Biomedical subjects

W F Stewart

Publications and source records attributed to W F Stewart.

At least 109 records · Page 6Linked to original sources

PubMed1993

Miscarriages among female physical therapists who report using radio- and microwave-frequency electromagnetic radiation.

Physical therapists are exposed to radio- and microwave-frequency electromagnetic radiation by operating shortwave and microwave diathermy units. Recent studies suggest that use of shortwave diathermy is associated with an excess risk of birth defects, perinatal deaths, and late spontaneous abortions among the offspring of exposed female therapists. To assess the impact of occupational use of microwave and shortwave diathermy at the time of conception, the authors mailed questionnaires to 42,403 physical therapists in 1989. Both occupational and reproductive histories were obtained. Exposures to shortwave and microwave diathermy were both assessed in the same fashion and were examined in relation to early recognized fetal loss in a nested case-control design. A total of 1,753 case pregnancies (miscarriages) were matched to 1,753 incidence density control pregnancies (other pregnancies except ectopic pregnancies). A pregnancy was considered "exposed" if the mother reported using microwave or shortwave diathermy anytime during the 6 months prior to the first trimester or during the first trimester. Pregnancies of mothers reporting microwave use 6 months prior to the pregnancy or during the first trimester were more likely to result in miscarriage (odds ratio (OR) = 1.28, 95% confidence interval (CI) 1.02-1.59). The odds ratio increased with increasing level of exposure (chi 2 = 7.25, p < 0.005). The odds ratio in the highest exposure group (20 or more exposures/month) was 1.59. The overall odds ratio was slightly lower after it was controlled for prior fetal loss (OR = 1.26, 95% CI 1.00-1.59), but the exposure-response effect remained (chi 2 = 5.17, p < 0.01). The risk of miscarriage was not associated with reported use of shortwave diathermy equipment (OR = 1.07, 95% CI 0.91-1.24). The odds ratio in the highest exposure group was 0.87.

Abortion, Spontaneous↗

PubMed1993

Reliability in headache diagnosis.

The reliability of headache diagnosis using the criteria of the International Headache Society (IHS) has not been well studied. One definition of reliability refers to the reproducibility of diagnoses assigned to the same individual at different times. Reproducibility of diagnosis should be assessed using different clinicians at different times, with or without specific diagnostic instruments. A diagnosis may be unreliable because of variability in diagnostic criteria, in the clinical information used to assign diagnoses, or in the interpretation and application of clinical information to a given set of diagnostic criteria. Reliable diagnostic methods are essential to the development of valid diagnostic methods, as well as for the identification of headache risk factors, biological markers, and effective treatments. An approach to studying the reliability of the International Headache Society criteria is outlined, modeled after the extensive studies conducted in the area of psychiatric diagnosis.

Evaluation Studies as Topic↗

PubMed1993

Migraine headache: epidemiology and health care utilization.

Population-based studies of headache can help inform the development of diagnostic criteria. In population-based studies, migraine has been consistently revealed as a common disabling condition that affects males and females of all ages. From data obtained in a national survey of the United States population, we show that the prevalence of migraine and the frequency of attacks increase as household income decreases. Disability from attacks is not related to income. In contrast, physician diagnosis is more likely as household income increases. Moreover, physician diagnosis is more likely among females, older cases, those more likely to experience disability, and migraine sufferers reporting nausea (males), vomiting, and visual and sensory aura. Analysis of our data leads us to conclude that the symptoms most strongly associated with diagnosis may provide the greatest concern and interest on the part of physicians to make a diagnosis, even though other migraine-related symptoms are more common in the population and in clinical settings. Finally, among migraine sufferers with severe disability, a very large proportion do not receive the benefits of medical diagnosis and treatment. Though most migraine sufferers use OTC medications, given the frequency and associated disability of their migraine attacks, current therapy appears unsatisfactory.

Adolescent↗

PubMed1993

Measuring work organization exposure over the life course with a job-exposure matrix.

