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W F Stewart

Publications and source records attributed to W F Stewart.

At least 73 records · Page 4Linked to original sources
PubMed1998

Questionnaires for collecting detailed occupational information for community-based case control studies.

In case control studies, collection of information on the workplace environment has generally been limited to self-reports of exposures or to job title, type of employer, and the dates the jobs were held, supplemented sometimes by work activities. This information, however, may be insufficient to assess the potential and level of exposure accurately due to recall difficulties and the variability of exposures within a job. A solution to this problem is to use job-specific questionnaires. The organization of a series of such questionnaires developed for a case control study of brain tumors is described. Three types of questionnaires, or modules, were developed, task-based, industry-based, and modules based on jobs with nonspecific types of tasks (e.g., laborer). The format of these modules starts with questions on the general work environment (type of employer) and proceeds to questions on tasks. More detailed information is then gathered on materials and equipment used, sensory descriptions, dermal exposure, work practices, engineering controls, and personal protective equipment use. The questionnaires cover a wide variety of exposures including solvents, heavy metals, polycyclic aromatic hydrocarbons, machining fluids, electromagnetic frequency fields, and many other exposures and, therefore, can be used in other case control studies.

Brain Neoplasms↗
PubMed1998

Migraine and reduced work performance: a population-based diary study.

OBJECTIVE: This article estimates lost work days and lost work day equivalents in a population sample of migraineurs, differentiating work loss due to headache episodes that met criteria for migraine from migrainous headaches not meeting full criteria and nonmigrainous headaches. METHODS: A random digit dialing survey of 5,071 adults identified 800 subjects with migraine headaches. By clinical examination, a subsample of 225 met migraine diagnostic criteria; 174 of these patients completed at least 11 weeks of daily diaries. This report concerns the subgroup of 122 individuals with regular paid employment. Subjects completed a daily diary over a 3-month period to assess the occurrence of headaches and International Headache Society (IHS) criteria for each headache occurrence. We report estimates of lost work days and lost work day equivalents by type of headache. RESULTS: Participants reported headaches on 8.1 work days, of which 2.2 headache days met criteria for migraine (IHS 1.1, 1.2), and an additional 2.1 headache days were migrainous without meeting full migraine criteria (IHS 1.7). On average, migraineurs missed 1.1 days of work due to headache in 3 months, of which 0.7 lost work days were due to migraine and 0.3 were due to migrainous headaches. When at work with headache, work effectiveness was reduced 41% for migraine headaches, 28% for migrainous headaches, and 24% for other headaches. Over 3 months, migraineurs experienced an average of 3.0 lost work day equivalents, of which 1.4 were due to migraine and an additional 0.7 were due to migrainous headaches. The most disabled 20% of the participants accounted for 77% of the lost work days; 40% of subjects accounted for 75% of the lost work day equivalents. CONCLUSIONS: Employed migraine sufferers experienced considerable work loss and reduced work performance due to headache. The most severely affected migraineurs accounted for most of the reduced work performance. Targeting the most severely affected persons may be necessary to reduce work loss among migraineurs substantially.

Absenteeism↗
PubMed1998

Migraine headaches: epidemiology and comorbidity.

Migraine imposes substantial burdens both on individual headache sufferers and on society. Prevalence studies reveal that the condition affects about 18% of women and about 6% of men. Prevalence is highest between the ages of 25 and 55, during the peak productive years. Despite the development of new and effective treatment options, migraine remains an underdiagnosed and undertreated condition. In this article, we review the incidence, prevalence, and distribution of migraine and the conditions which are comorbid with migraine.

Age of Onset↗
PubMed1997

Familial risk of migraine: a population-based study.

Estimates of familial aggregation of migraine have varied considerably due, in part, to methodological differences among studies. We concluded a population-based study of 73 clinically confirmed probands with migraine, 72 matched control probands, and 511 of their first-degree relatives, all of whom were directly interviewed. The risk of migraine was 50% more likely in relatives of migraine probands than in relatives of controls. Migraine risk was considerably higher among relatives of probands with disabling migraine compared with relatives of probands with minimal disability. Moreover, for probands with minimal disability, no excess risk of migraine in female relatives was observed. Finally, in relatives of male migraine probands, there appears to be an excess risk of migraine with aura. A borderline significant relative risk of 4.04 was observed. No excess risk was observed among relatives of male probands who had migraine without aura. This study suggests that familial factors (environment related to the family or genetic factors) account for less than one-half of all migraine cases in the population. Degree of disability in the proband appears to influence familial risk. These results suggest that the development of migraine is determined by complex genetic as well as environmental factors.

Adult↗
PubMed1997

Prevalence and impact of migraine.

