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1.  Using verbal autopsy to measure causes of death: the comparative performance of existing methods 
BMC Medicine  2014;12:5.
Background
Monitoring progress with disease and injury reduction in many populations will require widespread use of verbal autopsy (VA). Multiple methods have been developed for assigning cause of death from a VA but their application is restricted by uncertainty about their reliability.
Methods
We investigated the validity of five automated VA methods for assigning cause of death: InterVA-4, Random Forest (RF), Simplified Symptom Pattern (SSP), Tariff method (Tariff), and King-Lu (KL), in addition to physician review of VA forms (PCVA), based on 12,535 cases from diverse populations for which the true cause of death had been reliably established. For adults, children, neonates and stillbirths, performance was assessed separately for individuals using sensitivity, specificity, Kappa, and chance-corrected concordance (CCC) and for populations using cause specific mortality fraction (CSMF) accuracy, with and without additional diagnostic information from prior contact with health services. A total of 500 train-test splits were used to ensure that results are robust to variation in the underlying cause of death distribution.
Results
Three automated diagnostic methods, Tariff, SSP, and RF, but not InterVA-4, performed better than physician review in all age groups, study sites, and for the majority of causes of death studied. For adults, CSMF accuracy ranged from 0.764 to 0.770, compared with 0.680 for PCVA and 0.625 for InterVA; CCC varied from 49.2% to 54.1%, compared with 42.2% for PCVA, and 23.8% for InterVA. For children, CSMF accuracy was 0.783 for Tariff, 0.678 for PCVA, and 0.520 for InterVA; CCC was 52.5% for Tariff, 44.5% for PCVA, and 30.3% for InterVA. For neonates, CSMF accuracy was 0.817 for Tariff, 0.719 for PCVA, and 0.629 for InterVA; CCC varied from 47.3% to 50.3% for the three automated methods, 29.3% for PCVA, and 19.4% for InterVA. The method with the highest sensitivity for a specific cause varied by cause.
Conclusions
Physician review of verbal autopsy questionnaires is less accurate than automated methods in determining both individual and population causes of death. Overall, Tariff performs as well or better than other methods and should be widely applied in routine mortality surveillance systems with poor cause of death certification practices.
doi:10.1186/1741-7015-12-5
PMCID: PMC3891983  PMID: 24405531
Verbal autopsy; VA; Validation; Cause of death; Symptom pattern; Random forests; InterVA; King-Lu; Tariff
2.  Trends of public health research output from India during 2001-2008 
BMC Medicine  2009;7:59.
Background
An understanding of how public health research output from India is changing in relation to the disease burden and public health priorities is required in order to inform relevant research development. We therefore studied the trends in the public health research output from India during 2001-2008 that was readily available in the public domain.
Methods
The scope and type of the published research from India in 2007 that was included in the PubMed database was assessed and compared with a previous similar assessment for 2002. Papers were classified based on the review of abstracts and original public health research papers were assessed in detail. Impact factors for the journals were used to compute quality-adjusted research output. The websites of governmental organizations, academic and research institutions and international organizations were searched in order to identify and review reports on original public health research produced in India from 2001 to 2008. The reports were classified based on the topics covered and quality and their trends over time were assessed.
Results
The number of original health research papers from India in PubMed doubled from 4494 in 2002 to 9066 in 2007. This included a 3.1-fold increase in public health research papers, but these comprised only 5% of the total papers in 2007. Within public health, the increase was lowest for the health system and policy category. Several major causes of disease burden in India continued to be underrepresented in the quality-adjusted public health research output in 2007. The number of papers evaluating population health interventions increased from 2002 to 2007, but there were none on the leading non-communicable causes of disease burden or on road traffic injuries. The number of identified original public health research reports increased by 64.7% from 204 in 2001-2004 to 336 in 2005-2008. The proportion of reports on reproductive and child health was very high but decreased slightly from 38.7% of the total in 2001-2004 to 31.5% in 2005-2008 (P = 0.09); those on the leading chronic non-communicable conditions and injuries increased from 6.4% to 13.4% (P = 0.01) but this was still much lower than their contribution to the disease burden. Health system/policy issues were the topic in 27.4% reports but health information issues were covered in a miniscule 0.6% reports. The proportion of reports that were evaluations increased slightly from 26% in 2001-2004 to 31.5% in 2005-2008, with this proportion being higher among the reports commissioned by international organizations (P < 0.001). The proportion of reports commissioned by Indian governmental organizations alone, or in collaboration with international organizations, doubled from 2001-2004 to 2005-2008 (P < 0.001). Only 25% of the total 540 reports had a quality score of adequate or better. The quality of reports produced by collaborations between Indian and international organizations was higher than those produced by Indian or international organizations alone (P < 0.001).
