southern Oscillation and Weather on Dengue in Kalutara District, Sri Lanka

Dengue is the major public health burden in Sri Lanka. Kalutara is one of the highly affected districts. Understanding the drivers of dengue is vital in controlling and preventing the disease spread. This study focuses on quantifying the influence of weather variability on dengue incidence over 10 Medical Officer of Health (MOH) divisions of Kalutara district. Weekly weather variables and data on dengue notifications, measured at 10 MOH divisions in Kalutara from 2009 to 2013, were retrieved and analysed. Distributed lag non-linear model and hierarchical-analysis was used to estimate division specific and overall relationships between weather and dengue. We incorporated lag times up to 12 weeks and evaluated models based on the Akaike Information Criterion. Consistent exposure-response patterns between different geographical locations were observed for rainfall, showing increasing relative risk of dengue with increasing rainfall from 50 mm per week. The strongest association with dengue risk centred around 6 to 10 weeks following rainfalls of more than 300 mm per week. With increasing temperature, the overall relative risk of dengue increased steadily starting from a lag of 4 weeks. We found similarly a strong link between the Oceanic Niño Index to weather patterns in the district in Sri Lanka and to dengue at a longer latency time confirming these relationships. Part of the influences of rainfall and temperature can be seen as mediator in the causal pathway of the Ocean Niño Index, which may allow a longer lead time for early warning signals. Our findings describe a strong association between weather, El Niño-Southern Oscillation and dengue in Sri Lanka.

The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA): Data on mortality, by HIV status and stage on the HIV care continuum, among the general population in seven longitudinal studies between 1989 and 2014.

Timely progression of people living with HIV (PLHIV) from the point of infection through the pathway from diagnosis to treatment is important in ensuring effective care and treatment of HIV and preventing HIV-related deaths and onwards transmission of infection. Reliable, population-based estimates of new infections are difficult to obtain for the generalised epidemics in sub-Saharan Africa. Mortality data indicate disease burden and, if disaggregated along the continuum from diagnosis to treatment, can also reflect the coverage and quality of different HIV services. Neither routine statistics nor observational clinical studies can estimate mortality prior to linkage to care nor following disengagement from care. For this, population-based data are required. The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa brings together studies in Kenya, Malawi, South Africa, Tanzania, Uganda, and Zimbabwe. Eight studies have the necessary data to estimate mortality by HIV status, and seven can estimate mortality at different stages of the HIV care continuum. This data note describes a harmonised dataset containing anonymised individual-level information on survival by HIV status for adults aged 15 and above. Among PLHIV, the dataset provides information on survival during different periods: prior to diagnosis of infection; following diagnosis but before linkage to care; in pre-antiretroviral treatment (ART) care; in the first six months after ART initiation; among people continuously on ART for 6+ months; and among people who have ever interrupted ART.