Knowledge of the epidemiology of migraine has expanded because of the recent proliferation of large scale population-based studies using standardized case definitions. Migraine is a highly prevalent disorder, affecting about 6% of men and 15% to 18% of women. Migraine prevalence is highest between the ages of 25 and 55 years, accounting for its enormous impact in the workplace. Migraine imposes a substantial burden on society as measured by direct and indirect costs. Because the indirect costs greatly exceed the direct costs and because migraine is underdiagnosed and undertreated, improvements in treatments in treatment should reduce individual suffering and reduce work loss in a cost-effective manner.

Age Distribution↗
PubMed1997

Lost workdays and decreased work effectiveness associated with headache in the workplace.

Little is known about the impact of different types of headache on lost work time and work effectiveness in the United States. Estimation of the distribution and magnitude of the impact of headache in the workplace is necessary before workplace interventions can be developed. During 1993 and 1994 in Baltimore County, Maryland, study subjects were contacted by random-digit dialing and interviewed by telephone about their headaches. Headache diagnoses were assigned using International Headache Society criteria for migraine and episodic tension-type headache. Measures of workplace impact were derived based on self-reports of missing work because of headache and frequency and magnitude of reduced work level because of headache. Of the 13,343 respondents, 9.4% reported missing work more than rarely because of headache, 31% reported that their work level was reduced more than rarely by headache, and 9.2% reported that their work level was reduced more than 50% by headaches during work. In accounting for both actual lost workdays and reduced effectiveness at work, individuals lost the equivalent of 4.2 days per year because of headache. Of the 9922 annual estimated actual lost workdays because of headache, 57% were due to migraine and 43% were due to tension-type and other headache types. Of the 23,287 annual estimated reduced effectiveness workday equivalents, 64% were due to tension-type and other headache types, and 36% were due to migraine. Headache type, headache severity, and education level were each independent predictors of workplace impact of headache. Subjects with migraine headache were much more likely to report actual lost workdays because of headache, whereas tension-type and other headache types accounted for a large proportion of decreased work effectiveness because of headache. The results have implications regarding the control of indirect costs in the workplace because of headache, and on workplace-based treatment and prevention programs.

Adolescent↗
PubMed1997

Clinical applications of zolmitriptan (Zomig, 311C90).

Zolmitriptan (Zomig, formerly 311C90) is a novel, oral antimigraine drug that is consistently effective and well tolerated in the acute treatment of migraine headache and its associated symptoms. The purpose of this article is to review data available from pharmacological and clinical trials with zolmitriptan and to summarize the clinically relevant features that distinguish this agent. We will review the attributes desirable in a migraine drug and use this as a template for assessing zolmitriptan. Zolmitriptan provides a new oral treatment option for physicians which should help improve patient outcomes.

Acute Disease↗
PubMed1997

Risk of Alzheimer's disease and duration of NSAID use.

In a longitudinal study of 1,686 participants in the Baltimore Longitudinal Study of Aging, we examined whether the risk of Alzheimer's disease (AD) was reduced among reported users of aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). In addition, we examined use of acetaminophen, a pain-relief medication with little or no anti-inflammatory activity, to assess the specificity of the association between AD risk and self-reported medications. Information on use of medications was collected during each biennial examination between 1980 and 1995. The relative risk (RR) for AD decreased with increasing duration of NSAID use. Among those with 2 or more years of reported NSAID use, the RR was 0.40 (95% confidence interval [CI]: 0.19-0.84) compared with 0.65 (95% CI: 0.33-1.29) for those with less than 2 years of NSAID use. The overall RR for AD among aspirin users was 0.74 (95% CI: 0.46-1.18), and no trend of decreasing risk of AD was observed with increasing duration of aspirin use. No association was found between AD risk and use of acetaminophen (RR = 1.35; 95% CI: 0.79-2.30), and there was no trend of decreasing risk with increasing duration of use. These findings are consistent with evidence from cross-sectional studies indicating protection against AD risk among NSAID users and with evidence suggesting that one stage of the pathophysiology leading to AD is characterized by an inflammatory process.

Acetaminophen↗
PubMed1997

Burden of migraine: societal costs and therapeutic opportunities.

Migraine imposes an enormous health burden on individual headache sufferers and on society. The condition affects about 18% of women and about 6% of men across their lifespan. Because prevalence peaks during the most productive years, between the ages of 25 and 55, migraine is an important cause of lost work time. Despite the widespread underdiagnosis and undertreatment of migraine, health care costs for the condition are considerable. Add to this the indirect costs, in the form of absenteeism and reduced productivity at work, and the overall burden of migraine becomes apparent. Work loss is not uniformly distributed, with the most disabled half of migraineurs accounting for more than 80% of all work loss. Although improvements in health care delivery for migraine may increase direct cost (i.e., drug or medical care), this may be offset by savings in indirect costs (i.e., reduced and lost productivity).

