This paper describes the development, psychometric properties, and construct and incremental validity of a Headache-Specific Locus of Control Scale (HSLC). The HSLC is a 33 item scale designed specifically for recurrent headache sufferers. It assesses the individual's perceptions that headache problems and headache relief are determined primarily by: the individual's behavior (Internal factors), Health Care Professionals, or Chance factors. The psychometric properties of the HSLC were satisfactory. Among our findings were that: (1) the belief that headache problems and relief are determined by chance factors was associated with higher levels of depression, physical complaints, reliance on maladaptive pain coping strategies (p less than .001), and greater headache-related disability (p less than .01); (2) the belief that headache problems and relief are influenced primarily by the ministrations of health care professionals was associated with higher levels of medication use (p less than .01) and preference for medical treatment (p less than .001); and (3) the belief that headache problems are determined by the individual's responses and behaviors was associated with a preference for self-regulation treatment (p less than .01). These findings suggest adaptation to headache problems is influenced not only by the frequency and severity of the headache episodes, but by locus of control beliefs. The assessment of locus of control beliefs may provide useful information not typically obtained from standard medical evaluations.

Considerable burden is reported by informal caregivers of older individuals with cognitive impairment. Significant progress in the understanding of determinants of this burden has been achieved. However, further progress could be attained if we considered important methodological issues that may have limited our understanding of caregiver burden. These issues include subgroups of care recipients and caregivers, measurement issues, research design, and statistical techniques. Fifty-three studies published between 1980 and 1997 (inclusive) that focused on caregiver burden were abstracted to determine the extent to which the methodological issues discussed above were considered. Overall, we found considerable variability among the studies surveyed. Further understanding of the caregiving process and reductions in caregiver burden will depend on the attention to methodological issues and understanding of burden across the whole caregiving career.

Background: Previous research on risk of delirium in acute hospital settings identified mainly patient variables (e.g., age) that are not amenable to intervention. The purpose of this study was to develop a model for new delirium in hospitalized older patients that included process of care and social variables. Methods: A prospective cohort study was undertaken in a community hospital in Ontario, Canada. Research paticipants included 156 hospitalized patients age 65+ years and without delirium on admission who were admitted to a medical or surgical unit. The measures included daily appraisal of delirium using a standardized and validated tool, and assessment of patient, process of care, and social variables. Results: Delirium developed in 28 of the 156 patients (17.9%). Older age and cognitive impairment were significant patient variables. Significant process of care variables included a high number of medications administered during hospitalization, surgery, a high number of procedures during early hospitalization (e.g., x-rays, blood tests), and intensive care treatment. Conclusions: Approximately one older patient in five developed delirium after admission to a medical or surgical unit. Risks not easily amenable to intervention included age, cognitive dysfunction, surgery, and intensive care requirements. Risk factors that are potentially modifiable included number of medications and number of procedures. Future research might focus on the efficacy of such intervention to reduce new-onset delirium in acute hospital settings.

This paper describes the development, construct and discriminant validity, and incremental utility of a headache self-efficacy scale. The Headache Self-Efficacy Scale is a 51 item scale designed specifically for recurrent headache sufferers. It assesses individuals' belief that they are able to do the things necessary to prevent a moderately painful headache when confronted with personally relevant headache precipitants. High self-efficacy was associated with less depression, anxiety, and physical symptoms, and less use of passive coping strategies (P < .01), even when headache frequency, intensity and chronicity were controlled statistically. Self-efficacy also explained unique variance in psychological and somatic symptoms beyond that explained by locus of control and general self-efficacy. These findings suggest that adaptation to headaches is influenced by self-efficacy beliefs, and that the assessment of self-efficacy may provide useful information in the evaluation of recurrent headache sufferers.

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Data obtained with any research tool must be reproducible, a concept referred to as reliability. Three techniques are often used to evaluate reliability of tools using continuous data in aging research: intraclass correlation coefficients (ICC), Pearson correlations, and paired t tests. These are often construed as equivalent when applied to reliability. This is not correct, and may lead researchers to select instruments based on statistics that may not reflect actual reliability. The purpose of this paper is to compare the reliability estimates produced by these three techniques and determine the preferable technique. A hypothetical dataset was produced to evaluate the reliability estimates obtained with ICC, Pearson correlations, and paired t tests in three different situations. For each situation two sets of 20 observations were created to simulate an intrarater or inter-rater paradigm, based on 20 participants with two observations per participant. Situations were designed to demonstrate good agreement, systematic bias, or substantial random measurement error. In the situation demonstrating good agreement, all three techniques supported the conclusion that the data were reliable. In the situation demonstrating systematic bias, the ICC and t test suggested the data were not reliable, whereas the Pearson correlation suggested high reliability despite the systematic discrepancy. In the situation representing substantial random measurement error where low reliability was expected, the ICC and Pearson coefficient accurately illustrated this. The t test suggested the data were reliable. The ICC is the preferred technique to measure reliability. Although there are some limitations associated with the use of this technique, they can be overcome.

Restriction enzyme profiles of group G beta-hemolytic streptococci associated with a point source outbreak and an outbreak of sporadic pharyngitis in two different communities were compared. To assess the epidemiologic utility of this approach for studying group G streptococci, DNA fingerprints of strains responsible for a point source outbreak of pharyngitis associated with the consumption of contaminated food were compared with DNA fingerprints of pharyngeal isolates from children with pharyngitis seen at a pediatric practice during a 6-month period. In each epidemiologic situation, a single strain characterized by a unique restriction enzyme pattern predominated. The results are compatible with the conclusion that human infections could be limited to a few strains of group G streptococci which have the capacity to spread through a given population. The restriction enzyme profiles proved to be a highly specific and precise means of evaluating strain relatedness and of providing further understanding of the epidemiology of group G streptococcal infections.