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PubMed1996

Migration of persons with AIDS--a search for support from elderly parents?

In this paper we investigate the interstate migration of people with AIDS to Florida under the hypothesis that a significant proportion of these moves are made to access care and support from elderly parents. We present a variety of aggregate data to support this hypothesis. Data recording interstate moves to Florida show that over 19% of interstate migrants with AIDS chose small cities and largely rural counties as their destinations, places without well-developed medical and social service facilities beneficial to people with AIDS. Moreover, the highest in-migration rates are in counties with the greatest proportion of elderly people, who are mostly retirees from other states. A Poisson regression model of destination choice indicates that the attraction of places with a high proportion of the population over 65 is statistically significant, after controlling for other factors that may also draw migrants with AIDS. We infer from analysis of trends in migration flows, that some people with AIDS may be relocating to seek support from elderly parents.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Computers and the clinical laboratory.

Quality control in the clinical laboratory has long been an important concern. The techniques used for several decades have relied heavily on aggregated data analysis of the data within the clinical laboratory itself, techniques which were feasible even in a system of manually maintained laboratory records. The development of increasingly sophisticated computerized hospital information systems presents an opportunity to significantly expand upon traditional quality control efforts.

Clinical Laboratory Information Systems↗

PubMed1994

Detecting survival effects of socioeconomic status: problems in the use of aggregate measures.

Direct measures of SES are seldom included in medical records or large databases on disease incidence or survival, forcing researchers to infer the SES characteristics of individuals from aggregate data (e.g. census tract-level income, education, etc.). This paper assesses the degree of error that results from such inference and the impact this error may have on reported relationships between SES and survival. The authors obtained both individual and census tract-level data on 536 persons diagnosed with cancer between 1980 and 1982 and monitored their survival through 1992. Pearson correlations between individual-level and census tract-level SES variables ranged between 0.2 and 0.4. Statistically significant relationships between SES and survival were observed in the models based on individual-level but not census tract-level SES data. The authors computed the degree to which inference of individual-level from census tract-level SES reduces estimates of risk ratios across SES. It appears likely that much larger numbers of observations than have been used in published studies will be needed to better understand the relationship of SES to survival and other disease outcomes.

Age Factors↗

PubMed1996

Sufentanil plasma concentrations following lower extremity tourniquet release.

STUDY OBJECTIVE: To investigate whether release of a tourniquet on the lower extremity affects plasma concentrations of sufentanil, as previously demonstrated with fentanyl and midazolam. DESIGN: Prospective. SETTING: University tertiary-care institution with residency program. PATIENTS: 20 ASA status I, II, and III patients undergoing total knee arthroplasty under a tourniquet using a sufentanil, nitrous oxide, relaxant regimen. INTERVENTIONS: Each patient received sufentanil 1 to 2 micrograms/kg at induction of anesthesia and in 12.5 to 25 microgram increments as needed thereafter, until 15 minutes prior to tourniquet release. MEASUREMENTS AND MAIN RESULTS: Plasma sufentanil concentrations were determined before tourniquet inflation, immediately before tourniquet deflation, and 1, 2, 5, 10, 20, 30, and 40 minutes following deflation. A 15% elevation of plasma sufentanil concentration above that predicted by elimination pharmacokinetics defined a secondary peak. Although the aggregate data did not indicate an overall statistically significant rise in plasma concentrations after deflation, 9 (45%) patients exhibited a secondary peak in sufentanil plasma concentration following tourniquet deflation (range of secondary peaks, 16% to 89% above predicted values). No patient experienced clinically significant respiratory depression. CONCLUSION: Release of a tourniquet on the lower extremity may yield a detectable rise in plasma sufentanil concentration.

Aged↗

PubMed2005

Bicycle safety helmet legislation and bicycle-related non-fatal injuries in California.

