A SAS macro for constructing simultaneous confidence intervals for multinomial proportions

Prevalence and clinical implications of biochemical hypogonadism in patients with nonobstructive azoospermia undergoing infertility evaluation

Objective

To investigate the prevalence and clinical implications of biochemical hypogonadism in infertile men with nonobstructive azoospermia (NOA).

Design

Cohort study.

Setting

University-affiliated tertiary center for male reproductive health.

Patients

767 consecutive normogonadotropic or hypergonadotropic patients with NOA undergoing infertility evaluation from 2014 to 2021.

Intervention

Patients aged 23-55 years underwent comprehensive clinical, hormonal, genetic, semen analysis, and histopathology evaluations and were classified on the basis of predefined baseline follicle-stimulating hormone (12 IU/L) and total testosterone (350 ng/dL) serum levels cutpoints into four groups: hypergonadotropic hypogonadal, hypergonadotropic eugonadal, normogonadotropic hypogonadal, and normogonadotropic eugonadal. All patients were naïve regarding previous sperm retrieval (SR) or hormonal therapy use.

Main Outcome Measures

The period prevalence of biochemical hypogonadism, defined as testosterone levels of <350 ng/dL, and the distribution of patients per group were computed. The associations between hypogonadism, clinical factors, and SR success were evaluated using multivariable logistic regression analyses. Adjusted relative risks (aRRs) and 95% confidence intervals (CIs) were estimated to assess the association between SR and patient classification.

Results

The overall period prevalence of biochemical hypogonadism was 80.8% (95% CI 77.9%-83.4%). The prevalence of patients by group was hypergonadotropic hypogonadal (42.4%, 38.9%-45.9%), normogonadotropic hypogonadal (38.5%; 35.1%-41.9%), hypergonadotropic eugonadal (8.3%; 6.6%-10.5%), and normogonadotropic eugonadal (10.8%; 8.8%-13.2%). Reduced testicular volume and lower estradiol levels were associated with an increased likelihood of hypogonadism. Paternal age was also an independent predictor, with higher age linked to an increased likelihood of hypogonadism. Hypogonadism was less likely in patients with germ cell maturation arrest and more likely in those with Sertoli cell-only. Patients with hypergonadotropic hypogonadism had lower SR success than normogonadotropic eugonadal counterparts (aRR 0.611; 95% CI 0.398-0.855). In the subset of hypogonadal men, hypergonadotropic patients had lower SR success than normogonadotropic participants (aRR 0.632; 0.469-0.811).

Conclusion

The prevalence of biochemical hypogonadism among men with NOA is substantial. Hypogonadism is associated with testicular volume, estradiol levels, age, and histopathology patterns. This condition impacts SR success and emphasizes the need for improved care for men with NOA.

Combining formal methods and Bayesian approach for inferring discrete-state stochastic models from steady-state data

Stochastic population models are widely used to model phenomena in different areas such as cyber-physical systems, chemical kinetics, collective animal behaviour, and beyond. Quantitative analysis of stochastic population models easily becomes challenging due to the combinatorial number of possible states of the population. Moreover, while the modeller easily hypothesises the mechanistic aspects of the model, the quantitative parameters associated to these mechanistic transitions are difficult or impossible to measure directly. In this paper, we investigate how formal verification methods can aid parameter inference for population discrete-time Markov chains in a scenario where only a limited sample of population-level data measurements-sample distributions among terminal states-are available. We first discuss the parameter identifiability and uncertainty quantification in this setup, as well as how the existing techniques of formal parameter synthesis and Bayesian inference apply. Then, we propose and implement four different methods, three of which incorporate formal parameter synthesis as a pre-computation step. We empirically evaluate the performance of the proposed methods over four representative case studies. We find that our proposed methods incorporating formal parameter synthesis as a pre-computation step allow us to significantly enhance the accuracy, precision, and scalability of inference. Specifically, in the case of unidentifiable parameters, we accurately capture the subspace of parameters which is data-compliant at a desired confidence level.

