Identifying deaths from AIDS in South Africa: an update

Agreement between cause of death assignment by computer-coded verbal autopsy methods and physician coding of verbal autopsy interviews in South Africa

BACKGROUND

The South African national cause of death validation (NCODV 2017/18) project collected a national sample of verbal autopsies (VA) with cause of death (COD) assignment by physician-coded VA (PCVA) and computer-coded VA (CCVA).

OBJECTIVE

The performance of three CCVA algorithms (InterVA-5, InSilicoVA and Tariff 2.0) in assigning a COD was compared with PCVA (reference standard).

METHODS

Seven performance metrics assessed individual and population level agreement of COD assignment by age, sex and place of death subgroups. Positive predictive value (PPV), sensitivity, overall agreement, kappa, and chance corrected concordance (CCC) assessed individual level agreement. Cause-specific mortality fraction (CSMF) accuracy and Spearman's rank correlation assessed population level agreement.

RESULTS

A total of 5386 VA records were analysed. PCVA and CCVAs all identified HIV/AIDS as the leading COD. CCVA PPV and sensitivity, based on confidence intervals, were comparable except for HIV/AIDS, TB, maternal, diabetes mellitus, other cancers, and some injuries. CCVAs performed well for identifying perinatal deaths, road traffic accidents, suicide and homicide but poorly for pneumonia, other infectious diseases and renal failure. Overall agreement between CCVAs and PCVA for the top single cause (48.2-51.6) indicated comparable weak agreement between methods. Overall agreement, for the top three causes showed moderate agreement for InterVA (70.9) and InSilicoVA (73.8). Agreement based on kappa (-0.05-0.49)and CCC (0.06-0.43) was weak to none for all algorithms and groups. CCVAs had moderate to strong agreement for CSMF accuracy, with InterVA-5 highest for neonates (0.90), Tariff 2.0 highest for adults (0.89) and males (0.84), and InSilicoVA highest for females (0.88), elders (0.83) and out-of-facility deaths (0.85). Rank correlation indicated moderate agreement for adults (0.75-0.79).

CONCLUSIONS

Whilst CCVAs identified HIV/AIDS as the leading COD, consistent with PCVA, there is scope for improving the algorithms for use in South Africa.

Mortality transition over a quarter century in rural South Africa: findings from population surveillance in Agincourt 1993-2018

Background

Mortality burden in South Africa since the mid-1990s has been characterized by a quadruple disease burden: HIV/AIDS and tuberculosis (TB); other communicable diseases (excluding HIV/AIDS and TB), maternal causes, perinatal conditions and nutritional deficiencies; non-communicable diseases (NCDs); and injuries. Causes from these broad groupings have persistently constituted the top 10 causes of death. However, proportions and rankings have varied over time, alongside overall mortality levels.

Objective

To provide evidence on the contributions of age and cause-of-death to changes in mortality levels in a rural South African population over a quarter century (1993–2018).

Methods

Using mortality and cause-of-death data from the Agincourt Health and Socio-Demographic Surveillance System (HDSS), we derive estimates of the distribution of deaths by cause, and hazards of death by age, sex, and time period, 1993–2018. We derive estimates of life expectancies at birth and years of life expectancy gained at age 15 if most common causes of death were deleted. We compare mortality indicators and cause-of-death trends from the Agincourt HDSS with South African national indicators generated from publicly available datasets.

Results

Mortality and cause-of-death transition reveals that overall mortality levels have returned to pre-HIV epidemic levels. In recent years, the concentration of mortality has shifted towards older ages, and the mortality burden from cardiovascular diseases and other chronic NCDs are more prominent as people living with HIV/AIDS access ART and live longer. Changes in life expectancy at birth, distribution of deaths by age, and major cause-of-death categories in the Agincourt population follow a similar pattern to the South African population.

Conclusion

The Agincourt HDSS provides critical information about general mortality, cause-of-death, and age patterns in rural South Africa. Realigning and strengthening the South African public health and healthcare systems is needed to concurrently cater for the prevention, control, and treatment of multiple disease conditions.

HIV/AIDS in South Africa: how many people died from the disease between 1997 and 2010?

OBJECTIVES

Empirical estimates of the number of HIV/AIDS deaths are important for planning, budgeting, and calibrating models. However, there is an extensive misattribution of HIV/AIDS as an underlying cause-of-death. This study estimates the true numbers of AIDS deaths from South African vital statistics between 1997 and 2010.

