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Search Results: 1 - 10 of 32714 matches for " Daniel Chandramohan "
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Validation and validity of verbal autopsy procedures
Daniel Chandramohan
Population Health Metrics , 2011, DOI: 10.1186/1478-7954-9-22
Abstract: The gold standard diagnosis of cause of death (COD) for assessing the validity of VA has been the COD derived from hospital medical records. The main limitations of using hospital-based CODs as the gold standard are: (1) The accuracy of medical records-based COD is debatable, even though some studies have refined the diagnosis with expert review of hospital records; and (2) the composition and distribution of hospital CODs may not be representative of deaths occurring in the community. In addition, if diagnostic algorithms for CCVA are developed from subsets of validation study datasets, their external validity may be compromised. Nevertheless, hospital diagnosis of COD based on defined clinical and laboratory criteria are the only useful gold standard available at present for validating VAs.The validity of InterVA has not previously been tested against a gold standard diagnosis. The reliability of InterVA has been determined by examining the concordance of CSMFs estimated by InterVA and PCVA. Given that the accuracy of PCVA is questionable, estimating concordance between causes of death derived by PCVA and InterVA as a measure of validity needs to be interpreted with caution.Measures used to assess the validity of VA include sensitivity, specificity, positive predictive value, and absolute (absolute error) or relative (relative error) difference between CSMF estimated by VA and true CSMF in the validation data. Sensitivity and specificity that measure accuracy at the individual level vary substantially between causes of death across different VA interpretation methods. The absolute and relative errors of CSMF measure the accuracy of VA at the population level. The variability of the absolute error in CSMF appears to be reasonable for most CODs because often the number of false positive and false negative diagnoses balance out. However, the relative error in CSMF tends to be exaggerated, especially if the CSMF is low.Murray and colleagues in this series recommend de
Verbal autopsy: current practices and challenges
Soleman,Nadia; Chandramohan,Daniel; Shibuya,Kenji;
Bulletin of the World Health Organization , 2006, DOI: 10.1590/S0042-96862006000300020
Abstract: cause-of-death data derived from verbal autopsy (va) are increasingly used for health planning, priority setting, monitoring and evaluation in countries with incomplete or no vital registration systems. in some regions of the world it is the only method available to obtain estimates on the distribution of causes of death. currently, the va method is routinely used at over 35 sites, mainly in africa and asia. in this paper, we present an overview of the va process and the results of a review of va tools and operating procedures used at demographic surveillance sites and sample vital registration systems. we asked for information from 36 field sites about field-operating procedures and reviewed 18 verbal autopsy questionnaires and 10 cause-of-death lists used in 13 countries. the format and content of va questionnaires, field-operating procedures, cause-of-death lists and the procedures to derive causes of death from va process varied substantially among sites. we discuss the consequences of using varied methods and conclude that the va tools and procedures must be standardized and reliable in order to make accurate national and international comparisons of va data. we also highlight further steps needed in the development of a standard va process.
Methods for evaluating delivery systems for scaling-up malaria control intervention
Webster Jayne,Chandramohan Daniel,Hanson Kara
BMC Health Services Research , 2010, DOI: 10.1186/1472-6963-10-s1-s8
Abstract: Background Despite increased resources over the past few years the coverage of malaria control interventions is still inadequate to reach national and international targets and achieve the full potential of the interventions to improve population health. One of the reasons for this inadequate coverage of efficacious interventions is the limited understanding of the optimum delivery systems of the interventions in different contexts. Although there have been debates about how to deliver interventions, the methods for evaluating the effectiveness of different delivery systems have rarely been discussed. Delivery of interventions is relatively complex and a thorough evaluation would need to look holistically at multiple steps in the delivery process and at multiple factors influencing the process. A better understanding of the strength of the evidence on delivery system effectiveness is needed in order to optimise delivery of efficacious interventions. Methods A literature review was conducted of methods used to evaluate delivery systems for insecticide treated nets, intermittent preventive treatment in pregnant women, and treatment for malaria in children. Results The methodology of delivery system evaluations varied. There were inconsistencies between objectives and methods of the evaluations including inappropriate outcome measures and unnecessary controls. There were few examples where the delivery processes were adequately described, or measured. We propose a cross sectional observational study design with attribution of the outcomes to a specific delivery system as an appropriate method for evaluating delivery systems at scale. Conclusions The proposed evaluation framework is adaptable to natural experiments at scale, and can be applied using data from routine surveys such as the Demographic and Health Surveys, modified by the addition of one to two questions for each intervention. This framework has the potential to enable wider application of rigorous evaluations and thereby improve the evidence base on which decisions about delivery systems for malaria control and other public health interventions are taken.
