Biomedical subjects

Walter F Stewart

Publications and source records attributed to Walter F Stewart.

31 records · Page 2Linked to original sources

PubMed2003

Reliability and validity of the Japanese Migraine Disability Assessment (MIDAS) Questionnaire.

OBJECTIVE: This study was designed to assess the test-retest reliability, internal consistency, and validity of a Japanese translation of the Migraine Disability Assessment (MIDAS) Questionnaire in a sample of Japanese patients with headache. BACKGROUND: Previous studies have demonstrated that the English-language version of the MIDAS Questionnaire is a reliable and valid instrument for the assessment of migraine-related disability. Any translations of the MIDAS Questionnaire must also be assessed for reliability and validity. METHODS: Study participants were recruited from the patient population attending either the Neurology Department of Kitasato University or an affiliated clinic. Participants were eligible for study entry if they had 6 or more primary headaches per year. For reliability testing, participants completed the MIDAS Questionnaire on 2 occasions, exactly 2 weeks apart. To assess validity, patients were also invited to participate in a 90-day daily diary study. Composite measures from the 90-day diaries were compared to equivalent MIDAS measures (ie, 5 questions on headache-related disability and 1 question each on average pain intensity and headache frequency in the last 3 months) and to the total MIDAS score obtained from a third MIDAS Questionnaire completed at the end of this 90-day period. RESULTS: One hundred one patients between the ages of 21 and 77 years were recruited (81 women and 20 men). Ninety-nine patients (80 women and 19 men) participated in the diary study. At baseline, 46.5% of patients were MIDAS grade I or II (minimal, mild, or infrequent disability), 22.2% were MIDAS grade III (moderate disability), and 31.3% were MIDAS grade IV (severe disability). Test-retest Spearman correlations for the 5 disability questions and the questions on average pain intensity and headache frequency ranged from 0.59 to 0.80 (P<.0001). The test-retest Spearman correlation coefficient for the total MIDAS score was 0.83 (P<.0001). The degree to which individual MIDAS questions correlated with the diary-based measures ranged from 0.36 to 0.88. The correlation between the total MIDAS score and the equivalent diary-based measure was 0.66. In general, the mean and median values for the MIDAS items and total MIDAS score were similar to the means and medians for the diary-based measures. However, the mean MIDAS scores for the number of days on which headache was experienced and the number of missed workdays were significantly different compared to the diary-based estimates for these items (P<.05). In addition, the mean MIDAS score for the number of days of missed housework was significantly higher than the corresponding diary-based estimate (P<.01). CONCLUSIONS: The results from this study show that the Japanese translation of the MIDAS Questionnaire is comparable with the English-language version in terms of reliability and validity.

Adult↗

PubMed2003

Screening for dementia by telephone using the memory impairment screen.

OBJECTIVES: : To develop and assess telephone-based screening tests for dementia, especially Alzheimer's disease (AD). DESIGN: : A cross-sectional validation study nested within a longitudinal study of aging and dementia. SETTING: : The Einstein Aging Study of the Albert Einstein College of Medicine, Bronx, New York. PARTICIPANTS: : Three hundred elderly community volunteers living in Bronx County, 27 of whom were diagnosed with dementia based on in-person clinical evaluation. Of the 27 individuals with dementia, 18 had AD. MEASUREMENTS: : A telephone battery was administered that included the Memory Impairment Screen by telephone (MIS-T, a test of semantic memory), the Category Fluency Test (CF-T), and the Telephone Instrument for Cognitive Status (TICS). An in-person evaluation then followed that included a neurological examination, a neuropsychological battery, demographics, and medical history. RESULTS: : The telephone battery was well accepted. The MIS-T required 4 minutes; the CF-T, 3 minutes; and the TICS, 10 minutes. The MIS-T had excellent sensitivity and specificity when compared with the CF-T and the TICS. Using cutscores on all three tests that provide a sensitivity of 78%, specificity was significantly higher for the MIS-T (93%) than for the CF-T (78%, P<.05) or the TICS (80%, P<.05). Combining the MIS-T and CF-T improved discriminative validity but increased screening time and the complexity of scoring. Normative data for the MIS-T, the CF-T, and the TICS for use in settings with different base rates (prevalence) of dementia are presented in this study. CONCLUSION: : The MIS-T outperforms the CF-T and the TICS as a valid and time-efficient telephone screen for dementia. For applications that require optimal efficiency and accuracy, the MIS-T is recommended.

