Use of placebo surgery in controlled trials of a cellular-based therapy for Parkinson's disease.
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Adult↗
Biomedical subjects
P E Leaverton
Publications and source records attributed to P E Leaverton.
Regional patterns in the incidence of aplastic anemia in Thailand. The Aplastic Anemia Study Group.
The annual incidence of aplastic anemia has been determined in a rigorous and standardized epidemiologic study conducted in Thailand. A total of 374 cases were identified over a period of 3-6 years in three geographically defined and distinct regions of the country; Bangkok, Khonkaen in the northeast, and Songkla in the south. The incidence was 3.9 cases per million persons in Bangkok, 3.0 per million in Songkla, and 5.0 per million in Khonkaen. These rates are as high or higher than in any region of Europe or Israel as reported in the International Agranulocytosis and Aplastic Anemia Study, in which the methods and case definition were the same. Rates were stable over the course of the study. There were marked differences in incidence between northern and southern rural regions of Thailand, and among Bangkok suburbs. These differences, together with an unusual peak in the incidence among young people in Bangkok, suggest the possibility of occupational and environmental factors in the etiology of aplastic anemia.
Adolescent↗
Agranulocytosis in Bangkok, Thailand: a predominantly drug-induced disease with an unusually low incidence. Aplastic Anemia Study Group.
Agranulocytosis, a syndrome characterized by a marked reduction in circulating granulocytes, is strongly associated with medical drug use in Europe and the United States. Unregulated use of common pharmaceutical agents in developing countries has been suspected of causing large numbers of cases of agranulocytosis and deaths, especially among children. To elucidate the incidence and etiology of agranulocytosis in Thailand, a population-based case-control study of symptomatic agranulocytosis that resulted in hospital admission was conducted in Bangkok from 1990 to 1994. An attempt was also made to study the disease in Khonkaen (in northeastern Thailand) and Songkla (in southern Thailand), but there were insufficient cases in the latter regions, and the analysis was confined to subjects from Bangkok. In that region, the overall incidence of agranulocytosis was 0.8 per million per year; there were no deaths. As expected, the incidence was higher in females (0.9 per million), and it increased with age (4.3 per million beyond age 60). Among 25 cases and 529 controls the relative risk estimate for a combined category of all suspect drugs was 9.2 (95% confidence interval = 3.9-21), and the proportion of cases that could be attributed to drug use was 68%. For individual drugs and drug classes the data were sparse; within these limitations, the strongest association appeared to be with antithyroid drugs. One case and three controls were exposed to dipyrone, a drug known to cause agranulocytosis; with such scanty data the risk could not be evaluated. Exposure to pesticides or solvents was not associated with an increased risk. This is the first formal epidemiologic study of agranulocytosis in a developing country. As in the West, most cases are attributable to medical drug use. However, the incidence of agranulocytosis in Bangkok, and apparently, in Thailand as a whole, is unusually low, and the disease does not pose a public health risk.
Adolescent↗
Evaluation of the accuracy of on-site multi-analyte drug testing devices in the determination of the prevalence of illicit drugs in drivers.
A principal goal of this research was to conduct a field evaluation of "on-site" multi-analyte drug testing devices to determine the most accurate, efficient, and cost-effective device available for the purpose of rapidly detecting drivers under the influence of drugs. Four on-site kits were selected and evaluated for accuracy and efficiency for the detection of tetrahydrocannabinol (THC), the cocaine metabolites (COC), and opiates (OPI). From 16 December 1995 to 17 March 1996, 303 voluntary urine specimens were collected by law enforcement officers from persons arrested for driving-under-the-influence (DUI). These specimens were tested using the four selected kits and aliquots of the specimens were sent to a DHHS certified lab for "gold standard" comparison testing by immunoassay and Gas Chromatography/Mass Spectrometry. On-site kit sensitivity ranged from 82.9% to 100% for THC, 82.5% to 100% for COC, and all were at 100% for OPI. Specificity, and positive and negative predictive values were also determined. Accuracy ranged from 94.0% to 98.3% for THC, 97.4% to 98.0% for COC, and 99.7% to 100% for OPI. All four kits were in very close agreement on prevalence: 15.5% to 15.8% for THC, all were at 13.2% for COC, and all were at 0.7% for OPI. For law enforcement purposes, sensitivity may be the most important indicator in these kits.