In most epidemiologic studies of occupational stress, work exposure is measured at only one point in time. This article presents a methodology for measuring the intensity and duration of work organization exposure over a lifetime. A job-exposure matrix for work organization was developed from data on a random sample (N = 12,084) of the Swedish labor force. The matrix consisted of mean exposure estimates for work control, social support, psychological and physical job demands, and job hazards for 261 occupations. Several validations of the matrix were undertaken. The matrix scores were found to be significantly correlated with individual self-report scores, and a similar increase in chronic disease prevalence with decreasing work control was found for both the matrix and the individual scores. The matrix was applied to occupational history data to construct lifetime exposure profiles. Potential problems in using attribution systems for exposure assessment are discussed.

Adolescent↗

PubMed1993

Migraine in the United States: a review of epidemiology and health care use.

According to the American Migraine Study, 17.6% of females and 6.0% of males in the United States currently suffer from severe migraine. These findings are based on the responses of more than 20,000 people to a self-administered questionnaire mailed to respondents. The study reveals that migraine prevalence varies according to age, gender, and income. Despite high rates of headache-related disability, the study also shows that most people with migraine have never been diagnosed by a doctor or treated with prescription medications. To improve diagnosis and treatment of migraine, public health interventions are indicated.

Age Factors↗

PubMed1992

Physician consultation for headache pain and history of panic: results from a population-based study.

In a population-based telephone interview survey of 10,169 respondents aged 12-29 years in Washington County, Maryland, data were collected on history of panic attacks, on the most recent headache and associated symptoms in the 2 weeks before the interview, and on physician consultation for headache-related problems. Of those who had a headache in the previous 12 months, 14.2% of females and 5.8% of males consulted a physician for headache. The proportion who recently consulted a physician increased with age among females but not among males. An unexpectedly high proportion of those who recently sought physician care for their headache problem had a history of panic. In particular, among those who sought care, 15% of females and 12.8% of males ages 24-29 had a history of panic disorder. Overall, females with panic disorder who had recently seen a physician for headache exhibited the most frequent, severe, and complex headaches. In particular, headaches were of considerably longer duration, more severe, and greater than 50% of these females had five or more headaches in a 4-week period. A very high proportion experienced disability (up to 46.7%) from their headache. Males with a history of panic who did or did not seek physician care differed only in that a considerably higher proportion of the former group (up to 45%) had frequent headaches. Overall, 11.8% of the total population had a migraine headache in the 2 weeks before the interview. In contrast, 21.8% of those who sought physician care and 36% of those with panic disorder who sought physician care had a migraine headache.

Adolescent↗

PubMed1992

Prevalence of migraine headache in the United States. Relation to age, income, race, and other sociodemographic factors.

OBJECTIVE: To describe the magnitude and distribution of the public health problem posed by migraine in the United States by examining migraine prevalence, attack frequency, and attack-related disability by gender, age, race, household income, geographic region, and urban vs rural residence. DESIGN: In 1989, a self-administered questionnaire was sent to a sample of 15,000 households. A designated member of each household initially responded to the questionnaire. Each household member with severe headache was asked to respond to detailed questions about symptoms, frequency, and severity of headaches. SETTING: A sample of households selected from a panel to be representative of the US population in terms of age, gender, household size, and geographic area. PARTICIPANTS: After a single mailing, 20,468 subjects (63.4% response rate) between 12 and 80 years of age responded to the survey. Respondents and non-respondents did not differ by gender, household income, region of the country, or urban vs rural status. Whites and the elderly were more likely to respond. Migraine headache cases were identified on the basis of reported symptoms using established diagnostic criteria. RESULTS: 17.6% of females and 5.7% of males were found to have one or more migraine headaches per year. The prevalence of migraine varied considerably by age and was highest in both men and women between the ages of 35 to 45 years. Migraine prevalence was strongly associated with household income; prevalence in the lowest income group (less than $10,000) was more than 60% higher than in the two highest income groups (greater than or equal to $30,000). The proportion of migraine sufferers who experienced moderate to severe disability was not related to gender, age, income, urban vs rural residence, or region of the country. In contrast, the frequency of headaches was lower in higher-income groups. Attack frequency was inversely related to disability. CONCLUSIONS: A projection to the US population suggests that 8.7 million females and 2.6 million males suffer from migraine headache with moderate to severe disability. Of these, 3.4 million females and 1.1 million males experience one or more attacks per month. Females between ages 30 to 49 years from lower-income households are at especially high risk of having migraines and are more likely than other groups to use emergency care services for their acute condition.

