Dose-Volume Histograms for bladder and rectum

: A careful examination of the foundation upon which the concept of the Dose-Volume Histogram (DVH) is built, and the implications of this set of parameters on the clinical application and interpretation of the DVH concept has not been conducted since the introduction of DVHs as a tool for the quantitative evaluation of treatment plans. The purpose of the work presented herein is to illustrate problems with current methods of implementing and interpreting DVHs when applied to hollow anatomic structures such as the bladder and rectum.

: A typical treatment plan for external beam irradiation of a patient with prostate cancer was chosen to provide a data set from which DVH curves for both the bladder and rectum were calculated. The two organs share the property of being shells with contents that are of no clinical importance. DVHs for both organs were computed using a solid model and using a shell model. Typical treatment plans for prostate cancer were used to generate DVH curves for both models. The Normal Tissue Complication Probability (NTCP) for these organs is discussed in this context.

: For an eight-field conformal treatment plan of the prostate, a bladder DVH curve generated using the shell model is higher than the corresponding curve generated using the solid model. The shell model also has a higher NTCP. A six-field conformal treatment plan slo results in a higher DVH curve for the shell model. A treatment plan consisting of bilateral 120-degree arcs, results in a higher DVH curve for the shell model, as well as a higher NTCP.

: The DVH concept currently used in evaluation of treatment plans is problematic because current practices of defining exactly what constitutes “bladder” and “rectum.” Commonly used methods of tracing the bladder and rectum imply use of a solid structure model for DVHs. In reality, these organs are shells and the critical structure associated with NTCP is obviously and indisputably the shell, as opposed to its contents. Treatment planning algorithms for DVH computation should thus be modified to utilize the shell model for these organs.     

Development of the multi-attribute Pediatric Asthma Health Outcome Measure (PAHOM).

OBJECTIVE: To develop a multi-attribute outcome measure for children with asthma that allows for the calculation of quality-adjusted life years in cost-effectiveness studies and can also be used to assign preference weights to asthma-symptom-free days. STUDY DESIGN: A literature review and two interviewer-administered surveys. SETTING: Homes or community centers of participants in Seattle, United States. MAIN MEASURE: Visual analog scale (VAS), standard gamble (SG), and relative risk attitude equation techniques were used to estimate two sets of preference weights for 10 health states. The PAHOM was used to record health states of pediatric asthma patients. RESULTS: A total of 94 subjects provided complete responses without any illogical ratings to VAS questions and 101 provided the same to SG questions. The VAS preference weights of the health states range from a maximum of 1 for perfect health to a minimum of 0.03 for severe asthma symptoms, emotional problems, and activity limitations. Those based on the relative risk attitude equation constructed with both VAS and SG preference weights range from 1 to 0.06. The mean PAHOM scores of pediatric asthma patients based on VAS and converted SG preference weights were 0.70 and 0.83, respectively. CONCLUSIONS: The PAHOM calendar can be used to identify asthma patients' health outcomes, to calculate the preference weights of asthma patients' health states, and to estimate the number of symptom-free days. These factors make the PAHOM a promising instrument for use in effectiveness and cost-effectiveness studies in children with asthma.     

Screening for domestic violence in public welfare offices: an analysis of case manager and client interactions

Despite a high prevalence of domestic violence among welfare clients, most studies of the implementation of the Family Violence Option (FVO) under welfare reform find that women rarely receive domestic violence services in welfare offices. This study reviews findings from current research on the factors that improve the likelihood that women will reveal their domestic violence experiences to service personnel, and uses the guidelines drawn from this review to evaluate domestic violence screening practices in welfare offices using 782 transcribed interviews between welfare workers and clients from 11 sites in four states. The analysis found that only 9.3% of case encounters involved screening for domestic violence. Screening rates differed by state, interview type, and length of worker employment. Qualitative analysis of the interviews showed that the majority of screening by workers was routine or consisted of informing clients of the domestic violence policy without asking about abuse. Only 1.2% of the interviews incorporated at least two of the procedures that increase the likelihood of disclosure among domestic violence survivors, suggesting deeply inadequate approaches to screening for abuse within the context of welfare offices, and a need for improved training, protocol, and monitoring of FVO implementation.     

