Inconclusive decisions and error rates in forensic science

In recent years, there has been discussion and controversy relating to the treatment of inconclusive decisions in forensic feature comparison disciplines when considering the reliability of examination methods and results. In this article, we offer a brief review of the various viewpoints and suggestions that have been recently put forth, followed by a solution that we believe addresses the treatment of inconclusive decisions. We consider the issues in the context of method conformance and method performance as two distinct concepts, both of which are necessary for the determination of reliability. Method conformance relates to an assessment of whether the outcome of a method is the result of the analyst's adherence to the procedures that define the method. Method performance reflects the capacity of a method to discriminate between different propositions of interest (e.g., mated and non-mated comparisons). We then discuss implications of these issues for the forensic science community.

Comparison of Intramedullary Screw Fixation, Plating, and K-Wires for Metacarpal Fracture Fixation: A Meta-Analysis

BACKGROUND

Metacarpal fractures are common injuries with multiple options for fixation. Our purpose was to compare outcomes in metacarpal fractures treated with intramedullary screw fixation (IMF), Kirschner wires (K-wires), or plating.

METHODS

A systematic literature review using the MEDLINE database was performed for studies investigating metacarpal fractures treated with IMF, plating, or K-wires. We identified 34 studies (9 IMF, 8 plating, 17 K-wires). A meta-analysis using both mixed and fixed effects models was performed. Outcome measures included mean Disabilities of the Arm, Shoulder, and Hand (DASH) scores, total active motion (TAM), grip strength, time to radiographic healing, and rates of infection and reoperation.

RESULTS

Patients with IMF had significantly lower DASH scores (0.6 [95% confidence interval [CI], 0.2-1.0]) compared with K-wires (7.4 [4.8-9.9]) and plating (9.8 [5.3-14.3]). Intramedullary screw fixation also had significantly lower rates of reoperation (4%, [2%-7%]), compared with K-wires (11% [7%-16%]) and plating (11% [0.07-0.17]). Grip strength was significantly higher in IMF (104.4% [97.0-111.8]) compared with K-wires (88.5%, [88.3-88.7]) and plating (90.3%, [85.4-95.2]). Mean odds ratio time was similar between IMF (21.0 minutes [10.4-31.6]) and K-wires (20.8 minutes [14.0-27.6]), but both were shorter compared with plating (52.6 minutes [33.1-72.1]). There were no statistically significant differences in time to radiographic healing, TAM, or rates of reoperation or infection.

CONCLUSIONS

This meta-analysis compared the outcomes of metacarpal fixation with IMF, K-wires, or plating. Intramedullary screw fixation provided statistically significant lower DASH scores, higher grip strength, and lower rates of reoperation, suggesting that it is a comparable method of fixation to K-wires and plating for metacarpal fractures.

Vascularized Bone Grafting Versus the 2-Stage Masquelet Technique for Upper-Extremity Bone Reconstruction: A Meta-Analysis

PURPOSE

Vascularized bone grafting (VBG) has been described as the technique of choice for larger bone defects in bone reconstruction, yielding excellent results at the traditional threshold of 6 cm as described in the literature. However, we hypothesize that the 2-stage Masquelet technique provides equivalent union rates for upper-extremity bone defects regardless of size, while having no increase in the rate of patient complications.

METHODS

A systematic literature review was conducted using PubMed and Scopus for outcomes after VBG and the Masquelet technique for upper-extremity bone defects of the humerus, radius, ulna, metacarpal, or phalanx (carpal defects were excluded). A meta-analysis was performed to compare outcomes following VBG and the Masquelet technique at varying defect sizes.

RESULTS

There were 77 VBG (295 patients) and 25 Masquelet (119 patients) studies that met inclusion criteria. Patients undergoing the Masquelet technique had defect sizes ranging from 0-15 cm (average 4.5 cm), while patients undergoing VBG had defect sizes ranging from 0-24 cm (average 5.9 cm). The union rate for Masquelet patients was 94.1% with an average time to union of 5.8 months, compared to 94.9% and 4.4 months, respectively, for VBG patients. We did not identify a defect size threshold at which VBG demonstrated a significantly higher union rate. No statistically significant difference was found in union rates between techniques when using multivariable logistic regression analysis.

CONCLUSION

There was no statistically significant difference in union rates between VBG and the Masquelet technique in upper-extremity bone defects regardless of defect size. Surgeons may consider the Masquelet technique as an alternative to VBG in large bone defects of the upper extremity.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Gender Equality in Plastic Surgery Training: A Canadian Nationwide Cross-sectional Analysis

Introduction: One of the important factors in achieving gender equity is ensuring equitable surgical training for all. Previous studies have shown that females get significantly lower surgical exposure than males in certain surgical specialties. Gender gap in surgical exposure has never been assessed in plastic surgery. To that end, the goal of this study was to assess if there are any differences in plastic surgery training between male and female residents. Methods: A survey was sent to all plastic surgery residency programs in Canada to assess the No. of surgeries residents operated on as a co-surgeon or primary assistant during their training. The survey also assessed career goals, level of interest in the specialty, and subjective perception of gender bias. Results: A total of 89 plastic surgery residents (59.3% participation rate) completed the survey and were included in the study. The average No. of reconstructive cases residents operated on as a co-surgeon or primary assistant was 245 ± 312 cases. There was no difference in either reconstructive or aesthetic surgery case logs between male and female residents (p > .05). However, a significantly larger proportion of females (39%) compared to males (4%) felt that their gender limited their exposure to surgical cases and led to a worsening of their overall surgical training (p < .001). Finally, a larger proportion of male residents were interested in academic careers while a larger proportion of female residents were interested in a community practice (p = .024). Conclusion: While there is no evidence of differences in the volume of logged cases between genders, female surgical residents still feel that their respective gender limits their overall surgical training. Gender inequalities in training should be addressed by residency programs.

Local Versus General Anesthesia in Pediatric Otoplasty: A Cost and Efficiency Analysis

OBJECTIVE

Quantify the cost benefits of otoplasty under local as opposed to general anaesthesia.

DESIGN

A cost analysis of all components of otoplasty surgery under local anaesthesia (LA) in a minor operating room (OR) and general anaesthesia in a main OR was performed.

SETTING

Our institution, compared to provincial/federal data, with costs converted into 2022 Canadian dollars.

PATIENTS, PARTICIPANTS

Patients undergoing otoplasty under LA in the last year.

INTERVENTIONS

An efficiency analysis was performed by means of an opportunity cost, and the cost of failure was added to the overall LA costs.

MAIN OUTCOME MEASURE

Expenses for infrastructure, surgical and anaesthetic material, salaries, and personnel costs were derived from the literature, our hospital OR catalog and federal/provincial salary data, respectively. The cost of failure to tolerate local anaesthesia for such cases was also tabulated.

