Maria Deloria-Knoll

Burden of disease caused by Streptococcus pneumoniae in children younger than 5 years: global estimates

BACKGROUND Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, and sepsis in children worldwide. However, many countries lack national estimates of disease burden. Effective interventions are available, including pneumococcal conjugate vaccine and case management. To support local and global policy decisions on pneumococcal disease prevention and treatment, we estimated country-specific incidence of serious cases and deaths in children younger than 5 years. METHODS We measured the burden of pneumococcal pneumonia by applying the proportion of pneumonia cases caused by S pneumoniae derived from efficacy estimates from vaccine trials to WHO country-specific estimates of all-cause pneumonia cases and deaths. We also estimated burden of meningitis and non-pneumonia, non-meningitis invasive disease using disease incidence and case-fatality data from a systematic literature review. When high-quality data were available from a country, these were used for national estimates. Otherwise, estimates were based on data from neighbouring countries with similar child mortality. Estimates were adjusted for HIV prevalence and access to care and, when applicable, use of vaccine against Haemophilus influenzae type b. FINDINGS In 2000, about 14.5 million episodes of serious pneumococcal disease (uncertainty range 11.1-18.0 million) were estimated to occur. Pneumococcal disease caused about 826,000 deaths (582,000-926,000) in children aged 1-59 months, of which 91,000 (63,000-102,000) were in HIV-positive and 735,000 (519,000-825,000) in HIV-negative children. Of the deaths in HIV-negative children, over 61% (449,000 [316,000-501,000]) occurred in ten African and Asian countries. INTERPRETATION S pneumoniae causes around 11% (8-12%) of all deaths in children aged 1-59 months (excluding pneumococcal deaths in HIV-positive children). Achievement of the UN Millennium Development Goal 4 for child mortality reduction can be accelerated by prevention and treatment of pneumococcal disease, especially in regions of the world with the greatest burden. FUNDING GAVI Alliance and the Vaccine Fund.

Survival Benefit of Initiating Antiretroviral Therapy in HIV-Infected Persons in Different CD4+ Cell Strata