Factors associated with 5-year risk of hip fracture in postmenopausal women

Context  The 329 000 hip fractures that annually occur in the United States are associated with high morbidity, mortality, and cost. Identification of those at high risk is a step toward prevention. Objective  To develop an algorithm to predict the 5-year risk of hip fracture in postmenopausal women. Design, Setting, and Participants  A total of 93 676 women who participated in the observational component of the Women's Health Initiative (WHI), a multiethnic longitudinal study, were used to develop a predictive algorithm based on commonly available clinical features. Selected factors that predicted hip fracture were then validated by 68 132 women who participated in the clinical trial. The model was tested in a subset of 10 750 women who had undergone dual-energy x-ray absorptiometry (DXA) scans for bone mass density assessment. Main Outcome Measure  The prediction of centrally adjudicated hip fracture, measured by the area under the receiver operator characteristic (ROC) curves. Results  During a mean (SD) follow-up of 7.6 (1.7) years, 1132 hip fractures were identified among women participating in the observational study (annualized rate, 0.16%), whereas during a mean follow-up of 8.0 (1.7) years, 791 hip fractures occurred among women participating in the clinical trial (annualized rate, 0.14%). Eleven factors predicted hip fracture within 5 years: age, self-reported health, weight, height, race/ethnicity, self-reported physical activity, history of fracture after age 54 years, parental hip fracture, current smoking, current corticosteroid use, and treated diabetes. Receiver operating characteristic curves showed that the algorithm had an area under the curve of 80% (95% confidence interval [CI], 0.77%-0.82%) when tested in the cohort of different women who were in the clinical trial. A simplified point score was developed for the probability of hip fracture. Receiver operating characteristic curves comparing DXA-scan prediction based on a 10% subset of the cohort and the algorithm among those who participated the clinical trial were similar, with an area under the curve of 79% (95% CI, 73%-85%) vs 71% (95% CI, 66%-76%). Conclusion  This algorithm, based on 11 clinical factors, may be useful to predict the 5-year risk of hip fracture among postmenopausal women of various ethnic backgrounds. Further studies are needed to assess the clinical implication of the algorithm in general and specifically to identify treatment benefits.      

Avidity of antibodies in sle

The avidity of antibodies to DNA in the sera of 8 patients with SLE was determined by saturation analysis and Scatchard plots. Five of the patients had severe lupus nephritis; the other 3 had relatively mild or no kidney disease. The Scatchard plots revealed components with high relative avidity in the patients with severe nephritis (K values 4.4–10.4 x 10⁵ M⁻¹ for nDNA), compared with the patients who had mild or no kidney disease (K values 0.3–1.8 x 10⁵ M⁻¹ for nDNA). Avidity measurements may be helpful in the evaluation and treatment of patients with SLE.     

An Agent Based Model for Simulating the Spread of Sexually Transmitted Infections

This work uses agent-based modelling (ABM) to simulate sexually transmitted infection (STIs) spread within a population of 1000 agents over a 10-year period, as a preliminary investigation of the suitability of ABM methodology to simulate STI spread. The work contrasts compartmentalized mathematical models that fail to account for individual agents, and ABMs commonly applied to simulate the spread of respiratory infections. The model was developed in C++ using the Boost 1.47.0 libraries for the normal distribution and OpenGL for visualization. Sixteen agent parameters interact individually and in combination to govern agent profiles and behaviours relative to infection probabilities. The simulation results provide qualitative comparisons of STI mitigation strategies, including the impact of condom use, promiscuity, the form of the friend network, and mandatory STI testing. Individual and population-wide impacts were explored, with individual risk being impacted much more dramatically by population-level behaviour changes as compared to individual behaviour changes.