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Combining individual patient data and aggregate data in mixed treatment comparison meta-analysis: Individual patient data may be beneficial if only for a subset of trials
No full textBackground Individual patient data (IPD) meta-analysis is the gold standard. Aggregate data (AD) and IPD can be combined using conventional pairwise meta-analysis when IPD cannot be obtained for all relevant studies. We extend the methodology to combine IPD and AD in a mixed treatment comparison (MTC) meta-analysis. Methods The proposed random-effects MTC models combine IPD and AD for a dichotomous outcome. We study the benefits of acquiring IPD for a subset of trials when assessing the underlying consistency assumption by including treatment-by-covariate interactions in the model. We describe three different model specifications that make increasingly stronger assumptions regarding the interactions. We illustrate the methodology through application to real data sets to compare drugs for treating malaria by using the outcome unadjusted treatment success at day 28. We compare results from AD alone, IPD alone and all data. Results When IPD contributed (i.e. either using IPD alone or combining IPD and AD), the chains converged, and we identified statistically significant regression coefficients for the interactions. Using IPD alone, we were able to compare only three of the six treatments of interest. When models were fitted to AD, the treatment effects and regression coefficients for the interactions were far more imprecise, and the chains did not converge. Conclusions The models combining IPD and AD encapsulated all available evidence. When exploring interactions, it can be beneficial to obtain IPD for a subset of trials and to combine IPD with additional AD. Copyright (c) 2012 John Wiley & Sons, Ltd
Bayesian estimation of the true prevalence, sensitivity and specificity of the Rose Bengal and indirect ELISA tests in the diagnosis of bovine brucellosis
No full textSerology is the most convenient method for detecting brucellosis but the efficient use of such tests in disease control requires evaluation of diagnostic performance and discriminative ability. The objective of this study was to assess the performance of the Rose Bengal test (RBT) and an indirect ELISA (iELISA) in diagnosing brucellosis in 995 serum samples collected from cattle in the Ivory Coast between 2005 and 2009. A Bayesian approach was used to evaluate the two tests by estimating their sensitivities and specificities. The correlation-adjusted sensitivity of the iELISA was estimated to be 96.1% (credibility interval [CrI], 92.7-99.8), whereas that of the RBT was 54.9% (CrI, 23.5-95.1). High correlation-adjusted specificities were found for both tests (95.0%; [CrI, 91.1-99.6] for the iELISA and 97.7%; [CrI, 95.3-99.4] for the RBT, respectively). The true prevalence of brucellosis was estimated from the serum samples to be 4.6% (95%; [CrI, 0.6-9.5]). The level of agreement between the two tests was evaluated using indices of agreement (n=995). Good agreement was found for negative results (96.6%; confidence interval [CI], 95.7-97.4), a finding supported by an estimated significant correlation of 0.37 (95%; CI, 0.01-0.73) within the sera testing negative. Agreement was lower for sera testing positive (52.2% CI: 41.9-62.5). The findings highlight the importance of using these two tests in combination as part of any brucellosis control programme
The linked response: lessons emerging from integration of HIV and reproductive health services in Cambodia
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First survey on canine leishmaniasis in a non classical area of the disease in Spain (Lleida, Catalonia) based on a veterinary questionnaire and a cross-sectional study
No full textThe Spanish distribution of canine leishmaniasis (CanL) is heterogeneous and very few data are available for the north of the country, including the province of Lleida (Catalonia, Spain). This work describes the results obtained from a questionnaire sent to veterinarians throughout the province of Lleida. The majority of veterinarians (25/32, 78.1%) believed CanL cases were increasing and that the dogs had been infected locally (30/32, 93.8%). Also, a cross-sectional study was performed on the seroprevalence of CanL in kennel dogs, with and without compatible clinical signs, in the county of Pallars Sobira (Pyrenees of Lleida), where an autochthonous case of CanL had been previously detected. Four serological tests were used (IFAT, ELISA, Western blot, ICF) and dogs that tested positive with at least two immunological methods were considered seropositive and probably infected. 33.1% (48/145) of the dogs were seropositive. The results of a mixed logistic regression model showed that the risk of seropositivity increased with age (OR=1.35, p-value=0.002), among dogs living in the southern part of Pallars Sobira (OR=6.20, p-value=0.025) and among dogs whose owners considered their animals to be at risk of leishmaniasis infection (OR=1.26, p-value=0.024) and who were unaware of anti-sand fly preventive methods (OR=11.6, p-value=0.009). The risk decreased when dogs lived in an urban-periurban habitat (OR=0.17, p-value=0.002). The information gathered in the veterinary questionnaires helped us to define the knowledge, perception and awareness of the disease in a naive region, supporting the hypothesis of an existing CanL focus in Pallars Sobira, which was confirmed by the seroepidemiological survey. The seroprevalence study carried out on kennel dogs of local origin proved useful for detecting an autochthonous focus of leishmaniasis through the analysis of a small number of animals
