2014, Number 2
Rev Mex Patol Clin Med Lab 2014; 61 (2)
Validation of the reliability and applicability of the nine fields table (9FT) for the diagnosis of diabetes mellitus
Terrés SAM, Sierra GQJJ, Santoscoy TFA, Santoscoy TA, Neri LRE, Ruiz AR, Lugo TM, Cruz HG
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Language: Spanish
References: 8
Page: 70-77
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ABSTRACT
Background: Mexico is undergoing an epidemiological transition resulting from a gradual aging of it’s population with increased incidence of chronic degenerative diseases on which diabetes mellitus —a problem that can be clinically silent for a period of over 10 years— plays a central role demanding for early detection and reliable diagnosis as a Preventive Medicine and Public Health priority challenge. Major improvements have occurred in diagnostic systems since 1977 when HbA1 was introduced in clinical laboratories. More than thirty years passed until HbA1c% was standardized by National Glycohemoglobin Standardization Program (NGSP) followed by American Diabetes Association (ADA) approval when in 2010 was finally positioned as the method of choice for the diagnosis of diabetes mellitus provided that methods used are certified by NGSP. Purpose: To evaluate the reliability and applicability of HbA1c% in the diagnosis of diabetes mellitus using a nine field contingency table developed in accordance with the recommendations of the American Diabetes Association 2010 that was previously described and published by us. Material and methods: This is a clinical, prospective, tangential, observational and descriptive study involving three Mexican clinical laboratories located in the cities of Guadalajara, Puebla and Merida which made determinations of BFG Basal Fasting Glucose (mg/dL) and HbA1c% (HPLC) to ambulatory individuals of all ages and both sexes. For the database eQAG Estimated Quarterly Average Glycemia (mg/dL) was calculated for each case to fill the contingency Nine Fields Table (9FT) in order to calculate the elements of Bayesian Conditional Probability Theorem. To ensure the reliability of the results, all procedures were carried out under the supervision of Qualitat which is an ISO 17043:2010 Accredited External Quality Assessment Scheme. All determinations of HbA1c% were performed with the HPLC method that is considered as the NGSP gold standard. Outcome: During the first semester of 2013 a database of 1,413 results with a range of 3-97 years of age (57 ± 16.3) was generated with a slight predominance of males (56%) in the BFG ranged from 39-402 mg/dL (116 ± 39) with HbA1c from 3.7% to 15.5% (7.0 ± 1.7%). A positive correlation was found between BFG vs. eQAG (r = 0.618). It was shown that the reliability of the diagnosis of DM with a BFG › 125 mg/dL with HbA1c › 6.5% has a sensitivity of 91% with a specificity of 62%. Discussion: Strict analytical control is the fundamental premise for medical relevance. NGSP certification of HbA1c% has conditioned strong reliability and applicability in order to use this test in clinical diagnosis. For diabetes mellitus detection is advisable to test all patients having a BFG › 100 mg/dL even IF it doesn’t exhibit the diabetic syndrome: polyuria, polydipsia, polyphagia, weight loss or gain. The application of the new ADA 2010 diagnostic criteria through the Nine Field Table (9FT) is of great simplicity and usefulness, especially when compared with Glucose Tolerance Tests (GTT). It is strongly advised that the results of this work may only be used by laboratories using the same analytical method that have previously achieved the analytical goals described herein since the procedure has not been validated with alternative methods other than HPLC for the quantification of HbA1c%. The diagnostic power of alternative systems must be considered as in the uncertainty area currently.REFERENCES