Automobile Driving↗
Low drug attributability of aplastic anemia in Thailand. The Aplastic Anemia Study Group.
From 1989 to 1994, a population-based, case-control study of aplastic anemia was conducted in Thailand, including the regions of Bangkok, Khonkaen in the northeast, and Songkla in the south. An annual incidence in Bangkok of 3.7 cases per million population, about twice as high as in Western countries, has been reported. To evaluate the etiologic role of drugs, 253 subjects were compared with 1,174 hospital controls. With multivariate adjustment for confounding, a significant association was identified for exposure 2 to 6 months before admission to thiazide diuretics (relative risk estimate 7.7; 1.5 to 40). There were crude associations with sulfonamides (relative risk estimate, 7.9; P = 0.004) and mebendazole (6.3; P = 0.03) (there were insufficient data for multivariate adjustment). Excess risks for the three drugs were in the range of 9 to 12 cases per million users. There was no significant association with chloramphenicol, although the multivariate relative-risk estimate was elevated (2.7; 0.7 to 10). Other drugs that have been reported to increase the risk of aplastic anemia, such as nonsteroidal anti-inflammatory drugs and anticonvulsants, were not commonly used. There were no associations with commonly used drugs, including benzodiazepines, antihistamines, oral contraceptives, and herbal preparations. For all associated drugs, the overall etiologic fraction (the proportion of cases attributable to an exposure) was 5%, compared with 25% in Europe and Israel. Drugs are uncommon causes of aplastic anemia in Thailand, and their use does not explain the relatively high incidence of the disease in that country.
Adolescent↗
Toward the use of surgical placebo-controlled trials.
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Cell Transplantation↗
Use of household pesticides and the risk of aplastic anaemia in Thailand. The Aplastic Anemia Study Group.
BACKGROUND: Aplastic anaemia is a severe blood dyscrasia that is more common in Thailand than in Western countries. Its a etiology remains poorly understood. METHODS: A case-control study was conducted in Bangkok and two rural regions of Thailand. The effect of household pesticides was evaluated among 253 incident cases of aplastic anaemia and 1174 hospital controls. RESULTS: A total of 54% of the cases and 61% of the controls were exposed 1-6 months previously. For most individual household pesticides and for groups classified according to chemical type (organophosphates, pyrethrins, and organochlorines), the relative risk (RR) estimates approximated 1.0; upper 95% confidence limits were below 2.0 for many comparisons. A significant association was observed for exposure to combination products containing dichlorvos and propoxur, with an overall RR estimate of 1.7 (95% confidence interval [CI]: 1.1-2.6); the estimate for regular use was 1.6 (95% CI: 0.9-2.9). CONCLUSIONS: The absence of a higher risk for the regular use of dichlorvos/propoxur reduces the credibility of the apparent association, which could well have been an artefact of multiple comparisons. We conclude that most household pesticides used in Thailand do not appear to increase the risk of aplastic anaemia.
Adult↗
An association of aplastic anaemia in Thailand with low socioeconomic status. Aplastic Anemia Study Group.
The relationship of socioeconomic status to the risk of aplastic anaemia was evaluated in a case-control study conducted in Bangkok and two rural regions of Thailand (Khonkaen and Songkla). Among 152 cases and 921 controls there were significant trends of increasing risk with decreasing years of education (P = 0.01) and total household income (P = 0.0001), after control for confounding. The relative risk estimate for those with monthly incomes of < 1500 baht (about $60 U.S.) was 3.9 (95% confidence interval 2.1-7.3) compared to those with monthly incomes of at least 5000 baht (about $200). The pattern of increasing risk with decreasing income was observed in all three regions, with significant trends in Bangkok (P = 0.004) and Khonkaen (P = 0.003). This finding may partly explain the high incidence of aplastic anaemia in Thailand. Low socioeconomic status may be a surrogate for one or more environmental factors that could cause aplastic anaemia, such as infectious pathogens or toxic exposures.
