PROSPECTIVE STUDY FOR VALIDATION OF A SINGLE PROTOCOL FOR THE 13C-UREA BREATH TEST USING TWO DIFFERENT DEVICES IN THE DIAGNOSIS OF H. PYLORI INFECTION.

BACKGROUND: 13C-urea breath test (UBT) is the gold-standard, noninvasive method for H. pylori diagnosis. However, there is no uniform standardization of the test. This situation can be unpractical for laboratories running with two or more devices. OBJECTIVE: To perform a prospective comparison validation study of UBT employing one validated protocol for two different devices: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), here called device A and IRIS-Doc2® (Wagner Analysen-Technik, Germany, now Mayoly Spindler Group, France), here called device B, in the diagnosis of H. pylori infection. METHODS: A total of 518 consecutive patients (365 females, 153 males, mean age 53 years) referred for UBT were included. All patients received device A protocol as follow: after at least one hour fasting, patients filled two bags prior to the test, then ingested an aqueous solution containing 75 mg of 13C-urea with a 4.0 g citric acid powder and filled another two bags 15 min after ingesting the test solution. One pair of breath sample bags (before and after ingestion) was analyzed by the two different devices. A delta over baseline (DOB) ≥5‰ indicated H. pylori infection. Statistics: Wilcoxon test, kappa coefficient with 95% CI, Wilson's method. RESULTS: Considering the device A protocol as the gold standard, its comparison with device B showed a sensitivity of 99.3% (95% CI: 96.3-99.9) and a specificity of 98.9% (95% CI: 97.3-99.6). Kappa coefficient was 0.976 (95% IC: 0.956-0.997). CONCLUSION: Correlation between the two devices was excellent and supports a uniform standardization of UBT.

Estudo prospectivo para validação de protocolo único para o teste respiratório com ureia marcada com carbono-13 empregando dois dispositivos diferentes, no diagnóstico da infecção por H. pylori / Prospective study for validation of a single protocol for the 13c-urea breath test using two different devices in the diagnosis of h. pylori infection

ABSTRACT BACKGROUND: 13C-urea breath test (UBT) is the gold-standard, noninvasive method for H. pylori diagnosis. However, there is no uniform standardization of the test. This situation can be unpractical for laboratories running with two or more devices. OBJECTIVE: To perform a prospective comparison validation study of UBT employing one validated protocol for two different devices: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), here called device A and IRIS-Doc2® (Wagner Analysen-Technik, Germany, now Mayoly Spindler Group, France), here called device B, in the diagnosis of H. pylori infection. METHODS: A total of 518 consecutive patients (365 females, 153 males, mean age 53 years) referred for UBT were included. All patients received device A protocol as follow: after at least one hour fasting, patients filled two bags prior to the test, then ingested an aqueous solution containing 75 mg of 13C-urea with a 4.0 g citric acid powder and filled another two bags 15 min after ingesting the test solution. One pair of breath sample bags (before and after ingestion) was analyzed by the two different devices. A delta over baseline (DOB) ≥5‰ indicated H. pylori infection. Statistics: Wilcoxon test, kappa coefficient with 95% CI, Wilson's method. RESULTS: Considering the device A protocol as the gold standard, its comparison with device B showed a sensitivity of 99.3% (95% CI: 96.3-99.9) and a specificity of 98.9% (95% CI: 97.3-99.6). Kappa coefficient was 0.976 (95% IC: 0.956-0.997). CONCLUSION: Correlation between the two devices was excellent and supports a uniform standardization of UBT.

