Estimating disease prevalence using census data.

We describe a method of working on publicly available data to estimate disease prevalence in small geographic areas using Helicobacter pylori as a model infection. Using data from the Third National Health and Nutrition Examination Survey, risk parameters for H. pylori infection were obtained by logistic regression and validated by predicting 737.5 infections in an independent cohort with 736 observed infections. The prevalence of H. pylori infection in the San Francisco Bay Area was estimated with the probabilities obtained from a predictive logistic model, using risk parameters with individual-level 1990 U.S. Census data as input. Predicted H. pylori prevalence was also compared to gastric cancer incidence obtained from the Northern California Cancer Center and showed a positive correlation with gastric cancer incidence (P<0.001, R2=0.87), and no statistically significant association with other malignancies. By exclusively using publicly available data, these methods may be applied to selected conditions with strong demographic predictors.

An evaluation model for syndromic surveillance: assessing the performance of a temporal algorithm.

INTRODUCTION: Syndromic surveillance offers the potential to rapidly detect outbreaks resulting from terrorism. Despite considerable experience with implementing syndromic surveillance, limited evidence exists to describe the performance of syndromic surveillance systems in detecting outbreaks. OBJECTIVES: To describe a model for simulating cases that might result from exposure to inhalational anthrax and then use the model to evaluate the ability of syndromic surveillance to detect an outbreak of inhalational anthrax after an aerosol release. METHODS: Disease progression and health-care use were simulated for persons infected with anthrax. Simulated cases were then superimposed on authentic surveillance data to create test data sets. A temporal outbreak detection algorithm was applied to each test data set, and sensitivity and timeliness of outbreak detection were calculated by using syndromic surveillance. RESULTS: The earliest detection using a temporal algorithm was 2 days after a release. Earlier detection tended to occur when more persons were infected, and performance worsened as the proportion of persons seeking care in the prodromal disease state declined. A shorter median incubation state led to earlier detection, as soon as 1 day after release when the incubation state was < or =5 days. CONCLUSION: Syndromic surveillance of a respiratory syndrome using a temporal detection algorithm tended to detect an anthrax attack within 3-4 days after exposure if >10,000 persons were infected. The performance of surveillance (i.e., timeliness and sensitivity) worsened as the number of persons infected decreased.

The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants.

Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a 2-year probability-based telephone survey (n=9386) of exposure-related human activities in the United States (U.S.) sponsored by the U.S. Environmental Protection Agency (EPA). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-h retrospective diaries and answers to a number of personal and exposure-related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day (i.e., each microenvironment). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board (CARB) sponsored a state-wide activity pattern study, and the mid-1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke (ETS) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.

Arteriovenous malformations of the uterus associated with medical abortion.

Seven cases of uterine arteriovenous malformations associated with pregnancy were initially suspected by the history of prolonged bleeding after a medical abortion and then confirmed by color Doppler scanning. All cases were managed expectantly and resolved spontaneously. When AVMs required diagnosis by pathology or angiography, only the most severe cases would have been reported. Now that they can be recognized on ultrasound, it is possible that mild cases such as these will be found to be much more common.

Investigations of the proximity effect for pollutants in the indoor environment.

More than a dozen indoor air quality studies have reported a large discrepancy between concentrations measured by stationary indoor monitors (SIMs) and personal exposure monitors (PEMs). One possible cause of this discrepancy is a source proximity effect, in which pollutant sources close to the respondent cause elevated and highly variable exposures. This paper describes three sets of experiments in a home using real-time measurements to characterize and quantify the proximity effect relative to a fixed distant location analogous to a SIM. In the first set of experiments, using sulfur hexafluoride (SF6) as a continuously emitting tracer pollutant from a point source, measurements of pollutant concentrations were made at different distances from the source under different air exchange rates and source strengths. A second set of experiments used a continuous point source of carbon monoxide (CO) tracer pollutant and an array of high time resolution monitors to collect simultaneous concentration readings at different locations in the room. A third set of experiments measured particle count density and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations emitted from a continuous particle point source (an incense stick) using two particle counters and two PAH monitors, and included human activity periods both before and during the source emission period. Results from the SF6 and CO experiments show that while the source is emitting, a source proximity effect can be seen in the increases in the mean and median and in the variability of concentrations closest to the source, even at a distance of 2.0 m from the source under certain settings of air exchange rate and source strength. CO concentrations at locations near the source were found to be higher and more variable than the predictions of the mass balance model. For particles emitted from the incense source, a source proximity effect was evident for the fine particle sizes (0.3 to 2.5 microm) and particle-bound PAH up to at least 1.0 m from the source. Analysis of spatial and temporal patterns in the data for the three tracer pollutants reveal marked transient elevations of concentrations as seen by the monitor, referred to as "microplumes," particularly at locations close to the source. Mixing patterns in the room show complex patterns and directional effects, as evidenced by the variable intensity of the microplume activity at different locations. By characterizing the spatial and temporal variability of pollutant concentrations in the home, the proximity effect can be quantified, leading to improved indoor monitoring designs and models of human exposure to air pollutants.