Adolescent↗
Physical activity as a risk factor for osteoarthritis of the knee.
A case-control study was conducted to evaluate the association between knee osteoarthritis (OA) and physical activity (PA) among a community group aged 40 years and older. Case patients (85 males, 154 females) had radiologically confirmed knee OA with grade 2+ changes, according to Kellgren and Lawrence criteria. Control subjects (85 males, 154 females) had no radiologic evidence of knee OA. A statistically significant positive association between high PA level and knee OA was observed for women, with an age-adjusted odds ratio (OR) of 1.66 and 95% confidence interval (CI) of 1.01 to 2.72. In men no association was observed (OR = 0.95; 95% CI, 0.49 to 1.83). These associations persisted when controlling simultaneously for potential confounders including age, obesity, history of knee injury, and socioeconomic status, indicating that the OA-PA association is limited to women. One possible explanation is that risk factors for knee OA are influenced by hormones.
Aged↗
Scientific and ethical issues in the use of placebo controls in clinical trials.
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Clinical Trials as Topic↗
Sentinel event strategies in environmental health.
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Causality↗
Prevalence and mortality rate of congestive heart failure in the United States.
OBJECTIVES: The study was designed to determine the prevalence and mortality rate of congestive heart failure in noninstitutionalized men and women in the U.S. BACKGROUND: Congestive heart failure is a serious condition with significant morbidity and mortality. Earlier epidemiologic descriptions of congestive heart failure were constructed from small surveys, limited data, hospital records or death certificates. No nationally representative data from noninstitutionalized persons have been examined. METHODS: Data collected from the National Health and Nutrition Examination Survey (NHANES-I, 1971 to 1975) were used to determine the prevalence of heart failure on the basis of both self-reporting and a clinical definition. Mortality data were derived from the NHANES-I Epidemiologic Follow-up Study (1982 to 1986). RESULTS: The prevalence of self-reported congestive heart failure approximates 1.1% of the noninstitutionalized U.S. adult population; the prevalence of congestive heart failure based on clinical criteria is 2%. These estimates suggest that between 1 and 2 million adults are affected. Mortality at 10 and 15 years for those persons with congestive heart failure increases in graded fashion with advancing age, with men more likely to die than women. In the group greater than or equal to 55 years old, the 15-year total mortality rate was 39.1% for women and 71.8% for men. CONCLUSIONS: Congestive heart failure is a common problem in the U.S., with significant prevalence and mortality, both of which increase with advancing age. As the population of the U.S. becomes older, the health care impact of congestive heart failure will probably grow.
Adult↗
Bronchodilator testing "confidence intervals" based on the level of bronchial responsiveness.
"Confidence intervals" based upon inhalation of placebo have been proposed as criteria for defining a significant response to an inhaled bronchodilator. The published intervals were derived from a clinically heterogeneous population. We calculated the difference (delta) between spirometric data before and after placebo in 109 consecutive patients referred for methacholine bronchoprovocation challenge testing. The mean delta, expressed both as a percent change and as actual volume change for both the FVC and FEV1, was not significantly different in patients with bronchial hyperresponsiveness, as compared to subjects with a negative methacholine challenge test; however, the variance of measurements in hyperresponsive subjects was significantly greater than that of the normal population. In addition, as the category of responsiveness increased from mild to moderate to severe hyperresponsiveness, so did the variance within these groups. A negative correlation between the measured PC20FEV1 and the volume and percent change was noted. We conclude that patients with hyperresponsive airways may display increased spirometric variation before and after placebo. This general approach for establishing normal limits for defining a significant response appears to be valid, but the actual values used may vary, depending on the composition of the population tested and the goals of the study. Also, the use of the term, "confidence intervals," in this context is inappropriate; and we propose, instead, the use of percentiles and the simpler terms, upper 90th or 95th percentiles.