Appropriateness of Antibiotic Prescriptions in Chinese Primary Health Care and the Impact of the COVID-19 Pandemic: A Typically Descriptive and Longitudinal Database Study in Yinchuan City

Background: The appropriateness of antibiotic prescriptions in primary care has not been well evaluated in China in recent years. Furthermore, the impact of coronavirus disease 2019 (COVID-19) on antibiotic prescriptions has not yet been investigated in China. We aimed to assess the appropriateness of antibiotic prescriptions and to evaluate the potential association between the COVID-19 pandemic and antibiotic prescriptions in primary care settings of Yinchuan, a city in China.

Methods: This study included 155 primary care institutions and 10,192,713 outpatient visits. Outpatient prescriptions were classified as appropriate, potentially appropriate, inappropriate, or not linked to any diagnosis for antibiotic use following a validated evaluation scheme. Interrupted time-series analyses were performed to assess the effects of the COVID-19 pandemic on antibiotic prescriptions in Chinese primary care facilities.

Results: During the study period, 1,287,678 (12.6%, 95% confidence interval [12.6–12.7]) of 10,192,713 outpatient visits in primary care resulted in antibiotic prescriptions. Among 1,287,678 antibiotic prescriptions, 653,335 (50.7% [50.6–50.9]) were inappropriate, 463,081 (36.0% [35.8–36.1]) were potentially appropriate, 171,056 (13.3% [13.1–13.5]) were appropriate, and 206 could not be linked to any diagnosis. Furthermore, patient, physician, and institutional factors were associated with inappropriate antibiotic prescriptions; there was an overall decreasing trend in the proportions of inappropriate antibiotic prescriptions, with the highest level in 2017 (67.1% [66.8–67.5]) and the lowest in 2021 (40.8% [40.3–41.3]). A total of 1,416,120 individual antibiotics were prescribed, of which 1,087,630 (76.8%) were broad-spectrum and 777,672 (54.9%) were classified in the World Health Organization’s “Watch” category. In addition, the COVID-19 pandemic was associated with changes of −2.8% (−4.4 to −1.3) in the level and 0.3% (0.2–0.3) in the monthly trend of antibiotic prescription rates, as well as changes of −5.9% (−10.2 to −1.5) in the level and 1.3% (1.0–1.6) in the monthly trend of the proportions of inappropriate antibiotic prescriptions.

Conclusion: More than half of the antibiotic prescriptions were inappropriate during the study period in primary care in Yinchuan. The COVID-19 pandemic may be associated with a decrease in the overall and inappropriate use of antibiotics in primary care settings in China.

Antibiotic Prescriptions among China Ambulatory Care Visits of Pregnant Women: A Nationwide Cross-Sectional Study

BACKGROUND

Antibiotic use in pregnant women at the national level has rarely been reported in China.

OBJECTIVES

We aimed to investigate antibiotic prescriptions during pregnancy in ambulatory care settings in China.

METHODS

Data of 4,574,961 ambulatory care visits of pregnant women from October 2014 to April 2018 were analyzed. Percentages of Antibiotic prescriptions by different subgroups and various diagnosis categories and proportions of inappropriate antibiotic prescriptions for different subgroups were estimated. Food and Drug Administration (FDA) pregnancy categories were used to describe the antibiotic prescription patterns. The 95% confidence intervals (CIs) were estimated using the Clopper--Pearson method or Goodman method.