Context When to start antiretroviral therapy (ART) for HIV infection is controversial. Starting too early exposes patients to side effects and uncertain benefits. Starting too late deprives patients of benefits. Contribution In this cohort study, HIV-infected patients with baseline CD4+ cell counts between 0.201 and 0.350 109 cells/L who began ART immediately had lower mortality rates than those who started therapy after their CD4+ cell count decreased to less than 0.201 109 cells/L. Optimal timing of therapy is unclear when the CD4+ cell count is greater than 0.350 109 cells/L. Cautions A randomized, controlled trial is the best way to identify the optimal timing of ART. The Editors Optimal timing of antiretroviral therapy (ART) initiation for persons with HIV infection is of great clinical and public health importance. Therapy reduces HIV-related mortality and morbidity for patients with substantial CD4+ cell depletion (<0.100 109 cells/L) who initiate treatment (1). Although data demonstrate the viral suppressive and immunologic (CD4+ cell count) benefits of therapy in persons with higher CD4+ cell counts (2-8), long-term improvements in disease-associated morbidity and mortality with earlier therapy are less clear (9, 10). In such patients, the potential benefits of ART and highly active ART (HAART) will probably be weighed against possible untoward sequelae of earlier treatment, including the development of metabolic abnormalities; emergence of drug-resistant virus, with resultant exhaustion of effective remaining therapies; cost; and access (9, 11-13). Current treatment guidelines allowing for the delay of ART until a lower CD4+ thresholdusually 0.350 109 cells/L or, for some patients, 0.200 109 cells/Lreflect a lack of consensus on the benefits of earlier initiation of therapy (13, 14). Sparse data exist on which to base specific recommendations for the initiation of ART relative to CD4+ cell count. Longitudinal data comparing ART recipients to appropriate comparison groups not receiving ART (especially patients with CD4+ cell counts > 0.200 109 cells/L) are limited (10, 15). Analyses that include extended follow-up data on such patients are critical because these patients are unlikely to develop or die of an HIV-related condition over the short term, in contrast to those who start therapy with lower CD4+ cell counts. Another challenge is related to the relatively brief time that HAART has been available (since early 1996), making comparative longitudinal studies of sufficient duration difficult. We compare mortality rates among ambulatory HIV-infected patients who initiated ART and those who delayed ART in various CD4+ strata. Patients were enrolled in the HIV Outpatient Study (HOPS), a dynamic cohort of ambulatory HIV-infected patients demographically representative of treated HIV-infected patients in the United States. Methods HOPS HOPS is an ongoing prospective observational cohort study into which patients have been continuously recruited and followed since 1993 (1, 16). Study sites are 10 clinics (8 private, 2 public) in 8 U.S. cities that provide care for more than 2400 HIV-infected patients per year. Participating physicians have extensive experience treating HIV-infected patients. Information is abstracted from outpatient charts at each visit and entered electronically by trained staff; it is then compiled centrally and reviewed and edited before being analyzed. Information abstracted includes demographic characteristics and risk factors for HIV infection; symptoms; diagnosed diseases (both definitive and presumptive); medications prescribed, including dose and duration; and laboratory values, including CD4+ cell counts and measurements of plasma HIV-1 RNA (viral load). Selection of Patients for Analysis We identified HOPS participants who had at least two CD4+ measurements and reliable data on ART initiation and use for at least 30 consecutive days from January 1994 through March 2001. We defined HAART as the use of at least three drugs simultaneously, including one protease inhibitor or non-nucleoside reverse-transcriptase inhibitor, or any regimen with at least two full-dose protease inhibitors. Three patient subgroups were analyzed: those observed to have a pre-ART CD4+ cell count of 0.501 to 0.750 109 cells/L, those with a pre-ART CD4+ cell count of 0.351 to 0.500 109 cells/L, and those with a pre-ART CD4+ cell count of 0.201 to 0.350 109 cells/L. Patients could be in more than one subgroup if they had a pre-ART CD4+ cell count in more than one of the defined ranges. Thus, analyses within a subgroup are distinct from analyses in other subgroups. We then stratified patients in each subgroup into one of three treatment groups: those who began ART while still in the same CD4+ subgroup range (subsequently called patients who initiated ART), those who began ART after their CD4+ cell count decreased to less than the CD4+ subgroup range (subsequently called patients who delayed ART), and those who never received ART (untreated patients). The closest (in time) CD4+ cell count available within 6 months before or 2 weeks after ART initiation was used to define the CD4+ cell count at the start of therapy. By definition, because patients who delayed ART had to have at least 1 additional CD4+ measurement during follow-up, patients who initiated ART and those who were untreated were also required to have at least 1 additional CD4+ measurement during follow-up to reduce potential bias in the analysis as a result of differential time under observation. For all treatment groups, time under observation began with the date of the earliest CD4+ cell count within the CD4+ stratum in which the patient was analyzed. Patients included in the analyses of the CD4+ subgroups of 0.201 to 0.350 109 cells/L and 0.351 to 0.500 109 cells/L were those whose earliest CD4+ cell count within the subgroup-defined range was observed after 1 January 1994. The analysis of the CD4+ subgroup of 0.501 to 0.750 109 cells/L was limited to those whose earliest CD4+ cell count within this range was observed between January 1994 and December 1995. This allowed longer elapsed time to observe clinical events. For analysis, the observation period for each patient ended at 6 months after the last contact with a HOPS clinic or at death. We analyzed all deaths, including those not directly due to AIDS or indirectly from conditions exacerbated by HIV infection (such as hepatic, renal, or cardiac disease). Causes of death were ascertained through review of clinic and hospital charts, death certificates, and national AIDS surveillance data. Deaths from suicide (one patient in the CD4+ subgroup of 0.201 to 0.350 109 cells/L who delayed ART and one patient in the CD4+ subgroup of 0.501 to 0.750 109 cells/L who initiated treatment) were treated as censored. Statistical Analysis We used SAS software, version 8.0 (SAS Institute, Inc., Cary, North Carolina), for all analyses. Patient characteristics were compared by chi-square test or the Fisher exact test for categorical variables and the Wilcoxon rank-sum test or t-test for continuous variables. We analyzed mortality rates per 1000 person-years and calculated the relative risk for death, 95% CIs, and approximate two-sided P values for each subgroup (17). Cox proportional-hazards regression was used to estimate hazard ratios, adjusted for age, sex, race, insurance status, viral load (log scale) at time of first ART (a dummy variable was used to include patients missing viral load data), receipt of HAART, and CD4+ cell count at the time of first observation within each stratum. Role of the Funding Source The funding source participated in the design, conduct, analysis, and reporting of the study and in the decision to submit the manuscript for publication. Results We evaluated data from 1464 HIV-infected HOPS participants. Of these patients, 596 who initiated ART had at least one additional CD4+ measurement after ART initiation, and 175 who delayed ART had at least one additional recorded CD4+ cell count in a higher stratum before ART initiation. We compared the demographic and baseline characteristics of patients described in this report to those of the larger overall group of HOPS participants and found no meaningful differences (data not shown). We analyzed data from 399 patients (340 who initiated and 59 who delayed ART) with pre-ART CD4+ cell counts between 0.201 and 0.350 109 cells/L, 327 patients (240 who initiated and 87 who delayed ART) with pre-ART CD4+ cell counts between 0.351 and 0.500 109 cells/L, and 122 patients (55 who initiated and 67 who delayed ART) with pre-ART CD4+ cell counts between 0.501 and 0.750 109 cells/L. Median years of follow-up for patients who initiated and those who delayed ART, by CD4+ subgroup, were as follows: 3.8 and 3.9 years for the subgroup of 0.201 to 0.350 109 cells/L, 4.1 and 4.2 years for the subgroup of 0.351 to 0.500 109 cells/L, and 5.4 and 5.3 years for the subgroup of 0.501 to 0.750 109 cells/L, respectively. Table 1 shows the demographic, immunologic, virologic, and care characteristics of patients who initiated ART and those who delayed ART, by CD4+ subgroup. Across subgroups, at least 69% of patients were men, 64% were younger than 40 years of age, 62% were white, and 35% had private health care insurance. Patients who initiated ART and those who delayed ART did not differ significantly except for the following: Patients in the CD4+ subgroup of 0.351 to 0.500 109 cells/L with private insurance tended to initiate rather than delay ART, and men in the CD4+ subgroup of 0.501 to 0.750 109 cells/L tended to delay therapy. Table 1. Characteristics of the HIV Outpatient Study Patients Who Initiated or Delayed Antiretroviral Therapy, by Preantiretroviral CD4+ Cell Count Stratum In general, most patients in a CD4+ subgroup who delayed ART initiated therapy in the next lowest CD4+ subgroup, that is, those who did not start in one subgroup started approximat

