Biomedical subjects

Walter F Stewart

Publications and source records attributed to Walter F Stewart.

At least 19 recordsLinked to original sources

PubMed2006

Back pain exacerbations and lost productive time costs in United States workers.

STUDY DESIGN: Cross-sectional with follow-up case-control component. OBJECTIVES: To measure the prevalence of back pain (BP) and back pain exacerbations, describe BP features and functional impairment, estimate BP-related lost productive time (LPT) and costs, and assess the relation between pain exacerbations and lost productive time. SUMMARY OF BACKGROUND DATA: BP is associated with substantial lost work time. However, little is known about the extent to which BP with or without exacerbation explains lost work time. METHODS: A national telephone survey of the U.S. workforce identified 320 workers 40 to 65 years of age with BP defined by NHANES I criteria and 91 matched non-BP controls. Participants self-reported pain characteristics, lost productive time (absenteeism and presenteeism) in the previous 2 weeks, activity limitations, and demographics. A population-weighting adjustment was applied to estimates to account for selection bias and ensure that estimates of certain sample demographic subgroups' totals conformed to the Current Population Survey. RESULTS: The 2-week period prevalence of BP was 15.1%; 42% of workers with BP experienced pain exacerbations. BP prevalence was associated with demographic factors, but BP exacerbations were not. BP was reported by 42.6% of all workers. Workers with exacerbations reported more days with BP than those without exacerbations. Workers with exacerbations were significantly more likely than those without such exacerbations to report activity limitation (88.4% vs. 60.7%; P < 0.0001) and BP-related LPT (22.1% vs. 13.0%; P = 0.0259). BP in workers 40 to 65 years of age costs employers an estimated $7.4 billion/year. Workers with BP exacerbations account for 71.6% of this cost. CONCLUSIONS: Workers with BP exacerbations account for a disproportionate share of the cost of BP-related lost productive time.

Absenteeism↗

PubMed2006

The comorbidity of headache with other pain syndromes.

In this article, we consider the possible reasons and supporting evidence for the comorbidity of chronic pain conditions. To simplify the discussion, we primarily focus on the epidemiology of headache with other pain conditions, dividing studies into those based on children or adolescents and those based on adults. We consider exogenous and endogenous factors, and methodological challenges, in understanding whether and how 2 pain conditions may be related.

Adaptation, Psychological↗

PubMed2006

Findings on brain MRI from research studies of occupational exposure to known neurotoxicants.

OBJECTIVE: The expanding use of MRI in large-scale epidemiologic studies of CNS outcomes has led to increasing concern for the consistent handling of incidental findings. Our purpose is to identify the prevalence of incidental neuroradiologic abnormalities in an adult population with past occupational exposure to lead who underwent brain MRI as part of a large, longitudinal cohort study. MATERIALS AND METHODS: Structural MR images obtained for the research study were reviewed by a neuroradiologist on an ongoing basis for findings of clinical concern. The subjects were recruited as part of a longitudinal research study designed to examine the effects of past lead exposure on CNS structures. The cohort examined consisted of 589 men who previously worked at an organolead manufacturing facility and had a wide range of lead exposure durations and intensities. MR images were also reviewed from 67 population-based control subjects from the same study who had no history of occupational lead exposure. RESULTS: Incidental findings were detected in 84% (548/656) of research subjects. Of the 548 subjects with abnormalities, 30% (167) required no referral, 51% (280) required routine referral, 17% (93) required urgent referral, and 1.5% (8) required immediate referral. Incidental findings of all categories were observed in a larger percentage of older subjects, aged 60 years and above. Using multivariable logistic regression analysis, we found that age (p < 0.0001), but not lead history, was associated with an increased risk of incidental neuroradiologic abnormalities. CONCLUSION: In the population examined, there was a high prevalence of incidental brain and head and neck abnormality. Of particular concern were the serious health problems observed requiring urgent or immediate referral in 18.5% of the subjects. These findings underscore the need for radiologists to evaluate the anatomic images generated by research studies, particularly those with an older population base.

Adult↗

PubMed2005

Pain exacerbation as a major source of lost productive time in US workers with arthritis.

