Logistics of a multinational population study.

The shaping of epidemiology as a clinical science prompted the perpetuation of large scale population studies aimed to determine causality and assessment of new therapeutical modalities. In order to achieve meaningful conclusions one has to rely on large masses of data, assembled by several teams of investigators in multi-geographical localities. The larger the number and diversity of participating groups, the more complex are the methodology and the final interpretation of outcome. A number of key principles in the undertaking of a long term joint population study are pointed out along 6 study stages: contemplation, planning, organization, data collection, analysis and outcome. The hypothesis has to be clearly formulated, financial resources mobilized, and lines of authority and communications strictly defined, before onset. Subsequently, the step by step routine of monitoring of the individual satellite centers, quality control and budget allocation, have to be established. The interpretation of the data may become final stumbling block since outcome is dependent on the quality of input and may be influenced by preconceived ideas of the investigators. Finally, the cooperative spirit behind the study may disappear once personalities and interests change. Hence, the future ownership of the data should be agreed upon before the conglomerate of data is split and fragmentated.