Absenteeism↗
PubMed1997

The effect of dementia risk factors on comparative and diagnostic selective reminding norms.

Robust comparative and diagnostic norms for the elderly are provided for the Selective Reminding Test (Buschke, 1973). Correcting for factors such as age and education level are appropriate for comparative norms, which are intended for ranking individuals with respect to their age and education matched peers. However, because age and education are both risk factors for dementia, correcting for these factors decreases test sensitivity for detecting dementia. Age- and education-corrected Selective Reminding scores have a sensitivity for detecting dementia that is 28% lower than uncorrected scores. Using information about age in combination with memory scores provided optimal discrimination of dementia. It is concluded that statistically removing the contribution of dementia risk factors from memory test scores can severely decrease discriminative validity for detecting dementia in the elderly.

Aged↗
PubMed1996

Work-related disability: results from the American migraine study.

Migraine headache is a highly prevalent, often severely painful and frequently disabling disorder. The indirect costs related to disability greatly exceed the direct cost of medical care. The objective of this paper is to describe work-related disability associated with migraine headache and predictors of disability. In a two-stage survey of the US population, we estimate missed workdays and impairment at work in a sample of 1663 migraine suffers, age 18 years and older. Lost workday equivalents (LWDE) was derived as the sum of actual missed workdays and the product of percentage effectiveness at work and days at work with the most severe headache. Overall, reported actual lost workdays and reduced effectiveness at work contributed approximately equally to total LWDE. A total of 51.1% of females and 38.1% of male migraineurs experienced six or more LWDE per year. This subgroup of migraine sufferers accounted for about 90% of the total LWDE experienced by all respondents. Among women, headache duration was the strongest predictor of LWDE followed by less significant associations with number of symptoms and pain level. Among men, only pain level was significantly associated with LWDE. Among sociodemographic factors, disability was more likely among older (40+) subjects and less likely among individuals with higher education and higher income (females only), even after adjusting for headache features. Health-care interventions may yield the greatest individual benefit (by reducing pain and disability) and the greatest societal benefit (by reducing indirect costs) if they are directed to those who account for the greatest proportion of disability.

Adolescent↗
PubMed1996

A novel approach to data collection in a case-control study of cancer and occupational exposures.

BACKGROUND: In community and hospital-based case-control studies, the occupational data collected in interviews are usually limited to responses to general questions asked of all study subjects. A procedure is described in which more detailed information can be collected in an efficient, standardized and systematic way. METHODS: A generic work history is initially collected from all subjects using a computer-assisted interview. The work history includes job title, type of business, job activities, materials and chemicals, and tools and equipment used. After responses are entered into the computer by the interviewer, the computer searches a synonym file to identify possible job-specific modules relevant to the reported job. The modules are detailed questionnaires that address specific jobs administered after obtaining the generic work history. The modules are used to ask questions about the work environment; sources of exposure; factors affecting the movement of the agent from the source to the subject, such as local exhaust ventilation; and individual and job characteristics. After the interview is completed, the work history and responses to the modules are sent electronically to an industrial hygienist who reviews the information using a custom-designed software package. Where ambiguities or contradictions occur in information reported by the respondent, or for jobs for which no module had been developed, the industrial hygienist generates up to 10 additional questions per job. These questions are sent back to the interviewer for administration of a short, second interview. CONCLUSIONS: These procedures, which are being successfully implemented in an on-going case-control study of brain tumours, should improve disease risk estimates over those derived from more traditional approaches to exposure assessment.

Brain Neoplasms↗
PubMed1996

Variation in migraine prevalence by race.

PURPOSE: Estimates of migraine prevalence from African and Asian populations are lower than those observed in European and North American populations. To determine if these international differences reflect differences in cultural, environmental, or genetic factors, we compared the prevalence of migraine among Caucasians, African Americans, and Asian Americans in the United States. If genetic factors predominate, racial differences should persist in the United States. METHODS: In Baltimore County, Maryland, 12,328 individuals 18 to 65 years of age were selected by random-digit dialing and interviewed by telephone about their headaches. Migraine diagnoses were assigned using International Headache Society criteria. RESULTS: In women, migraine prevalence was significantly higher in Caucasians (20.4%) than in African (16.2%) or Asian (9.2%) Americans. A similar pattern was observed among men (8.6%, 7.2%, and 4.2%). African Americans were less likely to report nausea or vomiting with their attacks, but more likely to report higher levels of headache pain. In contrast, African Americans tended to be less disabled by their attacks than Caucasians. There were no statistically significant differences in associated features between Asian American and Caucasian migraineurs. CONCLUSIONS: In the United States, migraine prevalence is highest in Caucasians, followed by African Americans and Asian Americans. While differences in socioeconomic status, diet, and symptom reporting may contribute to differences in estimated prevalence, we suggest that race-related differences in genetic vulnerability to migraine are more likely to predominate as an explanatory factor.