RESULTS

The true cost of LA otoplasty was computed as the absolute cost ($611.73) added to the cost of failure ($10.80), resulting in a total of $622.53/procedure. The true cost of GA otoplasty was calculated as the absolute cost ($2033.05) added to the opportunity cost ($1108.94), representing 3141.99$/procedure. The total savings when performing LA otoplasty to GA otoplasty are thus 2519.44$/case, with 1 GA otoplasty costing 5.05 LA otoplasties.

CONCLUSION

Otoplasty under local anaesthesia offers significant cost savings when compared with the same procedure under general anaesthesia. Economic considerations must be given particular attention given the elective nature of this procedure, which is often publicly funded.

Anatomic study of an anterior portal for percutaneous internal fixation of capitellum fractures

BACKGROUND

Fractures of the capitellum are uncommon and difficult to treat surgically. Capitellar open reduction-internal fixation uses a lateral open approach with posterior-to-anterior or anterior-to-posterior screw fixation. We investigated the use of an anterior portal for placement of anterior-to-posterior screw fixation through cadaveric measurement of the anatomic relationships from an anteriorly to posteriorly placed Kirschner wire (K-wire) to anterior elbow structures and calculated the percentage of articular surface accessed from the anterior portal.

METHODS

Eight fresh-frozen cadaveric elbows without radiographic or cutaneous evidence of prior trauma or surgery were used for this study. An arthroscopic proximal anteromedial portal was cannulized, and the radiocapitellar joint was evaluated. A single 1-cm portal was placed 1 cm distal to the elbow flexion crease and based lateral to the biceps tendon. The location of the portal was confirmed with a spinal needle, and blunt dissection with a hemostat was performed down to capsular tissue and for arthrotomy. A spinal needle sheath was threaded over a blunt switching stick and served as a cannula for placement of a 0.062 K-wire. Articular mapping was performed with cartilage scraping by the K-wire; the K-wire was then placed at the perceived center along the proximal-to-distal and radial-to-ulnar axis of the capitellum. Fluoroscopic confirmation of the wire's location was performed. Under loupe magnification, anatomic dissection was performed and the shortest distance measurements were recorded with digital calipers from the K-wire to the dissected structures. Capitellar articular measurements were recorded, in addition to the articular area defined by the K-wire. Data analysis was performed, and the average distance and standard deviation (in millimeters) were calculated. For structures that were pierced by or touching the K-wire, the distance was recorded as 0.1 mm.

RESULTS

The average distance from the K-wire to the radial, lateral antebrachial cutaneous, and median nerves was 1.8 mm, 11.5 mm, and 28.0 mm, respectively. The average distance from the median cubital vein and biceps tendon was 3.7 mm and 13.4 mm, respectively. The pin track pierced the brachioradialis and supinator muscles in all but 1 specimen. The average capitellar articular surface marked was 39.1% of the calculated articular footprint of the capitellum.

CONCLUSIONS

The anterior portal to the capitellum is directly adjacent to the radial nerve and lateral antebrachial cutaneous nerve, where each is susceptible to injury. We recommend blunt dissection and insertion of a cannula to allow drilling and placement of internal fixation in a relatively safe manner with respect to neurovascular structures.

Clinical outcomes following reverse total shoulder arthroplasty with tuberosity excision for treatment of proximal humerus fractures: a case series

Background

Reverse total shoulder arthroplasty (RTSA) has become an increasingly popular treatment option for complex 3- and 4-part proximal humerus fractures in elderly patients. The literature has demonstrated that tuberosity repair likely improves postoperative range of motion (ROM). However, the difference between tuberosity repair and excision may not be appreciable to patients in their day-to-day lives. This case series reports both objective and subjective clinical outcomes of patients who underwent RTSA with tuberosity excision for proximal humerus fractures.

Methods

We reviewed the records of 41 patients who underwent RTSA for complex 3- and 4- part proximal humerus fractures. All RTSA procedures were performed by a single surgeon between 2014 and 2017. All patients underwent RTSA with extended proximal stem cementation and tuberosity excision. Postoperative outcomes were measured at least 2 years postoperatively and included ROM measurements for forward flexion, internal rotation, abduction, and external rotation. Patient-reported outcome measures included Simple Shoulder Test scores, American Shoulder and Elbow Surgeons scores, and Penn Shoulder Score were also reported.

Results

In this case series, we report on 41 patients, 33 females and 8 males. Objective measurements of ROM for forward flexion, abduction, and external rotation were 125, 95, and 36 degrees, respectively. On average, patients had an internal rotation score of 2.06 and were able to get their thumb to their iliac crest. Clinical outcome scores of these patients were 9.11, 77.79, and 74.12 for the Simple Shoulder Test, American Shoulder and Elbow Surgeons, and Penn Shoulder Score, respectively. Strength of the deltoid was 5/5 in all 41 patients.

Conclusions

When compared with the current literature, our tuberosity excision patients demonstrated deficits in forward flexion and abduction, with preserved external rotation. Our clinical outcome score measurements were consistent with clinical outcome measurements from previous studies of patients undergoing RTSA with tuberosity repair. We believe that tuberosity excision may be a reasonable and simpler surgical option for surgeons with lower volumes of shoulder fractures and patients with multiple comorbidities and higher surgical risk, owing to the similarity of outcome scores between our cohort and previous tuberosity repair groups.

Examining performance and likelihood ratios for two likelihood ratio systems using the PROVEDIt dataset

A likelihood ratio (LR) system is defined as the entire pipeline of the measurement and interpretation processes where probabilistic genotyping software (PGS) is a piece of the whole LR system. To gain understanding on how two LR systems perform, a total of 154 two-person, 147 three-person, and 127 four-person mixture profiles of varying DNA quality, DNA quantity, and mixture ratios were obtained from the filtered (.CSV) files of the GlobalFiler 29 cycles 15s PROVEDIt dataset and deconvolved in two independently developed fully continuous programs, STRmix v2.6 and EuroForMix v2.1.0. Various parameters were set in each software and LR computations obtained from the two software were based on same/fixed EPG features, same pair of propositions, number of contributors, theta, and population allele frequencies. The ability of each LR system to discriminate between contributor (H1-true) and non-contributor (H2-true) scenarios was evaluated qualitatively and quantitatively. Differences in the numeric LR values and their corresponding verbal classifications between the two LR systems were compared. The magnitude of the differences in the assigned LRs and the potential explanations for the observed differences greater than or equal to 3 on the log10 scale were described. Cases of LR < 1 for H1-true tests and LR > 1 for H2-true tests were also discussed. Our intent is to demonstrate the value of using a publicly available ground truth known mixture dataset to assess discrimination performance of any LR system and show the steps used to understand similarities and differences between different LR systems. We share our observations with the forensic community and describe how examining more than one PGS with similar discrimination power can be beneficial, help analysts compare interpretation especially with low-template profiles or minor contributor cases, and be a potential additional diagnostic check even if software in use does contain certain diagnostic statistics as part of the output.