Burden of disease caused by Haemophilus influenzae type b in children younger than 5 years: global estimates

BACKGROUND Haemophilus influenzae type b (Hib) is a leading cause of childhood bacterial meningitis, pneumonia, and other serious infections. Hib disease can be almost completely eliminated through routine vaccination. We assessed the global burden of disease to help national policy makers and international donors set priorities. METHODS We did a comprehensive literature search of studies of Hib disease incidence, case-fatality ratios, age distribution, syndrome distribution, and effect of Hib vaccine. We used vaccine trial data to estimate the proportion of pneumonia cases and pneumonia deaths caused by Hib. We applied these proportions to WHO country-specific estimates of pneumonia cases and deaths to estimate Hib pneumonia burden. We used data from surveillance studies to develop estimates of incidence and mortality of Hib meningitis and serious non-pneumonia, non-meningitis disease. If available, high-quality data were used for national estimates of Hib meningitis and non-pneumonia, non-meningitis disease burden. Otherwise, estimates were based on data from other countries matched as closely as possible for geographic region and child mortality. Estimates were adjusted for HIV prevalence and access to care. Disease burden was estimated for the year 2000 in children younger than 5 years. FINDINGS We calculated that Hib caused about 8.13 million serious illnesses worldwide in 2000 (uncertainty range 7.33-13.2 million). We estimated that Hib caused 371,000 deaths (247,000-527,000) in children aged 1-59 months, of which 8100 (5600-10,000) were in HIV-positive and 363,000 (242,000-517,000) in HIV-negative children. INTERPRETATION Global burden of Hib disease is substantial and almost entirely vaccine preventable. Expanded use of Hib vaccine could reduce childhood pneumonia and meningitis, and decrease child mortality. FUNDING GAVI Alliance and the Vaccine Fund.