Differential exposure misclassification in case-control studies of environmental tobacco smoke and lung cancer.

We review some of the literature on the effects of exposure misclassification on the statistical analysis of case-control studies. In particular, we focus on evidence for exposure misclassification which may be different for cases and controls in studies of environmental tobacco smoke (ETS). For example, such misclassification could induce relative risk estimates below unity for low exposure which appears to be the case in U.S. lung cancer and ETS studies. We describe procedures for systematically examining the sensitivity of dose-response statistics on exposure misclassification. The procedures demonstrate how p-values for the null hypothesis of no dose-response trend could be adjusted to account for exposure misclassification. The adjustment procedures were applied to an example based on a recently published large study of ETS and lung cancer in which a p-value for trend was reported as 0.03. In this example it is seen that modest differential exposure misclassification can induce substantial increases in the actual p-value, changing what appears to be statistically significant to decidedly nonsignificant.

Daily exposure to environmental tobacco smoke: smokers vs nonsmokers in California.

OBJECTIVES: This study examined the differences in environmental tobacco smoke exposure between smokers and non-smokers. METHODS: A probability sample of 1579 California adults completed a 1-day time diary of a full day's activities in which they reported whether any smoker was present during each activity. RESULTS: Some 61% of respondents reported at least some environmental tobacco smoke exposure in these diary accounts (for an average of up to 5 hours per day), and potential exposure rose monotonically with number of cigarettes actively smoked. Heaviest smokers reported about four times as much such exposure as nonsmokers. CONCLUSIONS: Because smokers lead life-styles that expose them to far higher levels of environmental tobacco smoke exposure, that factor needs to be controlled in studies estimating the effects of active smoking.

The Kiva project.

The treatment program for patients involved in the Kiva Project was individualized. Growth was reinforced and regression was accepted as a natural part of the treatment process. Discharge was never discussed until the patient indicated readiness to leave the hospital and willingness to undertake a particular placement opportunity in the community. Rehospitalization, if it occurred was considered a part of the process and the staff continued to be supportive of the patient regardless of whether or not they remained in the Department of Mental Health system. As of March, 1993, 21 patients had been successfully discharged to the community. Eleven of these patients have been out of the hospital for more than a year, and three for as long as six years. In financial terms, this means a savings in the long-term institutional care of these patients as opposed to more cost-effective outpatient services. The Project currently serves 17 patients. It continues to be a viable treatment modality for the Division of Psychiatric Rehabilitation.

A habilitation center for individuals with a dual diagnosis of mental retardation and mental illness.

The ICF/MR provides services to individuals with a dual diagnosis of mental retardation and mental illness. These services prepare these individuals to the least restrictive environment analogous to the norms and patterns of the mainstream of society. The individuals served are more than 22 years of age and have behavioral problems associated with mental retardation and/or mental illness. In addition, they have multiple medical problems which are related or unrelated to their physical or mental disabilities. These individuals have multiple changing needs which are addressed by an interdisciplinary team. The team develops a unified Individual Program Plan which is the framework for a comprehensive care for these individuals. This is to enable them to live a normal life as possible and to achieve gainful occupational pursuits like any other citizen in the State of South Carolina.

Carbon monoxide exposures inside an automobile traveling on an urban arterial highway.

Carbon monoxide (CO) exposures were measured inside a motor vehicle during 88 standardized drives on a major urban arterial highway, El Camino Real (traffic volume of 30,500-45,000 vehicles per day), over a 13-1/2 month period. On each trip (lasting between 31 and 61 minutes), the test vehicle drove the same 5.9-mile segment of roadway in both directions, for a total of 11.8 miles, passing through 20 intersections with traffic lights (10 in each direction) in three California cities (Menlo Park, Palo Alto, and Los Altos). Earlier tests showed that the test vehicle was free of CO intrusion. For the 88 trips, the mean CO concentration was 9.8 ppm, with a standard deviation of 5.8 ppm. Of nine covariates that were examined to explain the variability in the mean CO exposures observed on the 88 trips (ambient CO at two fixed stations, atmospheric stability, seasonal trend function, time of day, average surrounding vehicle count, trip duration, proportion of time stopped at lights, and instrument type), a fairly strong seasonal trend was found. A model consisting of only a single measure of traffic volume and a seasonal trend component had substantial predictive power (R2 = 0.68); by contrast, the ambient CO levels, although partially correlated with average exposures, contributed comparatively little predictive power to the model. The CO exposures experienced while drivers waited at the red lights at an intersection ranged from 6.8 to 14.9 ppm and differed considerably from intersection to intersection.(ABSTRACT TRUNCATED AT 250 WORDS)

Value and Limitations of Obstetrical Ultrasound: Uncovering abnormalities at earlier stages.

