Is Adverse Selection Relevant? Spence-Mirlees Meets the Tunisian Peasant

In the standard problem of mechanism design under adverse selection, it is well known that the transfer function from the principal to the agent will be increasing in the agent's unknown productivity when there exists an incentive compatible mechanism. Cost-sharing contracts in LDC agriculture are a particularly interesting form of such mechanisms. In this paper, we develop a simple model of cost sharing contracts and construct a measure of potentially unobservable household productivity by estimating a plot level production function with household-specific fixed effects, which are then purged of observable household characteristics. We then use the implications of the model and our measure of potentially unobservable tenant productivity to test whether the productivity of tenants is indeed unobservable to landlords. Our empirical results strongly suggest that adverse selection concerns are not empirically important : in the Tunisian village we consider, it would appear that peasants do much better than is expected by Spence and Mirlees.empirical methods, economic development, adverse selection, Mechanism design

Conjugate Haemophilus influenzae type b vaccines for sickle cell disease.

BACKGROUND: People affected with sickle cell disease are at high risk of infection from Haemophilus influenzae type b. Before the implementation of Haemophilus influenzae type b conjugate vaccination in high-income countries, this was responsible for a high mortality rate in children under five years of age. In African countries, where coverage of this vaccination is still extremely low, Haemophilus influenzae type b remains one of the most common cause of bacteraemias in children with sickle cell disease. The increased uptake of this conjugate vaccination may substantially improve the survival of children with sickle cell disease. OBJECTIVES: The primary objective was to determine whether Haemophilus influenzae type b conjugate vaccines reduce mortality and morbidity in children and adults with sickle cell disease.The secondary objectives were to assess the following in children and adults with sickle cell disease: the immunogenicity of Haemophilus influenzae type b conjugate vaccines; the safety of these vaccines; and any variation in effect according to type of vaccine, mode of administration (separately or in combination with other vaccines), number of doses, and age at first dose. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group\u27s Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also contacted relevant pharmaceutical companies to identify unpublished trials.Date of last search: 23 November 2015. SELECTION CRITERIA: All randomised and quasi-randomised controlled trials comparing Haemophilus influenzae type b conjugate vaccines with placebo or no treatment, or comparing different types of Haemophilus influenzae type b conjugate vaccines in people with sickle cell disease. DATA COLLECTION AND ANALYSIS: No trials of Haemophilus influenzae type b conjugate vaccines in people with sickle cell disease were found. MAIN RESULTS: There is an absence of evidence from randomised controlled trials relating to the subject of this review. AUTHORS\u27 CONCLUSIONS: There has been a dramatic decrease in the incidence of invasive Haemophilus influenzae type b infections observed in the post-vaccination era in people with sickle cell disease living in high-income countries. Therefore, despite the absence of evidence from randomised controlled trials, it is expected that Haemophilus influenzae type b conjugate vaccines may be useful in children affected with sickle cell disease, especially in African countries where there is a high prevalence of the disease. The implementation of childhood immunisation schedules, including universal Haemophilus influenzae type b conjugate vaccination, may substantially improve the survival of children with sickle cell disease living in low-income countries. We currently lack data to evaluate the potential effect of Haemophilus influenzae type b vaccination among unvaccinated adults with sickle cell disease. Further research should assess the optimal Hib immunisation schedule in children and adults with sickle cell disease

EHA Research Roadmap on Hemoglobinopathies and Thalassemia: An Update

The inherited disorders of hemoglobin, which include sickle cell disease and thalassemias, are the most common and widespread distributed monogenic disorders. Due to a selective advantage in malaria regions, these hemoglobin defects are particularly frequent in Africa, Asia, or in the Mediterranean areas, where malaria was endemic until the last century. In recent decades, the globalization of migration has contributed to generate multiethnic European societies. Due to migration from countries or regions with high hemoglobinopathy frequencies such as Africa, Middle East, or Asia, large numbers of patients with these disorders are living in almost every European country today. Furthermore, the numbers are increasing because of increasing refugee flows toward Europe. Additional requirements are the development of European recommendations and guidelines for diagnosis and effective therapeutic approaches. These, together with the advancement of clinical trials using new drugs and therapeutic procedures could ameliorate the quality of life of patients affectedwith these diseases and increase their life expectancy. Lastly, coordinated efforts should bemade todevelop diagnostic pathways for thalassemias and hemoglobinopathies, in order to plan interventions, including prenatal diagnosis and cure. For these reasons, the development of new tools to reliably diagnose anemias is urgently needed and fits well with the needs of personalized medicine. In the last 15 years, hematology research has made many big leaps forward. Our general aim will be to solve several hematologic problems using these new approaches. We expect that the development of such a diagnostic tool will improve timely diagnosis throughout Europe, especially in those countries where it is difficult to gain access to \u201cclassical\u201d diagnostic tests