Systematic evaluation of serotypes causing invasive pneumococcal disease among children under five: the pneumococcal global serotype project.

Hope Johnson and colleagues calculate the global and regional burden of serotype-specific pneumococcal disease in children under the age of five.

Estimating the Burden of Pneumococcal Pneumonia among Adults: A Systematic Review and Meta-Analysis of Diagnostic Techniques

Background Pneumococcal pneumonia causes significant morbidity and mortality among adults. Given limitations of diagnostic tests for non-bacteremic pneumococcal pneumonia, most studies report the incidence of bacteremic or invasive pneumococcal disease (IPD), and thus, grossly underestimate the pneumococcal pneumonia burden. We aimed to develop a conceptual and quantitative strategy to estimate the non-bacteremic disease burden among adults with community-acquired pneumonia (CAP) using systematic study methods and the availability of a urine antigen assay. Methods and Findings We performed a systematic literature review of studies providing information on the relative yield of various diagnostic assays (BinaxNOW® S. pneumoniae urine antigen test (UAT) with blood and/or sputum culture) in diagnosing pneumococcal pneumonia. We estimated the proportion of pneumococcal pneumonia that is bacteremic, the proportion of CAP attributable to pneumococcus, and the additional contribution of the Binax UAT beyond conventional diagnostic techniques, using random effects meta-analytic methods and bootstrapping. We included 35 studies in the analysis, predominantly from developed countries. The estimated proportion of pneumococcal pneumonia that is bacteremic was 24.8% (95% CI: 21.3%, 28.9%). The estimated proportion of CAP attributable to pneumococcus was 27.3% (95% CI: 23.9%, 31.1%). The Binax UAT diagnosed an additional 11.4% (95% CI: 9.6, 13.6%) of CAP beyond conventional techniques. We were limited by the fact that not all patients underwent all diagnostic tests and by the sensitivity and specificity of the diagnostic tests themselves. We address these resulting biases and provide a range of plausible values in order to estimate the burden of pneumococcal pneumonia among adults. Conclusions Estimating the adult burden of pneumococcal disease from bacteremic pneumococcal pneumonia data alone significantly underestimates the true burden of disease in adults. For every case of bacteremic pneumococcal pneumonia, we estimate that there are at least 3 additional cases of non-bacteremic pneumococcal pneumonia.

The Pneumonia Etiology Research for Child Health Project: A 21st Century Childhood Pneumonia Etiology Study

The Pneumonia Etiology Research for Child Health (PERCH) project is a 7-country, standardized, comprehensive evaluation of the etiologic agents causing severe pneumonia in children from developing countries. During previous etiology studies, between one-quarter and one-third of patients failed to yield an obvious etiology; PERCH will employ and evaluate previously unavailable innovative, more sensitive diagnostic techniques. Innovative and rigorous epidemiologic and analytic methods will be used to establish the causal association between presence of potential pathogens and pneumonia. By strategic selection of study sites that are broadly representative of regions with the greatest burden of childhood pneumonia, PERCH aims to provide data that reflect the epidemiologic situation in developing countries in 2015, using pneumococcal and Haemophilus influenzae type b vaccines. PERCH will also address differences in host, environmental, and/or geographic factors that might determine pneumonia etiology and, by preserving specimens, will generate a resource for future research and pathogen discovery.

IMPACT OF PNEUMOCOCCAL CONJUGATE VACCINES ON NASOPHARYNGEAL CARRIAGE AND INVASIVE DISEASE AMONG UNVACCINATED PEOPLE: REVIEW OF EVIDENCE ON INDIRECT EFFECTS

