Intra week reliability of Fibrinolytic and metabolic parameters and stability of their covariance structure

Interactions between lipoproteins and fibrinolytic parameters inducing cardiovascular disease are gradually being disclosed. The multivariate analyses often used in studies investigating this relationship implicitly assume 1) that the reliability of the parameters in a cluster is comparably high, and 2) that their covariance structure, i.e. the interrelationships among all parameters, is reasonable stable over time, conditions and groups. In the present study we tested the short-term stability of eight target parameters of the Insulin Resistance Syndrome (1RS): fasting insulin, LDL-cholesterol, HDL-cholesterol, triglycérides (TG), fibrinogen, tPA-antigen (tPA-ag), tPA-activity (tPA-act) and PAI-1-antigen (PAI-l-ag). In 125 sedentary male clerical workers (age 45.2 1 5.3 years) blood was drawn on Monday, Wednesday and Friday. In a second group of 107 female nurses (age 33.7 1 8.0 years) blood was drawn at the first and third day of a normal daytime shift. Participants were requested to fast and refrain from use of alcohol, coffee and tea after 11:00 p.m. the preceding night and to refrain from high impact physical activity the preceding day. Male had higher levels on TG, LDL, tPA-ag and PAI-l-ag then females. Females had higher levels of HDL and tPA-act then males. Test-retest correlations varied between .62 (for tPA-act) and .95 (for LDL) and were all highly significant. To assess the stability of the covariance structure of these parameters within the work week and across gender we used structural equation models (LISREL8).Within both genders the correlation matrices and accompanying standard deviations were equal at the first and third blood withdrawal day. However, the correlation structures between the two genders differed from each other. In males fasting insulin and triglycérides were associated with the fibrinolytic parameters tPA-act, tPA-ag and PAI-l-ag, these associations were not found in females. Concluding, the intra week reliability of the eight parameters of the 1RS was good and the stability of the interrelationships among all parameters is stable over time and conditions, but differed between the male and female population. © Harcourt Brace & Co. Ltd 1999.