A comparison of differential leucocyte counts measured by conventional automated venous haematology and darkfield microscopic examination of fresh capillary blood
Reeve, K, Arellano, JM, Gruner, T, Reilly, W, Smith BG & Zhou, S 2015, 'A comparison of differential leucocyte counts measured by conventional automated venous haematology and darkfield microscopic examination of fresh capillary blood', Advances in Integrative Medicine, vol. 2, no. 3, pp. 125-129.
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Analysis of fresh capillary blood using darkfield microscopy (FCB-DM) is a point of care screening tool, used by healthcare practitioners in Australia. However, the relationship between the outcomes of FCB-DM measures and the automated venous haematology measures has not been determined. The aim of this study was to compare differential white blood cell counts obtained using automated haematology and FCB-DM. Data of 125 individuals were collected either retrospectively (n = 74) or from participants specifically recruited for the project (n = 51). Retrospective data were collected from active files at a naturopathic clinic. Newly recruited participants provided a fasting capillary blood sample for FCB-DM analysis within 1 h of providing a venous blood sample at a commercial laboratory for automated haematologic analysis. The mean score of neutrophils was found to be higher, and lymphocytes and basophils to be lower, in FCB-DM analysis (p < 0.05). A significant and positive Pearson's correlation coefficient was found between automated haematology and FCB-DM in the cell counts for neutrophils (r = 0.60, p < 0.05) and lymphocytes (r = 0.63, p < 0.05), and a significant and positive Spearman's correlation was found for monocytes (rs = 0.32, p < 0.05) and eosinophils (rs = 0.596, p < 0.05). Linear regression analysis was also conducted to assess the relationship between the two techniques. The variance explained by the regression model was large for neutrophil (37%), lymphocyte (39%), and eosinophil (37%) scores. Despite significant differences in the mean scores of cells counts, significant correlations between the data obtained by the two techniques for neutrophil, lymphocyte, monocyte and eosinophil cells were observed. Given the small amount of blood sample required, FCB-DM would have an advantage in clinical practice, though further research is required to determine the clinical implications of the FCB-DM cell counts.