RESULTS

Among the 4,574,961 outpatient visits during pregnancy, 2.0% (92,514 visits; 95% CI, 2.0-2.0%) were prescribed at least one antibiotic. The percentage of antibiotic prescriptions for pregnant women aged >40 years was 4.9% (95% CI, 4.7-5.0%), whereas that for pregnant women aged 26-30 years was 1.5% (95% CI, 1.4-1.5%). In addition, percentages of antibiotic prescriptions varied among different trimesters of pregnancy, which were 5.4% (95% CI, 5.3-5.4%) for the visits in the first trimester of pregnancy and 0.5% (95% CI, 0.4-0.5%) in the third trimester of pregnancy. Furthermore, the percentages of antibiotic prescriptions substantially varied among different diagnosis categories and nearly three-quarters of antibiotic prescriptions had no clear indications and thus might be inappropriate. In total, 130,308 individual antibiotics were prescribed; among these, 60.4% (95% CI, 60.0-60.8%) belonged to FDA category B, 2.7% (95% CI, 2.1-3.5%) were classified as FDA category D and 16.8% (95% CI, 16.2-17.4%) were not assigned any FDA pregnancy category.

CONCLUSIONS

Antibiotic prescriptions in ambulatory care during pregnancy were not highly prevalent in mainland China. However, a substantial proportion of antibiotics might have been prescribed without adequate indications. Antibiotics whose fetal safety has not been sufficiently illustrated were widely used in pregnant women.

Low Prognosis by the POSEIDON Criteria in Women Undergoing Assisted Reproductive Technology: A Multicenter and Multinational Prevalence Study of Over 13,000 Patients

OBJECTIVE

To estimate the prevalence of low-prognosis patients according to the POSEIDON criteria using real-world data.

DESIGN

Multicenter population-based cohort study.

SETTINGS

Fertility clinics in Brazil, Turkey, and Vietnam.

PATIENTS

Infertile women undergoing assisted reproductive technology using standard ovarian stimulation with exogenous gonadotropins.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Per-period prevalence rates of POSEIDON patients (overall, stratified by POSEIDON groups and by study center) and the effect of covariates on the probability that a patient be classified as "POSEIDON".

RESULTS

A total of 13,146 patients were included. POSEIDON patients represented 43.0% (95% confidence interval [CI] 42.0-43.7) of the studied population, and the prevalence rates varied across study centers (range: 38.6-55.7%). The overall prevalence rates by POSEIDON groups were 44.2% (group 1; 95% CI 42.6-45.9), 36.1% (group 2; 95% CI 34.6-37.7), 5.2% (group 3; 95% CI 4.5-6.0), and 14.4% (group 4; 95% CI: 13.3-15.6). In general, POSEIDON patients were older, had a higher body mass index (BMI), lower ovarian reserve markers, and a higher frequency of female factor as the primary treatment indication than non-POSEIDON patients. The former required larger doses of gonadotropin for ovarian stimulation, despite achieving a 2.5 times lower number of retrieved oocytes than non-POSEIDON patients. Logistic regression analyses revealed that female age, BMI, ovarian reserve, and a female infertility factor were relevant predictors of the POSEIDON condition.

CONCLUSIONS

The estimated prevalence of POSEIDON patients in the general population undergoing ART is significant. These patients differ in clinical characteristics compared with non-POSEIDON patients. The POSEIDON condition is associated with female age, ovarian reserve, BMI, and female infertility. Efforts in terms of diagnosis, counseling, and treatment are needed to reduce the prevalence of low-prognosis patients.

Regional and field-specific differences in Fusarium species and mycotoxins associated with blighted North Carolina wheat