OBJECTIVE: To estimate the prevalence of arthritis and arthritis pain exacerbations in US workers including impact on functioning and lost productive work time (LPT). METHODS: The research was conducted as a nested case-control study of participants in the Caremark American Productivity Audit, a US national random-digit-dial survey of US workers. The sample included 329 workers ages 40-65 years meeting the First National Health and Nutrition Examination Survey criteria for arthritis, and 91 workers not meeting arthritis inclusion criteria. Participants completed a telephone interview to measure the prevalence of arthritis and pain exacerbations, LPT (in hours and dollars), functional disability using the Western Ontario and McMaster Universities Knee and Hip Osteoarthritis Index (WOMAC) and the Australian/Canadian Osteoarthritis Hand Index, and demographics. RESULTS: The prevalence of arthritis in US workers ages 40-65 years was 14.7% during the 2-week period. Pain exacerbation occurred among 38% of participants with arthritis. Workers with pain exacerbations were significantly more likely to have higher WOMAC scores (38.6 versus 29.6; P = 0.0041) and report arthritis-related LPT (24.4% versus 13.3%; P = 0.0118) than workers without exacerbations. Among those with LPT, average LPT did not differ (4.1 hours per week) between persons with and without exacerbations. The estimated annual LPT cost from arthritis in the US workforce was $7.11 billion, with 65.7% of this cost attributed to the 38% of workers with pain exacerbations. CONCLUSION: Workers with arthritis pain exacerbation account for a disproportionate share of the arthritis-related LPT cost. Stratifying workers for appropriate treatment management based on pain exacerbation status could significantly decrease arthritis-related LPT and offer employees and employers an effective return on health care use.

Absenteeism↗

PubMed2005

Prevalence and socioeconomic impact of upper gastrointestinal disorders in the United States: results of the US Upper Gastrointestinal Study.

BACKGROUND & AIMS: This study examined the prevalence of upper gastrointestinal (GI) symptoms and symptom groupings and determined impact on disability days in a nationally representative US sample. METHODS: A telephone survey of 21,128 adults was conducted including questions about the presence of upper GI symptoms during the past 3 months. Respondents were categorized as symptomatic (ie, reported GI symptoms once per month) or asymptomatic. The survey included questions about missed work, leisure activity, or household activity days. Symptom groupings were identified by using factor analysis, and cluster analysis was used to assign respondents into distinct groups on the basis of these symptom groupings. RESULTS: The prevalence of an average of 1 or more upper GI symptoms during the past 3 months was 44.9%. The most common symptoms experienced during the past 3 months were early satiety, heartburn, and postprandial fullness. Factor analysis identified 4 symptom groupings: (1) heartburn/regurgitation; (2) nausea/vomiting; (3) bloating/abdominal pain; and (4) early satiety/loss of appetite. Five respondent clusters were identified; the largest clusters were primarily early satiety/fullness (44%) and gastroesophageal reflux disease-like symptoms (28%). Two small clusters reflected nausea and vomiting (7%) and a heterogeneous symptom profile (4%). Symptomatic respondents reported significantly more missed work, leisure, and household activity days than asymptomatic respondents (all P < .0001). CONCLUSIONS: Factor analysis separated GI symptoms into groupings reflecting gastroesophageal reflux disease and dyspepsia: early satiety, postprandial fullness, and loss of appetite; bloating and abdominal pain/discomfort; and nausea and vomiting. These upper GI symptoms were associated with significant loss of work and activity days.

Adolescent↗

PubMed2005

Multivariate modeling of age and retest in longitudinal studies of cognitive abilities.

Longitudinal multivariate mixed models were used to examine the correlates of change between memory and processing speed and the contribution of age and retest to such change correlates. Various age- and occasion-mixed models were fitted to 2 longitudinal data sets of adult individuals (N>1,200). For both data sets, the results indicated that the correlation between the age slopes of memory and processing speed decreased when retest effects were included in the model. If retest effects existed in the data but were not modeled, the correlation between the age slopes was positively biased. The authors suggest that although the changes in memory and processing speed may be correlated over time, age alone does not capture such a covariation.

Age Factors↗

PubMed2004

Caffeine as a risk factor for chronic daily headache: a population-based study.

