European Project on OSteoArthritis (EPOSA): methodological challenges in harmonization of existing data from five European population-based cohorts on aging.

BACKGROUND: The European Project on OSteoArthritis (EPOSA), here presented for the first time, is a collaborative study involving five European cohort studies on aging. This project focuses on the personal and societal burden and its determinants of osteoarthritis (OA). The aim of the current report is to describe the purpose of the project, the post harmonization of the cross-national data and methodological challenges related to the harmonization process METHODS: The study includes data from cohort studies in five European countries (Germany, Italy, the Netherlands, Spain and the United Kingdom) on older community-dwelling persons aged ≥ 59 years. The study design and main characteristics of the five cohort studies are described. Post harmonization algorithms are developed by finding a "common denominator" to merge the datasets and weights are calculated to adjust for differences in age and sex distribution across the datasets. RESULTS: A harmonized database was developed, consisting of merged data from all participating countries. In total, 10107 persons are included in the harmonized dataset with a mean age of 72.8 years (SD 6.1). The female/male ratio is 53.3/46.7%. Some variables were difficult to harmonize due to differences in wording and categories, differences in classifications and absence of data in some countries. The post harmonization algorithms are described in detail in harmonization guidelines attached to this paper. CONCLUSIONS: There was little evidence of agreement on the use of several core data collection instruments, in particular on the measurement of OA. The heterogeneity of OA definitions hampers comparing prevalence rates of OA, but other research questions can be investigated using high quality harmonized data. By publishing the harmonization guidelines, insight is given into (the interpretation of) all post harmonized data of the EPOSA study.

Interventions involving a major dietary component improve cognitive function in cognitively healthy adults: a systematic review and meta-analysis.

Accumulating evidence suggests a role for diet in promoting brain health. The purpose of this systematic review was to (1) quantitatively assess whether interventions with a major dietary component can enhance cognition in cognitively healthy adults and (2) identify responsive domains of cognition to inform the design of future dietary trials. Electronic databases were systematically searched to find eligible randomized controlled trials that assessed the effect of interventions with a major dietary component on cognitive function or incident dementia in adults without known cognitive impairment. Standardized mean differences (SMDs) (95% confidence interval [CI]) were combined using a random-effects meta-analysis, and tests of homogeneity of variance were calculated. Two trials reported dementia outcomes and were qualitatively described. Fifteen trials encompassing 6480 participants were eligible for meta-analysis. Compared to control, intervention improved performance on measures of global cognition (SMD = 0.14, 95% CI 0.01-0.27, P = .05, I2 76%), executive function (SMD = 0.11, 95% CI 0.04-0.18, P = .003, I2 0%), and processing speed (SMD = 0.12, 95% CI 0.05-0.19, P = .001, I2 0%). There was no effect of intervention on delayed memory (SMD = 0.04, 95% CI -0.02 to 0.09, P = .18, I2 4%). Significant heterogeneity and funnel plot asymmetry were detected for global cognition, but removal of studies with high risk of bias did not change the pooled findings. Current evidence is limited but indicates that diverse interventions improve nonmemory cognitive functions during normal cognitive aging. Measures of executive function and processing speed should be considered as feasible end points in future dietary intervention trials.