Microsurgical and Endovascular Management of Congenital Iliac Aneurysms in the Neonatal Period: Two Cases and a Literature Review

Introduction

Congenital aneurysms of major arteries are very rare diagnoses and prognosis can be poor if treatment is not initiated rapidly. This is the presentation of two cases of infants with congenital iliac aneurysms who underwent treatment in the neonatal period. The report then proceeds with a literature review of paediatric iliac aneurysms.

Report

Case 1: A female neonate was diagnosed antenatally with right common iliac (CIA) and internal iliac (IIA) artery aneurysms. Embolisation on day of life (DOL) eight was impossible because of partial thrombosis. The infant was subsequently observed for several months and the aneurysm was injected percutaneously with thrombin on DOL 78. A small residual aneurysm was coil embolised at five months of age. Satisfactory results were observed at one year follow up. Case 2: A female neonate was diagnosed antenatally on routine third trimester ultrasound with voluminous, bilateral CIA aneurysms. The patient underwent surgery on DOL 9 for aneurysm resection and microsurgical vascular reconstruction. The intervention was successful with triphasic flow through the anastomoses on colour Doppler ultrasound at six week follow up.

Discussion

Ten cases of congenital iliac aneurysms have been reported previously, with just two diagnosed in the neonatal period and eight undergoing surgical intervention. Definitive management to avoid aneurysm rupture or thrombosis should be timed carefully, and sometimes delayed with watchful waiting, to maximise success and minimise complications. Surgery is the key treatment modality, but endovascular intervention can be considered in selected cases. Congenital iliac aneurysms should be addressed at the safest time for the patient. Following resection, primary microvascular anastomosis is the ideal reconstructive technique, but other options for neonates have been described. Endovascular treatment should be considered for anatomically amenable saccular aneurysms.

Apolipoprotein E Induced Cognitive Dysfunction: Mediation Analysis of Lipids and Glucose Biomarkers in an Elderly Cohort Study

INTRODUCTION

Prior evidence suggested Apolipoprotein E (APOE), lipids, and glucose metabolism may act through the same pathways on the pathogenesis of Alzheimer's disease (AD).

METHODS

This prospective study used data from the Chinese Longitudinal Healthy Longevity Study. We tested the associations of APOE genotype (ε2ε2, ε2ε3, ε2ε4, ε3ε3, ε3ε4, and ε4ε4) and cognitive function using generalized estimating equations (GEE). We examined for possible mediation and effect modification by lipids and glucose level in this association.

RESULTS

APOE ε2 showed significant direct protective effect and indirect harmful effect through TC on cognitive function. Abnormal lipids or glucose levels were not consistently associated with cognitive dysfunction in our study. We did not detect significant indirect effects through lipids for APOE ε4 or any indirect effects through glucose.

DISCUSSION

These findings suggested complicated relationships among APOE, lipids, glucose, and cognitive function. Further study can make validations in other populations.

Quantitative evaluation of footwear evidence: Initial workflow for an end-to-end system

In the United States, footwear examiners make decisions about the sources of crime scene shoe impressions using subjective criteria. This has raised questions about the accuracy, repeatability, reproducibility, and scientific validity of footwear examinations. Currently, most footwear examiners follow a workflow that compares a questioned and test impression with regard to outsole design, size, wear, and randomly acquired characteristics (RACs). We augment this workflow with computer algorithms and statistical analysis so as to improve in the following areas: (1) quantifying the degree of correspondence between the questioned and test impressions with respect to design, size, wear, and RACs, (2) reducing the potential for cognitive bias, and (3) providing an empirical basis for examiner conclusions by developing a reference database of case-relevant pairs of impressions containing known mated and known nonmated impressions. Our end-to-end workflow facilitates all three of these points and is directly relatable to current practice. We demonstrate the workflow, which includes obtaining and interpreting outsole pattern scores, RAC comparison scores, and final scores, on two scenarios-a pristine example (involving very high quality Everspry EverOS scanner impressions) and a mock crime scene example that more closely resembles real casework. These examples not only demonstrate the workflow but also help identify the algorithmic, computational, and statistical challenges involved in improving the system for eventual deployment in casework.

Comparing footwear impressions that are close non-matches using correlation-based approaches

Forensic activities related to footwear evidence may be broadly classified into the following two categories: (1) intelligence gathering and (2) evidential value assessment. Intelligence gathering provides additional leads for investigators. Assessment of evidential value, as practiced in the United States, involves a trained footwear examiner evaluating the degree of similarity between a known shoe of interest (together with its test impressions) and footwear impressions obtained from a crime scene, by performing side-by-side visual comparisons. However, the need for developing quantitative approaches for expressing similarities during such comparisons is being increasingly recognized by the forensic science community. In this paper, we explore the ability of similarity metrics to discriminate between impressions made by a shoe of interest and impressions made by close non-matching shoes. Close non-matching shoes largely share the same design and size. Therefore, the ability to effectively discriminate between them requires considering, either explicitly or implicitly, not only design and size, but also wear patterns and, to some extent, individual characteristics. This type of discrimination is necessary for assessment of evidential value. The similarity metrics examined in this paper are correlation-based metrics, including normalized cross-correlation, phase-only correlation, AvNCC, and AvPOC. The latter two metrics are based on features obtained from a convolutional neural network. Experiments are performed using Everspry impressions, FBI boot impressions, and the West Virginia University footwear impression collection. The results show that phase-only correlation performs as well as or better than the other metrics in all cases for the datasets we considered.

The All Babies Count Initiative: Impact of a Health System Improvement Approach on Neonatal Care and Outcomes in Rwanda

A health system improvement program combining facility readiness support, clinical training/mentoring, and improvement collaboratives increased quality improvement capacity, improved maternal and newborn quality of care, and reduced neonatal mortality. These results can be used to inform system improvement approach design to transform quality of care and outcomes for newborns.

Introduction:

Poor-quality care contributes to a significant portion of neonatal deaths globally. The All Babies Count (ABC) initiative was an 18-month district-wide approach designed to improve clinical and system performance across 2 rural Rwandan districts.

Methods:

This pre-post intervention study measured change in maternal and newborn health (MNH) quality of care and neonatal mortality. Data from the facility and community health management information system and newly introduced indicators were extracted from facility registers. Medians and interquartile ranges were calculated for the health facility to assess changes over time, and a mixed-effects logistic regression model was created for neonatal mortality. A difference-in-differences analysis was conducted to compare the change in district neonatal mortality with the rest of rural Rwanda.