Worldwide, while Fusarium graminearum is the main causal species of Fusarium head blight (FHB) in small-grain cereals, a diversity of FHB-causing species belonging to different species complexes has been found in most countries. In the U.S., FHB surveys have focused on the Fusarium graminearum species complex (FGSC) and the frequencies of 3-ADON, 15-ADON, and nivalenol (NIV) chemotypes. A large-scale survey was undertaken across the state of North Carolina in 2014 to explore the frequency and distribution of F. graminearum capable of producing NIV, which is not monitored at grain intake points. Symptomatic wheat spikes were sampled from 59 wheat fields in 24 counties located in three agronomic zones typical of several states east of the Appalachian Mountains: Piedmont, Coastal Plain, and Tidewater. Altogether, 2197 isolates were identified to species using DNA sequence-based methods. Surprisingly, although F. graminearum was the majority species detected, species in the Fusarium tricinctum species complex (FTSC) that produce "emerging mycotoxins" were frequent, and even dominant in some fields. The FTSC percentage was 50-100% in four fields, 30-49% in five fields, 20-29% in five fields, and < 20% in the remaining 45 fields. FTSC species were at significantly higher frequency in the Coastal Plain than in the Piedmont or Tidewater (P < .05). Moniliformin concentrations in samples ranged from 0.0 to 38.7 μg g^-1. NIV producing isolates were rare statewide (2.2%), and never >12% in a single field, indicating that routine testing for NIV is probably unnecessary. The patchy distribution of FTSC species in wheat crops demonstrated the need to investigate the potential importance of their mycotoxins and the factors that allow them to sometimes outcompete trichothecene producers. An increased sampling intensity of wheat fields led to the unexpected discovery of a minority FHB-causing population.

Association of Disability With Mortality From Opioid Overdose Among US Medicare Adults

Importance

Patients qualifying for Medicare disability have the highest rates of opioid use compared with older Medicare beneficiaries and commercial insurance beneficiaries. Research on opioid overdose deaths in this population can help identify appropriate interventions.

Objective

To assess the rate of opioid overdose death and to identify its associated risk factors.

Design, Setting, and Participants

This cohort study included a 20% national sample of Medicare enrollees aged 21 to 64 years whose initial Medicare entitlement was based on disability and who resided in 50 US states and Washington, DC, in 2012 to 2016. Data analyses were performed from March 15, 2019, through September 23, 2019.

Exposures

Fifty-five chronic or potentially disabling conditions were selected from the Centers for Medicare & Medicaid Services Chronic Disease Data Warehouse.

Main Outcomes and Measures

Opioid overdose death rate estimated from Medicare National Death Index linkage data.

Results

Among 1 766 790 Medicare enrollees younger than 65 years who qualified for Medicare because of disability, the mean (SD) age was 52.2 (10.2) years, and 866 914 (49.1%) were women. These enrollees represent 14.9% (95% CI, 14.9%-15.0%) of the entire Medicare population and accounted for 80.8% (95% CI, 78.9%-82.7%) of opioid overdose deaths among all Medicare enrollees. Opioid overdose mortality in this population increased from 57.4 per 100 000 (95% CI, 53.9-61.0 per 100 000) in 2012 to 77.6 per 100 000 (95% CI, 73.5-81.8 per 100 000) in 2016. Results from the stepwise logistic regression model revealed that 3 categories of conditions are associated with opioid overdose death: substance abuse, psychiatric diseases, and chronic pain. Among the 11.1% (95% CI, 11.0%-11.2%) of adults with disability who had all 3 conditions, the rate of opioid overdose death was 363.7 per 100 000 (95% CI, 326.7-402.6 per 100 000), which is 23.4 times higher than the rate for individuals with none of the conditions (15.5 per 100 000; 95% CI, 11.6-20.1 per 100 000).

Conclusions and Relevance

This study identifies differences in opioid overdose mortality among subgroups of Medicare enrollees younger than 65 years who qualify for Medicare because of disability. Understanding the heterogeneity of medical and psychiatric conditions associated with opioid use and misuse is key to developing specific, data-driven interventions targeted to each subgroup of high-risk populations.