Aged↗

PubMed2003

The longitudinal association of lead with blood pressure.

BACKGROUND: Several investigators have reported an association of blood lead or bone lead with increased blood pressure and hypertension, but questions remain concerning whether these effects are acute or chronic in nature. METHODS: In this longitudinal study, we evaluated the relation of lead, measured in blood and tibia, to changes in blood pressure between 1994 and 1998. We studied 496 current and former employees of a chemical-manufacturing facility in the eastern United States who had previous occupational exposure to inorganic and organic lead. Cohort members who provided three or four blood pressure measurements during the study were included. RESULTS: Mean age at baseline was 55.8 years with a mean of 18 years since last occupational exposure to lead. Blood lead at baseline averaged 4.6 microg/dL (standard deviation [SD] = 2.6) or 0.22 micromole/Liter (SD = 0.13). Tibia lead at year three averaged 14.7-microg/gm (SD = 9.4) bone mineral. Change in systolic blood pressure during the study was associated with lead dose, with an average annual increase of 0.64 mmHg (standard error [SE] = 0.25), 0.73 mmHg (SE = 0.26), and 0.61 mmHg (SE = 0.27) for every standard deviation increase in blood lead at baseline, tibia lead at year three, or peak past tibia lead, respectively. CONCLUSIONS: The results support an etiologic role for lead in the elevation of systolic blood pressure among adult males and are consistent with both acute and chronic modes of action.

Adult↗

PubMed2003

Lost productive work time costs from health conditions in the United States: results from the American Productivity Audit.

The American Productivity Audit (APA) is a telephone survey of a random sample of 28,902 U.S. workers designed to quantify the impact of health conditions on work. Lost productive time (LPT) was measured for personal and family health reasons and expressed in hours and dollars. Health-related LPT cost employers 225.8 billion US dollars/year (1685 US dollars/employee per year); 71% is explained by reduced performance at work. Personal health LPT was 30% higher in females and twice as high in smokers (> or =1 pack/day) versus nonsmokers. Workers in high-demand, low-control jobs had the lowest average LPT/week versus the highest LPT for those in low-demand, high-control jobs. Family health-related work absence accounted for 6% of all health-related LPT. Health-related LPT costs are substantial but largely invisible to employers. Costs vary significantly by worker characteristics, suggesting that intervention needs vary by specific subgroups.

Absenteeism↗

PubMed2003

Associations of renal function with polymorphisms in the delta-aminolevulinic acid dehydratase, vitamin D receptor, and nitric oxide synthase genes in Korean lead workers.

We analyzed data from 798 lead workers to determine whether polymorphisms in the genes encoding delta-aminolevulinic acid dehydratase (ALAD), endothelial nitric oxide synthase (eNOS), and the vitamin D receptor (VDR) were associated with or modified relations of lead exposure and dose measures with renal outcomes. Lead exposure was assessed with job duration, blood lead, dimercaptosuccinic acid (DMSA)-chelatable lead, and tibia lead. Renal function was assessed with blood urea nitrogen (BUN), serum creatinine, measured creatinine clearance, calculated creatinine clearance and urinary N-acetyl-beta-D-glucosaminidase (NAG), and retinol-binding protein. Mean (+/- SD) tibia lead, blood lead, and DMSA-chelatable lead levels were 37.2 +/- 40.4 microg/g bone mineral, 32.0 +/- 15.0 microg/dL, and 767.8 +/- 862.1 microg/g creatinine, respectively. After adjustment, participants with the ALAD(2) allele had lower mean serum creatinine and higher calculated creatinine clearance. We observed effect modification by ALAD on associations between blood lead and/or DMSA-chelatable lead and three renal outcomes. Among those with the ALAD(1-2) genotype, higher lead measures were associated with lower BUN and serum creatinine and higher calculated creatinine clearance. Participants with the eNOS variant allele were found to have higher measured creatinine clearance and BUN. In participants with the Asp allele, longer duration working with lead was associated with higher serum creatinine and lower calculated creatinine clearance and NAG; all were significantly different from relations in those with the Glu/Glu genotype except NAG (p = 0.08). No significant differences were seen in renal outcomes by VDR genotype, nor was consistent effect modification observed. The ALAD findings could be explained by lead-induced hyperfiltration.

Adult↗

PubMed2002

Self-awareness of migraine: interpreting the labels that headache sufferers apply to their headaches.