Conclusion
This is the first analysis from India that includes research reports in addition to published papers. It provides the most up-to-date understanding of public health research output from India. The increase in available public health research output and the increase in commissioning of this research by Indian governmental organizations are encouraging. However, the distribution of research topics and the quality of research reports continue to be unsatisfactory. It is necessary for health policy to address these continuing deficits in public health research in order to reduce the very large disease burden in India.
doi:10.1186/1741-7015-7-59
PMCID: PMC2766381  PMID: 19828017
3.  A population-based study of human immunodeficiency virus in south India reveals major differences from sentinel surveillance-based estimates 
BMC Medicine  2006;4:31.
Background
The human immunodeficiency virus (HIV) burden among adults in India is estimated officially by direct extrapolation of annual sentinel surveillance data from public-sector antenatal and sexually transmitted infection (STI) clinics and some high-risk groups. The validity of these extrapolations has not been systematically examined with a large sample population-based study.
Methods
We sampled 13838 people, 15–49 years old, from 66 rural and urban clusters using a stratified random method to represent adults in Guntur district in the south Indian state of Andhra Pradesh. We interviewed the sampled participants and obtained dried blood spots from them, and tested blood for HIV antibody, antigen and nucleic acid. We calculated the number of people with HIV in Guntur district based on these data, compared it with the estimate using the sentinel surveillance data and method, and analysed health services use data to understand the differences.
Results
In total, 12617 people (91.2% of the sampled group) gave a blood sample. Adjusted HIV prevalence was 1.72% (95% confidence interval 1.35–2.09%); men 1.74% (1.27–2.21%), women 1.70% (1.36–2.04%); rural 1.64% (1.10–2.18%), urban 1.89% (1.39–2.39%). HIV prevalence was 2.58% and 1.20% in people in the lower and upper halves of a standard of living index (SLI). Of women who had become pregnant during the past 2 years, 21.1% had used antenatal care in large public-sector hospitals participating in sentinel surveillance. There was an over-representation of the lowest SLI quartile (44.7%) in this group, and 3.61% HIV prevalence versus 1.08% in the remaining pregnant women. HIV prevalence was higher in that group even when women were matched for the same SLI half (lower half 4.39%, upper 2.63%) than in the latter (lower 1.06%, upper 1.05%), due to referral of HIV-positive/suspected women by private practitioners to public hospitals. The sentinel surveillance method (HIV prevalence: antenatal clinic 3%, STI clinic 22.8%, female sex workers 12.8%) led to an estimate of 112635 (4.38%) people with HIV, 15–49 years old, in Guntur district, which was 2.5 times the 45942 (1.79%) estimate based on our population-based study.
Conclusion
The official method in India leads to a gross overestimation of the HIV burden in this district due to addition of substantial extra HIV estimates from STI clinics, the common practice of referral of HIV-positive/suspected people to public hospitals, and a preferential use of public hospitals by people in lower socioeconomic strata. India may be overestimating its HIV burden with the currently used official estimation method.
doi:10.1186/1741-7015-4-31
PMCID: PMC1764025  PMID: 17166257
4.  Revision of visual impairment definitions in the International Statistical Classification of Diseases 
BMC Medicine  2006;4:7.
Background
The existing definitions of visual impairment in the International Statistical Classification of Diseases are based on recommendations made over 30 years ago. New data and knowledge related to visual impairment that have accumulated over this period suggest that these definitions need to be revised.
