Institutional practices and policies in acid-base testing: a self reported Croatian survey study on behalf of the Croatian society of medical biochemistry and laboratory medicine Working Group for acid-base balance

ntroduction: The aim of this survey study was to assess the current practices and policies in use related to the various steps in the blood gas testing process, across hospital laboratories in Croatia. Materials and methods: First questionnaire was sent by email to all medical biochemistry laboratories (N = 104) within general, specialized and clinical hospitals and university hospital centres to identify laboratories which perform blood gas analysis. Second questionnaire with detailed questions about sample collection, analysis and quality control procedures, was sent only to 47 laboratories identified by the first survey. Questionnaire was designed as combination of questions and statements with Likert scale. Third questionnaire was sent to all participating laboratories (N=47) for additional clarification for either indeterminate or unclear answers. Results: Blood gas analysis is performed in 47/104 hospital laboratories in Croatia. In 25/41 (0.61) of the laboratories capillary blood gas sampling is the preferred sample type for adult patient population, whereas arterial blood sample is preferentially used in only 5/44 laboratories (0.11). Blood sampling and sample processing for capillary samples is done almost always by laboratory technicians (36/41 and 37/44, respectively), whereas arterial blood sampling is almost always done by the physician (24/29) and only rarely by a nurse (5/28). Sample acceptance criteria and sample analysis are in accordance with international recommendations for majority of laboratories. 43/44 laboratories participate in the national EQA program. POCT analyzers are installed outside of the laboratory in 20/47 (0.43) institutions. Laboratory staff is responsible for education and training of ward personnel, quality control and instrument maintenance in only 12/22, 11/20 and 9/20 institutions, respectively. Conclusions: Practices related to collection and analysis for blood gases in Croatia are not standardised and vary substantially between laboratories. POCT analyzers are not under the direct supervision by laboratory personnel in a large proportion of surveyed institutions. Collective efforts should be made to harmonize and improve policies and procedures related to blood gas testing in Croatian laboratories

Peer-review policy and guidelines for Biochemia Medica Journal

Peer review is widely used system for evaluating manuscripts prior to publication. It has been and still is widely used tool for making justified and fair editorial decision. However, the evidence of its efficacy is limited and it has been criticized to be time-consuming, biased, inconsistent, conservative, and open to abuse. As a result, researchers, editors and policymakers have questioned its objectivity and purpose. Nevertheless, this should not be the reason for abandoning the principles of peer review, but to make the additional efforts towards its improvement. Therefore, this Research Integrity Corner aims to describe basic principles of peer review and to introduce Biochemia Medica’s guidelines for peer reviewers. Our intention is to help our peer reviewers provide evaluations that are as fair and objective as possible, while helping the journal publish innovative research of the highest qualit

Confidence interval

Interval pouzdanosti za bilo koju statističku mjeru predstavlja raspon mogućih vrijednosti unutar kojega se s izvjesnom vjerojatnosti nalazi ta statistička mjera populacije. Kao takav, interval pouzdanosti je objektivna procjena (ne)preciznosti i veličine uzorka nekog istraživanja. Stoga, na interval pouzdanosti posredno možemo gledati i kao na mjerilo kvalitete uzorka i istraživanja. Interval pouzdanosti je omeđen granicama. Ovisno o razini pouzdanosti koju biramo, mijenja se i raspon, tj. granice intervala. Najčešće korišteni intervali pouzdanosti u biomedicinskoj literaturi su 90%-tni, 95%-tni, 99%-tni i nešto rjeđe 99,9%-tni interval pouzdanosti. Što su granice intervala uže, preciznost procjene je veća. Tradicionalno se u literaturi najčešće koristi 95%-tni interval pouzdanosti, koji je u svezi s opće prihvaćenom razinom statističke značajnosti P < 0,05. Za uzorak iste veličine vrijedi pravilo: štoje manja razina pouzdanosti - veća je preciznost procjene. Samo istraživanja provedena na velikom uzorku će dati vrlo uski interval pouzdanosti koji ukazuje na veliku preciznost procjene, s visokom razinom pouzdanosti. Interval pouzdanosti moguće je pridružiti gotovo svakom statističkom pokazatelju. Iako postoje i neki drugi načini, interval pouzdanosti najčešće računamo pomoću standardne greške. Interval pouzdanosti je komplementaran statistički pokazatelj s P vrijednosti. Oni govore o istoj stvari na dva različita načina i međusobno se nadopunjuju. P vrijednost nam govori o vjerojatnosti s kojom je moguće da se uočeni fenomen (razlika) dogodio slučajno, dok interval pouzdanosti nudi granice unutar kojih je moguće očekivati vrijednost tog fenomena. Posljednjih dvadesetak godina sve je više časopisa u kojima je obveza autora prikazati intervale pouzdanosti za svoje ključne rezultate. Prikaz intervala pouzdanosti pruža dodatnu informaciju o našem uzorku i rezultatima, i nadasve je korisna i nezamjenjiva nadopuna klasičnom testiranju hipoteze i opće prihvaćenoj P vrijednosti. Prikaz ključnih rezultata uz pripadajuće intervale pouzdanosti trebao bi postati standard svih znanstvenih časopisa, jer zainteresiranom čitatelju omogućuje bolje razumijevanje prikazanih podataka.Confidence interval presents a range of possible values within which, with some certainty, we can find the statistical measure of the population. As such, it is an objective estimate of (in)precision and sample size of certain research. Therefore, we can consider confidence interval also as a measure of the sample and research quality. Confidence interval is defined by its margins of error. Depending on the confidence level that we choose, the interval margins of error and respective range also change. The most used confidence intervals in the biomedical literature are the 90%, 95%, 99% and not so often 99.9% one. The narrower the margins of an interval are, the higher is the estimate accuracy. The 95% confidence interval is traditionally the most used interval in the literature and this relates to the generally accepted level of statistical significance P < 0.05. There is a rule for same sized samples: the smaller the confidence level is, the higher is the estimate accuracy. Only the studies with a large sample will give a very small confidence interval, which points to high estimate accuracy with a high confidence level. A confidence interval can be attributed to almost every statistical measure. Although there are some other ways of calculating it, the confidence interval is generally and most frequently calculated using standard error. The P value and the confidence interval are two complementary statistical indicators. They describe the same thing, but in two different ways. The P value describes probability that the observed phenomenon (difference) occurred by chance, whereas the confidence interval provides margins of error within which it is possible to expect the value of that phenomenon. In the last twenty years, increasing number of journals require reporting of the confidence intervals for each of their key results. Reporting of this confidence interval provides additional information about the sample and the results. It is, moreover, very useful and irreplaceable supplement to a classical hypothesis testing and to the generally accepted P value. It should become a standard of all scientific journals to report key results with respective confidence intervals because it enables better understanding to the interested reader