Although people with migraine are aware of their headaches they are often not aware that they have migraine. This can lead to inappropriate or ineffective use of treatments, delays in seeking appropriate care, and miscommunication during clinical encounters. This article assesses self-recognition of migraine and identifies terms used by migraine sufferers to describe their migraine headaches. Individuals were selected for telephone interview by random digit dialing in several large United States cities as a part of a clinical trials recruiting initiative. Individuals (n = 30,758) aged 18 to 65 years of age were interviewed about their headaches using a validated computer-assisted telephone interview. Among the 23,564 respondents who reported headache, their headaches were classified as migraine (with or without aura) by the criteria of the International Headache Society (IHS). The relationships among the terms subjects used for their headaches and their IHS diagnosis of migraine were assessed. Of the 23,564 respondents, 4,967 individuals called their headache migraine and 3,074 individuals reported headache that met the IHS criteria for migraine. The positive predictive value for self-assessed migraine is 33.1%; the negative predictive value for a self-assessment other than migraine is 92.3%. Therefore, individuals who called their headaches migraine were about three times more likely to meet IHS criteria for migraine. Among the 3,074 individuals meeting IHS criteria for migraine, only 53.4% recognized their headaches as migraine (sensitivity 54%; specificity 83.8%). Among migraineurs, stress headaches (n = 345) and sinus headaches (n = 365) were the most common erroneous labels reported. Age influenced the erroneous terminology. Individuals less than 40 years of age were more likely to misidentify their migraine as stress headaches, whereas individuals 40 years of age and older were more likely to misidentify their migraines as sinus headaches. In a population sample, 54% of individuals with IHS migraine did not know that their headaches are migraine. Those who called their headaches migraine were much more likely to have migraine. Migraine awareness programs that rely solely on the term "migraine" may miss individuals who urgently need to be reached. Therefore, public education should target people with severe or disabling headache and aim to create awareness of the diagnostic possibilities.

Adolescent↗

PubMed2002

Apolipoprotein E epsilon 4 and short-term recovery from predominantly mild brain injury.

OBJECTIVE: To determine whether APOE genotype explained variability in short-term recovery from predominantly mild traumatic brain injury (TBI). METHODS: A total of 87 adult patients presenting with mild or moderate TBI to a shock trauma center were enrolled prospectively. A battery of 13 neuropsychological tests was administered twice, at approximately 3 and 6 weeks after injury. Eighty of 87 patients were successfully genotyped for APOE using a buccal swab technique. RESULTS: Ninety percent of study patients had mild TBI (Glasgow Coma Scale score of 13 to 15); 18 (22.5%) had one APOE epsilon 4 and none had two epsilon 4 alleles. After adjusting for potential confounders, patients positive for the APOE epsilon 4 allele had lower mean scores on 12 of 13 neuropsychological outcomes at visit 1 compared with APOE epsilon 4-negative patients. Two of the differences were significant (grooved pegboard test, p = 0.005; paced auditory serial addition task 2.8-second trial, p = 0.004). At visit 2, APOE epsilon 4-positive patients had lower adjusted mean scores on 11 of the 13 neuropsychological outcomes. None of the differences was significant. CONCLUSIONS: APOE genotype may influence the severity of the acute injury. However, with no consistent pattern to the recovery curves, it is not clear if APOE genotype influences the rate of recovery.

Adolescent↗

PubMed2002

Migraine and autonomic nervous system function: a population-based, case-control study.

OBJECTIVE: This study determines if measures of the function of the autonomic nervous system (ANS) differ in a population study of 80 migraine cases vs 85 controls matched for age, race, and sex. BACKGROUND: The authors sought to confirm clinic-based studies suggesting that migraine is associated with abnormal ANS function. METHODS: Resting systolic and diastolic blood pressure, Valsalva maneuver, heart rate variability (pulse rate [RR] variation) during deep breathing, and cardiovascular reactivity were measured during headache-free intervals. Migraineurs were subdivided into those with (n = 28) and without (n = 52) disabling headaches. RESULTS: Resting diastolic, but not systolic, blood pressure was elevated in disabled (73.2 mm) compared with nondisabled cases (71.6 mm; p < 0.10) and controls (69.8 mm; p < 0.096). RR variation also was significantly different among the three groups. Disabled migraine cases (1.19) had significantly lower RR variation compared with nondisabled migraine cases (1.26; p < 0.001) and controls (1.26; p < 0.001). The Valsalva ratio and mean circular resultant were lower in disabled cases compared with other migraine cases and with controls, but the differences were not statistically significant. No differences were found between the three groups when comparing blood pressure response to a psychological stressor. CONCLUSIONS: Migraineurs with disabling attacks may be prone to ANS hypofunction. These findings may suggest that ANS dysfunction either may be a risk factor for migraine headaches or be a consequence of frequent disabling attacks. Moreover, ANS dysfunction and migraine may share a common neural substrate.

