Using extended reality (XR) for medical training and real-time clinical support during deep space missions.

Medical events can affect space crew health and compromise the success of deep space missions. To successfully manage such events, crew members must be sufficiently prepared to manage certain medical conditions for which they are not technically trained. Extended Reality (XR) can provide an immersive, realistic user experience that, when integrated with augmented clinical tools (ACT), can improve training outcomes and provide real-time guidance during non-routine tasks, diagnostic, and therapeutic procedures. The goal of this study was to develop a framework to guide XR platform development using astronaut medical training and guidance as the domain for illustration. We conducted a mixed-methods study-using video conference meetings (45 subject-matter experts), Delphi panel surveys, and a web-based card sorting application-to develop a standard taxonomy of essential XR capabilities. We augmented this by identifying additional models and taxonomies from related fields. Together, this "taxonomy of taxonomies," and the essential XR capabilities identified, serve as an initial framework to structure the development of XR-based medical training and guidance for use during deep space exploration missions. We provide a schematic approach, illustrated with a use case, for how this framework and materials generated through this study might be employed.

Assessment of the Non-Technical Skills for Surgeons (NOTSS) framework in the USA.

BACKGROUND: Surgeons' non-technical skills are important for patient safety. The Non-Technical Skills for Surgeons assessment tool was developed in the UK and recently adapted to the US surgical context (NOTSS-US). The aim of this study was to evaluate the reliability and distribution of non-technical skill ratings given by attending (consultant) surgeons who underwent brief online training. METHODS: Attending surgeons across six specialties at a large US academic medical centre underwent a 10-min online training, then rated 60-s standardized videos of simulated operations. Intraclass correlation coefficient (ICC), and mean(s.d.) values for NOTSS-US ratings were determined for each non-technical skill category (score range 1-5, where 1 indicates poor, 3 average and 5 excellent) and for total NOTSS-US score (range 4-20; sum of 4 category scores). Outcomes were adjusted for rater characteristics including sex, specialty and clinical experience. RESULTS: A total of 8889 ratings were submitted by 81 surgeon raters on 30 simulated intraoperative videos. The mean(s.d.) total NOTSS-US score for all videos was 9·5(4·8) of 20. The within-video ICC for total NOTSS-US score was 0·64 (95 per cent c.i. 0·57 to 0·70). For individual non-technical skill categories, the ICC was highest for social skills (communication/teamwork: 0·63, 95 per cent c.i. 0·56 to 0·71; leadership: 0·64, 0·55 to 0·72) and lowest for cognitive skills (situation awareness: 0·54, 0·45 to 0·62; decision-making: 0·50, 0·41 to 0·59). Women gave higher total NOTSS-US scores than men (adjusted mean difference 0·93, 95 per cent c.i. 0·44 to 1·43; P = 0·001). CONCLUSION: After brief online training, the inter-rater reliability of the NOTSS-US assessment tool achieved moderate strength among trained surgeons rating simulated intraoperative videos.

ANTECEDENTES: Las habilidades no técnicas de los cirujanos (Non-Technical Skills for Surgeons, NOTSS) son importantes para la seguridad del paciente. La herramienta de evaluación de habilidades no técnicas para cirujanos se desarrolló en el Reino Unido y se adaptó recientemente al contexto quirúrgico de los Estados Unidos (NOTSS-US.). El objetivo de este estudio fue evaluar la fiabilidad y distribución de las calificaciones de habilidades no técnicas obtenidas por cirujanos adjuntos de cirugía (consultores) que recibieron una breve formación online. MÉTODOS: Cirujanos adjuntos de 6 especialidades en un gran centro universitario de Estados Unidos recibieron una formación online de 10 minutos de duración y seguidamente puntuaron vídeos estandarizados de operaciones simuladas de 60 minutos de duración. Se calcularon el coeficiente de correlación intraclase (intraclass correlation coefficient, ICC), la media y la desviación estándar (standard deviation, SD) para la puntuación de cada categoría de habilidad no técnica del NOTSS-US (rango 1-5, siendo 1 = pobre, 3 = promedio, 5 = excelente) y para la puntuación global de NOTSS-US (rango 4-20, suma de las puntuaciones de las cuatro categorías). Los resultados se ajustaron de acuerdo con las características del evaluador, incluyendo sexo, especialidad, experiencia clínica. RESULTADOS: En 30 videos intraoperatorios simulados, 81 cirujanos evaluadores proporcionaron 8.889 puntaciones. La puntuación media global de NOTSS-US para todos los vídeos fue de 9,5 sobre 20 (SD 4,8). El ICC de los vídeos para la puntuación global de NOTSS-US fue 0,64 (i.c. del 95% 0,57-0,70). Para las categorías individuales de habilidades no técnicas, el ICC más alto fue para las habilidades sociales (comunicación / trabajo en equipo: 0,63, (i.c. del 95% 0,56-0,71); liderazgo, 0,64 (i.c. del 95% 0,55-0,72)) y el más bajo para las habilidades cognitivas (conciencia de la situación 0,54 (i.c. del 95% 0,45-0,62); toma de decisiones 0,50 (i.c. del 95% 0,41-0,59)). Las evaluadoras femeninas presentaron puntuaciones globales de NOTSS-US más altas que los evaluadores masculinos (diferencia 0,93, i.c. del 95% 0,44-1,43; P = 0,001)). CONCLUSIÓN: Después de una breve formación online, la fiabilidad de la herramienta de evaluación NOTSS-US mostró una correlación moderada entre los cirujanos que puntuaron vídeos de simulaciones de intervenciones quirúrgicas.

