Harmonization of indirect reference intervals calculation by the Bhattacharya method

Luisa Martinez-Sanchez, Pablo Gabriel-Medina, Yolanda Villena-Ortiz, Alba E. Garciá-Fernández, Albert Blanco-Grau, Christa M. Cobbaert, Daniel Bravo-Nieto, Sarai Garriga-Edo, Clara Sanz-Gea, Gonzalo Gonzalez-Silva, Joan López-Hellín, Roser Ferrer-Costa, Ernesto Casis, Francisco Rodríguez-Friás, Wendy P. J. den Elzen

Research output: Contribution to journalArticleAcademicpeer-review


Objectives: The aim of this study was to harmonize the criteria for the Bhattacharya indirect method Microsoft Excel Spreadsheet for reference intervals calculation to reduce between-user variability and use these criteria to calculate and evaluate reference intervals for eight analytes in two different years. Methods: Anonymized laboratory test results from outpatients were extracted from January 1st 2018 to December 31st 2019. To assure data quality, we examined the monthly results from an external quality control program. Reference intervals were determined by the Bhattacharya method with the St Vincent’s hospital Spreadsheet firstly using original criteria and then using additional harmonized criteria defined in this study. Consensus reference intervals using the additional harmonized criteria were calculated as the mean of four users’ lower and upper reference interval results. To further test the operation criteria and robustness of the obtained reference intervals, an external user validated the Spreadsheet procedure. Results: The extracted test results for all selected laboratory tests fulfilled the quality criteria and were included in the present study. Differences between users in calculated reference intervals were frequent when using the Spreadsheet. Therefore, additional criteria for the Spreadsheet were proposed and applied by independent users, such as: to set central bin as the mean of all the data, bin size as small as possible, at least three consecutive bins and a high proportion of bins within the curve. Conclusions: The proposed criteria contributed to the harmonization of reference interval calculation between users of the Bhattacharya indirect method Spreadsheet.

Original languageEnglish
Pages (from-to)266-274
Number of pages9
JournalClinical Chemistry and Laboratory Medicine
Issue number2
Early online date2022
Publication statusPublished - 1 Jan 2023


  • Bhattacharya
  • harmonization
  • indirect approach
  • reference intervals

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