The Norsjo-Cooperstown healthy heart project: A case study combining data from different studies without the use of meta-analysis

Objectives: This paper aims to develop and describe a method for combining, comparing, and maximizing the statistical power of two longitudinal studie s of risk factors for cardiovascular disease that did not have identical da ta collection methodologies, Methods: Subjects from a 1986 cross-sectional study (n = 180) were pair-mat ched with subjects of corresponding gender and age (+5 years) from a 1990 c ross-sectional study. The methodology is described and results are calculat ed for various measures of cardiovascular risk or risk factors (e.g. choles terol, Finnish Risk Score). Results: Box's test of equality and symmetry of covariance matrices gave ch i-square values of 223.8 and 710.0 for two cardiovascular risk factors (cho lesterol and cardiac risk score. respectively) these values were highly sig nificant (p=0.0001). For the North Karelia Risk Score. repeated measures AN OVA revealed a borderline significant interaction for treatment by time (p= 0.054) and a significant interaction for treatment by time by country (p=0. 035). These probabilities compared favorably with a randomized blocks model . Conclusions: Creation of a synthetic longitudinal control group resulted in a statistically valid ANOVA model that increased the statistical power of the study.