EHA Research Roadmap on Hemoglobinopathies and Thalassemia: An Update

The inherited disorders of hemoglobin, which include sickle cell disease and thalassemias, are the most common and widespread distributed monogenic disorders. Due to a selective advantage in malaria regions, these hemoglobin defects are particularly frequent in Africa, Asia, or in the Mediterranean areas, where malaria was endemic until the last century. In recent decades, the globalization of migration has contributed to generate multiethnic European societies. Due to migration from countries or regions with high hemoglobinopathy frequencies such as Africa, Middle East, or Asia, large numbers of patients with these disorders are living in almost every European country today. Furthermore, the numbers are increasing because of increasing refugee flows toward Europe. Additional requirements are the development of European recommendations and guidelines for diagnosis and effective therapeutic approaches. These, together with the advancement of clinical trials using new drugs and therapeutic procedures could ameliorate the quality of life of patients affected with these diseases and increase their life expectancy. Lastly, coordinated efforts should be made to develop diagnostic pathways for thalassemias and hemoglobinopathies, in order to plan interventions, including prenatal diagnosis and cure. For these reasons, the development of new tools to reliably diagnose anemias is urgently needed and fits well with the needs of personalized medicine. In the last 15 years, hematology research has made many big leaps forward. Our general aim will be to solve several hematologic problems using these new approaches. We expect that the development of such a diagnostic tool will improve timely diagnosis throughout Europe, especially in those countries where it is difficult to gain access to "classical" diagnostic tests

Measuring gaze and arrow cuing effects with a short test adapted to brain damaged patients with unilateral spatial neglect: A preliminary study

People with left unilateral spatial neglect (USN) following a right brain lesion show difficulty in orienting their attention toward stimuli presented on the left. However, cuing the stimuli with gaze direction or a pointing arrow can help some of them to compensate for this difficulty. In order to build a tool that helps to identify these patients, we needed a short version of the paradigm classically used to test gaze and arow cuing effects in healthy adults, adapted to the capacities of patients with severe attention deficit. Here, we tested the robustness of the cuing effects measured by such a short version in 48 young adult healthy participants, 46 older healthy participants, 10 patients with left USN following a right brain lesion (USN+), and 10 patients with right brain lesions but no USN (USN–). We observed gaze and arrow cuing effects in all populations, independently of age and presence or absence of a right brain lesion. In the neglect field, the USN+ group showed event greater cuing effect than older healthy participants and the USN– group. We showed that gaze and arrow cuing effects are powerful enough to be detected in a very short test adapted to the capacities of older patients with severe attention deficits, which increases their applicability in rehabilitation settings. We further concluded that our test is a suitable basis to develop a tool that will help neuropsychologists to identify USN patients who respond to gaze and/or arrow cuing in their neglect field

Associations between environmental factors and hospital admissions for sickle cell disease

Sickle cell disease (SCD) is an increasing global health burden. This inherited disease is characterised by a remarkable phenotypic heterogeneity, which can only partly be explained by genetic factors. Environmental factors are likely to play an important role but studies of their impact on disease severity are limited and their results are often inconsistent. This study investigated associations between a range of environmental factors and hospital admissions of young patients with SCD in London and in Paris between 2008 and 2012. Specific analyses were conducted for sub-groups of patients with different genotypes and for the main reasons of admissions. Generalized additive models and distributed lag non-linear models were used to assess the magnitude of the associations and to calculate relative risks. Some environmental factors significantly influence the numbers of hospital admissions of children with SCD, although the associations identified are complicated. Our study suggests that meteorological factors are more likely to be associated with hospital admissions for SCD than air pollutants. It confirms previous reports of risks associated with wind speed (RR: 1.06/SD [95% confidence interval (CI): 1.00-1.12]) and also with rainfall (RR: 1.06/SD [95%CI: 1.01-1.12]). Maximum atmospheric pressure was found to be a protective factor (RR: 0.93/SD [95%CI: 0.88-0.99]). Weak or no associations were found with temperature. Divergent associations were identified for different genotypes or reasons of admissions, which could partly explain the lack of consistency in earlier studies. Advice to patients with SCD usually includes avoiding a range of environmental conditions that are believed to trigger acute complications, including extreme temperatures and high altitudes. Scientific evidence to support such advice is limited and sometimes confusing. This study shows that environmental factors do explain some of the variations in rates of admission to hospital with acute symptoms in SCD, but the associations are complex, and likely to be specific to different environments and the individual's exposure to them. Furthermore, this study highlights the need for prospective studies with large numbers of patients and standardised protocols across Europe