Predictive model of response to tafamidis in hereditary ATTR polyneuropathy

BACKGROUNDThe hereditary transthyretin (TTR) amyloidoses are a group of diseases for which several disease-modifying treatments are now available. Long-term effectiveness of these therapies is not yet fully known. Moreover, the existence of alternative therapies has resulted in an urgent need to identify patient characteristics that predict response to each therapy.METHODSWe carried out a retrospective cohort study of 210 patients with hereditary TTR amyloidosis treated with the kinetic stabilizer tafamidis (20 mg qd). These patients were followed for a period of 18-66 months, after which they were classified by an expert as responders, partial responders, or nonresponders. Correlations between baseline demographic and clinical characteristics, as well as plasma biomarkers and response to therapy, were investigated.RESULTS34% of patients exhibited an almost complete arrest of disease progression (classified by an expert as responders); 36% had a partial to complete arrest in progression of some but not all disease components (partial responders); whereas the remaining 30% continued progressing despite therapy (nonresponders). We determined that disease severity, sex, and native TTR concentration at the outset of treatment were the most relevant predictors of response to tafamidis. Plasma tafamidis concentration after 12 months of therapy was also a predictor of response for male patients. Using these variables, we built a model to predict responsiveness to tafamidis.CONCLUSIONOur study indicates long-term effectiveness for tafamidis, a kinetic stabilizer approved for the treatment of hereditary TTR amyloidosis. Moreover, we created a predictive model that can be potentially used in the clinical setting to inform patients and clinicians in their therapeutic decisions.

Influence of structured counseling on women's selection of hormonal contraception in Israel: results of the CHOICE study

Background

The multinational CHOICE (Contraceptive Health Research Of Informed Choice Experience) study evaluated the effects of structured counseling on women’s contraceptive decisions, their reasons for making those decisions, and their perceptions of combined hormonal contraceptive (CHC) methods in eleven countries. The aim of this paper to present data from the 1,802 women participating in Israel’s CHOICE program.

Methods

Women (aged 17–40 years) who consulted their health care providers about contraception and who would consider a CHC method qualified to participate. After indicating their intended CHC method, the women received counseling about the daily pill, weekly patch, and monthly vaginal ring. After counseling, the women completed a questionnaire about their contraceptive decisions.

Results

Before counseling, 67%, 6%, and 5% of women (mean age 27 years) intended to use the pill, patch, or ring, respectively. Counseling significantly influenced the women’s CHC choice, with 56%, 12%, and 23% of women selecting the pill, patch, or ring (P<0.0001 for all contraceptive methods versus before counseling). Logistic regression analysis suggested that age significantly increased the probability of switching from the pill to the ring.

Conclusion

Although the pill was the most popular choice overall, counseling appeared to influence Israeli women’s contraceptive decisions, with significantly more women selecting the patch. More than four times as many women selected the ring after counseling than before counseling.

The CHOICE study: effect of counselling on the selection of combined hormonal contraceptive methods in 11 countries

OBJECTIVES

To encourage healthcare professionals to counsel women seeking combined hormonal contraceptives (CHCs) about alternative CHCs and to study the influence of counselling on women's selection of CHCs.

METHODS

Women (15-40 years old) in 11 countries who consulted HCPs about CHCs were counselled about the pill, transdermal patch, and vaginal ring. Both the HCPs and the women completed questionnaires.

RESULTS

Of women who were counselled (n = 18,787), 47% selected another CHC method than originally planned. One in four who intended to use the pill chose another method (16% chose the patch; 65% chose the ring). In total, patch use increased from 5% -8% (difference = 3.7% [97.5% CI: 3.3-4.2]; p < 0.0001). Ring use nearly quadrupled from 8% -30% (difference = 21.7% [97.5% CI: 21.0-22.5]; p < 0.0001). Nearly all women who were undecided prior to counselling selected a method after counselling. Selection of the pill increased most in Russia (+ 11%) and Sweden (+ 5%); patch selection was greatest in Russia (+ 7%) and Israel (+ 6%); ring use increased most in Ukraine and in the Czech Republic and Slovakia (+ 36%).

CONCLUSIONS

Counselling increases use of alternative CHCs, such as the patch and the ring. Considerable differences between countries were noted.

