title: [Variation in serum cholesterol level in the same person: what is the true value and when is it called a significant change?].
abstract: The blood cholesterol level is not constant over time. Changing values may be found when rechecking high values, especially in patients on a diet or receiving medication. Repeated measurements are necessary. It will then be possible to estimate the 'true mean value'. This is the theoretical average of a large number of measurements taken from one person. The study concentrated on the intra-individual variation of the serum cholesterol and the consequences for screening and follow-up. For this purpose, during a period of four weeks, cholesterol levels were measured 12 times in 33 men aged 25-40. The mean coefficient of variation was 5.7%, with wide differences between participants, ranging from 2.9% to 9.8%. The position of the 'true mean value' was estimated (with 90% confidence), after I resp. 3 determinations. These findings have consequences for the classification of subjects in the different risk categories as defined in the Dutch Cholesterol Consensus. It is also possible to determine if, after a period of intervention, there is a significant decline in the cholesterol level. Roughly, a decline of 10-12% indicates a significant difference.
authors.affiliation: Vrije Universiteit, vakgroep Theorie der Geneeskunde, Epidemiologie en Biostatistiek, Amsterdam.
authors.forename: I J
authors.initials: IJ
authors.lastname: Hendriksen
authors.forename: P D
authors.initials: PD
authors.lastname: Bezemer
authors.forename: G J
authors.initials: GJ
authors.lastname: Boerma
authors.forename: U
authors.initials: U
authors.lastname: Zuiderveld
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002784:Cholesterol / Q000097:blood*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011336:Probability; D012016:Reference Values; D015203:Reproducibility of Results
chemical_list: D002784:Cholesterol
vernacular_title: Schommeling van het serumcholesterolgehalte bij één persoon: wat is de werkelijke waarde en wanneer is er sprake van een significante verandering?