Adult↗

PubMed2002

Quality of life in a US national sample of adults with diabetes and motility-related upper gastrointestinal symptoms.

Our objective was to describe the health-related quality of life (HRQoL) of individuals with diabetes with and without motility-related upper gastrointestinal symptoms compared to individuals without diabetes. A total of 483 individuals with diabetes and 422 age- and gender-matched nondiabetic controls were recruited from a prior US national health survey for a telephone interview on upper gastrointestinal symptoms. Individuals with diabetes self-reported a physician's diagnosis of diabetes and provided confirming information on clinical management measures. Subjects were asked about upper gastrointestinal symptoms in the month before interview using an instrument with demonstrated high reliability. HRQoL was measured using the SF-12 Health Survey. Individuals with diabetes reporting upper gastrointestinal symptoms scored significantly lower in HRQoL measures of physical health and mental health than either individuals with diabetes who did not report upper gastrointestinal symptoms or individuals without diabetes (P < 0.0001). Individuals with diabetes and no upper gastrointestinal symptoms had physical and mental health summary scores similar to those of individuals without diabetes. Early satiety was the strongest predictor (P < 0.0001) of differences in physical health scores between individuals with and without diabetes. Nausea was the strongest predictor (P < 0.0001) of differences in mental health scores between individuals with and without diabetes. In conclusion, this is the first US national survey to demonstrate that motility-related upper gastrointestinal symptoms are associated with a significantly lower quality of life in individuals with diabetes.

Adult↗

PubMed2002

Protein kinase C activity and the relations between blood lead and neurobehavioral function in lead workers.

At picomolar concentrations, lead activates protein kinase C (PKC). This activation has been implicated in the neurotoxicity of lead. No prior study has evaluated the association of PKC activity with neurobehavioral function in humans. The purpose of this study was to determine whether PKC activity is associated with neurobehavioral function or modifies the relationship between blood lead levels and neurobehavioral test scores. In this cross-sectional study of 212 current lead workers in the Republic of Korea, we assessed blood lead levels, neurobehavioral test scores, and PKC activity. PKC activity was determined by measuring the levels of phosphorylation of three erythrocyte membrane proteins (spectrin and the 52-kDa and 48-kDa subunits of band 4.9), using an in vitro back-phosphorylation assay. When linear regression was used to control for confounding variables, blood lead was a significant predictor of decrements in performance on tests of psychomotor function, manual dexterity, and executive ability. In linear regression models, back-phosphorylation levels were not associated with neurobehavioral test scores, but when dichotomized at the median, back-phosphorylation levels modified the relationship between blood lead and test scores. For spectrin and the 52-kDa and 48-kDa subunits of band 4.9, 5, 2, and 5 of 14 interaction terms, respectively, had associated p-values less than 0.10, all with positive signs, indicating that blood lead was associated with worse test scores only in subjects with lower back-phosphorylation levels. These data indicate that blood lead levels are associated with decrements in neurobehavioral test scores, mainly in the domains of manual dexterity and psychomotor function, but only in subjects with lower in vitro back-phosphorylation levels, which is equivalent to higher in vivo PKC activity. We hypothesize that subjects with higher PKC activity in the presence of lead may be more susceptible to the health effects of lead.

Adult↗

PubMed2002

ApoE genotype, past adult lead exposure, and neurobehavioral function.