Contraceptive counselling and factors affecting women's contraceptive choices: results of the CHOICE study in Austria

Empirical evidence of the impact of contraceptive counselling and factors affecting women's contraceptive choices are limited. CHOICE (Contraceptive Health Research Of Informed Choice Experience) was a large-scale study in 11 European countries. Women in Austria aged 15-40 years considering a short-acting, reversible form of combined hormonal contraceptive were eligible to participate. The choices included the combined daily pill, weekly transdermal patch, and monthly vaginal ring. This study assessed and compared 2478 women's original preferences with their post-counselling choices and evaluated their perceptions and criteria for their choice. Women who were 'undecided' decreased from 18.1% pre-counselling to 3.2% post-counselling; significantly more women post-counselling chose the monthly ring (8.7% to 23.8%; difference 15.1%, 95% CI 13.3-16.8%; P<0.0001) or the weekly patch (6.2% to 7.8%; difference 1.7%, 95% CI 0.5-2.9%; P=0.0014). Women's primary reasons for choosing a method included 'easy to use' (daily pill, weekly patch and monthly ring) and 'still effective if I experience vomiting, diarrhoea' (weekly patch and monthly ring). Structured and balanced counselling led to changes in the method chosen.

Comprehensive counseling about combined hormonal contraceptives changes the choice of contraceptive methods: results of the CHOICE program in Sweden

OBJECTIVE

To study the influence of counseling on women's contraceptive decisions.

DESIGN

A cross-sectional multicenter study.

SETTING

Seventy Swedish family planning clinics.

POPULATION

Women aged 15-40 years attending for a contraceptive consultation who expressed interest in a combined hormonal contraceptive (CHC) method.

METHODS

Structured counseling about three CHCs and questionnaires completed after counseling from the healthcare professional.

MAIN OUTCOME MEASURES

Method originally requested, perceptions of CHC attributes, method chosen and reasons for the choice.

RESULTS

In all, 173 healthcare professionals and 1,944 women participated. The mean standard deviation (SD) age of the women was 22.6(6.1) years. After structured counseling, a majority of women (56.0%; n=1 069; 95% confidence interval (CI) 53.1-58.9) chose the daily pill, 6.2% (n=118; 95% CI 4.9-7.8) chose the weekly patch, and 22.5% (n=430; 95% CI 20.2-25.1) chose the monthly ring. The weekly patch was chosen more often after counseling (6.2 vs 2.4% before counseling; p<0.0001). The greatest change was in the proportion of women who chose the contraceptive ring after counseling (22.5% vs. 8.5% before counseling; p<0.0001). The proportion of undecided women after counseling was reduced considerably (3.9% vs. 27.8% before counseling). Among the 523 women who were undecided before counseling, 50.6% chose the pill, 10.2% the patch and 24.6% the ring, while 20.9% of women who initially requested the pill changed to another method.

CONCLUSIONS

Structured counseling facilitated choice of contraceptive method for most women, leading to changes in women's selection of a CHC method.

Ultrasound assessment of the vertebral level of the intercristal line in pregnancy

BACKGROUND

The intercristal line is known to most frequently cross the L4 spinous process or L4-5 interspace; however, it is speculated to be positioned higher during pregnancy because of the exaggerated lumbar lordosis. Clinical estimation of vertebral levels relying on the use of the intercristal line has been shown to often be inaccurate. We hypothesized that the vertebral level of the intercristal line determined by palpation would be higher than the level determined by ultrasound in pregnant women.

METHODS

Fifty-one term pregnant patients were recruited. Two experienced anesthesiologists performed estimates of the position of the intercristal line by palpation. Using ultrasound, another anesthesiologist who was blinded to the clinical estimates, determined the position of the superior border of the iliac crest in the transverse and longitudinal planes and then identified the lumbar vertebral levels. The vertebral level at which the clinical estimates of the intercristal line crossed the spine was recorded and compared with the ultrasound-determined level of the superior border of the iliac crest.