Variation in global uptake of the Surgical Safety Checklist.

BACKGROUND: The Surgical Safety Checklist (SSC) is a patient safety tool shown to reduce mortality and to improve teamwork and adherence with perioperative safety practices. The results of the original pilot work were published 10 years ago. This study aimed to determine the contemporary prevalence and predictors of SSC use globally. METHODS: Pooled data from the GlobalSurg and Surgical Outcomes studies were analysed to describe SSC use in 2014-2016. The primary exposure was the Human Development Index (HDI) of the reporting country, and the primary outcome was reported SSC use. A generalized estimating equation, clustering by facility, was used to determine differences in SSC use by patient, facility and national characteristics. RESULTS: A total of 85 957 patients from 1464 facilities in 94 countries were included. On average, facilities used the SSC in 75·4 per cent of operations. Compared with very high HDI, SSC use was less in low HDI countries (odds ratio (OR) 0·08, 95 per cent c.i. 0·05 to 0·12). The SSC was used less in urgent compared with elective operations in low HDI countries (OR 0·68, 0·53 to 0·86), but used equally for urgent and elective operations in very high HDI countries (OR 0·96, 0·87 to 1·06). SSC use was lower for obstetrics and gynaecology versus abdominal surgery (OR 0·91, 0·85 to 0·98) and where the common or official language was not one of the WHO official languages (OR 0·30, 0·23 to 0·39). CONCLUSION: Worldwide, SSC use is generally high, but significant variability exists. Implementation and dissemination strategies must be developed to address this variability.

ANTECEDENTES: Se ha demostrado que la utilización de la lista de verificación de seguridad quirúrgica (Surgical Safety Checklist, SSC) reduce la mortalidad y mejora el trabajo en equipo, así como el cumplimiento de las prácticas de seguridad perioperatorias. Los resultados de un trabajo piloto original se publicaron hace 10 años. El objetivo de este estudio fue determinar la prevalencia actual y los predictores de uso de la SSC a nivel mundial. MÉTODOS: Se analizaron los datos agrupados de los estudios GlobalSurg y Surgical Outcomes para describir la utilización de la SSC entre 2014-2016. La principal variable de exposición fue el índice de desarrollo humano (Human Development Index, HDI) del país informante y la principal variable de resultado, la tasa de utilización de la SCC. Para determinar las diferencias en la utilización de la SSC por paciente, centro y características nacionales se utilizó una ecuación de estimación generalizada con conglomerados por centros. RESULTADOS: Se incluyeron 85.957 pacientes de 1.464 centros en 94 países. La tasa media de utilización de la SSC fue del 75,4% de las operaciones. Al compararlos con países de HDI muy alto, la utilización de la SCC fue menor en los países con HDI bajo (razón de oportunidades, odds ratio, OR 0,08, i.c. del 95% 0,05-0,12). En países con HDI bajo, la SSC se utilizó menos en operaciones urgentes en comparación con operaciones electivas (OR 0,68, i.c. del 95% 0,53- 0,86) a diferencia de los países con HDI elevado, en los que se utilizó por igual en ambas situaciones (OR 0,96, i.c. del 95% 0,87-1,06). La utilización de la SSC fue menor en operaciones de obstetricia y ginecología que en cirugía abdominal (OR 0,91, i.c. del 95% 0,85 a 0,98) y en aquellos países en los que el idioma habitual u oficial era diferente a los idiomas oficiales de la OMS (OR 0,30, i.c. del 95% 0,23 a 0,39). CONCLUSIÓN: A nivel mundial, el uso de SSC en general es alto, pero existe una variabilidad significativa. Se deben desarrollar estrategias de implementación y difusión para resolver esta variabilidad.