METHODS

Individual-level cause-of-death data were grouped according to a local burden of disease list and source causes (i.e. causes under which AIDS deaths are misclassified) that recorded a rapid increase. After adjusting for completeness of registration, the mortality rate of the source causes, by age and sex, was regressed on the lagged HIV prevalence to estimate the rate of increase correlated with HIV. Background trends in the source-cause mortality rates were estimated from the trend experienced among 75-84 year olds.

RESULTS

Of 214 causes considered, 19 were identified as potential sources for cause misattribution. High proportions of deaths from tuberculosis, lower respiratory infections (mostly pneumonia), diarrhoeal diseases, and ill-defined natural causes were estimated to be HIV-related, with only 7% of the estimated AIDS deaths being recorded as HIV. Estimated HIV/AIDS deaths increased rapidly, then reversed after 2006, totalling 2.8 million deaths over the whole period. The number was lower than model estimates from Joint United Nations Programme on HIV/AIDS (UNAIDS) and the Global Burden of Disease Study.

CONCLUSION

Empirically based estimates confirm the considerable loss of life from HIV/AIDS and should be used for calibrating models of the AIDS epidemic which generally appear too low for infants but too high for other ages. Doctors are urged to specify HIV on death notifications to provide reliable cause-of-death statistics.

Excess Mortality Associated with Influenza among Tuberculosis Deaths in South Africa, 1999-2009

Background

Published data on the interaction between influenza and pulmonary tuberculosis (PTB) are limited. We aimed to estimate the influenza-associated mortality among individuals with PTB in South Africa from 1999–2009.

Methods

We modelled the excess influenza-associated mortality by applying Poisson regression models to monthly PTB and non-tuberculosis respiratory deaths, using laboratory-confirmed influenza as a covariate.

Results

PTB deaths increased each winter, coinciding with influenza virus circulation. Among individuals of any age, mean annual influenza-associated PTB mortality rate was 164/100,000 person-years (n = 439). The rate of non-tuberculosis respiratory deaths was 27/100,000 (n = 1125) for HIV-infected and 5/100,000 (n = 2367) for HIV-uninfected individuals of all ages. Among individuals aged <65 years, influenza-associated PTB mortality risk was elevated compared to influenza-associated non-tuberculosis respiratory deaths in HIV-infected (relative risk (RR): 5.2; 95% CI: 4.6–5.9) and HIV-uninfected individuals (RR: 61.0; CI: 41.4–91.0). Among individuals aged ≥65 years, influenza-associated PTB mortality risk was elevated compared to influenza-associated non-tuberculosis respiratory deaths in HIV-uninfected individuals (RR: 13.0; 95% CI: 12.0–14.0).

Conclusion

We observed an increased risk of influenza-associated mortality in persons with PTB compared to non-tuberculosis respiratory deaths. If confirmed in other settings, our findings may support recommendations for active inclusion of patients with TB for influenza vaccination and empiric influenza anti-viral treatment of patients with TB during influenza epidemics.

Prevalence of traditional cardiovascular risk factors and evaluation of cardiovascular risk using three risk equations in nigerians living with human immunodeficiency virus

BACKGROUND

Reports from middle- and high-income countries suggest that the improved health outcome from highly active antiretroviral therapy (HAART) in people living with human immunodeficiency virus (PLWHIV) is being mitigated by increase in deaths from cardiovascular disease (CVD).

AIMS

This study was to determine the prevalence of traditional cardiovascular risk factors (CVRFs) and the 10-year cardiovascular risk using three risk equations in PLWHIV with no overt vascular disease.

MATERIALS AND METHODS

This cross-sectional study involved 265 PLWHIV. We classified the subjects as having low, moderate or high cardiovascular risk using the Framingham, World Health Organization/International Society of Hypertension (WHO/ISH) and Systematic Coronary Risk Evaluation (SCORE) equations.