Adolescent↗
PubMed1995

Population variation in migraine prevalence: a meta-analysis.

A meta-analysis of published studies was conducted to identify factors which explained variation in estimates of migraine prevalence. Twenty-four population based studies contributed a total of 168 gender and age specific estimates of migraine prevalence. In linear regression analysis, 70.6% of the variation in these prevalence estimates was explained by gender, age (AGE+AGE2), a binary variable for case definition, and an interaction term between age and the case definition. Initially, we identified five groups of case definitions among the 24 studies. Only the definition of Waters (any 2 of warning, nausea, or unilateral pain) was associated with statistically significant differences in prevalence estimates among studies; accordingly the other 4 groups were combined. Several other factors were examined as predictors of migraine prevalence including the method of selecting the study population, the source of the population, the response rate and whether diagnoses were confirmed by a clinical assessment. None of these factors substantially increased explained variance. We conclude that after taking sociodemographic factors and case definition into account, estimates of migraine prevalence are remarkably stable among studies.

Age Distribution↗
PubMed1995

Bias from nondifferential misclassification in case-control studies with three exposure levels.

In case-control studies with three exposure levels where disease risk is associated with exposure, the direction of bias in the odds ratios (ORs) from nondifferential misclassification depends on the risk level, misclassification rates, and exposure distributions. To extend these generalizations, we present a graphical analysis of bias from nondifferential misclassification assuming linear and nonlinear monotonic increasing exposure-risk patterns. In both middle and upper exposure levels, bias is usually toward the null, increasing in magnitude as the misclassification rates increase and as the skewness of the exposure distribution increases. In the middle exposure level, bias away from the null may occur when the misclassification rate is low in the reference level and moderate to high in the upper exposure level, and risk increases with exposure. Bias away from the null does not occur in the upper exposure level. In both excess risk levels, crossover bias (that is, a reversal of the OR) may occur when exposure classification is worse than chance. The magnitude of bias away from the null is constrained by the unbiased OR of the upper exposure level, whereas that of crossover bias is constrained by the inverse of the unbiased OR of the upper exposure level.

Bias↗
PubMed1995

Migraine impact and functional disability.

This article reviews the substantial impact of migraine on individual headache sufferers and on society. While the individual impact of migraine is determined by pain and role dysfunction, the societal impact is primarily determined by work loss and disability in the work place and at home. Epidemiologic studies demonstrate that migraine is very common, substantially under diagnosed and often inadequately treated. Improving health care delivery to persons with migraine could substantially reduce the individual and societal impact of the illness. Migraine ranges in severity, with mild headache and no disability on one extreme and excruciating pain and complete disability on the other. Because of this spectrum of severity, diagnosis alone does not provide enough information to permit the selection of optimal therapy. A headache grading system might help headache sufferers and clinicians match the therapy not only to the diagnosis but to the overall severity of illness; such a system provides the best hope for cost effective health care interventions.

Absenteeism↗
PubMed1995

Relationship of headache to phase of the menstrual cycle among young women: a daily diary study.

We investigated the relationship between headache occurrence and phase of the menstrual cycle in a 4-month daily diary study of 74 women, 22 to 29 years old, residing in Washington County, Maryland. We selected subjects from women reporting a history of migraine symptoms and at least two migraine headache attacks per month in a 1986 to 1987 population-based survey. Data collection was from March 1987 through April 1988. By using detailed headache symptom information collected daily, we classified headaches into four categories: migraine with aura, migraine without aura, tension-type, and all other headaches. Odds ratios were separately estimated for the individual headache types and all types combined during each of three phases of the menstrual cycle. Risk of migraine without aura was significantly elevated during the first 3 days of menstruation (odds ratio, 1.66; 95% confidence interval, 1.21 to 2.26), but headache risk was not significantly increased during the 2 days immediately preceding onset of menstruation or on the estimated day of ovulation (day 14 before the onset of menstruation). Participants reported headaches on 28% of the study days overall, suggesting that onset of menstruation is an independent but not exclusive precipitating factor for headache attacks among young adult women with migraine. Our data show that onset of menstruation only accounts for a small proportion of migraine attacks among young women with frequent episodes of migraine.

Adult↗