Accuracy and precision evaluation of Thai plastic microhematocrit tubes: the first product from Thailand

In Thailand, the spun microhematocrit method is usually performed using glass microhematocrit tubes even though broken glass tube during use may result in a risk of injury and blood-borne infection. The main reason is that the safer product alternatives such as plastic microhematocrit tubes are more expensive. Now, plastic tubes for hematocrit determination can be produced in Thailand at a much cheaper price. However precision and accuracy studies are necessary before being able to use them.

To compare the accuracy and precision of Thai plastic microhematocrit tubes against the routinely used glass microhematocrit tubes and imported plastic microhematocrit tubes using spun microhematocrit method.

One hundred residual EDTA blood samples from the Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand along with the three level hematology control materials were measured with spun microhematocrit values using three different types of plastic microhematocrit tubes. This was compared to the routinely used glass microhematocrit tubes as a gold standard.

The repeated measures one-way ANOVA found no significant difference between the hematocrit values from each type of tubes with an F(1,99) = 0.667 and p-value = 0.574. Intraclass correlation coefficient (ICC) between four types of microhematocrit tubes ranged from 0.996-0.998 (p-value < 0.001). Correlation coefficients (r) between four types of microhematocrit tubes ranged from 0.996-0.998 (p-value < 0.05). Coefficient of variation (CV) for precision of both within run and between run of Thai plastic microhematocrit tubes ranged from 1.44 to 2.17% compared to 1.39 to 4.01% of the imported plastic microhematocrit tubes.

The hematocrit values determined by all plastic microhematocrit tubes can be considered relatively equivalent to those of glass microhematocrit tubes in terms of accuracy and precision. The Thai plastic microhematocrit tubes are economical and with the cost-benefit over other plastic tubes of about 12 to 16 times. Therefore, the Thai plastic microhematocrit tubes should be the choice for glass tube replacement.