A method is presented to plan the required sample size when estimating regression-based reference limits

BACKGROUND AND OBJECTIVE: Reference limits are widely used in anthropometry, the behavioral sciences, medicine, and clinical chemistry. They describe the distribution of a quantitative variable in a healthy population, and are often a smooth function of age or another determinant. Thus, instead of estimating reference limits separately for several age groups, it is more economical and parsimonious to use regression methods to estimate reference limits as a function of age. Although the variability of regression-based reference limits has been addressed previously, the available methods to determine the sample sizes needed to estimate them are neither transparent nor user-friendly. METHODS: We propose a simple and intuitive formula using margins of error, to project the sample sizes required to achieve a given degree of precision, for different sampling strategies. RESULTS: We present two examples for the calculation of the sample size required to estimate a specific reference limit using various age distributions. CONCLUSION: We provide a simple formula to calculate the sample size needed to estimate a specific reference limit to a specified degree of precision. The structure of the formula can easily accommodate different age-sampling strategies.     

Access to non-funded health services (the legal implications)

The challenge to a healthcare system committed to providir universal access is how best to allocate the resources available. Resource allocation in the delivery of healthcare gives rise to the fundamental issue as to whether there is a right to healthcare recognized in law.     

职业化是卫生管理队伍建设的必由之路

卫生管理队伍是最重要的卫生资源，职业化是卫生管理人员发挥关键作用的必备条件。卫生管理队伍职业化的基本要求有：思想革命化，要求具有较高的思想觉悟，献身敬业的精神和公正廉洁的品质；知识现代化，要求具有较高的文化水平和广博的科学知识；能力专业化，要求具有较强的卫生管理专业的管理工作能力；工作专职化，要求全身心地投入到卫生管理工作中去。卫生管理队伍职业化的主要措施有：发展卫生管理学历教育，卫生管理专业毕业生应是卫生管理人员的主要来源；发展卫生管理专业继续教育开展岗位培训，进行上岗、在岗和转岗培训。     

Public assessment of health services provided to the population of the Moscow region

The articles deals with the results of a sociological pool of 2262 citizens of the Moscow Region for the purpose of studying the public assessment of rendering the medial care to population. The instruments related with shaping the public opinion about health care are discussed.     

A spreadsheet-based method for estimating the skin disposition of volatile compounds: application to N,N-diethyl-m-toluamide (DEET)

The disposition of N,N-diethyl-3-methylbenzamide (DEET) applied to split-thickness human cadaver skin was measured in modified Franz cells maintained at 32 degrees C and fitted with a vapor trap. Ethanolic solutions of DEET (1% w/w) spiked with (14)C radiolabel were applied to skin at a dose of 10 microL per cell, corresponding to a DEET dose of 127 microg/cm(2). Room air was drawn over the skin at velocities ranging from 10-100 mL/min. Evaporation of radiolabel from the skin surface and absorption into the receptor solution were monitored for 24 hr post-dose. The percentage of radioactivity collected in the vapor trap after 24 hr increased with airflow, ranging from 16 +/- 4% at 10 mL/min to 59 +/- 7% at 70 mL/min. The percentage of radioactivity absorbed through the skin after 24 hours decreased with increasing airflow, ranging from 69 +/- 7% at 10 mL/min to 20 +/- 1% at 80 mL/min. Tissue retention after 24 hr was 6-14% of the radioactive dose with no clear correlation to airflow. This data as well as DEET absorption data from two previous in vitro studies in which dose and location (fume hood or bench top) was varied were analyzed in terms of a recently developed diffusion/evaporation model for skin implemented on an Excel spreadsheet. A priori model calculations based on independently estimated transport parameters (Model 1) were compared with calculations based on fitted parameters (Models 2 and 3). The analysis of the combined dataset (n = 272 observations) showed that the Model 1 estimates matched the cumulative disposition profiles to within a root mean square error of 12.4% of the applied dose (r(2) = 0.65), whereas the Model 2 and Model 3 fits matched to within 9.4% (r(2) = 0.80) and 6.5% (r(2) = 0.91), respectively. The Model 3 fits were obtained using a concentration-dependent diffusivity of DEET in the stratum corneum, the value of which increased 3.4-fold between low concentrations and saturation. This result was consistent with the mild skin penetration enhancement effect for DEET reported elsewhere. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a word document containing tables and figures including more information on the spreadsheet skin absorption model.]     

Sales force can lead to dollars for OH (occupational health) services

As hospitals enter the 1990s, one of the challenges they will face is finding additional sources of revenue. Occupational Health (OH) programs offer an opportunity for increased dollars--but only for hospitals willing to use sales tactics common to corporate America. In the following article, the author tells how an institution can sell OH services.     

The case for developing publicly-accessible datasets for health services research in the Middle East and North Africa (MENA) region

Background  

The existence of publicly-accessible datasets comprised a significant opportunity for health services research to evolve into a science that supports health policy making and evaluation, proper inter- and intra-organizational decisions and optimal clinical interventions. This paper investigated the role of publicly-accessible datasets in the enhancement of health care systems in the developed world and highlighted the importance of their wide existence and use in the Middle East and North Africa (MENA) region.     