Verbal autopsy: current practices and challenges
Soleman Nadia,Chandramohan Daniel,Shibuya Kenji
Bulletin of the World Health Organization , 2006,
Abstract: Cause-of-death data derived from verbal autopsy (VA) are increasingly used for health planning, priority setting, monitoring and evaluation in countries with incomplete or no vital registration systems. In some regions of the world it is the only method available to obtain estimates on the distribution of causes of death. Currently, the VA method is routinely used at over 35 sites, mainly in Africa and Asia. In this paper, we present an overview of the VA process and the results of a review of VA tools and operating procedures used at demographic surveillance sites and sample vital registration systems. We asked for information from 36 field sites about field-operating procedures and reviewed 18 verbal autopsy questionnaires and 10 cause-of-death lists used in 13 countries. The format and content of VA questionnaires, field-operating procedures, cause-of-death lists and the procedures to derive causes of death from VA process varied substantially among sites. We discuss the consequences of using varied methods and conclude that the VA tools and procedures must be standardized and reliable in order to make accurate national and international comparisons of VA data. We also highlight further steps needed in the development of a standard VA process.
Intermittent Screening and Treatment versus Intermittent Preventive Treatment of Malaria in Pregnancy: A Randomised Controlled Non-Inferiority Trial
Harry Tagbor,Jane Bruce,Mitchell Agbo,Brian Greenwood,Daniel Chandramohan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014425
Abstract: The effectiveness of intermittent preventive treatment of malaria in pregnancy (IPTp) may be compromised by the spread of resistance to sulphadoxine/pyrimethamine (SP) across Africa. But little informtion exists on alternative drugs for IPTp or alternative strategies for the prevention of malaria in pregnancy. Therefore, we have investigated whether screening with a rapid diagnostic test and treatment of those who are positive (IST) at routine antenatal clinic attendances is as effective and as safe as SP-IPTp in pregnant women.
Azithromycin-chloroquine and the intermittent preventive treatment of malaria in pregnancy
R Matthew Chico, Rudiger Pittrof, Brian Greenwood, Daniel Chandramohan
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-255
Abstract: Each year, 30 million pregnancies are at risk of malaria infection in sub-Saharan Africa, representing a major public health problem. Malaria in pregnancy (MIP) is associated with low birth-weight (LBW) [1-3], pre-term delivery [4] intrauterine growth-retardation [4,5], and maternal anaemia [6]. LBW is a strong predictor of infant mortality in sub-Saharan Africa; death within the first year of life is three-times higher for LBW newborns compared to neonates of normal birth-weight [7]. Malaria is one of the few contributors to LBW that can be improved by specific interventions [8]. Thus, to reduce the effects of MIP in endemic areas, the World Health Organization (WHO) recommends use of Intermittent Preventive Treatment of Malaria in Pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP).IPTp has two primary objectives: (1) to clear asymptomatic peripheral and placental parasitaemia and (2) to provide intermittent chemoprophylaxis against malaria infection during pregnancy. The WHO recommends administration of two or three courses of SP, sulphadoxine (500 mg) and pyrimethamine (25 mg), after foetal quickening with each course given no less than one month apart, and all prior to the last month of pregnancy [9]. Anti-malarial chemoprophylaxis among paucigravidae increases birth-weight by an average of 127 g (95% CI 88.64 to 164.75 g) and reduces, by nearly half, the incidence of LBW (RR = 0.57, 95% CI 0.46 to 0.72) [10]. It has been estimated that universal coverage with IPTp would reduce all-cause neonatal mortality by 32% (95% CI -1 to 54%) [11].Standard IPTp dosing does not provide the same degree of protective efficacy for pregnant women who are HIV-positive. This can be overcome, however, by administering more frequent courses of SP throughout pregnancy. A study in Malawi compared monthly SP treatment versus two courses during the antenatal period among HIV-positive and HIV-negative women. An estimated 7.8% of HIV-positive pregnant women had placental malaria after
Intermittent preventive treatment for malaria in pregnancy in Africa: What's new, what's needed?
