Abstract
Background: Biological variation (BV) and reference change values (RCVs) have been widely described for the general population, but the use of these data derived from adults in the elderly population is a controversial issue. We determined the within- and between-subject BV and RCV in both elderly and young people and compared them with previously published analyses.
Methods: Samples were collected from 135 volunteers over 80 years of age at weekly intervals over 4 weeks. Eighteen biochemical and eight haematological analytes were measured. The Fraser and Harris methods were used to calculate the components of BV and RCV. To perform a comparative analysis, a reference group of 118 young subjects was studied under the same conditions.
Results: The obtained coefficients of BV showed statistical differences in many cases, but in general, both the elderly and young patient data fall within the ranges previously described for the general population. The indexes of individuality for the analytes investigated did not exceed 1.4 in any case and were <0.6 for some analytes. The RCVs derived from elderly subjects were similar to those published in the young population, both in healthy and diseased individuals.
Conclusions: The strong individuality observed supports the preferential use of RCVs rather than population-based reference intervals in elderly people. For most of the analytes studied, data from the young population can be applied to elderly people, but the specific elderly coefficients of BV and RCVs are a recommended option.
The authors thank the laboratory technical staff for their valuable assistance. This study was supported by the J.L. Castaño Foundation.
Conflict of interest statement
Authors’ conflict of interest disclosure: The authors stated that there are no conflicts of interest regarding the publication of this article.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Funding: The work was supported by the J.L. Castaño Foundation.
Ethical approval: The study was carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving human subjects.
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