Obesity Epidemiology

360 EPIDEMIOLOGIC STUDIES OF DETERMINANTS OF OBESITYoccupational stress. They found that the effects of both job strain and low job controlwere dependent on baseline BMI; par ticipants in the highest BMI quintile had the greatestweight gain over 5 years of follow-up. In addition, there is some evidence that gendermay moderate the effects of occupational stress on obesity; 165,170 this is not surprising asgender is correlated both with perceived stress and choice of coping response. As such,researchers interested in better understanding the stress-obesity relation are advised toconsider the potential for effect moderation by gender. 169Measurement IssuesAlthough it has been somewhat loosely defined, a number of strategies in the measurementof stress are apparent. The first has attempted to measure characteristics of the social environmentthat are believed to be particularly demanding (either objectively or normatively).Checklist measures of stressful life events have often been used in this regard. Such measuresinvite the participant to indicate which of a number of stressful events (e.g., death ofa spouse or child, divorce, job loss) have occurred to them within a specific time period.Generally speaking, these measures are scored by summing the number of stressful lifeevents, with higher scores indicating elevated stress; some measures, however, weigh theintensity of particular events. A number of other measures have been widely used to measurestressful life events, 171 though they are not particularly well suited to population-basedepidemiological investigations; these include semistructured personal interviews and stressfulevent measures (that are completed daily by a participant over a given time period). 172The other broad stress measurement approach has been to examine perceived stress,or an individual’s subjective ratings of their ability to manage (or cope with) the demandsof their social environment. 173 While there are comparatively fewer of these measures,Cohen’s Perceived Stress Scale 174,175 has been very widely used (in 4-, 10-, and 14-itemversions) to assess the degree to which individuals believe that their stress outweighstheir ability to cope. As exposure to stress can be associated with negative affect, adjectivechecklist measures can be used to assess participant’s mood. A number of suchmeasures exist, 176 although the number of items (which can exceed one hundred) may betoo large for routine epidemiologic use.Regardless of approach, stress measures have numerous limitations. Clearly, stress isa subjective construct and whether the existing stress measures are appropriate for useacross populations remains to be determined. Many suggest that there is a social classgradient in exposure to chronic stress, such that individuals of lower SEP are more likelyto encounter adverse stressors and less likely to be adequately prepared to manage thesedemands; racial/ethnic minority groups and women may similarly be at risk for higherstress levels. 177 Researchers should therefore be careful to ensure that the chosen measurehas been tested and is appropriate for administration in the target population. Further,investigators should be clear that the measure effectively distinguishes between stressorsthat are acute (which may be highly intense but resolve or become manageable over time)and those that are chronic (which may or may not be highly intense, but are unremittingover time). Ultimately, investigators should be clear regarding their research questionswhen selecting stress measures, as measures are not interchangeable and in some cases,use of multiple measures may be indicated.Social SupportThere is a vast literature that explores the benefits of interpersonal relationships for healthrelatedoutcomes. 178-185 These studies are based on the premise that greater connectedness