Life Events

Introduction

Although it is long established that stress is related to ill health and psychological distress, there remains ambiguity about the dimensions of stress involved in this process, specifically the types of stressors that have more deleterious effects on health. To study the naturalistic stress process, the field requires valid and reliable measures of life events, to use in conjunction [Page 562]with measures of vulnerability to stress. A life events scale is a comprehensive list of external events and situations (stressors) that are hypothesized to place demands that exceed the capacity of the average individual to adapt. Sample items in life events scales include recent divorce or separation, the death of a close family member, a job loss, moving, and the onset of a health problem.

Two types of life events assessment dominate the literature; exposure to out-of-the-ordinary events that have the capacity to change the patterns of life or arouse very unpleasant feelings (life events) and exposure to relatively minor, less emotionally arousing events whose effects disperse in a day or two (hassles). These measures often, but not always, take the environmental perspective on stress (e.g. Cohen, Kessler & Gordon, 1995), which tends to view events as triggers for disease. Life events measures differ to the extent to which they include self-reports of perceived stressfulness and threat posed by events (appraisals) and enduring or recurrent difficulties in an area of life (chronic stressors). The dimension of appraisal incorporates more fully the psychological perspective on stress (e.g. Lazarus, 1999). These variations in life event assessment have developed in response to different types of research questions, the outcome of interest in the investigation, and the period of time over which a particular event is thought to have impact, whether a few hours, or many years.

Life Events

There are two general methods of life events assessment, checklist measures (Turner & Wheaton, 1995) and personal interview measures (Wethington, Brown & Kessler, 1995). Interview measures incorporate qualitative probes that specify the characteristics of life events theorized to produce physical or psychological stress, the severity of the occurrence (the threat), and the timing of life events in relationship to the outcome. Some checklist measures use standardized probes to assess perceived severity, appraised threat, and timing of the event. Both checklist and interview measures can assess chronic stressors as well as acute or discrete life events.

A typical checklist measure consists of a series of yes/no questions, asking participants to report if any situation like the one described has occurred over a past period of time (e.g. one month, a year). Checklist measures may rely on respondent self-report to rate event severity and threat, or may assign average (‘normative’) severity ratings developed by investigators. Either method results in a summary score of the estimated stressfulness of events experienced over a period of time.

Checklist measures are popular, inexpensive, and easy to administer. They also yield consistent relationships with physical health outcomes, which is a property that makes them useful for exploratory studies (Turner & Wheaton, 1995). The Social Readjustment Rating Scale (SRSS: Holmes & Rahe, 1967) is the ancestor of many checklist measures in current use. The SRSS included both positive and negative events because its developers believed that change per se was associated with changes in health status. Over time, checklists have moved toward including only negative or undesirable events, based on repeated findings that undesirable events are more predictive of severe health problems than positive events. Special measures have been developed for other populations, including adolescents and ageing adults (Turner & Wheaton, 1995).

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