Adolescent↗

PubMed1992

Undiagnosed migraine headaches. A comparison of symptom-based and reported physician diagnosis.

BACKGROUND: Although migraine headaches are a common cause of temporary disability, many people with migraine have not been diagnosed. In a sample of the US population, we sought to determine the proportion of migraineurs diagnosed by a physician and to identify the headache characteristics and sociodemographic profiles associated with undiagnosed migraine. METHODS: A mail questionnaire survey was sent to 15,000 US households, selected from a panel to be representative of the US population. Of a total study base population of 23,611, excluding 3043 subjects less than 12 years of age and respondents with unreported gender, we analyzed data for 20,468 subjects aged 12 to 80 years. Migraine diagnoses were assigned on the basis of reported symptoms by means of operational diagnostic criteria. Physician diagnosis of migraine was ascertained on the basis of self-report. RESULTS: Forty-one percent of female and 29% of male migraineurs reported having been diagnosed by a physician. Diagnosis was more likely in females, in people with high income levels, and in individuals who reported migraine associated with aura, vomiting, or disability. Of the undiagnosed subjects, 80% experienced at least some headache-related disability. CONCLUSIONS: Results of this survey indicate that the majority of people with migraine in the United States do not report having been diagnosed by a physician. Given the high proportion of undiagnosed subjects with headache-related disability, efforts to improve the diagnosis and treatment of migraine are recommended.

Adolescent↗

PubMed1992

Headaches preceded by visual aura among adolescents and young adults. A population-based survey.

Clinical descriptions of migraine preceded by visual aura often include a composite of striking and severe symptoms of several attacks in individual patients, but few studies have characterized the spectrum of such attacks. In a population-based telephone survey of 8920 Washington County, Maryland, residents 12 through 29 years old, the attack rate for visual aura headaches during the week prior to the standardized interview was 3.7% in male and 6.1% in female subjects. Among female subjects, the risk for visual aura headache with tension-type symptoms increased with age, whereas the risk for visual aura headache without tension symptoms decreased with increasing age. No clear age-related patterns were observed among male subjects for either type of aura headache. The severity of visual aura headache with and without tension symptoms increased with age among female subjects, but showed an inconsistent pattern among male subjects except for decreasing disability with increasing age. The median interval between the onset of aura symptoms and the onset of headache (aura interval) was 15 minutes in male subjects and 25 minutes in female subjects, with aura intervals longer than 60 minutes reported by 12% of male subjects and 20% of female subjects. In one of the first large population-based studies to characterize the spectrum of visual aura headache, differing age, gender, and subtype patterns were found.

Adolescent↗

PubMed1992

Medication use and disability among migraineurs: a national probability sample survey.

OBJECTIVE: To measure the use of prescription medication in treating migraine headache and the associations between medication use and sociodemographic factors, and headache characteristics. DESIGN: National sample survey using a mailed questionnaire to determine symptoms accompanying or preceding severe headaches; frequency, duration, and disability from severe attacks: use of medications to control pain; and medical-care use for severe headaches. SETTING: A stratified sample of United States households. PATIENTS: A sample of 20,468 respondents, aged 12 to 80 years, who responded to a survey on "severe" headaches during the prior year. MEASUREMENTS AND MAIN RESULTS: Overall, 20.2% of respondents reported severe headaches. Migraine was found in 17.6% of females and 5.7% of males. Of the migraineurs, 40.1% of female and 28.3% of male migraineurs reported using prescription drugs to control pain. Blacks were less likely than whites to report prescription use. Insignificant differences were seen in rates of prescription use among various income levels and regions of the country. Use of prescription medication varied considerably by symptoms and characteristics of migraine attacks. Vomiting and sensory aura were most frequently associated with medication use, as were severity and duration of attacks. Use of urgent-care services for severe headache attacks was associated with frequent use of prescription medications. Patients who reported a physician diagnosis of migraine were more likely to use prescription medication than other migraineurs. CONCLUSIONS: Most migraineurs in the United States are not being treated with prescription medications. Many active migraine patients would benefit from appropriate treatment if care was sought and diagnosis made.

Adolescent↗

PubMed1991

Age- and sex-specific incidence rates of migraine with and without visual aura.