The objective of this study was to determine whether the bicycle safety helmet legislation in California, enacted in 1994, was associated with statistically significant reductions in head injuries among bicyclists aged 17 years and under who were subjected to the law. The study used 44,069 patient discharge cases from all public hospitals in California, from 1991 through 2000, and a case-control design to make direct comparisons between those subjected to the law (Youth) and those who were not (Adult) across the pre- and post-legislation periods. An aggregate data analysis approach and a pooled disaggregate data fitting technique using multinomial logit models were applied. The legislation was found to be associated with a reduction of 18.2% (99% confidence interval: 11.5-24.3%) in the proportion of traumatic brain injuries (Head-TBI) among Youth bicyclists. The proportions of other head, face, and neck injuries were not significantly changed across the pre- and post-legislation periods in this age group but there was a corresponding increase of 9% (5-13%) in the proportion of all other injuries. On the other hand, there was no statistically significant change in the proportions of injury outcomes for Adult bicyclists. The youngest riders, aged 0-9 years, had the greatest decrease in the proportion of Head-TBI. The reduction was the same for motor vehicle and non-motor-vehicle-related incidents. The bicycle safety helmet legislation was associated with a decrease in the likelihood of Head-TBI for non-urban residents but not for urbanites, for males but not for females, and for Whites, Asians, and Hispanics, but not Blacks and others.

Bicycling↗

PubMed2005

Quantitative assessment of thrombus burden predicts the outcome of treatment for venous thrombosis: a systematic review.

PURPOSE: Clot-burden change in patients receiving anticoagulant therapy, by predicting subsequent recurrent venous thromboembolism, may provide a clinically relevant surrogate endpoint of prognostic importance. The validity of this objective measure is yet to be established. METHODS: A PubMed search was performed to retrieve articles published up to December 2003. We identified 11 randomized trials reported from 1990 to 2003 that met our study identification and selection criteria. Anticoagulant therapy subsequently approved by regulatory affairs was assessed by clot-burden change and the validated outcome measure, long-term venous thromboembolism. Two additional randomized trials, partly meeting the inclusion criteria, were included in the sensitivity analysis. RESULTS: Individual studies suggested a predictive relationship between clot-burden change and likelihood of recurrent venous thromboembolism irrespective of the particular anticoagulant. The summary treatment effects strongly favored the therapy under evaluation and were in harmony for improved clot-burden (relative risk 0.82; 95% CI, 0.76-0.88; P <0.001) and for recurrent venous thromboembolism (relative risk 0.56; 95% CI, 0.42-0.76; P <0.001). The aggregate data show a striking predictive correlation for clot-burden change and subsequent recurrent venous thromboembolism using meta-regression analysis; (correlation = 0.81, P = 0.005) validating quantitative clot-burden assessment. CONCLUSION: Clot-burden change predicts long-term outcome, providing clinically relevant, patient-specific prognostic findings that may guide duration of anticoagulant therapy as well as provide a valid surrogate endpoint for clinical trials of innovative antithrombotic therapy, allowing more efficient trials exposing far fewer patients to the hazards of ineffective therapy than is required for outcome studies. Noninvasive assessment (duplex ultrasonography) of clot-burden change is currently being deployed for use in clinical trials.

Anticoagulants↗

PubMed2006

Secondary conditions in a community-based sample of women with physical disabilities over a 1-year period.

OBJECTIVE: To examine prevalence and predictors of secondary conditions in women with physical disabilities. DESIGN: Cross-sectional. SETTING: Women were recruited through private and public health clinics and various community organizations. PARTICIPANTS: A sample of 443 predominantly ethnic minority women with physical disabilities. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Health Conditions Checklist interference score. RESULTS: Aggregated data over a 1-year period showed that nearly the entire sample reported interference from pain (94.5%) and fatigue (93.7%) and that at least three quarters of the sample reported problems with spasticity (85.4%), weakness (81.8%), sleep problems (80.2%), vision impairment (77.9%), and circulatory problems (77.9%). Obesity was substantially more prevalent in this sample (47.6%) than in the general population of women (34.0%). The mean number of secondary conditions per woman +/- standard deviation was 14.6+/-6.2 (range, 1-42), with 75% of the sample endorsing 10 or more conditions. On average, women reported experiencing 5.7+/-4.03 (range, 0-20) conditions that they rated as significant or chronic. A third (33.4%) of the variance in interference scores was accounted for in the regression analysis, with significant variance accounted for by race, disability type (women with joint and connective tissue disorders and women with postpolio reported the highest overall interference scores), greater functional limitations, and lower levels of general mental health. CONCLUSIONS: Secondary conditions in women with physical disabilities are substantially more problematic than reported previously in the literature. Further research is needed to determine health disparities of women with and without disabilities. Measurement issues and the clinical relevance of these findings are discussed.