Andrew Vallely, Lisa Vallely, John Changalucha, Brian Greenwood, Daniel Chandramohan
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-16
Abstract: Falciparum malaria is an important cause of maternal anaemia, intra-uterine growth retardation, intrauterine death, stillbirth, premature delivery, low birth weight (LBW), perinatal and neonatal morbidity and mortality [1-5] and postpartum morbidity [6-8]. In sub-Saharan Africa, poor nutrition, micronutrient imbalances (particularly vitamin A, zinc, iron and folate)[1], HIV co-infection [9-12], poverty and limited access to effective primary health care and emergency obstetric services [13-15] exacerbate the impact of pregnancy-associated malaria.In areas of high or moderate transmission, most malaria infections in pregnant women are asymptomatic and infected women do not present for treatment. In such areas, the World Health Organization recommends a combination of interventions to prevent malaria in pregnancy including insecticide-treated bednets (ITNs), intermittent preventive treatment in pregnancy (IPTp) and effective case management and treatment[16,17]. A small number of randomized controlled trials and prospective studies conducted in Kenya[18,19] and Malawi[20,21] in the 1990s demonstrated the efficacy, safety and cost-effectiveness[22] of sulphadoxine-pyrimethamine (SP) IPTp in preventing maternal anaemia and LBW. The results of these studies led to a recommendation by the World Health Organization that, in areas of medium or high malaria transmission, IPTp with SP should be given on at least two occasions following quickening[17]. Many countries in sub-Saharan Africa have subsequently introduced SP-IPTp into national malaria control programmes [23-25], but levels of coverage are still only modest in most. Although strenuous efforts are being made to increase coverage levels with SP IPTp, its effectiveness is being threatened by increasing levels of resistance to SP across Africa[23,26-32] and in SE Asia[33,34]. Thus, some authors have suggested that SP should be combined with artemisinins or with cheaper and more readily available alternatives, such as ch
The safety of artemisinins during pregnancy: a pressing question
Stephanie Dellicour, Susan Hall, Daniel Chandramohan, Brian Greenwood
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-15
Abstract: To examine existing published evidence on the relationship between artemisinin compounds and adverse pregnancy outcomes and consider the published evidence with regard to the safety of these compounds when administered during pregnancy.Studies on ACT use in pregnancy were identified via searches of MEDLINE, EMBASE, Cochrane and Current Contents databases. Data on study characteristics, maternal adverse events, pregnancy outcomes and infant follow up were extracted.Fourteen relevant studies (nine descriptive/case reports and five controlled trials) were identified. Numbers of participants in these studies ranged from six to 461. Overall there were reports on 945 women exposed to an artemisinin during pregnancy, 123 in the 1st trimester and 822 in 2nd or 3rd trimesters. The primary end points for these studies were drug efficacy and parasite clearance. Secondary endpoints were birth outcomes including low birth weight, pre-term birth, pregnancy loss, congenital anomalies and developmental milestones. While none of the studies found evidence for an association between the use of artemisinin compounds and increased risk of adverse pregnancy outcomes, none were of sufficient size to detect small differences in event rates that could be of public health importance. Heterogeneity between studies in the artemisinin and comparator drugs used, and in definitions of adverse pregnancy outcomes, limited any pooled analysis.The limited data available suggest that artemisinins are effective and unlikely to be cause of foetal loss or abnormalities, when used in late pregnancy. However, none of these studies had adequate power to rule out rare serious adverse events, even in 2nd and 3rd trimesters and there is not enough evidence to effectively assess the risk-benefit profile of artemisinin compounds for pregnant women particularly for 1st trimester exposure. Methodologically rigorous, larger studies and post-marketing pharmacovigilance are urgently required.Every year over 50 milli
An exploratory study of factors that affect the performance and usage of rapid diagnostic tests for malaria in the Limpopo Province, South Africa