Results:

Improvements were seen in multiple measures of facility readiness and MNH quality of care, including antenatal care coverage, preterm labor management, and postnatal care quality. District hospital case fatality decreased, with a statistically significant reduction in district neonatal mortality (odds ratio [OR]=0.54; 95% confidence interval [CI]=0.36, 0.83) and among preterm/low birth weight neonates (OR=0.47; 95% CI=0.25, 0.90). Neonatal mortality was reduced from 30.1 to 19.6 deaths/1,000 live births in the intervention districts and remained relatively stable in the rest of rural Rwanda (difference in differences −12.9).

Conclusion:

The ABC initiative contributed to improved MNH quality of care and outcomes in rural Rwanda. A combined clinical and health system improvement approach could be an effective strategy to improve quality and reduce neonatal mortality.

Recurrent vulvar squamous cell carcinoma: An analysis of clinical outcomes by treatment modality including surgery, chemotherapy, and radiation

e18033

Background: Recurrent VSCC carries a poor prognosis, but real-world data on outcomes with standard treatment options are lacking. Specifically, progression free survival (PFS) in recurrent VSCC is ill-defined which is problematic for the design of clinical trials with novel therapies. We aim to address the paucity of outcome data in recurrent VSCC and to compare PFS and overall survival (OS) in patients (pts) undergoing surgery, chemotherapy, radiotherapy or a combination of these treatments. Methods: A retrospective chart review identified 246 pts from 2000-2018 diagnosed with VSCC treated at the Ottawa Hospital Cancer Center and 61 pts with recurrent disease. Data collected included patient demographics, tumour characteristics, recurrence pattern, and treatment modality (surgery only, surgery with chemotherapy, surgery with radiation, surgery with chemoradiation, chemoradiation only, chemotherapy only, or radiation only). Descriptive statistical analysis is reported. Results: Among all study pts, the stage distribution was stage I: 28%, II: 19%, III: 43% and IV: 10%. 61% of pts had one recurrence, 36% had two recurrences, and 3% had three recurrences. The 5-year survival rate was 78% for non-recurrent VSCC vs. 33% for recurrent cases. The median OS for all recurrent and non-recurrent cases was 3.7 years and 13.5 years, respectively. For primary treatment, 87% underwent surgical treatment, of which 60% also had radiation or chemoradiation. The most common treatments for first recurrence were: surgery (25%), radiation (20%), no treatment (16%) and chemotherapy (14%), and for second recurrence: no treatment (50%), radiation (25%), surgery (17%) and chemotherapy (8%). The median PFS after primary treatment and after first and second recurrences were 8.7, 5.3 and 1.4 months (mo), respectively, with no significant difference between treatment regimens. However, when grouped (surgery with or without chemotherapy, radiation or chemoradiation vs. non-surgical management), there was a significant PFS benefit for surgical (15.6 mo) over non-surgical management (0.7 mo) in the treatment of a second recurrence (p = 0.05). Conclusions: At our centre, surgery and radiation have been the mainstay of treatment for recurrent VSCC with particular advantage of surgery in the treatment of a second recurrence. Our study establishes a baseline for VSCC outcomes following standard treatment. Accurate PFS data is an important outcome for the design of future studies in recurrent VSCC with new drug therapies.

The sodium channel NaX : Possible player in excitation-contraction coupling

The sodium channel Na_X (encoded by the SCN7A gene) was originally identified in the heart and skeletal muscle and is structurally similar to the other voltage-gated sodium channels but does not appear to be voltage gated. Although Na_X is expressed at high levels in cardiac and skeletal muscle, little information exists on the function of Na_X in these tissues. Transcriptional profiling of ion channels in the heart in a subset of patients with Brugada syndrome revealed an inverse relationship between the expression of Na_X and Na_V 1.5 suggesting that, in cardiac myocytes, the expression of these channels may be linked. We propose that Na_X plays a role in excitation-contraction coupling based on our experimental observations. Here we show that in cardiac myocytes, Na_X is expressed in a striated pattern on the sarcolemma in regions corresponding to the sarcomeric M-line. Knocking down Na_X expression decreased Na_V 1.5 mRNA and protein and reduced the inward sodium current (I_Na+ ) following cell depolarization. When the expression of Na_V 1.5 was knocked down, ~85% of the I_Na+ was reduced consistent with the observations that Na_V 1.5 is the main voltage-gated sodium channel in cardiac muscle and that Na_X likely does not directly participate in mediating the I_Na+ following depolarization. Silencing Na_V 1.5 expression led to significant upregulation of Na_X mRNA. Similar to Na_V 1.5, Na_X protein levels were rapidly downregulated when the intracellular [Ca²⁺ ] was increased either by CaCl₂ or caffeine. These data suggest that a relationship exists between Na_X and Na_V 1.5 and that Na_X may play a role in excitation-contraction coupling.

Barriers to Cancer Evaluation Follow-Up: Reasons and Predictors of Missed Visits in a Rural Population in Botswana

Background: Missed clinical appointments contribute to delayed cancer diagnosis, treatment, and ultimately poorer outcomes. In Botswana, a middle income sub-Saharan African country where oncology treatment is available for free to all citizens, median time from first facility visit to treatment initiation is 160 days (IQR: 59-653). Aim: To identify patient and visit characteristics associated with missing appointments, and describe reasons for missed visits among adult patients undergoing evaluation for possible cancer at public facilities in a rural district in Botswana. Methods: Patients ≥ 18 years with symptoms or signs suggestive of cancer were enrolled in the Potlako trial, an ongoing prospective health systems pilot seeking to improve timely diagnosis and treatment of cancer. Study staff tracked patient visits and if a patient missed a visit, study staff administered a brief structured phone interview to 1) determine reasons, 2) reschedule visit and 3) arrange transport support if needed. Patients who enrolled and completed follow-up between May 1, 2016 and March 23, 2018 were included in analysis. We used logistic regression (STATA v12) to explore predictors of missed visits (patient as defaulter vs not, visit being missed vs not). All factors significant in univariate analysis ( P < 0.05) were included in final models. Results: A total of 488 cancer suspects completed their cancer evaluation following a median of 7 visits (IQR: 4-11) and 125 days (IQR: 55-228). Breast and cervical cancer were the most commonly suspected malignancies. Median age was 49 (IQR: 33-64), 358 (73.4%) were female, 143 (28.4%) had an ultimate diagnosis of cancer. There were 172 missed visits, involving 94 (19.3%) patients (defaulters), including 20 (21.3%) found to have cancer, of whom 38 (39.6%) missed more than one visit. Defaulters tended to be less than 40 years (aOR 0.49, 95% CI: 0.31-0.79) and had their first visit for cancer evaluation at a general outpatient unit (aOR 2.1, 95% CI: 1.15-3.87). In the adjusted model, we found no statistically significant association between defaulter status and gender, final diagnosis, and patient's next-of-kin. Missed visits were more likely to occur on Fridays (aOR 1.50, CI: 1.05-2.15) and less likely to occur ±1 week around a public holiday (aOR 0.55, CI: 0.33-0.91). Leading reasons for missed visits were: work obligations (18.0%), family duties including child care and attending funerals (16.3%), prohibitive transport fees (10.5%), not remembering appointment date (8.7%). Conclusion: Multiple visits are required to complete evaluation for cancer suspects and missed visits are common. Our findings suggest possible interventions to improve efficiency, which include: simplifying diagnostic cascade, transport support, visit reminders, intensified counseling for younger patients and those seen at general outpatient clinics, and avoidance of Friday scheduling.