RESUMO CONTEXTO: O teste respiratório com ureia-marcada com carbono-13 (TR-13C) é o método padrão-ouro para o diagnóstico não invasivo da infecção por H. pylori. Apesar disto, não existe uma uniformização de protocolos para a sua realização, trazendo dificuldades operacionais para laboratórios ou clínicas que operam com equipamentos de fabricantes diferentes. OBJETIVO: Estudo prospectivo e comparativo para validação do TR-13C para o diagnóstico de infecção por H. pylori, com emprego de protocolo único para dois equipamentos diferentes, a saber: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), aqui denominado equipamento A e IRIS-Doc2® (Wagner Analysen-Technik, Alemanha, agora Mayoly Spindler Group, França), aqui denominado equipamento B. MÉTODOS: Um total de 518 pacientes (365 mulheres e 153 homens, idade média de 53 anos) consecutivamente encaminhados para a realização do TR-13C foram incluídos no estudo. Todos os participantes realizaram TR-13C, que foi processado e analisado simultaneamente pelos dois equipamentos. Embora os dois equipamentos possuam protocolos independentes previamente validados, foi optado, por sua maior praticidade, pela utilização de um único protocolo, conforme recomendado pelo fabricante do equipamento A, e assim resumido: após jejum mínimo de 1h, foram amostras de ar expirado coletadas em dois pequenos sacos coletores (120 mL), correspondendo ao tempo-zero (amostra-1, controle). Em seguida, os pacientes ingeriram, em até 2 min, uma solução aquosa (200 mL) contendo 75 mg de 13C-ureia e 4,0 gramas de ácido cítrico em pó, adicionado com edulcorante. Uma segunda coleta de ar expirado era realizada 15 min após a ingestão do substrato em dois novos pequenos sacos coletores, correspondendo à amostra-2. Foram considerados positivos para a presença da infecção por H. pylori quando apresentavam um delta over baseline (DOB) igual ou maior que 5‰. Análise estatística foi realizada com o teste de Wilcoxon, coeficiente kappa com IC 95% e método de Wilson. RESULTADOS: Considerando o protocolo do equipamento A como o padrão-ouro, sua comparação com o equipamento B mostrou sensibilidade de 99,3% (IC 95%: 96,3-99,9) e especificidade de 98,9% (IC 95%: 97,3-99,6). O coeficiente kappa observado foi de 0,976 (IC 95%: 0,956-0,997). CONCLUSÃO: A correlação entre os dois equipamentos foi excelente e contribui para uma uniformização de protocolos para TR-13C.

PAX2 polymorphisms and congenital abnormalities of the kidney and urinary tract in a Brazilian pediatric population: evidence for a role in vesicoureteral reflux.

BACKGROUND AND OBJECTIVES: Congenital anomalies of the kidney and urinary tract (CAKUT) are common genetic malformations. Since the PAX2 gene has a role in kidney organogenesis, this study investigated the association of PAX2 gene polymorphisms with CAKUT in general and with specific phenotypes of CAKUT in a Brazilian pediatric population. METHODS: This study included 241 individuals with antenatal hydronephrosis and 259 healthy controls. For genotyping and allelic discrimination we used the probes to rs2077642, rs4244341, rs6421335, rs11190698, and rs11190693. RESULTS: No statistical differences in allele and genotype frequencies were observed for the single nucleotide polymorphism (SNP) rs11190693. At the SNPs rs4244341 and rs11190698, the frequencies of the ancestral alleles were significantly higher among CAKUT patients (rs4244341 allele G: 0.86 vs. 0.78; rs11190698 allele A: 0.85 vs. 0.79). At the SNP rs4244341, the genotype GG was increased in CAKUT group (0.72 vs. 0.61, P = 0.013), while the TT was higher in controls (0.01 vs. 0.05, P = 0.001). At the SNP rs11190698, the genotype CC was increased in controls (0.02 vs. 0.06, P = 0.01). The most frequent CAKUT phenotypes were vesicoureteral reflux (VUR), multicystic dysplastic kidney (MCDK), and ureteropelvic junction obstruction (UPJO). In patients with VUR, the frequencies of the monozygotic ancestral alleles decreased at the SNP rs11190693 (AA 0.13 vs. 0.26, P = 0.04) and increased at the SNP rs4244341 (GG 0.77 vs. 0.61, P = 0.03). No statistical differences were detected between controls and patients with UPJO and with MCDK for all SNPs. CONCLUSION: The PAX2 gene seems to be involved with the pathogenesis of VUR in our sample.