Devanand Moonasar, Ameena Goga, John Frean, Philip Kruger, Daniel Chandramohan
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-74
Abstract: This study was conducted in three malaria risk sub-districts of the Limpopo Province, in South Africa. Twenty nurses were randomly selected from 17 primary health care facilities, three nurses from hospitals serving the study area and 10 other key informants, representing the managers of the malaria control programmes, routine and research laboratories, were interviewed, using semi-structured questionnaires.There was a high degree of efficiency in ordering and distribution of RDTs, however only 13/20 (65%) of the health facilities had appropriate air-conditioning and monitoring of room temperatures. Sixty percent (12/20) of the nurses did not receive any external training on conducting and interpreting RDT. Fifty percent of nurses (10/20) reported RDT stock-outs. Only 3/20 nurses mentioned that they periodically checked quality of RDT. Fifteen percent of nurses reported giving antimalarial drugs even if the RDT was negative.Storage, quality assurance, end user training and use of RDT results for clinical decision making in primary care facilities in South Africa need to be improved. Further studies of the factors influencing the quality control of RDTs, their performance of RDTs and the ways to improve their use of RDTs are needed.The South African National Malaria treatment guidelines stipulate that malaria treatment (using artemesinin-based combination therapy) should be based on definitive diagnosis using microscopy or malaria rapid diagnostic tests (RDTs) [1]. South Africa has been implementing RDTs to diagnose malaria within malaria endemic areas since 2001[2]. In a primary health care setting, RDTs are most appropriate: they are easy to use, do not require sophisticated technology and give rapid results [3]. The functioning and accuracy of RDTs can be affected by several factors, including manufacturing defects, storage, transport, and end-user performance [4]. Malaria diagnostic tests need to be highly accurate because false negative and false positive diagno
Presumptive treatment of fever cases as malaria: help or hindrance for malaria control?
Roly D Gosling, Christopher J Drakeley, Alex Mwita, Daniel Chandramohan
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-132
Abstract: The authors explore an argument that presumptive treatment of fever cases as malaria may have played a role in reducing transmission of malaria by the prophylactic effect of antimalarials and their widespread use. This strategy, which is already in practise is termed Opportunistic Presumptive Treatment (OPT).Further comparison of epidemiological indicators between areas with OPT and more targeted treatment is required. If data suggest a benefit of OPT, combining long acting antimalarials that have an anti-gametocyticidal activity component plus using high levels of vector control measures may reduce transmission, prevent resistant strains spreading and be easily implemented.OPT is practised widely by presumptive treatment of fever in health facilities and home management of fever. Improving diagnosis using rapid diagnostic tests and thus reducing the number of doses of antimalarials given may have counter intuitive effects on transmission in the context of elimination of malaria in high to moderate transmission settings.There is an increasing body of evidence suggesting that the burden of malaria in sub-Saharan Africa has been decreasing over the past decade and continues to do so (see table 1) [1-7]. The causes of this decline are unclear yet with the current calls for elimination and eradication of malaria[8] the identification of factors causing this decrease, in particular those related to control strategies, would seem paramount.To date the decrease in malaria transmission has been documented in a number of countries including Kenya[2], Tanzania[3,4], Mozambique[5], Swaziland[5], South Africa[5], Guinea Bissau[6] and Eritrea[7]. The decrease in cases in Southern Africa coincides with indoor residual spraying (IRS) programmes[5] but for the other reports there is no single clear intervention that could explain the declines. In Kenya it was noted that the decline started before the widespread use of insecticide-treated nets (ITNs)[2]. The decline appears to be br
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