A Limited Time to Act: Cervical Cancer Stage Progression Prior to Treatment

Background: Cervical cancer is the leading cause of cancer death for women in sub-Saharan Africa where access to timely diagnosis and treatment remains a major challenge. Several investigators have documented the adverse impact of delays during curative chemoradiation on survival: 2%-5% decreased survival per week delay. However, the clinical impact of delays in initiating treatment has not previously been estimated and is key to direct allocation of resources and patient care. Aim: To estimate the duration treatment initiation delay leading to a one-stage progression in cervical cancer. Methods: Radiation is available in Botswana from a single linear accelerator and services are provided free of cost to Botswana citizens. Two prolonged service interruptions (late 2014 due to mechanical failure/upgrades, and late 2015 for machine replacement) contributed to substantial additional delays in accessing treatment of several months after service resumed. Using these natural experiments and the prospectively enrolling Thabatse Cancer Cohort (included cases enrolled from September 2014 to January 2018), we used instrumental variable methods to estimate the mean number of weeks to progress one stage (e.g., IIIA to IVA). Our instrument was a binary variable indicating treatment initiation occurred during service interruption. We used inverse probability weighting to adjust for possible bias in exposure to the instrument by HIV status, age, and income. Cancer stage was considered ordinal and we used Poisson regression to calculate weeks for stage progression. We calculated confidence limits using bootstrapping from 500 samples. Analyses were performed in SAS 9.4. Results: A total of 301 cervical cancer cases were included with 138 (46%) exposed to service disruption and 163 (54%) not exposed. The majority, 217 (72%), were HIV-infected with 86% on ART prior to cancer diagnosis. At time of treatment, 27 (9%) stage I, 108 (36%) stage II, 113 (38%) stage III, and 53 (18%) stage IV. Median time from diagnosis to initiation of treatment of all patients was 9.7 weeks (IQR 6.3-13.7), and was longer in those exposed to service disruption (11.0 weeks [IQR 7.7-15.1]) than those not exposed (8.0 weeks [IQR 5.3-11.7]. Time for progression of one cancer stage was 8.9 weeks (95% CI 4.6-15.8). Among HIV-infected women, estimated time for one-stage progression was 6.5 weeks (95% CI 2.3-12.3), significantly faster than HIV-uninfected women ( P < 0.001). The small number of HIV-uninfected women prevented separate estimation. Conclusion: Stage progression is rapid in locally advanced cervical cancer with typical treatment delays of two months associated with a full stage increase. These estimates may not generalize to contexts with lower HIV prevalence; however add urgency to effort to improve efficient access to treatment and avoidance of waiting lists.

Likelihood Ratio as Weight of Forensic Evidence: A Closer Look

The forensic science community has increasingly sought quantitative methods for conveying the weight of evidence. Experts from many forensic laboratories summarize their findings in terms of a likelihood ratio. Several proponents of this approach have argued that Bayesian reasoning proves it to be normative. We find this likelihood ratio paradigm to be unsupported by arguments of Bayesian decision theory, which applies only to personal decision making and not to the transfer of information from an expert to a separate decision maker. We further argue that decision theory does not exempt the presentation of a likelihood ratio from uncertainty characterization, which is required to assess the fitness for purpose of any transferred quantity. We propose the concept of a lattice of assumptions leading to an uncertainty pyramid as a framework for assessing the uncertainty in an evaluation of a likelihood ratio. We demonstrate the use of these concepts with illustrative examples regarding the refractive index of glass and automated comparison scores for fingerprints.

Race to the Top: evaluation of a novel performance-based financing initiative to promote healthcare delivery in rural Rwanda

BACKGROUND

Performance-based financing (PBF) has demonstrated a range of successes and failures in improving health outcomes across low- and middle-income countries. Evidence indicates that the success of PBF depends, in large part, on the model selected, in relation to a variety of contextual factors.

OBJECTIVE

Partners In Health∣Inshuti Mu Buzima aimed to evaluate health outcomes associated with a novel capacity-building model of PBF at health centers throughout Kirehe district, Rwanda.

DESIGN

Thirteen health centers in Kirehe district, which provide healthcare to a population of over 300,000 people, agreed to participate in a PBF initiative scheme that integrated data feedback, quality improvement coaching, peer-to-peer learning, and district-level priority setting. Health centers' progress toward collectively agreed upon site-specific health targets was assessed every 6 months for 18 months. Incentives were awarded only when health centers met goals on all three priorities health centers had collectively agreed upon: 90% coverage of community-based health insurance, 70% contraceptive prevalence rate, and zero acute severe malnutrition cases. Improvement across all four time points and facilities was measured using mixed-effects linear regression.

FINDINGS

At 6-month follow-up, 4 of 13 health centers had met 1 target. At 12-month follow-up, 7 centers had met 1 target, and by 18-month follow-up, 6 centers had met 2 targets and 2 centers had met all 3. Average health center performance had improved significantly across the district for all three targets: mean insurance coverage increased from 68% at baseline to 93% (p<0.001); mean number of acute malnutrition cases in the previous 6 months declined from 24 to 5 per facility (p<0.001); and contraceptive prevalence increased from 42 to 59% (p<0.001). A number of innovative improvement initiatives were identified.

CONCLUSION

The combining of PBF, district engagement/support, and peer-to-peer learning resulted in significant improvements despite resource constraints and is now being considered as a model for scale-up in other districts of Rwanda.

Conscious Augmentation of Creative State Enhances "Real" Creativity in Open-Ended Analogical Reasoning

Humans have an impressive ability to augment their creative state (i.e., to consciously try and succeed at thinking more creatively). Though this “thinking cap” phenomenon is commonly experienced, the range of its potential has not been fully explored by creativity research, which has often focused instead on creativity as a trait. A key question concerns the extent to which conscious augmentation of state creativity can improve creative reasoning. Although artistic creativity is also of great interest, it is creative reasoning that frequently leads to innovative advances in science and industry. Here, we studied state creativity in analogical reasoning, a form of relational reasoning that spans the conceptual divide between intelligence and creativity and is a core mechanism for creative innovation. Participants performed a novel Analogy Finding Task paradigm in which they sought valid analogical connections in a matrix of word-pairs. An explicit creativity cue elicited formation of substantially more creative analogical connections (measured via latent semantic analysis). Critically, the increase in creative analogy formation was not due to a generally more liberal criterion for analogy formation (that is, it appeared to reflect “real” creativity rather than divergence at the expense of appropriateness). The use of an online sample provided evidence that state creativity augmentation can be successfully elicited by remote cuing in an online environment. Analysis of an intelligence measure provided preliminary indication that the influential “threshold hypothesis,” which has been proposed to characterize the relationship between intelligence and trait creativity, may be extensible to the new domain of state creativity.