Activities of Daily Living↗

PubMed2006

New therapies in hepatitis C virus and chronic liver disease: antifibrotics.

Fibrotic liver disease occurs after any of the various forms of injury to the liver. Fibrosis is a critical factor leading to hepatic dysfunction and portal hypertension and its complications. The fibrogenic cascade is complex but leads to accumulation of extracellular matrix proteins, followed by nodular fibrosis, tissue contraction, and alteration in blood flow. A critical concept emerging is that activation of effector cells, which produce extracellular matrix, underlies the fibrogenic process. The aggregate data has not only helped lead to an understanding of the pathophysiologic basis of hepatic fibrogenesis, but it has also provided an important context with which to base novel antifibrotic therapy.

Colchicine↗

PubMed2006

Deaths rise in good economic times: evidence from the OECD.

This study uses aggregate data for 23 Organization for Economic Cooperation and Development (OECD) countries over the 1960-1997 period to examine the relationship between macroeconomic conditions and deaths. The main finding is that total mortality and deaths from several common causes rise when labor markets strengthen. For instance, controlling for year effects, location fixed-effects (FE), country-specific time trends and demographic characteristics, a 1% point decrease in the national unemployment rate is associated with growth of 0.4% in total mortality and the following increases in cause-specific mortality: 0.4% for cardiovascular disease, 1.1% for influenza/pneumonia, 1.8% for liver disease, 2.1% for motor vehicle deaths, and 0.8% for other accidents. These effects are particularly pronounced for countries with weak social insurance systems, as proxied by public social expenditure as a share of GDP. The findings are consistent with evidence provided by other recent research and cast doubt on the hypothesis that economic downturns have negative effects on physical health.

Cause of Death↗

PubMed2003

Antidepressant prescribing and suicide rate in Northern Ireland.

PURPOSE: Although antidepressants are the most commonly used treatment for depressive illness, there is uncertainty if their use is associated with a reduction in suicide rate. Antidepressant prescribing in Northern Ireland has increased over fivefold in the decade 1989-1999. The authors sought to explore whether this increase was associated with a reduction in suicide rate taking into account social and political factors thought also to have an influence on suicide. MATERIALS AND METHODS: Factors that have been suggested to influence suicide were entered into a linear regression with frequency of suicide and undetermined deaths (referred to as suicide rate) as the dependent variable. The above factors were antidepressant prescribing, unemployment rate, household alcohol expenditure and persons charged with terrorist offences. The rise in younger suicides, in recent decades, suggests this analysis should be carried out separately for younger (less than 30 years) and older (30 years and above) suicides separately. The predictors in the two models are based on aggregate data for the total group. RESULT: In the younger group there was no association between antidepressant prescribing and suicide. For the older group increased antidepressant prescribing was associated with a reduction in suicide rate over the 10 years of the study. CONCLUSION: Increasing antidepressant prescribing appears to be an effective strategy for reducing suicide. This has been demonstrated in older individuals.

Adult↗

PubMed2006

Income and health inequality across Canadian provinces.

This paper uses the aggregate data from the Public Use Microdata Files (PUMF) of Canadian National Population Health Survey to estimate income related health inequalities across the ten Canadian provinces. The unique features of the PUMF allow for a meaningful cross-provincial comparison of health indices and their measured inequalities. It concludes that health inequalities favouring the higher income people do exist in all provinces when health status is either self assessed or measured by the health utility index. Moreover, it finds considerable variations in measured health inequalities across the provinces with consistent rankings for certain provinces.

Canada↗

PubMed2005

Characteristics of psychiatric hospitals associated with length of stay in Japan.

