Statistical testing when the populations from which samples are drawn are uncertain

The topic of this article is hypothesis testing when the populations from which the data are drawn are known only with a given probability distribution. Some important areas of application for which such a situation arises is reviewed briefly. The specific cases herein considered are testing a one-sided hypothesis involving two populations. An illustrative small data set, involving six observations, is used to demonstrate relevant approaches and calculations for such testing. Both a frequentist approach and a Bayesian approach are developed. In both of these approaches, use is made of all possible data configurations along with their corresponding probabilities. Various measures of goodness are developed for each of the two approaches. A simulation approach is developed for larger data sets.     

What companies are learning from claims data

Health care claims show how medical services are used by employees and dependents. Analysis of this type of information is essential for financial management, program planning, and benefits plan design.     

Underage drivers are separating drinking from driving

OBJECTIVES: From 1985 to 1995, drivers younger than 21 years experienced a 50% drop in fatal crashes involving alcohol. This study addresses whether the decrease is explained by young drivers' drinking less or by their separating drinking from driving. METHODS: Nighttime roadside surveys were conducted in 3 communities to test drivers' breath and administer questionnaires on drinking practices. From 1992 to 1996, 34,898 drivers (21% of whom were younger than 21 years) were interviewed. RESULTS: Although drivers younger than 21 years were more likely to have consumed 6 or more drinks on at least 1 occasion during the previous month, a smaller percentage of younger drivers than of older drivers had blood alcohol concentrations of 0.01 or higher. CONCLUSIONS: Younger drivers are more likely than drivers older than 21 years to separate drinking from driving.     

Discussing STIs: doctors are from Mars,patients from Venus

BACKGROUND: Primary care plays an important role in promoting sexual health, but in this setting counselling regarding sexually transmitted infections (STIs) is rarely performed and often inadequate. OBJECTIVE: Our aim was to identify and quantify the barriers physicians encounter in discussing STIs with their patients. METHODS: A postal questionnaire-based survey was carried out in a random sample of 200 primary care physicians in Antwerp, Belgium. RESULTS: The response rate was 68%. Among the 122 respondents, only 44.3% provide some form of counselling (asking about sexual history, informing about safe sex or informing about STIs) regularly, at least once a week. Major barriers are language and comprehension problems (for 74.2% of respondents), ethnic differences (68.4%), insufficient training (69.4%), lack of time (60.8%), presence of the patient's partner (89.2%) or mother (94.2%), first contact with a patient (60.8%), fear of embarrassing the patient (30.6%) and a patient without genital complaints (71.4%). About half of the GPs fail to counsel an asymptomatic patient with obvious STI risk, and as many give no safe sex advice in a first contraception consultation. CONCLUSIONS: Physicians have many and various barriers to discussing STIs with their patients. Features of contemporary STI counselling and solutions to its problems are discussed. Education of health care providers should be given priority.     

Employers are demanding more from their claims administrators

Companies that have negotiated performance-based contracts with their TPAs expect to save anywhere from 3% to 10% of their paid claims expenses.     

Carotenoids are decreased in biopsies from colorectal adenomas

A lower intake of carotenoids is associated with an increased risk of colorectal cancer. In order to take advantage of the chemopreventive properties of carotenoids, it is necessary to determine carotenoid concentration at the target tissue. As early stages in the adenoma-carcinoma sequence of colorectal cancer might be susceptible to chemoprevention, we sought to determine carotenoid concentrations in biopsies from colorectal adenomas. METHODS: Biopsies from colorectal adenomas and non-involved mucosa were taken from seven patients. For controls, biopsies were obtained from the ascending and descending colon of patients without polyps (n = 5). Concentration of carotenoids (alpha-, beta-carotene, lutein, lycopene, zeaxanthin, beta-cryptoxanthin) were determined by optimizing gradient HPLC-analysis. Results are expressed as pmol/microg DNA. RESULTS: Except for alpha-carotene, all carotenoids could reliably be detected in all specimens. In control patients carotenoid concentrations were highest in the ascending colon, being followed by the descending colon and non-involved mucosa from polyp-carriers. In colorectal adenomas all carotenoids were significantly reduced as compared to-non-involved mucosa (beta-carotene: 0.37 vs 0.19, P<0.03; lycopene: 0.34 vs 0.21, P<0.06, beta-cryptoxanthin: 0.14 vs 0.09, P<0.03, zeaxanthin: 0.18 vs 0.09, P<0.02; lutein: 0.18 vs 0.13,P <0.02). CONCLUSION: All carotenoids investigated are reduced in colorectal adenomas, suggesting that mucosal carotenoids could serve as biomarkers for predisposition to colorectal cancer. Moreover, anti-tumor activity exerted by carotenoids is limited due to mucosal depletion. We speculate that supplementation of a larger array of carotenoids might be beneficial for patients with colorectal adenoma.     