Impact of integrated community case management on health-seeking behavior in rural Zambia

Provision of integrated community case management (iCCM) for common childhood illnesses by community health workers (CHWs) represents an increasingly common strategy for reducing childhood morbidity and mortality. We sought to assess how iCCM availability influenced care-seeking behavior. In areas where two different iCCM approaches were implemented, we conducted baseline and post-study household surveys on healthcare-seeking practices among women who were caring for children ≤ 5 years in their homes. For children presenting with fever, there was an increase in care sought from CHWs and a decrease in care sought at formal health centers between baseline and post-study periods. For children with fast/difficulty breathing, an increase in care sought from CHWs was only noted in areas where CHWs were trained and supplied with amoxicillin to treat non-severe pneumonia. These findings suggest that iCCM access influences local care-seeking practices and reduces workload at primary health centers.

Feasibility, safety and accuracy of regadenoson-atropine (REGAT) stress echocardiography for the diagnosis of coronary artery disease: an angiographic correlative study

Regadenoson (REG), a selective A2A receptor vasodilator, has not been widely evaluated in stress echocardiography (SE). We report results of 45 patients participating in REG + atropine (REGAT) SE protocol conducted in a single-center prospective trial. The REGAT study enrolled subjects before a clinically indicated cardiac catheterization for suspected coronary artery disease (CAD). After rest imaging, a 2 mg Atropine (AT) bolus followed by 400 mcg of REG was given. Standard stress imaging views were obtained and interpreted in blinded fashion. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) were calculated using cardiac catheterization >70 % stenosis as gold standard. Additional endpoints included major adverse cardiac events (MACE) and patient questionnaire responses. The mean duration of REGAT was 18 ± 7.2 min. There were no MACE, with only transient side-effects of dry mouth, shortness of breath, and headache. The incidence of significant CAD was 51.1 %. The sensitivity and specificity for significant stenosis was 60.9 and 86.4 %, with a PPV and NPV of 82.4 and 67.9 %. By coronary territories, the sensitivity, specificity, PPV, and NPV were: left anterior descending artery 58.8, 92.9, 83.3, and 78.8 %; left circumflex artery 6.7, 93.3, 33.3, and 67.7 %; and right coronary artery 16.7, 93.9, 50, and 75.6 %. Over 90 % of subjects reported feeling comfortable, with 83 % preferring REGAT as a future stress modality. The REGAT protocol is fast, safe, and well-tolerated with good specificity for CAD detection, but its low sensitivity and NPV precludes it from being an imaging modality for routine use.

International travel by persons with medical comorbidities: understanding risks and providing advice

OBJECTIVE

To describe the medical conditions, travel plans, counseling, and medications prescribed for high-risk international travelers.

PATIENTS AND METHODS

This cross-sectional study was conducted from March 1, 2008, through July 31, 2010, in 5 clinics in the greater Boston area. We assessed all travelers seen for pretravel care and compared demographic characteristics, travel plans, pretravel counseling, and interventions for healthy and high-risk travelers (as defined by medical history or pregnancy).

RESULTS

Of 15,440 travelers, 2769 (17.9%) were high-risk; 644 of 2769 (23.3%) were immunocompromised travelers, 2056 (74.3%) had medical comorbidities, and 69 (2.5%) were pregnant women. The median age of high-risk travelers was 47 years compared with 32 years for healthy travelers (P=.0001). High-risk travelers visited the clinic a median of 25 days (range, 10-44 days) before departure. Overall, 2562 (93.9%) of high-risk travelers visited countries with medium or high risk of typhoid fever, 2340 (85.7%) visited malaria-risk countries, and 624 (22.8%) visited yellow fever-endemic countries. Of travelers to yellow fever-endemic countries, 8 of 23 (34.8%) pregnant women and 64 of 144 (44.4%) immunocompromised travelers received yellow fever vaccine. Of eligible high-risk travelers, 11 of 76 (14.5%) received a pneumococcal vaccine, 213 of 640 (33.3%) influenza vaccine, and 956 of 2681 (35.7%) either tetanus-diphtheria or tetanus-diphtheria-pertussis vaccine.

CONCLUSION

High-risk travelers made up nearly 20% of patients in these travel clinics, and they mostly traveled to destinations with malaria and typhoid risk. For health care professionals caring for travelers with underlying medical problems, providing appropriate travel counseling and making vaccine decisions, such as for yellow fever, are complex. Travelers with complicated medical histories may warrant evaluation by an experienced travel medicine specialist.

Retention in care and outpatient costs for children receiving antiretroviral therapy in Zambia: a retrospective cohort analysis

BACKGROUND

There are few published estimates of the cost of pediatric antiretroviral therapy (ART) in Africa. Our objective was to estimate the outpatient cost of providing ART to children remaining in care at six public sector clinics in Zambia during the first three years after ART initiation, stratified by service delivery site and time on treatment.

METHODS

Data on resource utilization (drugs, diagnostics, outpatient visits, fixed costs) and treatment outcomes (in care, died, lost to follow up) were extracted from medical records for 1,334 children at six sites who initiated ART at <15 years of age between 2006 and 2011. Fixed and variable unit costs (reported in 2011 USD) were estimated from the provider's perspective using site level data.

RESULTS

Median age at ART initiation was 4.0 years; median CD4 percentage was 14%. One year after ART initiation, 73% of patients remained in care, ranging from 60% to 91% depending on site. The average annual outpatient cost per patient remaining in care was $209 (95% CI, $199-$219), ranging from $116 (95% CI, $107-$126) to $516 (95% CI, $499-$533) depending on site. Average annual costs decreased as time on treatment increased. Antiretroviral drugs were the largest component of all outpatient costs (>50%) at four sites. At the two remaining sites, outpatient visits and fixed costs together accounted for >50% of outpatient costs. The distribution of costs is slightly skewed, with median costs 3% to 13% lower than average costs during the first year after ART initiation depending on site.

CONCLUSIONS

Outpatient costs for children initiating ART in Zambia are low and comparable to reported outpatient costs for adults. Outpatient costs and retention in care vary widely by site, suggesting opportunities for efficiency gains. Taking advantage of such opportunities will help ensure that targets for pediatric treatment coverage can be met.