OBJECTIVE: Average length of inpatient stay at psychiatric hospitals in Japan has been consistently longer than that in any other developed country, and was 330 days in 1996. Although some reforms have been implemented with the intention of decreasing length of stay (LOS), appreciable reductions have not been achieved. The present study examined hospital characteristics associated with length of stay in regional psychiatric hospitals in Japan, in order to identify variables that might help to reduce LOS. METHOD: This cross-sectional study analysed the complete database of one district in Japan. Analyses were conducted using aggregate data from 24 hospitals. Multiple regression analysis was performed to determine hospital characteristics influencing LOS in psychiatric hospitals. RESULTS: Significant positive associations were identified between LOS and two hospital characteristics: inpatient capacity; proportion of involuntary admissions. Negative associations were observed for three variables: number of outpatients; human resources in terms of healthcare professionals available in each hospital; community activity. Multiple linear regression analysis for the 24 hospitals revealed that number of outpatients and proportion of patients receiving public aid were independently associated with shorter LOS, while proportion of involuntary admissions was independently associated with longer LOS. A negative association between human resources in terms of number of healthcare professionals and LOS was suggested. CONCLUSION: Several hospital characteristics are associated with LOS in psychiatric hospitals. Factors identified in this study offer insights into directions for effective psychiatric health policy to reduce LOS.

Adult↗

PubMed2005

The 2002 European registry of cardiac catheter interventions.

OBJECTIVE: The tradition of yearly reports on cardiac catheter interventions in Europe has been initiated in 1992. This 11th report presents aggregated data on cardiac catheter procedures in 30 European countries in the year 2002. DESIGN AND SETTING: A detailed questionnaire addressing summary data of all cardiac interventions was mailed to presidents or delegates of the national societies of cardiology in Europe. The questionnaire was distributed to all institutions with cardiac catheterisation programs. All questionnaires were compiled in a national summary data sheet, then entered into a central database and subsequently analysed. MAIN OUTCOME MEASURES: Coronary angiography, PTCA, and stenting in absolute numbers and per million inhabitants in the participating countries and the whole of Europe. RESULTS: Overall, 1,901,932 coronary angiograms were reported. The population-adjusted rate of coronary angiograms amounted to an absolute mean of 3358 per 10(6) inhabitants, an increase of 7% compared with 2001. A total of 686,869 PTCA procedures were reported. The mean European number of PTCAs per 10(6) inhabitants increased by 10% from 1103 in 2001 to 1213 in 2002. Procedures with stenting increased by 17% from 508,999 to 593,906. The stenting rate was 86% compared with 82% in 2001. CONCLUSIONS: In pace with epidemiological demand and the need to catch-up from underuse in certain countries, a continuous and considerable growth of coronary interventions can be observed. It will take years to find out whether the announced change of paradigm in the treatment of multivessel disease in the wake of drug-eluting stents will come true.

Angioplasty, Balloon, Coronary↗

PubMed2005

Systematic evaluation of wavefront-guided outcomes.

PURPOSE: To present a format for reporting outcomes of aberrometer-guided refractive procedures. SETTING: SurgiVision Consultants, Inc., Scottsdale, Arizona, and Food and Drug Administration, Center for Devices and Radiological Health, Rockland, Maryland, USA. METHODS: Reports of standard refractive and visual outcomes (uncorrected visual acuity, manifest refractive spherical equivalent, best spectacle-corrected visual acuity) should be provided for any refractive surgery report. Comparison of postoperative uncorrected visual acuity to preoperative best spectacle-corrected visual acuity should be included. Aberration reports should convert 2nd-order terms to refractions (measured in diopters) and use standard refractive reporting methods. Changes in coma, spherical aberration, and root-mean-square changes should be described using statistical methods for aggregate data. Underlying statistics should be reported. RESULTS: Aberration changes are well described by the mean error of the attempted versus achieved outcomes, comparison of the mean changes, and stability over time. Ancillary plots include histogram representation of the postoperative scores. Additional reports of visual function should be included, as appropriate. CONCLUSION: Use of standardized tables and graphs permits qualitative and quantitative comparison of outcomes of refractive treatment with wavefront-guided lasers. Modifications of the recommended formats can be expected over time.

Corneal Surgery, Laser↗

PubMed2004

Is cigarette smoking in poorer nations highly sensitive to price? Evidence from Russia and China.

