Using changes in binding globulins to assess oral contraceptive compliance

BackgroundValidity of oral contraceptive pill (OCP) clinical trial results depends on participant compliance. Ethinyl estradiol (EE2) induces increases in hepatic binding globulin (BG) levels. Measuring these BG increases may provide an effective and convenient approach to distinguish noncompliant from compliant OCP users in research settings. This analysis evaluated the usefulness of measuring increases in corticosteroid-, sex-hormone- and thyroxine-binding globulins (CBG, SHBG and TBG, respectively) as measures of OCP compliance.MethodsWe used frozen serum from a trial that compared ovarian suppression between normal-weight and obese women randomized to one of two OCPs containing EE2 and levonorgestrel (LNG). Based on serial LNG measurements during the trial, 17% of participants were noncompliant. We matched noncompliant participants with compliant participants by age, body mass index, ethnicity and OCP formulation. We measured CBG, SHBG and TBG levels and compared change from baseline to 3-month follow-up between the noncompliant and compliant participants. Construction of receiver operator characteristic (ROC) curves allowed comparison of various BG measures.ResultsChanges in CBG and TBG distinguished OCP noncompliant users from compliant users [area under the ROC curve (AUROC), 0.86 and 0.89, p<.01]. Changes in SHBG were less discriminating (AUROC 0.69)ConclusionsEE2-induced increases in CBG and TBG provide a sensitive integrated marker of compliance with an LNG-containing OCP.     

Serum lithium concentration can be used to assess dietary compliance in adults

With dietary intervention studies, it is important to ensure that subjects adhere to the test diet. Current methods to monitor adherence have substantial limitations. Therefore, a dose-response test curve was constructed to determine whether small differences in serum Li could be detected in response to ingestion of variable Li doses indicative of full or partial dietary compliance. During 3 separate weeks, subjects consumed a test meal that included a single food containing Li citrate daily for 4 d. Doses of 250, 213, or 175 micromol Li were used each week to approximate compliance levels of 100, 85, and 70%. On d 4, blood samples were taken before and 1, 2, 3, 5, 7, 9, and 24 h after ingesting the test meal. Compared with the 100% dose, serum Li was significantly lower at all times after the 70% dose and at most times after the 85% dose. Data were analyzed to determine a cutoff value so that if a subject's serum Li was below that value, they would be declared noncompliant. The probability that a subject was declared to be noncompliant when in fact they were compliant was set to 0.05 (specificity was set to 0.95) and the probability of noncompliance (sensitivity) was estimated. Test performance was best in the 3- to 9-h range, for which 90-95% of subjects "noncompliant" at the 70% dose were identified. Li can be used as a biomarker to determine dietary compliance. Measuring serum Li 3-9 h after the last dose provides the highest sensitivity and specificity for noncompliance at doses <70%.     

Use of a structured interview to assess portfolio-based learning

Context Portfolio‐based learning is a popular educational tool usually examined by document review which is sometimes accompanied by an oral examination. This labour‐intensive assessment method prohibits its use in the resource‐constrained settings typical of developing countries. Objectives We aimed to determine the feasibility and internal consistency of a portfolio‐based structured interview and its impact on student learning behaviour. Methods Year 4 medical students (n = 181) recorded 25 patient encounters during a 14‐week medical clerkship. Portfolios were examined in a 30‐minute, single‐examiner interview in which four randomly selected cases were discussed. Six standard questions were used to guide examiners in determining the ability of candidates to interpret and synthesise clinical data gathered during patient encounters. Examiners were trained to score responses using a global rating scale. Pearson’s correlation co‐efficient, Cronbach’s α coefficient and the standard error of measurement (SEM) of the assessment tool were determined. The number of students completing more than the required number of portfolio entries was also recorded. Results The mean (± standard deviation [SD], 95% confidence interval [CI]) interview score was 67.5% (SD ± 10.5, 95% CI 66.0–69.1). The correlation coefficients for the interview compared with other component examinations of the assessment process were: multiple‐choice question (MCQ) examination 0.42; clinical case‐based examination 0.37; in‐course global rating 0.08, and overall final score 0.54. Cronbach’s α coefficient was 0.88 and the SEM was 3.6. Of 181 students, 45.3% completed more than 25 portfolio entries. Conclusions Portfolio assessment using a 30‐minute structured interview is a feasible, internally consistent assessment method that requires less examination time per candidate relative to methods described in published work and which may encourage desirable student learning behaviour.     