Coma, hyperammonemia, metabolic acidosis, and mutation: lessons learned in the acute management of late onset urea cycle disorders

Urea cycle disorders are an important and treatable cause of hyperammonemia in the newborn and pediatric age group. Presentation in adolescence or adult life is rare and can manifest as frequent vomiting and behavioral changes. An inherited metabolic disorder should be considered in adults with obvious or occult encephalopathy. Failure to diagnose and treat rapidly may lead to irreversible neuronal damage. An improved understanding of the diagnosis and management of late-onset urea cycle disorders is needed to assist nephrologists in providing optimal care. This report describes the clinical characteristics of a young man with first presentation of hyperammonemia in adult life.

Abstract 4707: Discovery and characterization of PCAT-1, a novel lincRNA implicated in prostate cancer tumorigenesis

High-throughput sequencing of polyA+ RNA (RNA-Seq) in human cancer shows remarkable potential to identify both novel disease-specific markers for clinical uses and uncharacterized aspects of tumor biology, particularly non-coding RNA (ncRNA) species. To illustrate this approach, we employed RNA-Seq on a cohort of 102 prostate tissues and cells lines. We found that aberrant expression profiles of novel tissue-specific ncRNAs distinguished benign, cancerous, and metastatic tumors, and we defined a core set of 121 novel ncRNAs whose dysregulation characterizes prostate cancer. Among these, a novel prostate-cancer specific ncRNA (termed PCAT-1) defined a subset of aggressive cancers with low expression of the epigenetic regulator EZH2, a component of the Polycomb Repressive Complex 2 (PRC2) commonly upregulated in metastatic cancers. In vitro chromatin immunoprecipitation, RNA immunoprecipitation, and drug treatment assays for core PRC2 genes indicated that the PRC2 complex directly binds and represses PCAT-1, and that PCAT-1 transcript reciprocally binds PRC2. By contrast, in vitro models with high levels of endogenous PCAT-1 transcript did not recapitulate PRC2-mediated repression, and in these cells siRNA-mediated knockdown of PCAT-1 showed a 25 – 50% decrease in cell proliferation. Using gene expression arrays, we determined that PCAT-1 contributes to the transcriptional regulation of genes in several key biological processes, including cell cycle. These data suggest that PCAT-1 exhibits two biological states: a PRC2-repressed state and an active state that promotes proliferation.

Next, we showed that novel ncRNAs may serve a clinical purpose for the non-invasive detection and stratification of prostate cancer patients. We performed qPCR on patient urine samples (n=108) and found that a custom ncRNA expression signature, which includes PCAT-1, both diagnosed prostate cancer effectively and yielded prognostic information. Indeed, a high ncRNA expression signature value correlated with high-grade histology (Gleason score &gt;=7 vs. Gleason score =6; p = 0.01). Taken together, the findings presented herein establish the utility of RNA-Seq to comprehensively identify unannotated ncRNAs, such as PCAT-1, implicated in cancer. Our data suggest that PCAT-1 promotes cell proliferation, that in its inactive state PCAT-1 is mechanistically repressed by PRC2, and that PCAT-1 may serve as a candidate biomarker for non-invasive clinical tests. We further speculate that applying these methodologies to other diseases may reveal key aspects of disease biology and clinically important biomarkers, particularly for diseases that currently lack good non-invasive tests in fluids such as blood serum or urine.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4707. doi:10.1158/1538-7445.AM2011-4707

A dose range finding study of novel oral insulin (IN-105) under fed conditions in type 2 diabetes mellitus subjects

AIM

The objective of the study was to establish the dose response of IN-105 tablets and explore a possible therapeutic window in type 2 diabetes subjects poorly controlled on metformin.

METHODS

The primary objective was to examine the effect of sequential single ascending doses of IN-105 on the plasma glucose concentration under fed conditions. All subjects received, sequentially, matching placebo, 10, 15, 20 and 30 mg IN-105 tablets in five consecutive periods. Tablets were administered 20 min prior to meal in all the periods. Plasma levels of immunoreactive insulin, C-peptide and glucose were measured up to 180 min from the time of dosing. The changes in postprandial glucose levels at 120 min in response to IN-105 administration were also compared against those of placebo.

RESULTS

Changes in glucose from baseline (mean +/- s.d.) at 140 min (2 h postprandial) were 94.84 +/- 22.3, 79.45 +/- 43.00, 70.68 +/- 35.71, 63.47 +/- 42.75 and 53.06 +/- 47.27 mg/dL, respectively, and exhibited linear dose-response. The insulin C(max) values were found to be 50.8 +/- 26.0 mU/L for placebo, 100.3 +/- 66.7 with 10 mg IN-105, 177.69 +/- 150.3 with 15 mg IN-105, 246.2 +/- 245.2 with 20 mg IN-105 and 352.5 +/- 279.3 mU/L with 30 mg of IN-105.

CONCLUSIONS

IN-105 absorption is proportional to the dose administered. The 2-h postprandial glucose excursion was reduced in a dose proportional manner. Circulating C-peptide levels were found to be suppressed in proportion to the IN-105 exposure. IN-105 reduces glucose excursion despite lower endogenous insulin secretion. IN-105 seems to have a wide therapeutic window as no clinical hypoglycaemia was observed at any of the doses studied.

Differentially expressed genes during malting and correlation with malting quality phenotypes in barley (Hordeum vulgare L.)

Breeding for malting quality is an important goal of malting barley breeding programs. Malting quality is a complex phenotype that combines a large number of interrelated components, each of which shows complex inheritance. Currently, only a few genes involved in determining malting quality have been characterized. We combined transcript profiling with phenotypic correlations to identify candidate genes for malting quality. The Barley1 GeneChip array containing 22,792 probe sets was used to conduct transcript profiling of genes expressed in several different stages of malting of four malting cultivars. Genes that were differentially expressed in comparisons between different malting stages relative to ungerminated seed, as well as in comparisons between malting cultivars in the same malting stage were identified. Correlation analysis of 723 differentially expressed genes with malting quality phenotypes showed that 11-102 of these genes correlated with six malting quality phenotypes. Genes involved in carbohydrate metabolism were among the positively correlated genes. Genes for protein and lipid metabolism, cell wall organization and biogenesis, and genes involved in stress and defense response also correlated with malting quality phenotypes. Expressed sequence tags (ESTs) were generated from a 'malting-gene enriched' cDNA library made by suppression subtractive hybridization between malted and ungerminated seeds of 'Morex'. Eleven percent of the ESTs had no significant homology with sequences in the databases, suggesting that there may be other malting-related genes not represented in the barley gene chip array. The results provide candidate genes for malting quality phenotypes that need to be functionally validated.

