Whole blood viscosity: Affordances and re-evaluation of sensitivity and specificity for clinical use

Over the years, whole blood viscosity (WBV), an indicator of thickness and stickiness of blood has been a laboratory marker for blood stasis, and useful for monitoring several disorders including cardiovascular diseases (CVD). However, the use of WBV in clinical practice is still limited by affordances, knowledge and attitude. With the development of extrapolated whole blood viscosity (eWBV) method from hematocrit and total serum protein level, what is yet to be established is the sensitivity and specificity of eWBV to address the limitations in clinical practice. The objective of this study was to highlight the discourse on sensitivity, specificity and affordances (accessibility and affordability) of eWBV to re-evaluate the utilization of WBV in clinical practice, especially in low-mid income communities. This was a observational study that used archived data from haematology and biochemistry routine laboratory tests associated with cardiovascular phenomena. Statistical analysis adopted the conventional paired-contingency table method for sensitivities and specificities to assess validity of eWBV in CVD. Reliability was affirmed by consistent significant differences in WBV levels between thrombocytopenia and thrombocytosis (P < 0.005). Calculated validities show that eWBV is 264% specific and ≤38% sensitive to cardiovascular phenomena. In conclusion, eWB is generally less sensitive but more specific for CD. One major significant finding from this study is that in patients with haematocrit and serum protein results, the risk of bleeding and monitor the effects of therapy can be assessed using specific and accessible eWBV at no extra cost in laboratory service. Being accessible at no extra cost translates to widespread affordance for this laboratory test.