RESULTS

The mean age of the cohort was 38.7 ± 8.7 years; 179 (67.5%) were females and 214 (80.8%) were on HAART. The prevalent traditional CVRFs in our cohort were low physical activity (66%), low HDL-C (49.1%), hypercholesterolaemia (33.6%), BMI ≥ 25 kg/m(2) (32.8%) and elevated LDL-C (28.3%). The prevalence of smoking was very low (1.9%). The prevalence of moderate to high 10-year coronary risk was 11.7, 12.8, and 12.8% according to the Framingham, WHO/ISH and SCORE risk equations, respectively.

CONCLUSION

Most of our patients had low overall cardiovascular risk according to the three risk equations.

Influenza-related mortality among adults aged 25-54 years with AIDS in South Africa and the United States of America

BACKGROUND

Data are limited on human immunodeficiency virus (HIV)-associated influenza burden in sub-Saharan Africa and the impact of highly active antiretroviral therapy (HAART). We compared influenza-related mortality in adults with AIDS in South Africa and the United States in the pre-HAART era and evaluated mortality trends after HAART introduction in the United States.

METHODS

Monthly all-cause and pneumonia and influenza (P&I) mortality rates were compiled for adults with AIDS aged 25-54 years in South Africa (1998-2005) and the United States (pre-HAART era, 1987-1994; HAART era, 1997-2005). We estimated influenza-related deaths as excess mortality above a model baseline during influenza epidemic periods. Influenza-related mortality rates in adults with AIDS were compared with rates for age peers in the general population and adults ≥65 years old.

RESULTS

In the United States before HAART, influenza-related mortality rates in adults with AIDS were 150 (95% confidence interval [CI], 49-460) and 208 (95% CI, 74-583) times greater than in the general population for all-cause and P&I deaths, respectively, and 2.5 (95% CI, 0.9-7.2) and 4.1 (95% CI, 1.4-13) times higher than in elderly adults. After HAART introduction , influenza-related mortality in adults with AIDS dropped 3-6-fold but remained elevated compared with the general population (all-cause relative risk [RR], 44 [95% CI, 16-121]); P&I RR, 73 [95% CI, 47-113]). Influenza-related mortality in South African adults with AIDS in recent years was similar to that in the United States in the pre-HAART era.

CONCLUSIONS

Adults with AIDS experience substantially elevated influenza-associated mortality, which declines with widespread HAART introduction but does not disappear. These data support increased access to HAART and influenza vaccination for HIV-infected adults.

Assessing the population health impact of market interventions to improve access to antiretroviral treatment

Despite extraordinary global progress in increasing coverage of antiretroviral treatment (ART), the majority of people needing ART currently are not receiving treatment. Both the number of people needing ART and the average ART price per patient-year are expected to increase in coming years, which will dramatically raise funding needs for ART. Several international organizations are using interventions in ART markets to decrease ART price or to improve ART quality, delivery and innovation, with the ultimate goal of improving population health. These organizations need to select those market interventions that are most likely to substantially affect population health outcomes (ex ante assessment) and to evaluate whether implemented interventions have improved health outcomes (ex post assessment).

We develop a framework to structure ex ante and ex post assessment of the population health impact of market interventions, which is transmitted through effects in markets and health systems. Ex ante assessment should include evaluation of the safety and efficacy of the ART products whose markets will be affected by the intervention; theoretical consideration of the mechanisms through which the intervention will affect population health; and predictive modelling to estimate the potential population health impact of the intervention. For ex post assessment, analysts need to consider which outcomes to estimate empirically and which to model based on empirical findings and understanding of the economic and biological mechanisms along the causal pathway from market intervention to population health. We discuss methods for ex post assessment and analyse assessment issues (unintended intervention effects, interaction effects between different interventions, and assessment impartiality and cost). We offer seven recommendations for ex ante and ex post assessment of population health impact of market interventions.

