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Biomedical subjects

Jonathan M Samet

Publications and source records attributed to Jonathan M Samet.

At least 37 records · Page 2Linked to original sources
PubMed2005

Fasting serum glucose level and cancer risk in Korean men and women.

CONTEXT: Diabetes is a serious and costly disease that is becoming increasingly common in many countries. The role of diabetes as a cancer risk factor remains unclear. OBJECTIVE: To examine the relationship between fasting serum glucose and diabetes and risk of all cancers and specific cancers in men and women in Korea. DESIGN, SETTING, AND PARTICIPANTS: Ten-year prospective cohort study of 1,298,385 Koreans (829,770 men and 468,615 women) aged 30 to 95 years who received health insurance from the National Health Insurance Corp and had a biennial medical evaluation in 1992-1995 (with follow-up for up to 10 years). MAIN OUTCOME MEASURES: Death from cancer and registry-documented incident cancer or hospital admission for cancer. RESULTS: During the 10 years of follow-up, there were 20,566 cancer deaths in men and 5907 cancer deaths in women. Using Cox proportional hazards models and controlling for smoking and alcohol use, the stratum with the highest fasting serum glucose (> or =140 mg/dL [> or =7.8 mmol/L]) had higher death rates from all cancers combined (hazard ratio [HR], 1.29; 95% confidence interval [CI], 1.22-1.37 in men and HR, 1.23; 95% CI, 1.09-1.39 in women) compared with the stratum with the lowest level (<90 mg/dL [<5.0 mmol/L]). By cancer site, the association was strongest for pancreatic cancer, comparing the highest and lowest strata in men (HR, 1.91; 95% CI, 1.52-2.41) and in women (HR, 2.05; 95% CI, 1.43-2.93). Significant associations were also found for cancers of the esophagus, liver, and colon/rectum in men and of the liver and cervix in women, and there were significant trends with glucose level for cancers of the esophagus, colon/rectum, liver, pancreas, and bile duct in men and of the liver and pancreas in women. Of the 26,473 total cancer deaths in men and women, 848 were estimated as attributable to having a fasting serum glucose level of less than 90 mg/dL. For cancer incidence, the general patterns reflected those found for mortality. For persons with a diagnosis of diabetes or a fasting serum glucose level greater than 125 mg/dL (6.9 mmol/L), risks for cancer incidence and mortality were generally elevated compared with those without diabetes. CONCLUSION: In Korea, elevated fasting serum glucose levels and a diagnosis of diabetes are independent risk factors for several major cancers, and the risk tends to increase with an increased level of fasting serum glucose.

Adult↗
PubMed2005

Respiratory effects of inhalation exposure among workers during the clean-up effort at the World Trade Center disaster site.

During December 2001 we conducted a field study of 183 clean-up and recovery workers at the World Trade Center (WTC) disaster site to assess respiratory health effects potentially resulting from their work at the site. On site, we administered a respiratory health questionnaire designed to assess upper respiratory symptoms and lower respiratory symptoms, including cough, phlegm, and wheeze, as well as indices of exposure, including number of days worked at the site and job category. Spirometry was conducted for 175 workers. Sixty-five percent of the workers surveyed arrived at the site without lower respiratory symptoms. Of this group, 34% developed cough, 24% developed phlegm, and 19% developed wheeze. Prevalence rates of these symptoms were related to the number of days spent working at the WTC, but not job category. The mean percentage predicted FEV(1) and FVC were 6% and 5% lower, respectively, for workers who developed new lower respiratory symptoms compared to those who remained symptom free. While the development of new wheeze suggested the presence of airway obstruction, the near-normal distribution of age-adjusted FEV(1)/FVC ratios suggested that the degree of obstruction was mild. The prevalence rates of upper airway symptoms (nasal congestion, sore throat, hoarse throat) exceeded those of lower respiratory symptoms, however, it was not determined whether symptoms pre-dated arrival at the WTC site.

Adult↗
PubMed2005

Temperature and mortality among the elderly in the United States: a comparison of epidemiologic methods.

