Clinical performance of Swelab Alfa Plus hematology analyzer compared with reference instrument

Swelab Alfa Plus automated hematology analyzer is routinely used in laboratory diagnostics for determination of patients’ blood status. This work demonstrates the performance of Swelab Alfa Plus 3-part hematology analyzer in comparison with a more technically advanced 5-part reference analyzer in complete blood count (CBC) analyses of patient samples taken from the normal routine screening. The results show that the analyzers are in good agreement, indicating the suitability for use of Swelab Alfa Plus in general health screenings.

Introduction

A CBC is highly useful in general screenings as a tool to aid in diagnosis and monitoring of disease conditions. Automated instruments for this type of analyses were developed as early as in the 1950s, with the first European cell counter developed by Erik Öhlin, the founder of Swelab Instruments (now part of Boule Diagnostics).

Swelab Alfa Plus performance

Before, blood cell counts were performed manually by microscopy. Although manual examination of blood smears is still used as a control method for verification of results from abnormal samples, the automated hematology analyzers have largely replaced the manual method for determination of hematology parameters in the routine use.

The Swelab Alfa Plus system is an automated hematology analyzer for in vitro diagnostic use under laboratory conditions (Figure 1). The analyzer is intended for determination of hemoglobin (HGB) concentration, for counting of red blood cells (RBC) and platelets (PLT) as well as for counting and differentiation of white blood cells (WBC) into three subpopulations, namely lymphocytes (LYM), mid-sized white cells (MID, mainly monocytes), and granulocytes (GRAN, mainly neutrophils, eosinophils and basophils). The measurement principles of the Swelab Alfa Plus are based on impedance for cell counts and spectrophotometry for HGB.

Although such a 3-part hematology analyzer provides enough information for the smaller local hospital laboratory, trends show an increased interest in 5-part instruments, typically used in larger central hospital and hematology laboratories, also for use in small physician office laboratories (POL).

While a 5-part analyzer offers improved WBC assessment, differentiating them into neutrophils (NEU), lymphocytes (LYM), monocytes (MONO), eosinophils (EOS), and basophils (BASO), a 3-part instrument can offer great cost benefits to general screenings of patients’ blood status (1).

The objective of this study was to evaluate the performance of Swelab Alfa Plus 3-part hematology analyzer against a 5-part reference instrument.

Swelab Alfa Plus hematology instruments

Fig 1. Swelab Alfa Plus automated 3-part hematology analyzer is available in four versions. While both Basic and Standard support open tube aspiration, Standard features an integrated mixer. Cap and Sampler support closed-tube aspiration to minimize the risks associated with contaminated blood. In addition, Sampler is equipped with an Auto Sampler for up to 2 × 20 samples – just load and walk away.

Materials and methods

The following material was used in this study:

The evaluation of Swelab Alfa Plus (test instrument) was performed in collaboration with a Swedish hospital against Sysmex™ XE-5000 (reference instrument) in accordance with the standard SS-EN 13612 for compliance with the demands in the European IVD directive (98/79/EC). The correlation studies were based on > 340 samples taken from the normal routine. After analysis on the reference instrument, samples were run in the open tube (OT) inlet on the Swelab Alfa Plus system. All samples were analyzed in single assays.

Results


Fig 2. Correlation of (A) RBC, (B) PLT, (C), WBC, (D) LYM, (E) MID and (F) GRAN between test system and reference systems.

Results are presented in scatter plots in Figure 2, with the 95% confidence interval (prediction interval) of the indicated linear regression. As shown from the summary given in Table 1, the performance of Swelab Alfa Plus fulfills the specifications, and can thus be considered in good agreement with reference instrument.

Table 1. Summary of results

Table 1. Summary of results
N/A = not applicable

Conclusion

This study demonstrates that the performance of Swelab Alfa Plus hematology analyzer is in good agreement with that of the reference instrument. Although manual microscopic examination of blood smears is recommended as complementary method for confirming analytical data, the results indicate the suitability of Swelab Alfa Plus for use in routine hematology analysis.

Reference

1. Whitepaper: Hematology analyzers: 3-part or 5-part, that is the question. Boule Diagnostics, WP31183, Edition 2 (2019). 

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