Justices challenge notion that prisons are exempt from ADA

The U. S. Supreme Court questioned Paul Tufano, a Pennsylvania general council member, in a case involving whether prisoners are exempt from the Americans with Disabilities Act (ADA). The case, brought by former inmate Ronald Yeskey against the Pennsylvania Department of Corrections, claimed that because Yeskey suffered from hypertension he was prevented from participating in a boot camp program or other programs that might have led to an earlier release. As a result, Yeskey was incarcerated a year longer than he might have been. Pennsylvania's position is that prisoners are exempt from the ADA. However, under sharp questioning by several justices, Tufano agreed that the statute does apply to prison employees and visitors. The verdict could have wide-ranging implications for prisoners with HIV. Circuit courts have been divided on the issue of what a public entity is and whether the ADA applies. A decision is expected by June 30.     

Anthocyanins are efficiently absorbed from the small intestine in rats

Anthocyanins are natural pigments that possess antioxidant activities and are implicated in various health effects. Recent studies showed that the stomach is a site of anthocyanin absorption. However, the fate of anthocyanins in the small intestine remains unknown. We therefore investigated anthocyanin absorption after in situ perfusion of the jejunum + ileum in rats. The intestine was perfused for 45 min with a physiological buffer supplemented with various anthocyanins. Purified anthocyanin glycosides (9.2 nmol/min) or blackberry (9.0 nmol/min) or bilberry (45.2 nmol/min) anthocyanins were perfused. A high proportion of anthocyanin glycosides was absorbed through the small intestine after perfusion. The rate of absorption was influenced by the chemical structure of the anthocyanin and varied from 10.7 (malvidin 3-glucoside) to 22.4% (cyanidin 3-glucoside). Regardless of the anthocyanins perfused, only glycosides were recovered in the intestinal lumen. After perfusion of a high amount of blackberry anthocyanins (600 nmol/min), native cyanidin 3-glucoside was recovered in urine and plasma from the aorta and mesenteric vein. Methylated and/or glucuronidated derivatives were also identified. Analysis of bile samples revealed that cyanidin 3-glucoside and its methylated derivatives (peonidin 3-glucoside + peonidin glucuronide) quickly appeared in bile. This study demonstrated that anthocyanin glycosides are rapidly and efficiently absorbed from the small intestine. Furthermore, anthocyanins are quickly metabolized and excreted into bile and urine as intact glycosides as well as methylated forms and glucuronidated derivatives.     

Anthocyanins are efficiently absorbed from the stomach in anesthetized rats

After consumption, anthocyanins are rapidly absorbed as glycosides. Their rapid appearance in plasma could result from absorption through the gastric wall. The aim of this study was to evaluate the fate of anthocyanins in the stomach. Absorption of purified anthocyanins (14 micromol/L) as well as blackberry 14 and 750 micromol/L) and bilberry (88 micromol/L) anthocyanins was compared after in situ gastric administration for 30 min. A high proportion (approximately 25%) of anthocyanin monoglycosides (glucoside or galactoside) was absorbed from the stomach, whereas absorption of cyanidin 3-rutinoside was lower. Bilberry anthocyanins were also efficiently absorbed, but absorption varied greatly (19-37%) according to the anthocyanin structure; delphinidin glycosides were the most absorbed. When a high concentration of blackberry anthocyanins (750 micromol/L) was injected into the gastric lumen, the percentage of cyanidin 3-glucoside (Cy 3-glc) absorption was lower than after administration of a low concentration (14 micromol/L). After administration of this high concentration, blackberry anthocyanins were observed in plasma from gastric vein and aorta, whereas neither aglycones nor metabolites were detected. Analysis of bile samples revealed that Cy 3-glc appeared in bile after as little as 20 min. Peonidin 3-glucoside (the methylated form of Cy 3-glc) as well as unknown anthocyanin metabolites were also observed in bile. Thus, this study demonstrated that anthocyanin glycosides were quickly and efficiently absorbed from the stomach and rapidly excreted into bile as intact and metabolized forms.     