BACKGROUND: Time-series analyses have been used for decades to investigate time-varying environmental exposures. Recently, the case-crossover design has been applied to assess acute effects of air pollution. Our objective was to compare time-series and case-crossover analyses using varying referent periods (ie, unidirectional, ambidirectional, and time-stratified). METHODS: We examined the association between temperature and cardiorespiratory mortality among the elderly population in the 20 largest metropolitan areas of the United States. Risks were estimated by season and geographic region in 1992. We obtained weather data from the National Climatic Data Center and mortality data from the Division of Vital Statistics. Conditional logistic regression (case-crossover) and Poisson regression (time-series) were used to estimate the increased risk of cardiorespiratory mortality associated with a 10 degrees F increase in daily temperature, accounting for dew-point temperature and other potential confounding factors. RESULTS: In the time-stratified case-crossover analysis, the strongest associations were found in the summer; in the Southwest, Southeast, Northwest, Northeast, and Midwest, the odds ratios were 1.15 (95% confidence interval=1.07-1.24), 1.10 (0.96-1.27), 1.08 (0.92-1.26), 1.08 (1.02-1.15), and 1.01 (0.92-1.11), respectively. Mostly null or negative associations were found in the winter, spring, and fall. The ambidirectional case-crossover and the time-series analyses produced quantitatively similar results to those from the time-stratified analysis. The unidirectional analysis produced conflicting results. CONCLUSIONS: Inferences from studies of weather and mortality using the ambidirectional or time-stratified case-crossover approaches and the time-series analyses are comparable and provide consistent findings in this study.

Aged↗
PubMed2005

A meta-analysis of time-series studies of ozone and mortality with comparison to the national morbidity, mortality, and air pollution study.

BACKGROUND: Although many time-series studies of ozone and mortality have identified positive associations, others have yielded null or inconclusive results, making the results of these studies difficult to interpret. METHODS: We performed a meta-analysis of 144 effect estimates from 39 time-series studies, and estimated pooled effects by lags, age groups, cause-specific mortality, and concentration metrics. We compared results with pooled estimates from the National Morbidity, Mortality, and Air Pollution Study (NMMAPS), a time-series study of 95 large U.S. urban centers from 1987 to 2000. RESULTS: Both meta-analysis and NMMAPS results provided strong evidence of a short-term association between ozone and mortality, with larger effects for cardiovascular and respiratory mortality, the elderly, and current-day ozone exposure. In both analyses, results were insensitive to adjustment for particulate matter and model specifications. In the meta-analysis, a 10-ppb increase in daily ozone at single-day or 2-day average of lags 0, 1, or 2 days was associated with an 0.87% increase in total mortality (95% posterior interval = 0.55% to 1.18%), whereas the lag 0 NMMAPS estimate is 0.25% (0.12% to 0.39%). Several findings indicate possible publication bias: meta-analysis results were consistently larger than those from NMMAPS; meta-analysis pooled estimates at lags 0 or 1 were larger when only a single lag was reported than when estimates for multiple lags were reported; and heterogeneity of city-specific estimates in the meta-analysis were larger than with NMMAPS. CONCLUSIONS: This study provides evidence of short-term associations between ozone and mortality as well as evidence of publication bias.

Age Factors↗
PubMed2005

Building capacity for international tobacco control research: the global tobacco research network.

The Global Tobacco Research Network (GTRN) was developed to enhance global tobacco control research through information sharing and collaboration among researchers. The formation of the GTRN is timely because of the need to ratify, implement, and track the Framework Convention on Tobacco Control. While the spectrum of international tobacco control research continues to expand, resources to support these efforts are still quite limited. As an issue-specific network focused on information sharing and capacity building associated with tobacco control research, the GTRN will provide an opportunity for enhancing the effectiveness of tobacco control initiatives.

Cooperative Behavior↗
PubMed2004

Cigarette smoking, alcohol drinking, hepatitis B, and risk for hepatocellular carcinoma in Korea.

BACKGROUND: Liver cancer is one of the most common cancers worldwide, particularly in Asia and Africa, where infectious hepatitis and aflatoxin exposures are common. We conducted a prospective cohort study of liver cancer in Korea to assess the independent effects and interactions of smoking, alcohol consumption, and hepatitis B on risk of mortality from hepatocellular carcinoma. METHODS: From a total of 1,283,112 men and women free of cancer at baseline, 3807 died from liver cancer during follow-up from 1993 to 2002. All participants reported their smoking and alcohol consumption, and hepatitis B surface antigen (HBsAg) status was documented for 47.2% of the participants. Relative risk and 95% confidence intervals (CIs) of mortality from hepatocellular carcinoma were calculated using proportional hazards models adjusted for age, alcohol drinking, diabetes, and HBsAg status. RESULTS: Current smoking was associated with increased risk of mortality from hepatocellular carcinoma in men (RR = 1.4; 95% CI = 1.3 to 1.6) but not women (RR = 1.1; CI = 0.8 to 1.7). The relative risk of mortality from hepatocellular carcinoma for male HBsAg carriers was 24.3 (95% CI = 21.9 to 26.9) times that in HBsAg-negative males; the relative risk for HBsAg-positive women was 54.4 (95% CI = 24.8 to 119.5). Heavy alcohol drinking was associated with hepatocellular carcinoma mortality risk in the subgroup of men who were tested for HBsAg (RR =1.5; 95% CI = 1.2 to 2.0). There was no interaction among smoking, alcohol drinking, and HBsAg in terms of hepatocellular carcinoma mortality. CONCLUSION: Cigarette smoking, heavy alcohol consumption, and HBsAg were independently associated with increased risk of mortality from hepatocellular carcinoma but did not interact synergistically. The relatively higher increase in mortality from hepatocellular carcinoma in HBsAg-seropositive women compared with men merits further research.