OBJECTIVE: To investigate the possible association of dietary caffeine consumption and medicinal caffeine use with chronic daily headache (CDH). METHODS: Population-based cases and controls were recruited from the Baltimore, MD, Philadelphia, PA, and Atlanta, GA, metropolitan areas. Controls (n = 507) reported 2 to 104 headache days/year, and cases (n = 206) reported > or =180 headache days/year. Current and past dietary caffeine consumption and medication use for headache were based on detailed self-report. High caffeine exposure was defined as being in the upper quartile of dietary consumption or using a caffeine-containing over-the-counter analgesic as the preferred headache treatment. RESULTS: In comparison with episodic headache controls, CDH cases were more likely overall to have been high caffeine consumers before onset of CDH (odds ratio [OR] = 1.50, p = 0.05). No association was found for current caffeine consumption (i.e., post CDH) (OR = 1.36, p = 0.12). In secondary analyses, associations were confined to younger (age <40) women (OR = 2.0, p = 0.02) and those with chronic episodic (as opposed to chronic continuous) headaches (OR = 1.69, p = 0.01), without physician consultation (OR = 1.67, p = 0.04) and of recent (<2 years) onset (OR = 1.67, p = 0.03). CONCLUSION: Dietary and medicinal caffeine consumption appears to be a modest risk factor for chronic daily headache onset, regardless of headache type.

Adolescent↗

PubMed2004

The epidemiology and impact of migraine.

Migraine is a highly prevalent headache disorder that has a substantial impact on the individual and society. In this article, we review the burden of migraine, emphasizing the population-based studies that used standardized diagnostic criteria. We highlight descriptive epidemiology, burden of disease, patterns of diagnosis, and treatment. We focus on the epidemiology and burden of probable migraine, a subtype of migraine where just one clinical feature is missing. We finish by describing approaches to improving healthcare delivery for migraine and probable migraine. Although migraine is a remarkably common cause of temporary disability, many migraineurs, even those with disabling headache, have never consulted a physician for the problem. Prevalence is highest in women, in persons between the ages of 25 and 55 years, and, at least in the United States, in individuals from low-income households. Nonetheless, prevalence is high in groups other than these high-risk groups. Probable migraine is a prevalent form of migraine, and like migraine with and without aura it produces decrements in health-related quality of life and increments in disability relative to control subjects.

Age Factors↗

PubMed2004

Hippocampal neurons in pre-clinical Alzheimer's disease.

In a previous study of hippocampal neurons in aging and AD [Lancet 344 (1994) 769], we demonstrated that the loss of neurons in the CA1 region was disease-specific and not related to aging. In the present study, we examined for loss of hippocampal neurons in preclinical AD, a period during which there are abundant amyloid deposits in the brain but no evidence of cognitive decline. We examined the postmortem brains of 33 subjects from the Baltimore Longitudinal Study of Aging and the Johns Hopkins Alzheimer's Disease Research Center. Using unbiased stereology, we estimated the total number of neurons in the granule cell layer, hilus, CA3-2, CA1, and subiculum of AD (n = 14) preclinical AD (n = 8), and age-matched control subjects (n = 11). The results from the present study confirm our previous finding of significant neuronal losses in the CA1 (48%), hilus (14%), and subiculum (24%) in AD [Lancet 344 (1994) 769]. However, we did not observe a significant loss of neurons in CA1 or any of the other subdivisions of the hippocampus in preclinical AD.

Aged↗

PubMed2004

Modeling age and retest processes in longitudinal studies of cognitive abilities.

Mixed effects models were used to examine the separate effects associated with age and retest on changes in various cognitive abilities. Individuals (N > 800) ranging in age from 40 to 70 years at the 1st measurement occasion were assessed with measures of memory, spatial abilities, and speed on 4 occasions. All cognitive abilities showed decline associated with increased age and improvement across the 4 measurement occasions. The age-related effects were similar across variables, but the practice effects were largest for memory and smallest for speed. When retest effects were not included in the models, the age-related effects were underestimated, with the magnitude of bias depending on the size of the ignored retest effects. It is suggested that both age and retest should be modeled simultaneously when analyzing longitudinal data because part of the change across occasions may be attributable to practice or reactive effects.