Age- and sex-specific incidence rates for the onset of migraine headache with and without preceding visual aura were estimated from a population-based telephone interview survey conducted between March 1986 and June 1987 of 10,169 randomly selected residents of Washington County, Maryland, between the ages of 12 and 29 years. A total of 392 males and 1,018 females were identified as having a history of migraine. Of these, 27% of male cases and 28% of female cases were defined as having migraine with visual aura. Among both males and females, the incidence rate for migraine with visual aura appears to have peaked as much as 3-5 years earlier than the age peak for migraine without aura. For males, the age-specific incidence for migraine with visual aura appears to have peaked on or before 5 years of age at 6.6/1,000 person-years, or possibly higher. In contrast, the highest incidence for migraine without aura occurred between 10 and 11 years of age at 10.1/1,000 person-years. New cases of migraine were uncommon among males in their late 20s. The initial onset of migraine headache begins at a later age among females than among males. For females, the highest incidence of migraine with aura occurred between 12 and 13 years of age at 14.1/1,000 person-years; the highest incidence for migraine without aura occurred between 14 and 17 years of age at 18.9/1,000 person-years. In contrast to males, new onset of migraine was relatively common among females in their late 20s.

Adolescent↗

PubMed1991

Occupational lead exposure and strabismus in offspring: a case-control study.

The authors conducted a population-based case-control study to investigate the association between strabismus and parental occupational lead exposure. Cases were children diagnosed with nonrestrictive strabismus between 1985 and 1986 at Baltimore, Maryland-area pediatric ophthalmology practices and clinics (n = 377). Controls were matched for age and hospital of birth (n = 377). Jobs held by parents were assessed for lead exposure by industrial hygienists. The time window for lead exposure was defined as the period from conception through age 9 months. The unadjusted odds ratio for maternal lead exposure and the esotropic form of strabismus was 2.6 (95% confidence interval (CI) 0.4-27). Unadjusted odds ratios for paternal occupational lead exposure and esotropia were 1.0 (95% CI 0.5-2.1) for low exposure, 2.1 (95% CI 0.9-5.3) for moderate exposure, and 1.2 (95% CI 0.4-3.3) for high exposure. The study results suggest the possibility of a weak association between paternal lead exposure and strabismus in offspring.

Amblyopia↗

PubMed1990

Gender differences in the experience of headache.

Since 1940 numerous studies have shown that women report higher rates of symptoms, illness, disability and medical care utilization than men. The present analysis addresses gender differences in headache, with a focus on symptom frequency and associated pain and duration of each subject's most recent headache attack experienced within 4 weeks of interview. A random sample of 10,167 Washington County, Maryland residents (ages 12-29 years) were administered a standardized telephone interview in a large epidemiologic study of headache during 1986-87. Among the respondents, 6347 described one or more headaches occurring within 4 weeks of the interview. Women reported few specific symptoms more frequently than men, and the relative rankings of the symptoms were nearly identical for each gender (rs = 0.98). Estimated pain associated with each subject's headache and the duration of the attack were systematically greater for women than men. Although the relative rankings of symptoms by associated pain were very similar (rs = 0.90), the correlation for the ranking of symptoms for duration by gender was less strong (rs = 0.59). Women were significantly more likely to report recent headache-related disability and to seek health care services for their headaches, even after adjusting for headache severity. The results suggest that a strong interplay of an underlying physiological difference with socially determined role perceptions and illness orientations lead to greater reporting of symptoms by women.

Activities of Daily Living↗

PubMed1990

The relationship of headache symptoms with severity and duration of attacks.

Efforts to develop clinically useful headache classification schemes have generally focused on linking specific symptom groupings with specific headache subtypes. An alternative conceptual approach, the "severity model" of headache, considers a continuum of headache ranging from mild to severe forms with specific headache subtypes distinguished by level of severity rather than unique constellations of symptoms. A population-based telephone interview was carried out among 10,169 subjects aged 12-29 to estimate the prevalence of serious headaches and better characterize symptoms that accompany headache attacks. In an analysis of frequency of occurrence, pain and duration of recent (within 4 weeks prior to interview) headache attacks, the data revealed that common symptoms (such as forehead pain and pain in the back of the head, neck and shoulders) were reported frequently, but headaches with these symptoms were generally characterized by low levels of pain and short duration. Although not an original study objective, the data were analyzed to determine whether distinct symptom constellations could be identified or whether symptoms overlapped between headache types. Symptoms of migraine were frequently experienced concomitant with tension-type symptoms; the resultant headaches were usually characterized as moderate in intensity. In contrast, symptoms usually associated with migraine in the absence of concomitant tension-type symptoms were infrequently experienced, but resulted in headaches causing the greatest disability. The data provide some support for the severity model of headache.