A regression approach for estimating multiday adverse health effects of PM10 when daily PM10 data are unavailable

The authors propose a regression-based approach for obtaining multiday estimates of the adverse health effects of ambient particulate matter less than 10 microm in diameter (PM(10)) when daily PM(10) time-series data are unavailable. This situation is common in the United States, because most US cities take PM(10) measurements every 6 days. Current evidence suggests that adverse effects of PM(10) are not concentrated on a single day but rather are spread out over multiple days, so the unavailability of daily PM(10) data presents a problem for the estimation of these effects. The proposed model estimates weights that are used to construct a linear combination of single-lag PM(10) effect estimates obtained from the available PM(10) data. It is shown that this new approach provides estimates of the effect of PM(10) on mortality that have less bias and mean squared error than currently available methods. Application of this method to the US cities contained in the National Morbidity, Mortality, and Air Pollution Study database produces an estimated national average effect of PM(10) on nonaccidental mortality in persons over age 65 years, corresponding to a 0.32% increase per 10-microg/m(3) increment in PM(10). The estimated effects for cardiorespiratory mortality and other mortality are 0.34% and 0.22%, respectively.     

Getting closer to the truth: overcoming research challenges when estimating the financial impact of worksite health promotion programs

The authors describe the most important methodological challenges often encountered in conducting research and evaluation on the financial impact of health promotion. These include selection bias, skewed data, small sample size, metrics. They discuss when these problems can and cannot be overcome and suggest how some of these problems can be overcome through a creating an appropriate framework for the study, and using state of the art statistical methods.     

A statistical method (cross-validation) for bone loss region detection after spaceflight

Astronauts experience bone loss after the long spaceflight missions. Identifying specific regions that undergo the greatest losses (e.g. the proximal femur) could reveal information about the processes of bone loss in disuse and disease. Methods for detecting such regions, however, remains an open problem. This paper focuses on statistical methods to detect such regions. We perform statistical parametric mapping to get t-maps of changes in images, and propose a new cross-validation method to select an optimum suprathreshold for forming clusters of pixels. Once these candidate clusters are formed, we use permutation testing of longitudinal labels to derive significant changes.     

A method for indirectly estimating gene-environment effect modification and power given only genotype frequency and odds ratio of environmental exposure

Both genes and environment are important determinants of disease. In this paper we model gene-environment effect modification on the odds ratio scale OR(GE|D) and show how to indirectly estimate the effect and 95% confidence intervals (CI) for the simple case of no main genetic and environmental effects [i.e., ]. A statistic is presented to test the null hypothesis and to calculate corresponding power, given the odds ratio for environmental exposure and population genotype frequency (g). Direct extension of the above model provides a mathematical framework for estimating confidence bounds in more complex cases involving partial genetic and/or environmental effects.     

A methodology for estimating the costs and benefits of health promotion

The publication of ‘The Health of the Nation’ [Departmentof Health (1992) The Health of the Nation. A Strategy for theHealth of England. CM 1986, HMSO.] has added increased emphasisto the long standing debate concerning the relative cost-effectivenessof health prevention versus health cure. The benefits arisingfrom curative interventions are highly visible, occur in identifiableindividuals and can be quantified using an increasing stockof clinical and quality of life measures. Unfortunately thebenefits of health promotion activities are much more difficultto quantify and measure given that their success depends uponill health not occurring. In order for health promotion to effectively compete for limitedhealth care resources it must ensure that the benefits of itswork are apparent to policy makers. This paper describes a methodologyby which such benefits can be quantified in readily measurableterms. This enables health promotion to make an effective casefor additional resources using ‘hard’ quantifieddata that emphasizes the value for money and health gain (orrather the prevention of health loss) that can be derived frominterventions of this nature. The methodology is based on readilyavailable data relating to the levels of morbidity and mortalityexperienced by any given population. Epidemiological data isthen utilized to quantify the link between ill health and theproblem being addressed by the health promotion activity. Themodel described in this paper was tested in relation to theanticipated impact of an anti-smoking programme upon the healthexperience of the population within the North West of England.     

The effects of institutional change on geographic variation and health services use in the U.S.A

This paper examines the impact of institutional change on patient care. Using panel data on obstetric deliveries from the state of California in the United States between 1983 and 2001, it develops and tests hypotheses predicting impacts of three features of institutional change-managed care insurance, changing professional controls and public attention to cost-control practices-on cesarean use and geographic variation in cesarean deliveries. It finds that managed care insurance promotes the diffusion of cost-effective patient care practices, reducing cesarean use and increasing variation. I found that over time, managed care patients experience continued lower use and reduced geographic variation as new practices become established. The combined effects of changing professional controls-the growing importance of clinical guidelines-and public attention to cost-control practices also diffuses cost-effective practices, increasing variation and decreasing cesarean use. Cesarean use increases and geographic variation declines in a period of managed care retreat in the late 1990s. The analysis extends prior research by documenting the impact of institutional change on health services use and variation and by suggesting that geographic variation is caused, in part, by the diffusion of new patient care practices.