Adult↗

PubMed2004

Health-related lost productive time (LPT): recall interval and bias in LPT estimates.

We examined the effect of interview characteristics (ie, recall interval, interview version) on estimates of health-related lost productive work time (LPT). Three versions of a telephone interview were administered using 7-day and 4-week recall periods. In a population-based survey, 7674 workers randomly were assigned to one of six interviews at contact; 615 participants received a follow-up interview. We found strong evidence of under-reporting using a 4-week recall period and a not significant trend in over-reporting LPT using a 7-day recall period. Of the three interviews, version 3 could be administered most quickly, on average, and yielded the most discriminating estimates of LPT by health condition (ie, headache, allergic rhinitis, and cold/flu). Our data suggest that variation in relatively short recall periods influences estimates of health-related LPT. A 2-week recall period may be optimal for minimizing overall reporting error but requires additional research to verify.

Adolescent↗

PubMed2004

Tools for diagnosing migraine and measuring its severity.

Migraine remains substantially underdiagnosed and undertreated in the United States. Tools to screen for migraine and to measure headache-related disability can help address barriers to effective diagnosis and treatment. In this article, public health criteria for screening programs for any medical condition are first reviewed. Modifications of these criteria for migraine and other chronic/episodic disorders are then proposed. Migraine is assessed to determine how well it meets criteria for screening and the steps that are necessary before firm public policy recommendations for screening for migraine are possible.

Disability Evaluation↗

PubMed2004

Disparities in cognitive functioning by race/ethnicity in the Baltimore Memory Study.

The Baltimore Memory Study is a cohort study of the multilevel determinants of cognitive decline in 50-70-year-old randomly selected residents of specific city neighborhoods. Prior studies have demonstrated that cognitive function differs by race/ethnicity, with lower scores in minorities than in whites, but the underlying basis for these differences is not understood. Studies have differed in the rigor with which they evaluated and controlled for such important confounding variables as socioeconomic status (SES), health-related behaviors, comorbid illnesses, and factors in the physical environment. The goal of this study was to describe differences in neurobehavioral test scores by race/ethnicity, before and after control for a four-dimensional measure of SES and health-related behaviors and health conditions, in a cross-sectional analysis of first visit data. Random samples of households in the study area were selected until enrollment goals were reached. Among the 2,351 persons on whom eligibility was determined, 60.8% were scheduled for an enrollment visit; of these, 1,140 (81.3%) were enrolled and tested. These study participants were 34.3% male and 65.7% female and were from 65 Baltimore, Maryland, neighborhoods. After adjustment for age, sex, and testing technician, there were large and statistically significant differences in neurobehavioral test scores by race/ethnicity, with African-American scores lower than those for whites, for both men and women. After adjustment for individual SES (educational status, household income, household assets, and occupational status), the average difference declined by 25.8%. After additional adjustment for SES, health-related behaviors and health conditions, and blood lead, the average difference declined another 10%, but large differences persisted; African Americans had test scores that averaged 0.43 standard deviation lower than those for whites across all neurobehavioral tests. These differences were present in all cognitive domains, including tests that would not be characterized as susceptible to differential item functioning by race/ethnicity, suggesting that the results are not due to race/ethnicity-associated measurement error.

Black or African American↗

PubMed2004

Validation of the work and health interview.

BACKGROUND: Instruments that measure the impact of illness on work do not usually provide a measure that can be directly translated into lost hours or costs. We describe the validation of the Work and Health Interview (WHI), a questionnaire that provides a measure of lost productive time (LPT) from work absence and reduced performance at work. METHOD: A sample (n = 67) of inbound phone call agents was recruited for the study. Validity of the WHI was assessed over a 2-week period in reference to workplace data (i.e. absence time, time away from call station and electronic continuous performance) and repeated electronic diary data (n = 48) obtained approximately eight times a day to estimate time not working (i.e. a component of reduced performance). RESULTS: The mean (median) missed work time estimate for any reason was 11 (8.0) and 12.9 (8.0) hours in a 2-week period from the WHI and workplace data, respectively, with a Pearson's (Spearman's) correlation of 0.84 (0.76). The diary-based mean (median) estimate of time not working while at work was 3.9 (2.8) hours compared with the WHI estimate of 5.7 (3.2) hours with a Pearson's (Spearman's) correlation of 0.19 (0.33). The 2-week estimate of total productive time from the diary was 67.2 hours compared with 67.8 hours from the WHI, with a Pearson's (Spearman's) correlation of 0.50 (0.46). CONCLUSION: At a population level, the WHI provides an accurate estimate of missed time from work and total productive time when compared with workplace and diary estimates. At an individual level, the WHI measure of total missed time, but not reduced performance time, is moderately accurate.