Adolescent↗

PubMed1989

An epidemiologic study of headache among adolescents and young adults.

Despite extensive description of headache among patients in specialty clinics and general practices in the United States, there have been few community-wide investigations. In a population-based telephone interview study of 10,169 Washington County, Maryland, residents who were 12 through 29 years old, 57.1% of males and 76.5% of females reported that their most recent headache occurred within the previous 4 weeks. Four or more headaches in the preceding month were reported by 6.1% of males and 14.0% of females. The average duration of the subjects' most recent headache was 5.9 hours for males and 8.2 hours for females; 7.9% and 13.9%, respectively, missed part of a day or more of school or work because of that headache. Within the month before interview, 3.0% of males and 7.4% of females had suffered from a migraine headache. Consultations with a physician, by specialty, for headache-related problems are described by sex and age of subjects, as is the use of specific prescription and nonprescription medications.

Absenteeism↗

PubMed1989

Disability, physician consultation, and use of prescription medications in a population-based study of headache.

In a population-based telephone interview survey of 9,380 residents aged 12 to 29 yr in Washington County, Maryland, who reported having had a headache, 60% of females and 41% of males had had one or more headaches during the previous week; 14.4% of females and 6.0% of males in the study group had consulted a physician in the previous 12 months for a headache problem. The likelihood of consulting a physician differed according to the type of headache. Subjects with headache during the week before the interview meeting the criteria for certain migraine or certain mixed tension--migraine were twice as likely as subjects with all other types of headaches to consult a physician during the previous 12 months. Females with tension headache were considerably more likely than males with the tension headache to have consulted a physician during the previous 12 months. On the other hand, males with migraine headache during the previous week were more likely than females with migraine to consult a physician. Disability (defined as being absent from school or from work for all or part of the day) was relatively common among those subjects with a headache during the previous week (13.7% of females and 7.9% of males). However, even among those reporting disability as a result of their headache during the previous week, only 31% of females and 18% of males reported consulting a physician during the previous 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Absenteeism↗

PubMed1988

Effect of temperature and expectations on liking for beverages.

Three experiments investigated the influence of expectation on liking ratings of beverages at different temperatures. The first confirmed the general belief that people like certain beverages at certain familiar temperatures and dislike them at others. In the second experiment, subjects tasted and rated how much they liked four beverages (chicken bouillon, red wine, fruit punch and water) at three different temperatures (hot, room temperature, and cold) with their eyes closed (beverages not identified by the experimenter) and with their eyes open (beverages identified by the experimenter). They then rated how much they thought they would like these same beverages plus a number of new beverages at the three temperatures. Subjects rated the tastes of the beverages at unfamiliar temperatures (e.g., cold bouillon) when tasting them better than they thought they would. However, even after a few opportunities to taste a beverage at an unfamiliar temperature, expectations about its taste did not change. Experiment 3 successfully altered liking ratings of beverages by changing expectations concerning the temperature at which an unfamiliar beverage is typically consumed. The results argue for an important role for culture-based expectations in determining preferred temperatures for foods.

Adult↗

PubMed1987

Polychotomous logistic regression methods for matched case-control studies with multiple case or control groups.

Two statistical methods, a polychotomous and pairwise approach, are presented to derive estimates of the relative odds in a matched case-control design when multiple case or control groups are used. Test statistics are derived to determine if the relative odds between groups are different. The polychotomous method is limited to case-control sets, i.e., where data are available on all members of a matched set. In contrast, the pairwise method makes use of data from both complete and incomplete sets. Nonetheless, efficiency calculations show that the polychotomous logistic regression model is more efficient even when 40 per cent of the case-control sets are incomplete. An example using a single dichotomous variable is provided.

Adolescent↗