A theoretical approach to assess microbial risks due to failures in drinking water systems

A failure in treatment or in the distribution network of a surface water-works could have serious consequences due to the variable raw water quality in combination with an extended distribution. The aim of this study was to examine the theoretical impact of incidents in the drinking water system on the annual risk of infection in a population served by a large water treatment plant in Sweden. Reported incidents in the system were examined and a microbial risk assessment that included three pathogens, Cryptosporidium parvum, rotavirus and Campylobacter jejuni, was performed. The main risk incidents in water treatment were associated with sub-optimal particle removal or disinfection malfunction. Incidents in the distribution network included cross-connections and microbial pollution of reservoirs and local networks. The majority of the annual infections were likely to be due to pathogens passing treatment during normal operation and not due to failures, thus adding to the endemic rate. Among the model organisms, rotavirus caused the largest number of infections. Decentralised water treatment with membranes was also considered in which failures upstream fine-pored membranes would have little impact as long as the membranes were kept intact.     

Use of ORAC to assess antioxidant capacity of human milk

The oxygen radical absorbance capacity (ORAC–FL) assay, a useful measure of the antioxidant capacity (AC) reported for some biological samples, supplements, and food samples, was standardized and validated for measuring AC of human milk. Limits of linearity, precision and accuracy of the ORAC–FL assay were made by constructing a Trolox Calibrator which included the addition of human milk as the sample matrix. AC assay results indicated excellent linearity (R² = 0.990 ± 0.005), precision (2.2%) and accuracy on recovery (94.8 ± 3.2%) over a wide range of Trolox concentrations. To validate the assay further, mature milk samples were collected from 100 lactating mothers in Vancouver and Winnipeg, and were measured for vitamin E isomers by HPLC and AC using the standardized ORAC–FL assay. Alpha-tocopherol (α-Toc) was the major vitamin E isomer detected in human milk, established using both ultra-violet and fluorescent detection methods. Milk α-Toc concentrations were found to correlate significantly (P < 0.01) with ORAC–FL assay values in milk obtained from mothers in both Vancouver (R = 0.439, n = 60) and Winnipeg (R = 0.408, n = 40). Although milk is a complex matrix with multiple components possessing potential antioxidant activity, our results indicated that the ORAC–FL assay is a very useful indicator for assessing the antioxidant capacity of human milk.     

Measuring statewide merchant compliance with tobacco minimum age laws: the Massachusetts experience.

OBJECTIVES: This study evaluated merchant compliance with laws prohibiting the sale of tobacco to minors in Massachusetts. METHODS: Stratified cluster sampling was used to select outlets from which youths aged 13 to 17 years attempted to purchase tobacco. RESULTS: Illegal sales were more common when the youth purchasing the tobacco was older, when the clerk was male, and when tobacco was obtained from a self-service display or unlocked vending machine. Failure to request proof of age was the strongest predictor of illegal sales. CONCLUSIONS: Measured compliance rates are strongly influenced by the age of the youths used to purchase tobacco.     

Methodologic issues regarding the use of three observational study designs to assess influenza vaccine effectiveness

BACKGROUND: Influenza causes substantial morbidity and annual vaccination is the most important prevention strategy. Accurately measuring vaccine effectiveness (VE) is difficult. The clinical syndrome most closely associated with influenza virus infection, influenza-like illness (ILI), is not specific. In addition, laboratory confirmation is infrequently done, and available rapid diagnostic tests are imperfect. The objective of this study was to estimate the joint impact of rapid diagnostic test sensitivity and specificity on VE for three types of study designs: a cohort study, a traditional case-control study, and a case-control study that used as controls individuals with ILI who tested negative for influenza virus infection. METHODS: We developed a mathematical model with five input parameters: true VE, attack rates (ARs) of influenza-ILI and non-influenza-ILI and the sensitivity and specificity of the diagnostic test. RESULTS: With imperfect specificity, estimates from all three designs tended to underestimate true VE, but were similar except if fairly extreme inputs were used. Only if test specificity was 95% or more or if influenza attack rates doubled that of background illness did the case-control method slightly overestimate VE. The case-control method usually produced the highest and most accurate estimates, followed by the test-negative design. The bias toward underestimating true VE introduced by low test specificity increased as the AR of influenza- relative to non-influenza-ILI decreases and, to a lesser degree, with lower test sensitivity. CONCLUSIONS: Demonstration of a high influenza VE using tests with imperfect sensitivity and specificity should provide reassurance that the program has been effective in reducing influenza illnesses, assuming adequate control of confounding factors.     