RESULTS

The clinical estimates of the spinal level of the intercristal line agreed with the ultrasound measurement 14% of the time (14 of 101; 95% confidence interval [CI]: 8%, 22%). The clinical estimates were 1 level higher than the ultrasound measurement 23% of the time (23 of 101; 95% CI: 16%, 32%) and >1 level higher 25% of the time (25 of 101; 1-tailed 95% CI: >18%). The distribution of the clinical estimates found clinicians locating the intercristal line at L3 or L3-4 54% of the time (54 of 101; 95% CI: 44%, 63%) and at L2-3 or higher 27% of the time (27 of 101; 1-tailed 95% CI: >20%).

CONCLUSION

The anatomical position of the intercristal line was at L3 or higher in at least 6% of term pregnant patients using ultrasound. Clinical estimates were found to be ≥1 vertebral level higher than the anatomical position determined by ultrasound at least 40% of the time. This disparity may contribute to misidentification of lumbar interspaces and increased risk of neurologic injury during neuraxial anesthesia.

Anteromedial thigh flaps: an anatomical study to localize and classify anteromedial thigh perforators

Until now, research on flaps in the anteromedial thigh region has focused on flaps in specific regions. To elucidate the complete pattern of suitable anteromedial thigh perforators, an anatomical study was performed by dissecting nine thighs from different cadavers. The ideal perforator has maximum length and diameter and runs through a septum. According to the data found in our study, these perforators can predominantly be found in the middle third of the anteromedial thigh region. All of the three main thigh vessels supply perforators which can be used for flaps. Pertaining to length and diameter the most suitable perforators originate from the deep femoral artery, which can be found in the proximal and middle third of the anteromedial thigh. Musculocutaneous perforators are found to be longer than septocutaneous perforators. Because of their position, the proximal and distal third perforators should preferentially be used for local pedicled flaps. Defects in the pelvic area and around the knee can be closed with perforator flaps from the proximal and distal anteromedial thigh, respectively. Because of their diameter, length, and number, the middle third perforators should be the first choice for harvesting free flaps. Skin closure is easily achieved in the anteromedial thigh region even when larger flaps are used.

The value of antihypertensive drugs: a perspective on medical innovation

Using national survey data and risk equations from the Framingham Heart Study, we quantify the impact of antihypertensive therapy changes on blood pressures and the number and cost of heart attacks, strokes, and deaths. Antihypertensive therapy has had a major impact on health. Without it, 1999-2000 average blood pressures (at age 40+) would have been 10-13 percent higher, and 86,000 excess premature deaths from cardiovascular disease would have occurred in 2001. Treatment has generated a benefit-to-cost ratio of at least 6:1, but much more can be achieved. More effective use of antihypertensive medication would have an impact on mortality akin to eliminating all deaths from medical errors or accidents.

Dose finding in the Ames Salmonella assay

Threshold dose/concentration values, such as the lowest effective dose, minimum effective dose or the lowest effective concentration (LED, MED or LEC, respectively) are in use as an alternative to the mutagen potency measures based on the 'rate' measurements (e.g., the slope of the initial part of the dose-response curve). In this respect, several statistical procedures for the corresponding so-called 'dose finding' were proposed during the last decades. However, most of them disregard the discrete nature of responses such as the plate colony count in the Ames Salmonella assay. When the plate counts agree with the Poisson assumption, two procedures considered here seem to be appropriate for the dose finding. One is based on the stepwise collapsing of the homogeneous control and dose counts; another consists of constructing the confidence limits for the mutation induction factor (MIF). When the dose and control counts are non-overlapping, the simple 'visual' non-parametric estimation of LED is possible. Applicability and validity of the methods is demonstrated with the two data sets on the mutagenicity of the beta-carboline alkaloid, harmine, and one of the oxidation products of apomorphine.