Variation in expenditure for common, high cost surgical procedures in a working age population: implications for reimbursement reform.

BACKGROUND: In the move toward value-based care, bundled payments are believed to reduce waste and improve coordination. Some commercial insurers have addressed this through the use of bundled payment, the provision of one fee for all care associated with a given index procedure. This system was pioneered by Medicare, using a population generally over 65 years of age, and despite its adoption by mainstream insurers, little is known of bundled payments' ability to reduce variation or cost in a working-age population. This study uses a universally-insured, nationally-representative population of adults aged 18-65 to examine the effect of bundled payments for five high-cost surgical procedures which are known to vary widely in Medicare reimbursement: hip replacement, knee replacement, coronary artery bypass grafting (CABG), lumbar spinal fusion, and colectomy. METHODS: Five procedures conducted on adults aged 18-65 were identified from the TRICARE database from 2011 to 2014. A 90-day period from index procedure was used to determine episodes of associated post-acute care. Data was sorted by Zip code into hospital referral regions (HRR). Payments were determined from TRICARE reimbursement records, they were subsequently price standardized and adjusted for patient and surgical characteristics. Variation was assessed by stratifying the HRR into quintiles by spending for each index procedure. RESULTS: After adjusting for case mix, significant inter-quintile variation was observed for all procedures, with knee replacement showing the greatest variation in both index surgery (107%) and total cost of care (75%). Readmission was a driver of variation for colectomy and CABG, with absolute cost variation of $17,257 and $13,289 respectively. Other post-acute care spending was low overall (≤$1606, for CABG). CONCLUSIONS: This study demonstrates significant regional variation in total spending for these procedures, but much lower spending for post-acute care than previously demonstrated by similar procedures in Medicare. Targeting post-acute care spending, a common approach taken by providers in bundled payment arrangements with Medicare, may be less fruitful in working aged populations.

Reducing surgical mortality in Scotland by use of the WHO Surgical Safety Checklist.

BACKGROUND: The WHO Surgical Safety Checklist has been implemented widely since its launch in 2008. It was introduced in Scotland as part of the Scottish Patient Safety Programme (SPSP) between 2008 and 2010, and is now integral to surgical practice. Its influence on outcomes, when analysed at a population level, remains unclear. METHODS: This was a population cohort study. All admissions to any acute hospital in Scotland between 2000 and 2014 were included. Standardized differences were used to estimate the balance of demographics over time, after which interrupted time-series (segmented regression) analyses were performed. Data were obtained from the Information Services Division, Scotland. RESULTS: There were 12 667 926 hospital admissions, of which 6 839 736 had a surgical procedure. Amongst the surgical cohort, the inpatient mortality rate in 2000 was 0·76 (95 per cent c.i. 0·68 to 0·84) per cent, and in 2014 it was 0·46 (0·42 to 0·50) per cent. The checklist was associated with a 36·6 (95 per cent c.i. -55·2 to -17·9) per cent relative reduction in mortality (P < 0·001). Mortality rates before implementation were decreasing by 0·003 (95 per cent c.i. -0·017 to +0·012) per cent per year; annual decreases of 0·069 (-0·092 to -0·046) per cent were seen during, and 0·019 (-0·038 to +0·001) per cent after, implementation. No such improvement trends were seen in the non-surgical cohort over this time frame. CONCLUSION: Since the implementation of the checklist, as part of an overall national safety strategy, there has been a reduction in perioperative mortality.

Minimally invasive surgery and its impact on 30-day postoperative complications, unplanned readmissions and mortality.

BACKGROUND: A critical appraisal of the benefits of minimally invasive surgery (MIS) is needed, but is lacking. This study examined the associations between MIS and 30-day postoperative outcomes including complications graded according to the Clavien-Dindo classification, unplanned readmissions, hospital stay and mortality for five common surgical procedures. METHODS: Patients undergoing appendicectomy, colectomy, inguinal hernia repair, hysterectomy and prostatectomy were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Non-parsimonious propensity score methods were used to construct procedure-specific matched-pair cohorts that reduced baseline differences between patients who underwent MIS and those who did not. Bonferroni correction for multiple comparisons was applied and P < 0·006 was considered significant. RESULTS: Of the 532 287 patients identified, 53·8 per cent underwent MIS. Propensity score matching yielded an overall sample of 327 736 patients (appendicectomy 46 688, colectomy 152 114, inguinal hernia repair 59 066, hysterectomy 59 066, prostatectomy 10 802). Within the procedure-specific matched pairs, MIS was associated with significantly lower odds of Clavien-Dindo grade I-II, III and IV complications (P ≤ 0·004), unplanned readmissions (P < 0·001) and reduced hospital stay (P < 0·001) in four of the five procedures studied, with the exception of inguinal hernia repair. The odds of death were lower in patients undergoing MIS colectomy (P < 0·001), hysterectomy (P = 0·002) and appendicectomy (P = 0·002). CONCLUSION: MIS was associated with significantly fewer 30-day postoperative complications, unplanned readmissions and deaths, as well as shorter hospital stay, in patients undergoing colectomy, prostatectomy, hysterectomy or appendicectomy. No benefits were noted for inguinal hernia repair.