A survey of women regarding factors affecting colorectal cancer screening compliance

BACKGROUND: Women participate in colorectal cancer (CRC) screening less often than men. Our study objective was to understand factors related to women's use of CRC screening. We examined the personal health, medical care, and psychosocial responses to CRC and screening use of a community-based sample of women. METHODS: Women aged 50-80 years at average CRC risk completed a telephone questionnaire. We asked about demographics, past use of CRC and other cancer screening tests, preventive health measures, source of primary care, and comorbidities. We also inquired about attitudes and risk perceptions regarding CRC, knowledge about CRC screening, and other frequent health concerns. Logistic regression identified predictors of screening compliance. RESULTS: Four hundred six women (52% of women contacted, average age 63 years) provided responses. Sixty-five percent had completed some form of CRC screening in the past 5 years. Four factors were positively related to CRC screening: increasing age [adjusted odds ratio (AOR) = 1.05, (95% CI 1.03, 1.08)], perceived CRC risk [AOR = 1.92, (95% CI 1.19, 3.16)], belief that screening reduces CRC risk (AOR = 2.49, 95% CI 1.45, 4.27), and belief in following screening guidelines [AOR = 4.95, (95% CI 2.07, 11.90)]. Belief that screening would be painful [AOR = 0.52, (95% CI 0.32, 0.84)] was inversely related. CONCLUSIONS: Fear about CRC screening-related pain was the strongest impediment to screening, whereas positive attitudes about the value of CRC screening were strongly related to compliance. Addressing fears and emphasizing positive messages by providers should be included in programs promoting CRC screening in women.     

多重填充方法评估日本血吸虫病感染率

目的 对血吸虫病监测点的粪检感染率进行评估。方法 从全国12个先经血检过筛后再用粪检进行确诊的监测点中随机抽取一个。采用统一的问卷调查居民与血吸虫病感染有密切关系的因素，采用多重填充方法对血吸虫病粪检感染率进行估计。结果 监测点居民粪检感染率约为20％，间接血凝试验(IHA)检测阴性者415人中有8％左右的居民被漏检。结论 居民血吸虫病粪检感染率被低估了5％左右。     

Use of qualitative and quantitative fluorescence techniques to assess dermal exposure

Fluorescent tracers provide a way of simultaneously assessing the mass of a contaminant hazardous substance on the surface of the skin of a worker and the area of skin exposed. These parameters, along with the duration of exposure and the estimated contaminant concentration in the skin contamination layer, can be used to calculate the likely uptake through the skin. Repeated assessment of the mass of tracer on a surface within a room or on the surface of the skin can also allow the net transfer of contaminant to that compartment to be estimated. Qualitative evaluation of transfer processes using fluorescent tracers can help identify important secondary sources of exposure.     

Use of 3,4-didehydroretinol to assess vitamin A status in rats

The acetate and palmitate esters of 3,4-didehydroretinol (DR; vitamin A2 alcohol) have been synthesized and characterized. When administered orally in corn oil to female rats, DR was present in the serum as the alcohol, but primarily as esters in the liver. As total stores of retinol (R; vitamin A1 alcohol) decrease, the ratio of DR to R in the serum markedly increases. The ratio of DR to R in serum was greater than 0.27 at liver vitamin A1 palmitate values of less than 3 micrograms/g, 0.05-0.14 at 3-19 micrograms/g, and less than 0.04 at greater than or equal to 20 micrograms/g. Thus, the ratio of DR to R in the serum at a suitable interval after the administration of dehydroretinyl acetate may aid in assessing marginal vitamin A status. DR was not demonstrably converted to R in these studies.     

氨碱生产职业病危害预评价方法的探讨

目的通过在氯碱企业建设项目职业病危害预评价工作中应用一些经验数学计算公式的实践和认识,探讨其作为定量评价的方法及在职业病危害预评价工作中的作用.方法应用数学计算公式结合事故案例分析,对某氯碱化工企业职业病危害的影响区域进行定量评价.结果经过数学公式估算的结果与国内发生的典型事故案例基本一致.结论通过应用数学公式并结合国内同类企业事故案例分析,对建设单位建立健全"职业病危害应急救援预案"工作有指导意义.     

Use of conjoint analysis to assess web-based communications on functional foods

This paper reports the results of conjoint analysis of communications about functional foods, run with women aged 40 and above, using messages found on the Internet. Each of 147 women evaluated 60 concepts, comprising 2-4 phrases per concept, with the phrases dealing with an aspect of functional foods. Three respondent segments emerged, based on the pattern of individual utilities, 'health optimists' (no deep interest in functional foods), 'food for life' (food for health), and 'food for cure' (looking to functional foods to help live a normal life). The utilities of the same elements differed far more across these segments than would be expected from conventional classification questionnaires.