BACKGROUND Invasive disease due to Streptococcus pneumoniae remains an important worldwide cause of morbidity and mortality, particularly in young children and the elderly. The development and use of pneumococcal conjugate vaccines (PCVs) have had a dramatic impact on rates of vaccine-type invasive pneumococcal disease (IPD) not only in the pediatric population targeted for vaccination but in non-vaccinated age-groups as well. This indirect effect is directly mediated by a reduction of vaccine-type nasopharyngeal carriage and thus transmission by vaccinated children. Current PCV licensing procedures do not take into consideration nasopharyngeal carriage impact, and thus the indirect effect. This review summarizes the evidence for the indirect effect of PCV on vaccine-type disease and its correlation with changes in carriage among unvaccinated populations, to assess the basis for inclusion of carriage in the PCV licensing process. METHODS Randomized controlled trials, surveillance and other observational studies published between 1994 and 2013 were systematically identified from global, regional and review databases and conference abstracts. We included as primary evidence, studies in non-vaccinated groups addressing changes in both vaccine-type IPD and carriage between pre- and post-PCV introduction periods; studies missing one of these four components were included as supporting rather than primary evidence. RESULTS We identified studies from 14 countries, nearly all developed countries. Vaccine-type IPD and carriage in non-targeted populations consistently decreased after PCV introduction, with the magnitude of decrease growing over time. Where IPD and carriage were observed in the same population, VT-decreases occurred contemporaneously. These relationships held true across age-groups and between indigenous and non-indigenous populations in the US and Australia. CONCLUSIONS Indirect PCV impact on VT-IPD and VT-carriage has been significant. Impact on carriage should be considered for inclusion in the PCV licensure process as a predictor of indirect effects.

The Definition of Pneumonia, the Assessment of Severity, and Clinical Standardization in the Pneumonia Etiology Research for Child Health Study

To develop a case definition for the Pneumonia Etiology Research for Child Health (PERCH) project, we sought a widely acceptable classification that was linked to existing pneumonia research and focused on very severe cases. We began with the World Health Organization’s classification of severe/very severe pneumonia and refined it through literature reviews and a 2-stage process of expert consultation. PERCH will study hospitalized children, aged 1–59 months, with pneumonia who present with cough or difficulty breathing and have either severe pneumonia (lower chest wall indrawing) or very severe pneumonia (central cyanosis, difficulty breastfeeding/drinking, vomiting everything, convulsions, lethargy, unconsciousness, or head nodding). It will exclude patients with recent hospitalization and children with wheeze whose indrawing resolves after bronchodilator therapy. The PERCH investigators agreed upon standard interpretations of the symptoms and signs. These will be maintained by a clinical standardization monitor who conducts repeated instruction at each site and by recurrent local training and testing.

Lower Respiratory Infections Among Hospitalized Children in New Caledonia: A Pilot Study for the Pneumonia Etiology Research for Child Health Project

Abstract We conducted a prospective pilot study over a 1-year period in New Caledonia in preparation for the Pneumonia Research for Child Health (PERCH) project. The pathogens associated with hospitalized lower respiratory infections in children were identified through the use of culture of induced sputum and blood, urinary antigen detection, polymerase chain reaction (PCR) on respiratory specimens, and serology on paired sera. Respiratory viruses were detected on respiratory specimens by immunofluorescence and PCR, and by serology on paired sera. Pathogens were detected in 87.9% of the 108 hospitalized cases. Viruses represented 81.6% of the 152 pathogens detected. Respiratory syncytial virus and rhinovirus were the most frequent, accounting for 32.2% and 24.3% of the pathogens identified, respectively. Only 26.3% of 99 induced sputum specimens collected were determined to be of good quality, which may be a consequence of the collection method used.

Identification and selection of cases and controls in the Pneumonia Etiology Research for Child Health project.

Methods for the identification and selection of patients (cases) with severe or very severe pneumonia and controls for the Pneumonia Etiology Research for Child Health (PERCH) project were needed. Issues considered include eligibility criteria and sampling strategies, whether to enroll hospital or community controls, whether to exclude controls with upper respiratory tract infection (URTI) or nonsevere pneumonia, and matching criteria, among others. PERCH ultimately decided to enroll community controls and an additional human immunodeficiency virus (HIV)–infected control group at high HIV-prevalence sites matched on age and enrollment date of cases; controls with symptoms of URTI or nonsevere pneumonia will not be excluded. Systematic sampling of cases (when necessary) and random sampling of controls will be implemented. For each issue, we present the options that were considered, the advantages and disadvantages of each, the rationale for the methods selected for PERCH, and remaining implications and limitations.