Ana Claudia Veras Mattar1, Claudio Leone2, Joaquim Carlos Rodrigues3, Fabíola Villac Adde4. 1. Pediatric Pulmonology Division, Instituto da Criança, Hospital das Clínicas, University of São Paulo, Av. Dr. Enéas Carvalho de Aguiar, 647, cep 05403-900 São Paulo - SP - Brazil. Electronic address: anacmattar@uol.com.br. 2. Department of Maternal and Child Health, College of Public Health, University of Sao Paulo, Av. Dr. Arnaldo, 715, cep 01246-904 São Paulo - SP - Brazil. Electronic address: leone.claudio@gmail.com. 3. Pediatric Pulmonology Division, Instituto da Criança, Hospital das Clínicas, University of São Paulo, Av. Dr. Enéas Carvalho de Aguiar, 647, cep 05403-900 São Paulo - SP - Brazil. Electronic address: jocarod@uol.com.br. 4. Pediatric Pulmonology Division, Instituto da Criança, Hospital das Clínicas, University of São Paulo, Av. Dr. Enéas Carvalho de Aguiar, 647, cep 05403-900 São Paulo - SP - Brazil. Electronic address: fabiola.adde@outlook.com.
Abstract
BACKGROUND: Sweat chloride test is the gold standard test for cystic fibrosis (CF) diagnosis. Sweat conductivity is widely used although still considered a screening test. METHODS: This was a prospective, cross-sectional, diagnostic research conducted at the laboratory of the Instituto da Criança of the Hospital das Clínicas, São Paulo, Brazil. Sweat chloride (quantitative pilocarpine iontophoresis) and sweat conductivity tests were simultaneously performed in patients referred for a sweat test between March 2007 and October 2008. Conductivity and chloride cut-off values used to rule out or diagnose CF were <75 and ≥90 mmol/L and <60 and ≥60 mmol/L, respectively. The ROC curve method was used to calculate the sensitivity, specificity, positive (PPV) and negative predictive value (NPV), as well as the respective 95% confidence intervals and to calculate the area under the curve for both tests. The kappa coefficient was used to evaluate agreement between the tests. RESULTS: Both tests were performed in 738 children, and CF was ruled out in 714 subjects; the median sweat chloride and conductivity values were 11 and 25 mmol/L in these populations, respectively. Twenty-four patients who had received a diagnosis of CF presented median sweat chloride and conductivity values of 87 and 103 mmol/L, respectively. Conductivity values above 90 mmol/L had 83.3% sensitivity, 99.7% specificity, 90.9% PPV and 99.4% NPV to diagnose CF. The best conductivity cut-off value to exclude CF was <75 mmol/L. Good agreement was observed between the tests (kappa: 0.934). CONCLUSIONS: The sweat conductivity test yielded a high degree of diagnostic accuracy and it showed good agreement with sweat chloride. We suggest that it should play a role as a diagnostic test for CF in the near future.
BACKGROUND:Sweat chloride test is the gold standard test for cystic fibrosis (CF) diagnosis. Sweat conductivity is widely used although still considered a screening test. METHODS: This was a prospective, cross-sectional, diagnostic research conducted at the laboratory of the Instituto da Criança of the Hospital das Clínicas, São Paulo, Brazil. Sweat chloride (quantitative pilocarpine iontophoresis) and sweat conductivity tests were simultaneously performed in patients referred for a sweat test between March 2007 and October 2008. Conductivity and chloride cut-off values used to rule out or diagnose CF were <75 and ≥90 mmol/L and <60 and ≥60 mmol/L, respectively. The ROC curve method was used to calculate the sensitivity, specificity, positive (PPV) and negative predictive value (NPV), as well as the respective 95% confidence intervals and to calculate the area under the curve for both tests. The kappa coefficient was used to evaluate agreement between the tests. RESULTS: Both tests were performed in 738 children, and CF was ruled out in 714 subjects; the median sweat chloride and conductivity values were 11 and 25 mmol/L in these populations, respectively. Twenty-four patients who had received a diagnosis of CF presented median sweat chloride and conductivity values of 87 and 103 mmol/L, respectively. Conductivity values above 90 mmol/L had 83.3% sensitivity, 99.7% specificity, 90.9% PPV and 99.4% NPV to diagnose CF. The best conductivity cut-off value to exclude CF was <75 mmol/L. Good agreement was observed between the tests (kappa: 0.934). CONCLUSIONS: The sweat conductivity test yielded a high degree of diagnostic accuracy and it showed good agreement with sweat chloride. We suggest that it should play a role as a diagnostic test for CF in the near future.
Authors: Scott C Bell; Marcus A Mall; Hector Gutierrez; Milan Macek; Susan Madge; Jane C Davies; Pierre-Régis Burgel; Elizabeth Tullis; Claudio Castaños; Carlo Castellani; Catherine A Byrnes; Fiona Cathcart; Sanjay H Chotirmall; Rebecca Cosgriff; Irmgard Eichler; Isabelle Fajac; Christopher H Goss; Pavel Drevinek; Philip M Farrell; Anna M Gravelle; Trudy Havermans; Nicole Mayer-Hamblett; Nataliya Kashirskaya; Eitan Kerem; Joseph L Mathew; Edward F McKone; Lutz Naehrlich; Samya Z Nasr; Gabriela R Oates; Ciaran O'Neill; Ulrike Pypops; Karen S Raraigh; Steven M Rowe; Kevin W Southern; Sheila Sivam; Anne L Stephenson; Marco Zampoli; Felix Ratjen Journal: Lancet Respir Med Date: 2019-09-27 Impact factor: 30.700
Authors: Harm A W M Tiddens; Michael Puderbach; Jose G Venegas; Felix Ratjen; Scott H Donaldson; Stephanie D Davis; Steven M Rowe; Scott D Sagel; Mark Higgins; David A Waltz Journal: Pediatr Pulmonol Date: 2014-12-30
Authors: Rodrigo Abensur Athanazio; Luiz Vicente Ribeiro Ferreira da Silva Filho; Alberto Andrade Vergara; Antônio Fernando Ribeiro; Carlos Antônio Riedi; Elenara da Fonseca Andrade Procianoy; Fabíola Villac Adde; Francisco José Caldeira Reis; José Dirceu Ribeiro; Lídia Alice Torres; Marcelo Bicalho de Fuccio; Matias Epifanio; Mônica de Cássia Firmida; Neiva Damaceno; Norberto Ludwig-Neto; Paulo José Cauduro Maróstica; Samia Zahi Rached; Suzana Fonseca de Oliveira Melo Journal: J Bras Pneumol Date: 2017 May-Jun Impact factor: 2.624
Authors: Cibele Zanardi Esteves; Letícia de Aguiar Dias; Estela de Oliveira Lima; Diogo Noin de Oliveira; Carlos Fernando Odir Rodrigues Melo; Jeany Delafiori; Carla Cristina Souza Gomez; José Dirceu Ribeiro; Antônio Fernando Ribeiro; Carlos Emílio Levy; Rodrigo Ramos Catharino Journal: Front Pediatr Date: 2018-01-10 Impact factor: 3.418