Verification of automatic analysers Roller 20PN and iSED for measuring erythrocyte sedimentation rate

Automated erythrocyte sedimentation rate (ESR) analysers are based on different methodology than Westergren method. It is questionable whether ESR values obtained from those analysers are comparable with determined values with Westergren method. The aim was verification of the precision, method comparison and accuracy of automated ESR analysers: Roller 20PN (Alifax S.p.A., Polverara, Italy) and iSED (Alcor Scientific, Smithfield, USA). Blood samples (N = 752 for Roller 20PN and N = 213 for iSED) were sampled into K2EDTA (Kima, Italy) tubes for automated and 3.8% Na-citrate tubes (Kima, Italy) for Westergren method. The data was divided into three groups according to the ESR values obtained with the Westergren method: Group Low (L) (ESR ≤ 20 mm), Group Medium (M) (ESR 21-60 mm), and Group High (H) (ESR ≥ 61 mm). Method agreement was assessed by Bland-Altman analysis and Passing-Bablok regression. Analyser iSED has shown better comparability with Westergren method (bias 0.0 (95%Cl -1.4 to 1.5) range than Roller 20 PN (bias = - 6.4 (95%Cl - 7.1 to -5.7) in the whole measuring. For Roller 20 PN, Passing-Bablok regression has shown constant and proportional difference for Groups L and M, and for iSED only for Group H. Roller 20 PN had lower sensitivity (0.51 (95%Cl: 0.45-0.57) than iSED (0.72 (95%Cl: 0.59-0.80) while they had comparable specificity (> 0.90) and accuracy (≥ 0.80) in comparison with the Westergren method. Both analysers are not comparable with the Westergren method and should not be used interchangeably

Verification of a 6-part differential haematology analyser Siemens Advia 2120i

The aim of this study was to perform a comprehensive verification of a 6-part differential haematology analyser Siemens Advia 2120i (Erlangen, Germany), prior to its routine implementation. Our verification protocol included: precision (within- and between-run), estimated bias (%) as measure of trueness, which was calculated from observed and manufacturers’ declared value, analytical measuring interval (AMI), carryover, confirmation of a limit of blank (LoB), determination of a limit of detection (LoD) and limit of quantitation (LoQ). The K2 ethylenediaminetetraacetic acid (EDTA) patients’ leftover samples were used for verification of analyser Advia 2021i. Acceptance criteria were based on manufacturer technical specifications (Siemens), 2016 state-of-the-art criteria (Vis and Huisman), and EFLM Biological Variation Database. The within- and between-run precision were acceptable for all parameters and the lowest coefficients of variation were observed for mean corpuscular volume (MCV) (0.3% and 0.6%, respectively). Estimated bias was within the acceptance criteria for all parameters except for MCV (the estimated bias was 2.2% (acceptance criteria 2.0%). AMI was confirmed for all tested parameters (r > 0.99). The carryover estimates ranged from 0.1% for platelet count (Plt) to 0.6% for red blood cell count and were within the manufacturers’ specifications (≤ 1%). Manufacturers’ claims for LoB were confirmed for leukocytes, erythrocytes, haemoglobin, and platelets. The estimated LoD and LoQ were 0.05 x109/L and 0.1 x109/L for white blood cell count, while for Plt values were 2 x109/L and 3 x109/L, respectively. Analytical performance of the Siemens Advia 2120i meets predefined quality goals and is suitable for routine use in a clinical laboratory