THE POPULATION MEAN PREDICTS THE NUMBER OF DEVIANT INDIVIDUALS

Objective - To examine the relation between the prevalence of deviation and the mean for the whole population in characteristics such as blood pressure and consumption of alcohol. Design - Re-examination of standardised data from the Intersalt study, an international, multicentre study on the determinants of blood pressure. Setting and subjects - Samples of adults representing 52 populations in 32 countries. Main outcome measures - The relations, expressed as correlation coefficients, between the mean population values for blood pressure, body mass index, alcohol consumption, and sodium intake and the prevalence of, respectively, hypertension (≥140 mm Hg), obesity (body mass index ≥ 30 kg/m2), high alcohol intake (≥300 ml/week), and high sodium intake (≥ 250 mmol/day). Results - There were close and independent associations between the population mean and the prevalence of deviance for each of the variables examined: correlation coefficients were 0.85 for blood pressure, 0.94 for body mass index, 0.97 for alcohol intake, and 0.78 for sodium intake. Conclusions - These findings imply that distributions of health related characteristics move up and down as a whole: the frequency of 'cases' can be understood only in the context of a population's characteristics. The population thus carries a collective responsibility for its own health and well being, including that of its deviants.