Adult↗
Incidence of aplastic anemia in Bangkok. The Aplastic Anemia Study Group.
The annual incidence of aplastic anemia in metropolitan Bangkok, Thailand, and its five suburban provinces was prospectively determined. All patients first diagnosed during the period from January through December 1989 who met specific clinical and pathologic criteria were included. Thirty-two cases were identified, yielding an overall incidence of 3.7 per million. The incidence rates for the age groups 0 through 24, 25 through 59, and over 60 years were 4.3, 3.2, and 2.1 per million, respectively; the highest rate, 7.2 per million, was found for individuals aged 15 to 24 years. The male-to-female ratio was 1.9. The incidence of aplastic anemia in Bangkok is higher than that reported in recent European studies. The peak rate in young persons is almost fourfold higher than in comparable recent western studies and suggests an environmental etiology peculiar to Thailand.
Adolescent↗
Identification of sentinel health events as indicators of environmental contamination.
The consensus process was applied to addressing a public health topic; this was a novel endeavor. The following question was addressed: What role, if any, should sentinel health events play in the decision-making process for identifying the effects of environmental exposure? The panel developed three levels of sentinel health events lists: those that are clearly identifiable, those that are potential signs, and those that are indicators of body burdens. Additionally, the panel developed several salient statements regarding the principles of environmental health surveillance and, especially, recommendations for future research.
Body Burden↗
Histopathology of lung cancers among smokers and nonsmokers in Florida.
A study was undertaken of the relationship between lung cancer cell type and age, race, sex and smoking characteristics. The study population consisted of 35 183 cases of microscopically confirmed carcinoma of the lung, first diagnosed between 1981 and 1985, among residents of the state of Florida. The data suggested that the histological types of lung cancer observed varied by age, sex and the use of cigarettes. The number of cigarettes smoked per day did not appear to influence the cell types observed. The study indicated that adenocarcinomas occurred more frequently in lung cancer cases diagnosed at earlier ages, among both men and women. Among women who smoked, there was an increased proportion of small cell carcinomas compared to nonsmoking women, while in male smokers, the increase appeared primarily in squamous cell carcinomas.
Adenocarcinoma↗
Representativeness of the Framingham risk model for coronary heart disease mortality: a comparison with a national cohort study.
The Framingham Heart Study has been the foundation upon which several national policies regarding risk factors for coronary heart disease mortality are based. The NHANES I Epidemiologic Followup Study is the first national cohort study based upon a comprehensive medical examination of a probability sample of United States adults. The average follow-up time was 10 years. This study afforded an opportunity to evaluate the generalizability of the Framingham risk model, using systolic blood pressure, total cholesterol, and cigarette smoking, to the U.S. population with respect to predicting death from coronary heart disease. The Framingham model predicts remarkably well for this national sample. The major risk factors for coronary heart disease mortality described in previous Framingham analyses are applicable to the United States white adult population.
Adult↗
Predictors of good function: the Framingham Study.
This paper asks the question: among 1474 Framingham Study participants aged 35-68 years who were healthy at their fourth examination (1954-1958), what are the physiologic, behavioral, and demographic characteristics that distinguish those who survive and report good function from those who do not after 21 years of biennial observations? Although a larger proportion of women than men survived, their functional status was not as good. Multiple logistic regression analysis revealed that age, alcohol intake, cigarette smoking, ventricular rate, and education were all significantly related to functional status for men, with all but the last of these factors inversely related to good function. For women, the only significant predictor other than age was education, which, as with men, was directly associated with good function. The effect of education is probably mediated by numerous factors such as availability and use of health care services, quality of health care, occupation, and lifestyle.
Adult↗