We examine cigarette demand in China and Russia using longitudinal micro-level household and community surveys. Previous developing-country price elasticity estimates of around -0.75 have been larger than United States estimates of about -0.4, but the former have relied primarily on aggregate data. In contrast, our micro-level price elasticity estimates in China and Russia range from 0 to -0.15. Thus, raising prices in poorer countries may not reduce smoking to the degree previously suggested.

Adult↗

PubMed2004

An empirical analysis of milk addiction.

We show the estimable rational addiction model tends to yield spurious evidence in favor of the rational addiction hypothesis when aggregate data are used. Direct application of the canonical model yields results seemingly indicative that non-addictive commodities such as milk, eggs, and oranges are rationally addictive. Monte Carlo simulation demonstrates that such results are likely to obtain whenever the commodity under scrutiny exhibits high serial correlation, or when even a small amount of the variation in prices is endogenous, or when overidentified instrumental variables estimators are used, or when commonly imposed restrictions are employed. We conclude that time-series data will often be insufficient to differentiate rational addiction from serial correlation in the consumption series.

Animals↗

PubMed2006

Relative income, race, and mortality.

This paper examines the relationship between relative income and mortality. Our research is motivated by recent literature that posits that, holding individual income fixed, those whose income are low relative to the incomes of those in a reference group will have worse health. We develop an empirical model in which an individual's health is a function of his or her own income and the incomes of those who live in the same geographical area. We show how this individual-level model can be estimated using semi-aggregated data on the mortality rates of people categorized by age, race, gender, and place of residence. The model is estimated using mortality data from the 1980 and 1990 Compressed Mortality Files, merged with income data from the 1980 and 1990 5% Public Use samples of the US Census. We find no evidence that having relatively wealthy neighbors, holding own income fixed, is associated with higher mortality. Instead, we find evidence that among some demographic and age groups--in particular working-aged black males--having relatively wealthy neighbors is associated with lower mortality. For example, among younger (aged 25-64) black men, an increase in the income of others is estimated to have a beneficial effect on mortality that is 40% as large as an equivalent increase in own income.

Adolescent↗

PubMed2004

Surfactant replacement therapy on ECMO does not improve outcome in neonates with congenital diaphragmatic hernia.

BACKGROUND PURPOSE: Respiratory failure in neonates with congenital diaphragmatic hernia (CDH) may in part be caused by a primary or secondary surfactant deficiency. Knowledge of the optimal approach to surfactant replacement in neonates with CDH and respiratory failure is limited. The aim of this study was to determine if surfactant replacement on extracorporeal membrane oxygenation (ECMO) results in improved outcomes in neonates > or =35 weeks' gestation with unrepaired CDH. METHODS: Using the CDH Study Group Registry, the authors identified 448 neonates with CDH who were > or =35 weeks' gestation, had no major anomalies, were treated with ECMO within the first 7 days of life, and underwent repair on or after ECMO therapy. Patients in 2 groups were compared: group 1 (- Surf, n = 334) consisted of patients who received no surfactant and group 2 (+ Surf, n = 114) consisted of patients who received at least 1 dose of surfactant while on ECMO. An analysis of all patients in both groups was performed. Additionally, subgroup analyses stratified by gestational age were performed for patients 351/7 to 366/7 weeks' gestation and for patients > or =37 weeks' gestation. Primary end-points for the study were survival and length of ECMO run. Secondary end-points were length of intubation, need for supplemental oxygen at 30 days of life, and at discharge to home. Demographic, clinical, and outcome variables were examined using Fisher's Exact tests for categorical variables and using unpaired t tests for continuous variables. Odds ratios were calculated for categorical end-point variables. RESULTS: Demographic and clinical variables were similar between groups. Analyses of aggregate data showed no significant differences between groups in length of ECMO run, survival, number of days intubated, and percent of patients requiring supplemental oxygen at 30 days or discharge. Subgroup stratification by gestational age did not show significant differences between groups in any of the outcome variables. CONCLUSIONS: The data from this study suggest that surfactant replacement on ECMO for neonates with congenital diaphragmatic hernia does not provide significant benefit in the infant's clinical course with respect to survival, length of ECMO course, length of intubation, or subsequent need for supplemental oxygen.

Extracorporeal Membrane Oxygenation↗