Study of the association between the BMP4 gene and congenital anomalies of the kidney and urinary tract / Estudo da associação entre o gene BMP-4 e anomalias congênitas do rim e trato urinário

OBJECTIVE: To determine the frequency of different phenotypes for congenital anomalies of the kidney and urinary tract (CAKUT) in a Brazilian sample, and to evaluate the association between the CAKUT phenotypes and the BMP4 gene. METHODS: In this study, 457 Brazilian individuals were analyzed in an attempt to establish the association between the BMP4 gene and the CAKUT diagnosis. A case-control sample was genotyped for three BMP4 gene polymorphisms. RESULTS: Association data was established with CAKUT sample as a whole and with the three most important CAKUT phenotypes: multicystic dysplastic kidney disease (MDK), ureteropelvic junction obstruction (UPJO) and vesicoureteral reflux (VUR). When the sample was segregated in these three phenotypes, associations between the BMP4 gene were observed with UPJO and with MDK. Conversely, VUR was not associated to the polymorphisms of the BMP4 gene. CONCLUSIONS: The present data suggest that Brazilian individuals with polymorphisms of the BMP4 gene have a higher risk to develop CAKUT, especially the malformations related to nephrogenesis and initial branching such as MDK and UPJO. Conversely, VUR appeared not to be related to BMP4 gene. .

OBJETIVO: Determinar a frequência de diferentes fenótipos de anomalias congênitas do rim e trato urinário (CAKUT) em uma amostra brasileira e avaliar a associação entre os CAKUT e o gene BMP-4. MÉTODOS: Neste estudo, analisamos 457 indivíduos brasileiros em uma tentativa de estabelecera associação entre o gene BMP-4 e o diagnóstico de CAKUT. As amostras de caso e de controle foram genotipadas em busca de três polimorfismos do gene BMP-4. RESULTADOS: Os dados de associação foram estabelecidos com a amostra de CAKUT como um todo e com os três fenótipos de CAKUT mais importantes: rim displásico multicístico (RDM), obstrução da junção ureteropélvica (UPJO) e refluxo vesico-ureteral (VUR). Quando a amostra foi separada nesses três fenótipos, encontramos associações entre o gene BMP-4 com UPJO e com RDM. Por outro lado, o VUR não foi associado aos polimorfismos do gene BMP-4. CONCLUSÕES: Esses dados sugerem que os indivíduos brasileiros com polimorfismos do gene BMP-4 apresentam maior risco de desenvolver CAKUT, principalmente as malformações relacionadas a nefrogênese e ramificação inicial, como RDM e UPJO. Por outro lado, o VUR parece não estar relacionado ao gene BMP-4. .

Study of the association between the BMP4 gene and congenital anomalies of the kidney and urinary tract.

OBJECTIVE: To determine the frequency of different phenotypes for congenital anomalies of the kidney and urinary tract (CAKUT) in a Brazilian sample, and to evaluate the association between the CAKUT phenotypes and the BMP4 gene. METHODS: In this study, 457 Brazilian individuals were analyzed in an attempt to establish the association between the BMP4 gene and the CAKUT diagnosis. A case-control sample was genotyped for three BMP4 gene polymorphisms. RESULTS: Association data was established with CAKUT sample as a whole and with the three most important CAKUT phenotypes: multicystic dysplastic kidney disease (MDK), ureteropelvic junction obstruction (UPJO) and vesicoureteral reflux (VUR). When the sample was segregated in these three phenotypes, associations between the BMP4 gene were observed with UPJO and with MDK. Conversely, VUR was not associated to the polymorphisms of the BMP4 gene. CONCLUSIONS: The present data suggest that Brazilian individuals with polymorphisms of the BMP4 gene have a higher risk to develop CAKUT, especially the malformations related to nephrogenesis and initial branching such as MDK and UPJO. Conversely, VUR appeared not to be related to BMP4 gene.