Our objective in this study was to determine if the known relation between tibia bone lead levels and neurobehavioral test scores are influenced by the apolipoprotein E (ApoE) genotype. We collected data on 20 neurobehavioral tests in 529 former organolead workers who had an average of 16 years since last occupational exposure to lead. We used linear regression to model the relations between each of 20 neurobehavioral test scores and tibia lead, a binary variable for ApoE genotype (i.e., at least one Epsilon4 allele vs. none), and an interaction term between tibia lead and the binary term for ApoE genotype. At the time of testing, former lead workers were an average of 57.6 years of age; 82% were younger than 65 years. In regression analysis, we observed one statistically significant and one borderline significant coefficient for ApoE genotype alone. Coefficients for the ApoE and tibia lead interaction term were negative in 19 of the 20 regression models. This indicates that the slope for the relation between tibia lead and each neurobehavioral test was more negative for individuals with at least one Epsilon4 allele than for those who did not have an Epsilon4 allele. Four of 19 negative coefficients for the interaction term were statistically significant (digit symbol, Purdue pegboard assembly, Purdue pegboard-dominant hand, complex reaction time); another three of the remaining 16 coefficients (symbol digit, trail-making A, Stroop) were borderline significant (i.e., p < 0.10). This study suggests that individuals may vary in susceptibility to the long-term effects of lead on the central nervous system (CNS). In particular, the persistent CNS effect of lead may be more toxic in individuals who have at least one ApoE-Epsilon4 allele.

Adult↗

PubMed2000

Validity of the Migraine Disability Assessment (MIDAS) score in comparison to a diary-based measure in a population sample of migraine sufferers.

The Migraine Disability Assessment (MIDAS) questionnaire is a brief, self-administered questionnaire designed to quantify headache-related disability over a 3 month period. The MIDAS score has been shown to have moderately high test-retest reliability in headache sufferers and is correlated with clinical judgment regarding the need for medical care. The aim of the study was to examine the validity of the MIDAS score, and the five items comprising the score, compared to data from a 90 day daily diary used, in part, to record acute disability from headache. In a population-based sample, 144 clinically diagnosed migraine headache sufferers were enrolled in a 90 day diary study and completed the MIDAS questionnaire at the end of the study. The daily diary was used to record detailed information on headache features as well as activity limitations in work, household chores, and non-work activities (social, family and leisure activities). The MIDAS score was the sum of missed work or school days, missed household chores days, missed non-work activity days, and days at work or school plus days of household chores where productivity was reduced by half or more in the last 3 months. Validity was assessed by comparing MIDAS items and the MIDAS score with equivalent measures derived from the diary. The MIDAS items for missed days of work or school (mean 0.96, median 0) and for missed days of household work (mean 3.64, median 2.0) were similar to the corresponding diary-based estimates of missed work or school (mean 1.23, median 0) and of missed household work (mean 3.93, median 2.01). Values for missed days of non-work activities (MIDAS mean 2.6 and median 1 versus diary mean 2.22 and median 0.95) were also similar. Responses to MIDAS questions about number of days where productivity was reduced by half or more in work (mean 3.77, median 2.00) and in household work (mean 3.92, median 2.00) significantly overestimated the corresponding diary-based measures for work (mean 2.94, median 1.06) and household work (mean 2.22, median 0.98). Nonetheless, the overall MIDAS score (mean 14.53, median 9.0) was not significantly different form the reference diary-based measure (mean 13.5, median 8.4). The correlation between the MIDAS summary score and an equivalent diary score was 0.63. The group estimate of the MIDAS score was found to be a valid estimate of a rigorous diary-based measure of disability. The mean and median values for the MIDAS score in a population-based sample of migraine cases were similar to equivalent diary measures. The correlation between the two measures was in the low moderate range, but expected given that two very different methods of data collection were compared.

Absenteeism↗

PubMedDate not supplied

Immune reactive cells in senile plaques and cognitive decline in Alzheimer's disease.

We examined the associations of postmortem neocortical immunoreactivities for microglia, astrocytes, Abeta and Tau with cognitive changes in clinically characterized subjects with pathological diagnoses (CERAD classification) of definite AD (9), possible AD (15) and age-matched controls (11). By measuring the fractional area (FA) of immunoreactivity, we found that Abeta deposits appear early in the pathogenesis of Abeta, but cannot account for cognitive decline. We found a significant increases in FA for microglia in possible AD cases (nondemented) compared to controls (P<0.05) and in FA for astrocytes in definite AD (demented) compared to possible AD (P<0.01). Tau immunoreactivity was observed only in the neuropil of definite AD cases (P<0.001). The significant increase in microglia between controls and AD possible cases suggests that activation of microglia occurs in the early pathogenesis of AD, whereas the significant association between astrocytic reaction and dementia, suggests that these cells play a role in the late stage of the disease, when dementia develops. Tau immunoreactivity appears as the strongest morphological correlate of dementia.

Aged↗