Measurement of plasma viscosity in stored frozen samples: a general population study.
To establish whether plasma viscosity could be accurately measured from frozen-stored (instead of fresh) plasma samples in epidemiological studies, we prospectively compared fresh and frozen-stored samples from 1361 men and women aged 25-74 years participating in the Glasgow MONICA survey. Mean plasma viscosity (37 degrees C) was significantly higher (P < 0.0001) in fresh samples (mean = 1.310 mPa/s, standard deviation = 0.079 mPa/s) compared with frozen samples (mean = 1.278 mPa/s, standard deviation = 0.075 mPa/s). However, this difference (mean = 0.030 mPa/s, 95% confidence interval = 0.029-0.031) did not vary significantly with increasing viscosity (kappa statistic for consistency of categorization by thirds = 0.824, standard error = 0.021). We conclude that frozen samples are acceptable for epidemiological studies of plasma viscosity, which should increase their utilization.
Woodward
Mark
M
Institute for International Health, University of Sydney, Australia.
Lowe
Gordon
G
Rumley
Ann
A
Imhof
Armin
A
Koenig
Wolfgang
W
D000328:Adult; D000368:Aged; D001793:Blood Preservation; D001809:Blood Viscosity / Q000502:physiology*; D015925:Cryopreservation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016481:Helicobacter Infections / Q000453:epidemiology / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012606:Scotland / Q000453:epidemiology; D012698:Serologic Tests; D013223:Statistics as Topic