Discussion
Three major issues need to be addressed in the revision of these definitions. First, the existing definitions are based on best-corrected visual acuity, which exclude uncorrected refractive error as a cause of visual impairment, leading to substantial underestimation of the total visual impairment burden by about 38%. Second, the cut-off level of visual impairment to define blindness in the International Statistical Classification of Diseases is visual acuity less than 3/60 in the better eye, but with increasing human development the visual acuity requirements are also increasing, suggesting that a level less than 6/60 be used to define blindness. Third, the International Statistical Classification of Diseases uses the term 'low vision' for visual impairment level less than blindness, which causes confusion with the common use of this term for uncorrectable vision requiring aids or rehabilitation, suggesting that alternative terms such as moderate and mild visual impairment would be more appropriate for visual impairment less severe than blindness. We propose a revision of the definitions of visual impairment in the International Statistical Classification of Diseases that addresses these three issues. According to these revised definitions, the number of blind persons in the world defined as presenting visual acuity less than 6/60 in the better eye would be about 57 million as compared with the World Health Organization estimate of 37 million using the existing International Statistical Classification of Diseases definition of best-corrected visual acuity less than 3/60 in the better eye, and the number of persons in the world with moderate visual impairment defined as presenting visual acuity less than 6/18 to 6/60 in the better eye would be about 202 million as compared with the World Health Organization estimate of 124 million persons with low vision defined as best-corrected visual acuity less than 6/18 to 3/60 in the better eye.
Conclusion
Our suggested revision of the visual impairment definitions in the International Statistical Classification of Diseases takes into account advances in the understanding of visual impairment. This revised classification seems more appropriate for estimating and tracking visual impairment in the countries and regions of the world than the existing classification in the International Statistical Classification of Diseases.
doi:10.1186/1741-7015-4-7
PMCID: PMC1435919  PMID: 16539739
5.  What is the global burden of visual impairment? 
BMC Medicine  2006;4:6.
Background
A recent estimate by the World Health Organization (WHO) suggests that 161 million persons worldwide have visual impairment, including 37 million blind (best-corrected visual acuity less than 3/60 in the better eye) and 124 million with visual impairment less severe than blindness (best-corrected acuity less than 6/18 to 3/60 in the better eye). This estimate is quoted widely, but because it is based on definitions using best-corrected visual acuity, uncorrected refractive error as a cause of visual impairment is excluded.
Methods
We reviewed data from population-based surveys of visual impairment worldwide published 1996 onwards that included presenting visual acuity, and estimated the proportion of visual impairment caused by uncorrected refractive error in different sub-regions of the world. We then extrapolated these data to estimate the worldwide burden of visual impairment including that caused by uncorrected refractive error.
Results
The total number of persons with visual impairment worldwide, including that due to uncorrected refractive error, was estimated as 259 million, 61% higher than the commonly quoted WHO estimate. This includes 42 million persons with blindness defined as presenting visual acuity less than 3/60 in the better eye, and 217 million persons with less severe visual impairment level defined as presenting visual acuity less than 6/18 to 3/60 in the better eye, 14% and 75% higher, respectively, than the WHO estimates based on best-corrected visual acuity. Sensitivity analysis, taking into account the uncertainty of the proportion of visual impairment caused by refractive error, revealed that the number of persons in the world with visual impairment due to uncorrected refractive error could range from 82 to 117 million.
Conclusion
The actual burden of visual impairment worldwide, including that caused by uncorrected refractive error, is substantially higher than the commonly quoted WHO estimate that is based on best-corrected visual acuity. We suggest that the indicative estimate of 259 million persons with visual impairment worldwide, which includes 42 million blind with visual acuity less than 3/60 in the better eye, be used for further planning of the VISION 2020 initiative instead of the often quoted 161 million estimate that includes 37 million blind.
doi:10.1186/1741-7015-4-6
PMCID: PMC1435918  PMID: 16539747

Results 1-5 (5)