A survival analysis of South African children under the age of five years

The South African Demographic Health Survey data set (SADHS) of 2003 contains massive individual-level information on South African children under the age of five years selected from a random sample of 7756 households. The data set contains data on socio-economic, demographic, health-related and sanitary variables gathered by using multistage cluster sampling. The objective of the study was to identify key predictors of mortality amongst children under the age of five years. Logistic regression analysis and Cox regression were used for data analysis.Under-five mortality was significantly influenced by three predictor variables (breastfeeding, marital status, and ownership of a flush toilet). The hazard ratio of the variable ‘breastfeeding’ was 3.09 with P = 0.000 and 95% confidence interval (CI) of (1.899, 5.033). The hazard ratio of the variable ‘toilet’ was 2.35 with P = 0.016 and 95% confidence interval of (1.172, 4.707). The hazard ratio of the variable ‘marital status’ was 1.74 with P = 0.035 and 95% confidence interval of (1.041, 2.912). Adjustment was factored in for the mother’s level of education and wealth index.OpsommingDie Suid-Afrikaanse Demografiese en Gesondheidsopname-datastel (The South African Demographic Health Survey data set [SADHS]) van 2003 bevat ‘n enorme hoeveelheid individuele-vlak inligting rakende kinders onder vyf jaar uit 7756 huishoudings in Suid-Afrika. Die datastel bevat inligting rakende sosio-ekonomiese, demografiese, en gesondheidsverwante veranderlikes, en sanitêre-veranderlikes, is versamel deur gebruik te maak van multistadiatrosanalise. Die oogmerk met die studie was die identifisering van sleutelpredikatore ten opsigte van sterftes van kinders onder die ouderdom van vyf jaar. Logistieke-opnameregressie analise en Cox-regressie is gebruik om die data te analiseer. Onder vyf-sterftes word beduidend beïnvloed deur drie predikatorveranderlikes (duurte van borsvoeding, huwelikstatus en toegang tot ‘n spoeltoilet). Die risikoverhouding van die borsvoeding-veranderlike was 3.09 met P = 0.000 en ‘n 95% sekerheidsinterval van (1.899, 5.033). Die risikoverhouding van die toiletveranderlike was 2.35 met P = 0.006 en 95% sekerheidsinterval van (1.172, 4.707). Die risikoverhouding van die huwelikstatus-veranderlike was 1.74 met P = 0.035 en 95% sekerheidsinterval van (1.041, 2.912). Aanpassings is gemaak vir die opvoedingsvlak van die moeder asook die welgesteldheidsindeks.

Exposing misclassified HIV/AIDS deaths in South Africa

OBJECTIVE

To quantify the deaths from human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS) that are misattributed to other causes in South Africa's death registration data and to adjust for this bias.

METHODS

Deaths in the World Health Organization's mortality database were distributed among 48 mutually exclusive causes. For each cause, age- and sex-specific global death rates were compared with the average rate among people aged 65-69, 70-74 and 75-79 years to generate "relative" global death rates. Relative rates were also computed for South Africa alone. Differences between global and South African relative death rates were used to identify the causes to which deaths from HIV/AIDS were misattributed in South Africa and quantify the HIV/AIDS deaths misattributed to each. These deaths were then reattributed to HIV/AIDS.

FINDINGS

In South Africa, deaths from HIV/AIDS are often misclassified as being caused by 14 other conditions. Whereas in 1996-2006 deaths attributed to HIV/AIDS accounted for 2.0-2.5% of all registered deaths in South Africa, our analysis shows that the true cause-specific mortality fraction rose from 19% (uncertainty range: 7-28%) to 48% (uncertainty range: 38-50%) over that period. More than 90% of HIV/AIDS deaths were found to have been misattributed to other causes during 1996-2006.

CONCLUSION

Adjusting for cause of death misclassification, a simple procedure that can be carried out in any country, can improve death registration data and provide empirical estimates of HIV/AIDS deaths that may be useful in assessing estimates from demographic models.

Estimating the extent of underreporting of mortality among HIV-infected individuals in Rio de Janeiro, Brazil

Non-HIV-related causes of death have been increasing after the introduction of highly active antiretroviral therapy. Underlying and contributing causes of death were assessed in respect to the presence/absence of HIV/AIDS among HIV-infected/AIDS patients in Rio de Janeiro, Brazil. Demographic variables (age, gender, ethnicity, and schooling) and CD4 cell counts closest to death were assessed through logistic regression models comparing those who did not have with those who had HIV/AIDS mentioned on the death certificate. The linkage with the two cohorts identified 1249 records, of which 370 (29.6%) did not have HIV/AIDS listed on any field of the death certificate [77 (20.8%) attributed to undefined and 72 (19.5%) to external causes]. After excluding external causes, 25.3% still did not have HIV/AIDS listed on the death certificate. Multiple logistic regression analysis showed that age >40 years (OR = 2.09; 95%CI = 1.49-2.93; p < 0.001) and CD4 cell count closest to the date of death (OR = 1.15; 95% CI = 1.07-1.23; p < 0.001 for 100 cell increase) were associated with an increased probability of not having HIV/AIDS mentioned on the death certificate, when external causes were excluded. Mortality among HIV-infected individuals is underreported in the Rio de Janeiro Mortality Registry, particularly among older individuals and those with higher CD4 counts. Physicians should be aware of the changing patterns of mortality among HIV individuals, and public health officials should regularly perform linkages between all-cause mortality and available HIV-infected patients databases, such as AIDS registries and large cohort studies.

