Editor,—With much interest, I read the review of Pickett and Pearl regarding the effect of neighbourhood socioeconomic level on health outcomes.1 They conclude that there is fairly consistent evidence for modest neighbourhood effects on health, because 23 of the 25 reviewed studies report a statistically significant association between at least one measure of social environment and a health outcome, after adjusting for individual level socioeconomic status.

I agree with the conclusion of the authors that most studies show only modest differences in health outcomes between neighbourhoods of varying socioeconomic level. However, I am far less sure than they are that this is a real neighbourhood effect. Incomplete adjustment for individual socioeconomic status may be a much more likely explanation for the modest differences as found. For instance, regarding mental health, differences between areas of varying socioeconomic level in Amsterdam, the Netherlands, become small and without statistical significance if individual socioeconomic status if adjusted for by several measures jointly. In contrast, adjustment for separate measures of individual socioeconomic status leaves modest differences between neighbourhoods of varying socioeconomic level. Some of these previously published …

Kate Pickett (kpickett{at}health.bsd.uchicago.edu)

Kate Pickett (kpickett{at}health.bsd.uchicago.edu)