Neurologic complications of sickle cell disease in Africa A systematic review and meta-analysis

To summarize prevalence data on the neurologic complications of sickle cell disease (SCD) in Africa

Associations between environmental factors and hospital admissions for sickle cell disease

The authors acknowledge METEO FRANCE for supplying meteorological data for Paris, and Véronique Ghersi from AirParif for advice about air quality data for Paris. This study had no specific funding. The authors would like to thank the Stroke Association for supporting some of the work involved in this stud

Ready-to-use food supplement, with or without arginine and citrulline, with daily chloroquine in Tanzanian children with sickle-cell disease: a double-blind, random order crossover trial

Background: Sickle-cell disease increases the risk of malnutrition. Low arginine and nitric oxide bioavailability are implicated in morbidity related to sickle-cell disease. Simple interventions are required, especially in low-income settings. We aimed to test the hypotheses that: (1) supplementary arginine, citrulline, and daily chloroquine increase bioavailable arginine and flow-mediated dilatation (FMD; maximal diameter change; FMDmax%), a measure of nitric oxide-dependent endothelial function; and (2) protein energy supplementation in the form of ready-to-use supplementary food (RUSF) improves the height-for-age and body-mass index-for-age Z-scores in children with sickle-cell disease. Methods: We performed a double-blind, random order crossover trial with two 4-month intervention periods (each followed by 4-month washout periods) in Muhimbili National Hospital in Dar-es-Salaam, Tanzania. We enrolled 119 children from the Muhimbili Sickle Cohort who were aged 8–12 years, naive to hydroxyurea, and had documented HbSS phenotype. Two formulations of RUSF (providing 500 kcal/day) were tested: basic (RUSF-b), with which children also received weekly chloroquine (150 mg or 225 mg chloroquine base, dependent on bodyweight); and vascular (RUSF-v), which was fortified with arginine and citrulline (designed to achieve mean intakes of 0·2 g/kg per day of arginine and 0·1 g/kg per day of citrulline), and with which children received daily chloroquine (maximum 3 mg chloroquine base/kg per day). Children were randomly allocated to receive either RUSF-b first or RUSF-v first and, after a washout period, were then given the other treatment. The primary outcomes in comparing the two RUSF formulations were mean plasma arginine, arginine to ornithine ratio, and arginine to asymmetric dimethylarginine ratio, and mean FMDmax%. The primary outcomes of the combined effect of both RUSF interventions were mean height-for-age Z-score and body-mass index-for-age Z-score. Analyses were done on the eligible intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01718054; and with ISRCTN74331412. Findings: Between Aug 9, 2012, and Feb 26, 2014, 145 children were randomised (71 children to RUSF-v first and 74 children to RUSF-b first) and 119 children were treated, of whom 114 children yielded complete data for all reported endpoints. The ratio of arginine to ornithine (mean of individual differences −8·67%, 95% CI −19·55 to 2·20; p=0·12) and the mean FMDmax% (1·00, −0·47 to 2·47; p=0·18) did not significantly differ between the RUSF-b and RUSF-v treatments. However, the arginine to asymmetric dimethylarginine ratio was significantly increased by RUSF-v compared with RUSF-b (56·26%, 31·13 to 81·38; p&lt;0·0001). In planned analyses that used mixed effects models to estimate the effect of each intervention compared with the participants at baseline or during washout periods, the arginine to asymmetric dimethylarginine ratio increased following both RUSF-v treatment (86%; p&lt;0·0001) and RUSF-b treatment (40%; p&lt;0·0001). However, FMDmax% was higher after treatment with RUSF-v (0·92; p&lt;0·0001) but not RUSF-b (0·39; p=0·22). Following either intervention (RUSF-b and RUSF-v, pooled) body-mass index-for-age Z-score (0·091; p=0·001) and height-for-age Z-score (0·013; p=0·081) increased compared with baseline and washout timepoints. In 83 participants in the treated population, there were 71 adverse events during the intervention, of which 21 (30%) were serious, and 81 adverse events during the washout periods, of which 26 (32%) were serious (p=0·31), including one patient who died in the second washout period. Interpretation: RUSF providing 500 kcal/day results in small weight gains in children with sickle-cell disease. However, even without arginine and citrulline fortification, RUSF seems to ameliorate arginine dysregulation and might improve endothelial function. Long-term studies are required to assess whether these physiological effects translate to improved clinical outcomes and better growth and development in patients with sickle-cell disease. Funding: Wellcome Trust.</p