Adult↗
PubMed2004

Ozone and short-term mortality in 95 US urban communities, 1987-2000.

CONTEXT: Ozone has been associated with various adverse health effects, including increased rates of hospital admissions and exacerbation of respiratory illnesses. Although numerous time-series studies have estimated associations between day-to-day variation in ozone levels and mortality counts, results have been inconclusive. OBJECTIVE: To investigate whether short-term (daily and weekly) exposure to ambient ozone is associated with mortality in the United States. DESIGN AND SETTING: Using analytical methods and databases developed for the National Morbidity, Mortality, and Air Pollution Study, we estimated a national average relative rate of mortality associated with short-term exposure to ambient ozone for 95 large US urban communities from 1987-2000. We used distributed-lag models for estimating community-specific relative rates of mortality adjusted for time-varying confounders (particulate matter, weather, seasonality, and long-term trends) and hierarchical models for combining relative rates across communities to estimate a national average relative rate, taking into account spatial heterogeneity. MAIN OUTCOME MEASURE: Daily counts of total non-injury-related mortality and cardiovascular and respiratory mortality in 95 large US communities during a 14-year period. RESULTS: A 10-ppb increase in the previous week's ozone was associated with a 0.52% increase in daily mortality (95% posterior interval [PI], 0.27%-0.77%) and a 0.64% increase in cardiovascular and respiratory mortality (95% PI, 0.31%-0.98%). Effect estimates for aggregate ozone during the previous week were larger than for models considering only a single day's exposure. Results were robust to adjustment for particulate matter, weather, seasonality, and long-term trends. CONCLUSIONS: These results indicate a statistically significant association between short-term changes in ozone and mortality on average for 95 large US urban communities, which include about 40% of the total US population. The findings indicate that this widespread pollutant adversely affects public health.

Air Pollution↗
PubMed2004

Smoking among adolescents in China: 1998 survey findings.

BACKGROUND: In China, tobacco smoking accounts for approximately 800 000 deaths annually and evidence suggests that tobacco use is rising. To improve tobacco control initiatives directed at youth, we conducted a population-based survey of children ages 11-20 years, both in and out of school. While there have been previous school-based studies on smoking prevalence and smoking-related knowledge, attitudes, and behaviours among adolescents in China, including the Global Youth Tobacco Survey, this survey also describes smoking behaviour among non-student youth. This population is important as approximately 40% of Chinese youths aged 15-19 years have already discontinued their studies. METHODS: A survey of smoking behaviour and smoking-related knowledge and attitudes was administered to 24 000 youths (students and non-students of middle school age) in 24 disease surveillance points in China, selected to include equal numbers of urban and rural children. RESULTS: The prevalence rates of experimenting were 47.8% for boys and 12.8% for girls. The prevalence of regular smoking among non-students was higher (8.3%) compared with students (5.2%). The strongest predictor of regular smoking was peer influence with 44% reporting that they obtained their first cigarette from peers. The majority of youths were aware that smoking was a cause of several diseases and addictive; however, non-students were less aware than students. CONCLUSIONS: The evidence highlights the need for tobacco control interventions aimed at youths in China including non-student youths. For males, prevention programmes should extend into young adulthood.

Adolescent↗
PubMed2004

Trends in use of inhaled corticosteroids for asthma management: 1994-1998.

PURPOSE: To evaluate trends in prescribing of inhaled corticosteroids for asthma between 1994 and 1998 and patterns of prescribing in relation to selected physician characteristics. METHODS: Using a HMO database, a physician sample (N = 335) was linked to patient encounter data and pharmacy claims (N = 51,345) for asthma patients ages 5 to 45 years (N = 6,944). Longitudinal and cross-sectional analytic methods were used to examine physician prescribing patterns across the study period. RESULTS: The percent of physicians prescribing an inhaled corticosteroid increased over time with consistently greater prescribing among specialists. Annual comparisons by specialty groups revealed that specialists (allergy and pulmonary) prescribed inhaled steroids to a larger proportion of their patients than generalists (family practice, internal medicine, pediatrics, pediatric emergency department); (range: 0.61-0.69 vs. 0.31-0.39, p < .01). The lowest proportions were found among pediatric emergency department physicians (range: 0.00-0.10) and pediatricians (range: 0.17-0.27). CONCLUSIONS: Significant linear trends in either physician group were not observed during this 5-year period. Differences across physician groups were evident.