Physician Perceptions and Beliefs about Generating and Providing a Clinical Summary of the Office Visit.

BACKGROUND: A core measure of the meaningful use of EHR incentive program is the generation and provision of the clinical summary of the office visit, or the after visit summary (AVS), to patients. However, little research has been conducted on physician perceptions and beliefs about the AVS. OBJECTIVES: Evaluate physician perceptions and beliefs about the AVS and the effect of the AVS on workload, patient outcomes, and the care the physician delivers. METHODS: A cross-sectional online survey of physicians at two academic medical centers (AMCs) in the northeast who are participating in the meaningful use EHR incentive program. RESULTS: Of the 1 795 physicians at both AMCs participating in the incentive program, 853 completed the survey for a response rate of 47.5%. Eighty percent of the respondents reported that the AVS was easy (very easy or quite easy or somewhat easy) to generate and provide to patients. Nonetheless, more than three-fourths of the respondents reported a negative effect of generating and providing the AVS on workload of office staff (78%) and workload of physicians (76%). Primary care physicians had more positive beliefs about the effect of the AVS on patient outcomes than specialists (p<0.001) and also had more positive beliefs about the effect of the AVS on the care they delivered than specialists (p<0.001). CONCLUSIONS: Achieving the core meaningful use measure of generating and providing the AVS was easy for physicians but it did not necessarily translate into positive beliefs about the effect of the AVS on patient outcomes or the care the physician delivered. Physicians also had negative beliefs about the effect of the AVS on workload. To promote positive beliefs among physicians around the AVS, organizations should obtain physician input into the design and implementation of the AVS and develop strategies to mitigate its negative impacts on workload.

Physician beliefs about the impact of meaningful use of the EHR: a cross-sectional study.

BACKGROUND: As adoption and use of electronic health records (EHRs) grows in the United States, there is a growing need in the field of applied clinical informatics to evaluate physician perceptions and beliefs about the impact of EHRs. The meaningful use of EHR incentive program provides a suitable context to examine physician beliefs about the impact of EHRs. OBJECTIVE: Contribute to the sparse literature on physician beliefs about the impact of EHRs in areas such as quality of care, effectiveness of care, and delivery of care. METHODS: A cross-sectional online survey of physicians at two academic medical centers (AMCs) in the northeast who were preparing to qualify for the meaningful use of EHR incentive program. RESULTS: Of the 1,797 physicians at both AMCs who were preparing to qualify for the incentive program, 967 completed the survey for an overall response rate of 54%. Only 23% and 27% of physicians agreed or strongly agreed that meaningful use of the EHR will help them improve the care they personally deliver and improve quality of care respectively. Physician specialty was significantly associated with beliefs; e.g., 35% of primary care physicians agreed or strongly agreed that meaningful use will improve quality of care compared to 26% of medical specialists and 21% of surgical specialists (p=0.009). Satisfaction with outpatient EHR was also significantly related to all belief items. CONCLUSIONS: Only about a quarter of physicians in our study responded positively that meaningful use of the EHR will improve quality of care and the care they personally provide. These findings are similar to and extend findings from qualitative studies about negative perceptions that physicians hold about the impact of EHRs. Factors outside of the regulatory context, such as physician beliefs, need to be considered in the implementation of the meaningful use of the EHR incentive program.

Utilizing hospital discharge data (HD) to compare fatal and non-fatal work-related injuries among Hispanic workers in New Jersey.

