Abstract
The instrument precision and between-patient variability of haemorheological measurements have been determined using six commercially available instruments: Technicon Ektacytometer, Contraves LS30, SEFAM Erythro-Agregametre, IMH Hemorheometre, Carri-Med St. George’s Filtrometer, and ABX Cell Transit Analyser. Instrument performance was similar at 25°C and 37°C. The different instruments, and sometimes the different parameters of one instrument, showed important differences in precision. Variability of results between patients was often greater than between healthy subjects. The results indicate that both instrument precision and biological variability should be determined in advance of rheological studies so that the required number of subjects can be estimated. A nomogram is presented to facilitate determination of sample size for studies in which the data are to be analysed by either parametric or non-parametric tests.
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