Administration, Inhalation↗
PubMed2004

Smoking and cancer risk in Korean men and women.

OBJECTIVE: In Korea, male smoking prevalence is among the world's highest, and mortality rates from smoking-caused cancers, particularly lung cancer, are escalating. This cohort study examined the effects of cigarette smoking on the risk of cancer mortality and incidence, and characterized the relationship of cancer risk with the amount and duration of cigarette smoking. METHOD: A nine-year prospective cohort study was carried out on 1,212,906 Koreans, 30-95 years of age. The study population includes participants in a national insurance program, who completed a questionnaire on smoking and other risk factors. The main outcome measures were death from cancer and cancer incidence, obtained through record linkage. At baseline, 472,970 men (57.0%) and 20,548 (5.4%) women were current cigarette smokers. RESULTS: In multivariate Cox proportional hazards models, controlling for age, current smoking among men increased the risks of mortality for cancer of the lung (relative risk (RR), 4.6; 95% confidence interval (CI), 4.0-5.3) and other cancers, including larynx, bile duct, esophagus, liver, stomach, pancreas, bladder, and also leukemia. Current smoking among women increased the risk of lung cancer mortality (RR = 2.5, 95% CI = 2.0-3.1). Similar results were found for incidence among men and women. CONCLUSION: In Korea, smoking is an independent risk factor for a number of major cancers. The findings affirm the need for aggressive tobacco control in Korea in order to minimize the epidemic of smoking-caused disease.

Adult↗
PubMed2004

Determinants of salivary cotinine levels among current smokers in Mexico.

The present study describes salivary cotinine levels and their relationship to cigarettes smoked per day in Mexican smokers. Using a sampling strategy based on the number of cigarettes per day, we recruited 1,222 smokers from Mexico City and the state of Morelos in Mexico during 1999. Smoking behaviors and other factors known to affect nicotine intake and cotinine level were identified in an interview using a standardized questionnaire. Salivary cotinine was measured by capillary gas chromatography with nitrogen-phosphorus detection. We used generalized additive models to describe the relationship between salivary cotinine levels and variables of interest. The mean age of the population was 39.7 years (SD=15.6 years), with a mean cotinine level of 194.7 ng/ml (SD=134.8; range=10.1-767). Participants smoked a mean of 15.5 cigarettes per day (SD=11.3). Salivary cotinine and cigarettes smoked per day were positively related, although the association was not linear, flattening above 20 cigarettes per day. After adjusting for cigarettes per day, we found that significant predictors of cotinine levels included age, body mass index, cigarette producer, and smoking behavior variables. These results may have implications for dosing with nicotine medications to aid smoking cessation in Mexican smokers and suggest that whether the cigarette is labeled light or regular has no relationship to nicotine dose from smoking cigarettes.

Adolescent↗
PubMed2004

Hierarchical bivariate time series models: a combined analysis of the effects of particulate matter on morbidity and mortality.

In this paper we develop a hierarchical bivariate time series model to characterize the relationship between particulate matter less than 10 microns in aerodynamic diameter (PM10) and both mortality and hospital admissions for cardiovascular diseases. The model is applied to time series data on mortality and morbidity for 10 metropolitan areas in the United States from 1986 to 1993. We postulate that these time series should be related through a shared relationship with PM10. At the first stage of the hierarchy, we fit two seemingly unrelated Poisson regression models to produce city-specific estimates of the log relative rates of mortality and morbidity associated with exposure to PM10 within each location. The sample covariance matrix of the estimated log relative rates is obtained using a novel generalized estimating equation approach that takes into account the correlation between the mortality and morbidity time series. At the second stage, we combine information across locations to estimate overall log relative rates of mortality and morbidity and variation of the rates across cities. Using the combined information across the 10 locations we find that a 10 microg/m3 increase in average PM10 at the current day and previous day is associated with a 0.26% increase in mortality (95% posterior interval -0.37, 0.65), and a 0.71% increase in hospital admissions (95% posterior interval 0.35, 0.99). The log relative rates of mortality and morbidity have a similar degree of heterogeneity across cities: the posterior means of the between-city standard deviations of the mortality and morbidity air pollution effects are 0.42 (95% interval 0.05, 1.18), and 0.31 (95% interval 0.10, 0.89), respectively. The city-specific log relative rates of mortality and morbidity are estimated to have very low correlation, but the uncertainty in the correlation is very substantial (posterior mean = 0.20, 95% interval -0.89, 0.98). With the parameter estimates from the model, we can predict the hospitalization log relative rate for a new city for which hospitalization data are unavailable, using that city's estimated mortality relative rate. We illustrate this prediction using New York as an example.

Air Pollutants↗