Short communication: Prioritizing communities for HIV prevention in sub-Saharan Africa

HIV prevalence is the most commonly used measure to prioritize communities for HIV prevention. We show that data on two HIV infection stages (early vs. nonearly and late vs. nonlate) allow estimation of two better measures of prevention need: HIV incidence (for prevention of HIV acquisition) and expected probability of HIV transmission in unprotected sex acts between HIV-infected community members and susceptible individuals (for prevention of HIV transmission). The three ranking schemes--by prevalence, incidence, and transmission probability--lead to significantly different community rank orders. Disease stage information should be collected in HIV surveys.

Verbal autopsy can consistently measure AIDS mortality: a validation study in Tanzania and Zimbabwe

BACKGROUND

Verbal autopsy is currently the only option for obtaining cause of death information in most populations with a widespread HIV/AIDS epidemic.

METHODS

With the use of a data-driven algorithm, a set of criteria for classifying AIDS mortality was trained. Data from two longitudinal community studies in Tanzania and Zimbabwe were used, both of which have collected information on the HIV status of the population over a prolonged period and maintained a demographic surveillance system that collects information on cause of death through verbal autopsy. The algorithm was then tested in different times (two phases of the Zimbabwe study) and different places (Tanzania and Zimbabwe).

RESULTS

The trained algorithm, including nine signs and symptoms, performed consistently based on sensitivity and specificity on verbal autopsy data for deaths in 15-44-year-olds from Zimbabwe phase I (sensitivity 79%; specificity 79%), phase II (sensitivity 83%; specificity 75%) and Tanzania (sensitivity 75%; specificity 74%) studies. The sensitivity dropped markedly for classifying deaths in 45-59-year-olds.

CONCLUSIONS

Verbal autopsy can consistently measure AIDS mortality with a set of nine criteria. Surveillance should focus on deaths that occur in the 15-44-year age group for which the method performs reliably. Addition of a handful of questions related to opportunistic infections would enable other widely used verbal autopsy tools to apply this validated method in areas for which HIV testing and hospital records are unavailable or incomplete.

Cause of death and presence of respiratory disease at autopsy in an HIV-1 seroconversion cohort of southern African gold miners

OBJECTIVES

To describe causes of death and respiratory infections in HIV-infected miners in the pre-antiretroviral era, by duration of HIV infection.

DESIGN

A retrospective cohort of 1950 gold miners with known dates of HIV seroconversion and 6164 HIV-negative miners was followed from the early 1990s to 2002.

METHODS

Causes of death were available from multiple sources: personnel records, clinical records, death certificates and autopsies of cardiorespiratory organs performed for compensation purposes.

RESULTS

Causes of death were known for 279 of 308 HIV-positive (91%) and 234 of 254 HIV-negative (92%) men who died while employed or within 6 months of leaving employment. The mortality rate from unnatural causes was similar in HIV-positive and HIV-negative miners and by duration of HIV infection. Among deaths from natural causes, 87% in HIV-positive and 41% in HIV-negative individuals were caused by infection (P < 0.001); 47% of HIV-positive and 26% of HIV-negative individuals had tuberculosis. The proportion of deaths from natural causes with any infection, or with specific infections (tuberculosis, cryptococcus, pneumocystis), did not vary with the duration of HIV infection. Autopsies were performed on 29% of men who died from natural causes: 83% of HIV-positive and 37% of HIV-negative men had respiratory infections (P < 0.001), half of which were clinically undiagnosed.

CONCLUSION

Tuberculosis was the leading cause of death in HIV-positive and negative men who died from natural causes. Although the mortality rate from natural causes increased greatly with the duration of HIV infection, the pattern of disease hardly changed, suggesting that slow and fast progressors succumb to the same range of diseases.