Iron bioavailability and utilization in rats are lower from lime-treated corn flour than from wheat flour when they are fortified with different sources of iron

Although iron bioavailability from wheat flour fortified with iron has been widely studied, the bioavailability of lime-treated corn flour has not been evaluated sufficiently. We compared iron bioavailability and utilization of lime-treated corn flour and wheat flour supplemented with various iron sources. Bioavailability and utilization were determined in Sprague-Dawley rats using the iron balance and hemoglobin depletion-repletion methods. Rats were iron depleted by feeding them a low iron, casein diet for 10 d. During the repletion period, the rats were fed diets based on lime-treated corn flour or wheat flour, both supplemented with ferrous fumarate, ferrous sulfate, ferric citrate and reduced iron for 14 d. Hemoglobin was determined at the end of depletion and repletion periods. The phytate concentration was lower in wheat flour (114 mg/100g) than in lime-treated corn flour (501 mg/100g). Iron bioavailability and utilization by rats were higher from fortified and unfortified wheat flour than from the lime-treated corn flour counterparts. Iron utilization was greater in rats fed wheat flour supplemented with ferrous sulfate, followed by fumarate and citrate than in rats fed reduced iron. In lime-treated corn flour, iron utilization by rats fed unfortified flour and flour fortified with reduced iron did not differ, but utilization was higher in rats fed corn flour fortified with iron sulfate, fumarate and citrate than with reduced iron. We conclude that fortification of lime-treated corn flour with reduced iron has no effect on iron bioavailability or utilization, probably due to the high phytate content. Other iron compounds must be selected to fortify lime-treated corn flour when intended for public nutrition programs.     

Lutein and beta-carotene from lutein-containing yellow carrots are bioavailable in humans

BACKGROUND: Lutein is a hydroxy-carotenoid constituting the macular pigment of the human retina. Increasing lutein intake from foods could increase the density of this pigment and decrease the risk of developing macular degeneration. Yellow carrots are a novel food source that could increase lutein consumption. OBJECTIVE: We evaluated and compared lutein uptake and clearance in humans from genetically selected lutein-containing yellow carrots fed chronically and from a lutein supplement. DESIGN: Four women and 5 men aged 23-28 y participated in this randomized, blinded, 3 x 3 crossover intervention. Treatments consisted of yellow carrots (YC treatment, 1.7 mg lutein/d), white carrots as a negative control (WC treatment, 0 mg lutein/d), and a lutein supplement in oil as a positive control (LS treatment, 1.7 mg lutein/d). Each treatment lasted 7 d and was followed by a 7-d washout period. RESULTS: Mean (+/- SD) peak changes in serum lutein concentration from baseline were 0.31 +/- 0.08, 0.19 +/- 0.08, and -0.04 +/- 0.04 micromol/L for the LS, YC, and WC treatments, respectively. The areas under the curve for 0-14 d (AUC(0-14d)) differed significantly (P < 0.0001) between treatments. Lutein from the YC treatment was 65% as bioavailable as that from the LS treatment. The AUC(0-14d) for beta-carotene (-0.01 +/- 0.28 micromol.d/L) also showed that the YC treatment maintained peak serum beta-carotene concentrations at 0.35 +/- 0.30 micromol/L, whereas the LS treatment did not (AUC(0-14d) = -0.71 +/- 0.59 micromol.d/L). CONCLUSION: Lutein from this novel food source significantly increases serum lutein concentrations and does not result in the decrease in beta-carotene concentrations that accompanies administration of lutein supplements.     

Isoflavones from soya foods are more bioavailable in children than adults

The purpose of the present study was to determine whether children experience a higher systemic exposure to isoflavonoids when consuming a body weight-adjusted dose of soya compared with adults. Forty study participants were recruited from a local Waldorf school, including twenty-one children and nineteen adults. Participants collected a baseline urine sample and ate immediately thereafter a body weight-adjusted dose of soya nuts (15 g/54.4 kg equivalent to 0.615 (SD 0.036) mg total isoflavones/kg) followed by a 12 h urine collection. Nineteen children and eighteen adults completed the protocol correctly (fourteen child-parent pairs). Children, compared with adults, showed a statistically significant (P < 0.05 by unpaired t test) higher urinary isoflavone excretion rate for daidzein (+39%), genistein (+44%), all non-metabolites (daidzein + genistein + glycitein; +41%) and total isoflavonoids (+32%). Isoflavones are more bioavailable in children v. adults. Urine is an excellent medium to determine systemic isoflavone exposure in children due to its non-invasiveness and high compliance, in particular when collected overnight; it also allows evaluation of completeness of specimen collection.