Short-Term and Long-Term Intra-Individual Variations and Critical Differences of Coagulation Parameters

Abstract

The intra-individual variations of 9 coagulation parameters were studied during short-term (withinone-day) and long-term (six months) periods. Two groups of healthy individuals (viz. 60 and 274 persons) were involved. Moreover, critical differences have been calculated from the total variations, comprising both biological and analytical variations. The influences of external factors such äs sex, smoking and the use of oral contraceptives have also been studied.The variability and critical differences found in coagulation parameters in this study appeared to be of the same order äs those observed in parameters usually determined in clinical chemistry and haematology. The application of critical differences in the evaluation and use of laboratory data, also in coagulation studies, enhances the objectivity of the judgement. Moreover, in the follow-up of patients the sensitivity of the parameters is increased. Kurz-und längzeitige intra-individuelle Änderungen sowie kritische Differenzen von GerinnungskenngrößenZusammenfassung: Für 9 Gerinnungskenngrößen wurden innerhalb eines Tages und über einen Zeitraum von 6 Monaten die intra4ndividuellen Variationen bestimmt. Dazu wurden 2 Gruppen von gesunden Individuen (bestehend aus 60 beziehungsweise 274 Personen) ausgewählt.Aus den Gesamtvariätiöneru sowohl die biologischen wie auch die analytischen Variationen umfassend, wurden die kritischen Differenzen errechnet. Einflußgrößen wie Geschlecht, Rauchen und Einnahme von oralen Kofttrazeptivä wurden dabei in Betracht gezogen.Die Variabilität und die kritischen Differenzen der untersuchten Gerinnungskenngrößen lagen in der gleichen Größenordnung wie die der üblichen klinisch-chemischen und haematologischen Laboratoriumskenngrößen.Die Anwendung der kritischen Differenzen für die Evaluation und richtige Interpretation der Laborbefunde erhöht auch bei Gerinnungsuntersuchungen die Objektivität der Beurteilung.Außerdem wird bei longitudinaler Betrachtungsweise der Patienten die Sensitivität der untersuchten Kenngrößen erhöht.

Confidence Intervals and Power Calculations for Within-Person Biological Variation: Effect of Analytical Imprecision, Number of Replicates, Number of Samples, and Number of Individuals

“…Investigations on biological variation have typically been performed with 10 -20 individuals (9 ) and up to 10 samples from each individual, or with up to 100 individuals and only 2 samples from each, although experiments have been described that have used up to 274 individuals and 6 samples from each (17 ). Fraser and Harris assert that "the components of variation can be obtained from a relatively small number of specimens collected from a small group of subjects over a reasonably short period of time," but do not provide any evidence or explanation for this.…”

Laboratory hematology in the history of Clinical Chemistry and Laboratory Medicine

“…In 1985 Costongs et al were the first to present data that proved to be useful for the interpretation of repeat measurements in a single individual, initially for cellular parameters and soon for routine coagulation assays as well [28,29] . Biological variability data have later been used for defining analytical goals in coagulation testing [30] .…”

Rapid Determination of Five Coagulation Parameters in One Sample with a Centrifugal Analyzer

“…During the time each patient has his own variability depending on biological and ana lytical error [19][20][21][22]. Intraindividual varia tion during 1 day and from month-to-month over a 6-month period are given in table IV as CVpso and CVP90 (median and 90 percen tile of intraindividual variation).…”