Absenteeism↗

PubMed2003

Lost productive time and cost due to common pain conditions in the US workforce.

CONTEXT: Common pain conditions appear to have an adverse effect on work, but no comprehensive estimates exist on the amount of productive time lost in the US workforce due to pain. OBJECTIVE: To measure lost productive time (absence and reduced performance due to common pain conditions) during a 2-week period. DESIGN AND SETTING: Cross-sectional study using survey data from the American Productivity Audit (a telephone survey that uses the Work and Health Interview) of working adults between August 1, 2001, and July 30, 2002. PARTICIPANTS: Random sample of 28 902 working adults in the United States. MAIN OUTCOME MEASURES: Lost productive time due to common pain conditions (arthritis, back, headache, and other musculoskeletal) expressed in hours per worker per week and calculated in US dollars. RESULTS: Thirteen percent of the total workforce experienced a loss in productive time during a 2-week period due to a common pain condition. Headache was the most common (5.4%) pain condition resulting in lost productive time. It was followed by back pain (3.2%), arthritis pain (2.0%), and other musculoskeletal pain (2.0%). Workers who experienced lost productive time from a pain condition lost a mean (SE) of 4.6 (0.09) h/wk. Workers who had a headache had a mean (SE) loss in productive time of 3.5 (0.1) h/wk. Workers who reported arthritis or back pain had mean (SE) lost productive times of 5.2 (0.25) h/wk. Other common pain conditions resulted in a mean (SE) loss in productive time of 5.5 (0.22) h/wk. Lost productive time from common pain conditions among active workers costs an estimated 61.2 billion dollars per year. The majority (76.6%) of the lost productive time was explained by reduced performance while at work and not work absence. CONCLUSIONS: Pain is an inordinately common and disabling condition in the US workforce. Most of the pain-related lost productive time occurs while employees are at work and is in the form of reduced performance.

Absenteeism↗

PubMed2003

Cost of lost productive work time among US workers with depression.

CONTEXT: Evidence consistently indicates that depression has adversely affected work productivity. Estimates of the cost impact in lost labor time in the US workforce, however, are scarce and dated. OBJECTIVE: To estimate the impact of depression on labor costs (ie, work absence and reduced performance while at work) in the US workforce. DESIGN, SETTING, AND PARTICIPANTS: All employed individuals who participated in the American Productivity Audit (conducted August 1, 2001-July 31, 2002) between May 20 and July 11, 2002, were eligible for the Depressive Disorders Study. Those who responded affirmatively to 2 depression-screening questions (n = 692), as well as a 1:4 stratified random sample of those responding in the negative (n = 435), were recruited for and completed a supplemental interview using the Primary Care Evaluation of Mental Disorders Mood Module for depression, the Somatic Symptom Inventory, and a medical and treatment history for depression. Excess lost productive time (LPT) costs from depression were derived as the difference in LPT among individuals with depression minus the expected LPT in the absence of depression projected to the US workforce. MAIN OUTCOME MEASURE: Estimated LPT and associated labor costs (work absence and reduced performance while at work) due to depression. RESULTS: Workers with depression reported significantly more total health-related LPT than those without depression (mean, 5.6 h/wk vs an expected 1.5 h/wk, respectively). Eighty-one percent of the LPT costs are explained by reduced performance while at work. Major depression accounts for 48% of the LPT among those with depression, again with a majority of the cost explained by reduced performance while at work. Self-reported use of antidepressants in the previous 12 months among those with depression was low (<33%) and the mean reported treatment effectiveness was only moderate. Extrapolation of these survey results and self-reported annual incomes to the population of US workers suggests that US workers with depression employed in the previous week cost employers an estimated 44 billion dollars per year in LPT, an excess of 31 billion dollars per year compared with peers without depression. This estimate does not include labor costs associated with short- and long-term disability. CONCLUSIONS: A majority of the LPT costs that employers face from employee depression is invisible and explained by reduced performance while at work. Use of treatments for depression appears to be relatively low. The combined LPT burden among those with depression and the low level of treatment suggests that there may be cost-effective opportunities for improving depression-related outcomes in the US workforce.