Fisher's combined p-value for detecting differentially expressed genes using Affymetrix expression arrays

Background

Currently, most tests of differential gene expression using Affymetrix expression array data are performed using expression summary values representing each probe set on a microarray. Recently testing methods have been proposed which incorporate probe level information. We propose a new approach that uses Fisher's method of combining evidence from multiple sources of information. Specifically, we combine p-values from probe level tests of significance.

Results

The combined p method and other competing methods were compared using three spike-in datasets (where probe sets corresponding differentially spiked transcripts are known) and array data from a biological study validated with qRT-PCR. Based on power and false discovery rates computed for the spike-in datasets, we demonstrate that the combined p method compares favorably with other methods. We find that probe level testing methods select many of the same genes as differentially expressed. We illustrate the use of the combined p method for diagnostic purposes using examples.

Conclusion

Combined p is a promising alternative to existing methods of testing for differential gene expression. In addition, the combined p method is particularly well suited as a diagnostic tool for exploratory analysis of microarray data.

The effects of scrubber installation at the Navajo Generating Station on particulate sulfur and visibility levels in the Grand Canyon

Grand Canyon National Park (GCNP) is a mandatory Class I federal area that is afforded visibility protection under the Federal Clean Air Act. In this paper, we have examined the effects on visibility and particulate sulfur (Sp) at GCNP as a result of reducing sulfur dioxide (SO2) emissions by 90% from the Navajo Generating Station (NGS). Scrubbers were retrofitted to each of the three units at NGS during 1997, 1998, and 1999. The Inter-agency Monitoring of Protected Visual Environments aerosol network database affords us an opportunity to examine trends in Sp and extinction both prescrubber and postscrubber. The NGS impacts GCNP primarily during the winter (December to February). During winter, at times, there are fogs, stratus, and high-relative humidity in the Grand Canyon. When the NGS plume interacts with these fogs and stratus, rapid conversion of SO2 to Sp can occur. A variety of analytical techniques were used, including cumulative frequency plots of Sp and extinction, and chemical mass balance and tracer source apportionment analysis. We also deployed P value statistical analysis of "extreme" Sp values. Before scrubbers were installed, values of Sp approaching 2 microg/m3 were occasionally observed. Because scrubbers have been installed, high levels of Sp have been markedly reduced. Statistical P value analysis suggests that these reductions were significant. Furthermore, we have also observed that Sp has been reduced throughout the cumulative frequency curve during winter by approximately 33% since scrubbers were installed. By contrast, during summer when the NGS impact on the Canyon is minimal, there has been only a relatively small decrease in Sp.

Tests for individual and population bioequivalence based on generalized p-values

The U.S. Food and Drug Administration (FDA) has proposed new regulations that address the 'prescribability' and 'switchability' of new formulations of already-approved drugs. These new criteria are known, respectively, as population and individual bioequivalence. Two methods have been proposed in the bioequivalence literature for assessing population and individual bioequivalence that calculate an upper 95 per cent confidence bound for the bioequivalence criterion in question, and then test bio-equivalence by comparing this bound to the limit established by the FDA. In this paper we propose applying the generalized test function (GTF) methodology of Tsui and Weerahandi (Journal of the American Statistical Association 1989; 602-607) to this problem to produce tests based on a generalized p-value (GPV). This methodology allows us to construct hypothesis tests in the presence of nuisance parameters. Using simulation we show that these tests perform well in comparison to the confidence interval methods and have superior power for assessing population bioequivalence.

An analysis of the yearly changes in sulfur concentrations at various national parks in the United States, 1980-1996

An apparent increasing trend in the summer concentrations of particulate sulfur at Shenandoah (for the time period 1982-1995) and at Great Smoky Mountains (for the time period 1984-1995) has been pointed out by some researchers. Others have suggested that these increasing trends may be an analytical artifact resulting from the switch from the Stacked Filter Units (SFU) measurement system to the IMPROVE (Interagency Monitoring of Protected Visual Environments) measurement system that occurred during the winter of 1987. To obtain a better understanding of the effect of the protocol change, we investigate the changes in the seasonal averages of sulfur concentrations for successive pairs of years for the period 1980-1996 for about 20 national park sites in the United States. For the period 1980-1987, we use sulfur data from the old (SFU) database and for the period 1988-1996, we use the IMPROVE database. Changes from one year to the next similar to that between 1987 and 1988 occurred during other years and seasons suggesting that chance causes alone could perhaps explain it, the degree to which chance could have caused the changes was measured using the permutation test for matched. At the very least, additional information such as side by side readings using SFU and IMPROVE measurement methods, may be needed to better understand any systematic effect in the sulfur measurements that may be ascribable to the protocol change.

Trends in the extremes of sulfur concentration distributions

Understanding the response of air quality parameters such as visibility to the implementation of new air quality regulations, population growth and redistribution, and federal land managing practices is essential to the evaluation of air quality management plans on air quality in federal Class I areas. For instance, the reduction of SO2 emissions from large single point sources should result in the decrease of extreme sulfate concentrations, while population growth in geographic areas outside of urban centers could cause a slow widespread increase of sulfate and organic concentrations. The change in federal land managing practice of increased prescribed fire on a year-round basis in lieu of large naturally occurring wild fires could have the same effect; that is, the frequency of high sulfur days increase and low sulfur days decrease as the result of the management practice. Therefore, it is of interest to examine the trends associated with the proportion of days during which the concentration of some aerosol species is above or below a certain threshold and decide whether this proportion of days is increasing or decreasing or shows a lack of trend. This is a direct indication of whether the quality of the environment is improving or worsening, or neither.

Sampling duration calculations

Routine air quality monitoring produces filter samples that, when analyzed, yield the total amount of the aerosol present in the volume of air drawn by the pump in the monitoring device during the given sampling period. From this we obtain an average concentration of the aerosol for the given duration. The samples are therefore really aggregate samples. A natural question then is "what is the effect of the duration of aggregation on the accuracy and precision of the estimate of the quantity of interest?" The answer depends on a number of factors, such as the quantity that is being estimated: a mean, or an extreme value, or some other quantity; the nature of the measurement error--additive versus multiplicative; the costs of laboratory analyses, and so on. In this paper, we investigate these issues when the interest is in estimating the mean concentration of a specified aerosol species over a fixed time period. In particular, we propose a method for determining a sampling duration that will yield the "best estimate" of the mean concentration for a given cost whenever appropriate statistical assumptions hold.

On an inequality for the normal distribution arising in bioequivalence studies

For (μ,σ2) ≠ (0,1), and 0 < z < ∞, we prove that where φ and Φ are, respectively, the p.d.f. and the c.d.f. of a standard normal random variable. This inequality is sharp in the sense that the right-hand side cannot be replaced by a larger quantity which depends only on μ and σ. In other words, for any given (μ,σ) ≠ (0,1), the infimum, over 0 < z < ∞, of the left-hand side of the inequality is equal to the right-hand side. We also point out how this inequality arises in the context of defining individual bioequivalence.