First-trimester ultrasound examination is of value to establish dates or assess fetal viability in cases of bleeding but provides limited information on the well-being of the fetus. At between 16 and 20 weeks' gestation, examination of fetal anatomy allows many abnormalities to be detected. Third-trimester ultrasound examination is predominantly for follow up of growth and normal development or of any abnormalities seen earlier.

Gd-DTPA enhanced MRI of herpes simplex encephalitis: a case report.

Herpes simplex encephalitis (HSE) has been well described by computed tomography (CT) and by non-enhanced magnetic resonance imaging (MRI). We present a case of Gd-DTPA enhanced MRI of HSE and its evolution under antiviral therapy.

Averaging time modeling of exposure simulation with application to the El Camino Real vehicle data.

When profiles of activity patterns are used to generate time series of simulated exposure, one typically samples from exposure distributions which are microenvironment-specific to each activity. If the simulation time step is short, then independent sampling at each time step, ignoring autocorrelation, will result in aggregates with too little variability from one simulation to another. Autocorrelation can often be modeled with one or two extra parameters and then used in the simulation. Furthermore, one may substantially reduce computation by generating a single averaged exposure for each activity segment whose distribution depends in a simple way on the activity duration and the modeled autocorrelation. The process is illustrated using the El Camino Real commuting exposure study data of Ott, Switzer, and Willits.

Efficacy of behavioral versus triazolam treatment in persistent sleep-onset insomnia.

OBJECTIVE: This study compared differential effects of behavioral therapy and triazolam in a clinical population with sleep-onset insomnia. Triazolam was hypothesized to decrease sleep latency and frequency and duration of awakening, with some effects during the first night's administration. But at follow-up, sleep measures were predicted to return to baseline levels. Behavioral treatment was hypothesized to effect sleep after 2 or more weeks of training which persisted at follow-up. METHOD: Thirty patients with average sleep latencies of 81.48 minutes, who reported chronic insomnia for an average of 2.6 years, were randomly assigned to one of two treatment groups: behavioral stimulus control/relaxation training and triazolam. RESULTS: Both treatments decreased sleep latency but differentially. Triazolam was effective immediately but maintained only some gains at follow-up. Behavioral treatment decreased sleep latency beginning the second week, when subjects expected no improvement, with gains maintained at follow-up. Comparisons showed that triazolam group latencies returned toward baseline, while behavioral group gains were maintained at follow-up. CONCLUSIONS: Triazolam treatment showed superior immediate treatment effects, while behavioral treatment showed superior treatment effects at follow-up, effects that accrued during the training period and differentially persisted at follow-up. One treatment strategy implied by these results would be to combine these two interventions concurrently. This would seem to use the immediate effects produced by the medication until the behavioral skills were learned, at which point medication would be terminated. This strategy could offer immediate relief and sustained effects at drug termination.

Personality disorders among depressed outpatients as identified by the MCMI.

Personality disorders frequently are seen among depressed psychiatric inpatients. In a group of 73 depressed psychiatric outpatients, this study identified 85% whose response to the Millon Clinical Multiaxial Inventory (MCMI) suggested a personality disorder. On retest 12 weeks later, only 64% manifested a response style consistent with the DSM-III personality disorders. These findings are discussed in relation to methodology, characteristics of the MCMI, and the response style of the depressed patient, which may lead to an overidentification of personality disorders on a self-report measure. Related aspects of the diagnostic criteria for personality disorders also are discussed.

Stability of the MCMI among depressed psychiatric outpatients.

The Millon Clinical Multiaxial Inventory (MCMI) is a promising, yet somewhat unproven psychometric inventory developed to identify clinical syndromes and personality traits consonant with the Diagnostic and Statistical Manual of Mental Disorders (3rd ed. [DSM-III]; American Psychiatric Association, 1980). The stability of its measures for both the theoretically more stable personality characteristics and the clinical syndromes was investigated in a group of depressed psychiatric outpatients. In this test-retest design with a 3-month interval between tests, clinical syndrome scales of relevance changed significantly as expected. However, many of the personality scales also changed significantly. Only four of the personality scales met a two-fold test of stability. Findings are discussed in terms of characteristics of self-report inventories such as the MCMI, the uniqueness of the depressed population, and characteristics of personality disorders.

Sonographic demonstration of heterotopic pregnancy: report of two cases.

We described two patients with heterotopic pregnancy. In one patient the transabdominal sonographic findings were non-specific and laparoscopy was required for diagnosis. In the second patient transabdominal sonographic findings suggested a diagnosis of heterotopic pregnancy. Endovaginal sonography confirmed this by allowing visualization of the live extrauterine gestation.