Adult↗

PubMed2003

Estimated economic costs of overactive bladder in the United States.

OBJECTIVES: To estimate the economic costs of overactive bladder (OAB), including community and nursing home residents, and to compare the costs in male versus female and older versus younger populations. METHODS: The National Overactive Bladder Evaluation Program included a representative telephone survey of 5204 community-dwelling adults 18 years and older in the United States and a follow-up postal survey of all individuals with OAB identified and age and sex-matched controls. The postal survey asked respondents about bladder symptoms, self-care use, treatment use, work loss, and OAB-related health consequences. Survey data estimates were combined with year 2000 average cost data to calculate the cost of OAB in the community. Institutional costs were estimated from the costs of urinary incontinence in nursing homes, limited to only those with urge incontinence or mixed incontinence (urge and stress). RESULTS: The estimated total economic cost of OAB was 12.02 billion dollars in 2000, with 9.17 and 2.85 billion dollars incurred in the community and institutions, respectively. Community female and male OAB costs totaled 7.37 and 1.79 billion dollars, respectively. The estimated total cost was sensitive to the estimated prevalence of OAB; therefore, we calculated the average cost per community-dwelling person with OAB, which was 267 dollars per year. CONCLUSIONS: By quantifying the total economic costs of OAB, this study-the first obtained from national survey data-provides an important perspective of this condition in society. The conservative estimates of the total cost of OAB were comparable to those of osteoporosis and gynecologic and breast cancer. Although this provides information on the direct and indirect costs of OAB, quality-of-life issues must be taken into account to gain a better understanding of this condition.

Adolescent↗

PubMed2003

Migraine disability assessment (MIDAS) score: relation to headache frequency, pain intensity, and headache symptoms.

OBJECTIVE: To determine the extent to which variation in the Migraine Disability Assessment (MIDAS) score is associated with headache frequency, pain intensity, headache symptoms, gender, and employment status. BACKGROUND: The MIDAS questionnaire is a 7-item questionnaire (with 5 scored items) designed to measure headache-related disability, to improve physician-patient communication, and to identify patients with high treatment needs. METHODS: Data from 3 population-based studies (total sample, n = 397) conducted in the United States and the United Kingdom were used to evaluate the relationship between headache features (attack frequency, pain intensity, pain quality, and associated symptoms) and MIDAS score. Data on headache features were collected by telephone using a standardized interview. The MIDAS questionnaire was completed shortly after the telephone interview. General linear models were used to determine the extent to which population variation in the MIDAS score was explained by headache features. RESULTS: Using linear regression, variables for all headache features (ie, headache frequency, pain intensity, pain quality, and associated symptoms) and demographic characteristics explained only 22% of the variation in MIDAS scores. Almost all (19.9%) the explained variance was accounted for by average pain intensity (12.0%), number of headache days (6.1%), and exacerbation of pain with movement (1.8%). When pain intensity and headache frequency were included in the model, no statistically significant differences in MIDAS scores were observed by gender or employment status. Although explaining only 2.1% of the variance, age was significantly associated with MIDAS scores, with those under 25 years demonstrating higher MIDAS scores than other age groups. No other variables (ie, frequency of occurrence of associated symptoms and other measures of quality of pain) were associated with MIDAS scores. CONCLUSIONS: Challenges to the utility of the MIDAS as a measure include whether headache-related disability is largely a function of other routine headache features and whether MIDAS is inherently biased based on work status and gender. While the MIDAS score was associated with headache frequency and average pain score, these two headache features explain only a modest proportion of the variation in MIDAS scores. Additionally, gender and work status were not related to MIDAS scores. These findings suggest that the MIDAS score captures information about disability that is not inherent to other headache features and is independent of gender and work status.

Adult↗