BACKGROUND: This study explores the utilization of Hospital Discharge (HD) data to obtain estimates of work-related non-fatal injuries rates in NJ to determine if Hispanics workers have an increased risk of specific work-related injuries. In addition, HD data are used to compare the rate ratios between fatal and non-fatal injuries in this population to demonstrate the effectiveness of using HD as a surveillance tool for monitoring injury trends and performing evaluations. METHODS: Several types of fatal and non-fatal injuries were modeled using Poisson regression with the following predictor variables: gender, ethnicity, and year. The estimated number of workers by ethnicity employed in NJ each year was obtained from the U.S. Census Bureau, DataFerrett, Current Population Survey, November 2006, a data mining tool which accesses CPS data. RESULTS: These analyses, utilizing estimates of working population at-risk, indicate that Hispanic workers have an increased risk of four particular work-related injuries compared with non-Hispanics, and Hispanics were injured at a younger age than non-Hispanics. In addition the rankings of the rate ratios from the comparison between non-fatal and fatal risk estimates were similar; indicating that occupational surveillance of non-fatal injuries is a viable component to be considered. CONCLUSIONS: HD data are effective for monitoring trends over time across ethnic groups and injury types. Therefore, non-fatal injury surveillance should be considered for targeting specific worker populations for interventions to reduce exposure to workplace hazards, and can be a valuable surveillance tool in efforts to reduce occupational injuries.

Mortality and drug exposure in a 5-year cohort of patients with chronic liver disease.

BACKGROUND: Chronic liver diseases are common in the general population. Drug treatment in this group may be challenging, as many drugs are hepatically metabolised and hepatotoxic. OBJECTIVES: We aimed to assess the mortality of patients with chronic liver disease according to specific drug exposures and the three laboratory parameters creatinine, bilirubin and International Normalised Ratio (INR). METHODS: We conducted a multicentre, 5-year retrospective cohort study in two tertiary university referral hospitals and a secondary referral hospital, using a research database to evaluate the crude and adjusted mortality. RESULTS: Of 1159362 individual patients 1.7% (n = 20158) had chronic liver disease and in this group 36.8% had unspecified chronic non-alcoholic liver disease, 30.1% chronic hepatitis C and 11.9% cirrhosis of the liver. 8.4% of patients presented a diagnosis associated with alcohol. The 4-year survival rates were significantly higher in the group with the most normal laboratory values (94.3%) versus 34.5% in the group with elevated parameters (p <0.001). Overall, drug exposure was not associated with higher mortality; in adjusted multivariate analysis the hazard ratio for anti-cancer drugs was 2.69 (95% CI 1.32-5.46). Of individual drugs, mortality hazard ratios for amiodarone, morphine oral, acetazolamide, sirolimus and lamivudine were 2.46 (95% CI 1.68-3.61), 2.26 (95% CI 1.78-2.86), 2.10 (95% CI 1.19-3.70), 1.81 (95% CI 1.02-3.21) and 1.72 (95% CI 1.17-2.53) respectively. CONCLUSIONS: Drug exposure in general was not associated with higher mortality except for a few categories. Mortality in patients with chronic liver disease was high and is associated with simple laboratory values.

Longitudinal Studies With Outcome-Dependent Follow-up: Models and Bayesian Regression.

We propose Bayesian parametric and semiparametric partially linear regression methods to analyze the outcome-dependent follow-up data when the random time of a follow-up measurement of an individual depends on the history of both observed longitudinal outcomes and previous measurement times. We begin with the investigation of the simplifying assumptions of Lipsitz, Fitzmaurice, Ibrahim, Gelber, and Lipshultz, and present a new model for analyzing such data by allowing subject-specific correlations for the longitudinal response and by introducing a subject-specific latent variable to accommodate the association between the longitudinal measurements and the follow-up times. An extensive simulation study shows that our Bayesian partially linear regression method facilitates accurate estimation of the true regression line and the regression parameters. We illustrate our new methodology using data from a longitudinal observational study.

Meta-analysis of binary data: which within study variance estimate to use?

We applied a mixed effects model to investigate between- and within-study variation in improvement rates of 180 schizophrenia outcome studies. The between-study variation was explained by the fixed study characteristics and an additional random study effect. Both rate difference and logit models were used. For a binary proportion outcome p(i) with sample size n(i) in the ith study, (circumflexp(i)(1-circumflexp(i))n)(-1) is the usual estimate of the within-study variance sigma(i)(2) in the logit model, where circumflexpi) is the sample mean of the binary outcome for subjects in study i. This estimate can be highly correlated with logit(circumflexp(i)). We used (macronp(i)(1-macronp)n(i))(-1) as an alternative estimate of sigma(i)(2), where macronp is the weighted mean of circumflexp(i)'s. We estimated regression coefficients (beta) of the fixed effects and the variance (tau(2)) of the random study effect using a quasi-likelihood estimating equations approach. Using the schizophrenia meta-analysis data, we demonstrated how the choice of the estimate of sigma(2)(i) affects the resulting estimates of beta and tau(2). We also conducted a simulation study to evaluate the performance of the two estimates of sigma(2)(i) in different conditions, where the conditions vary by number of studies and study size. Using the schizophrenia meta-analysis data, the estimates of beta and tau(2) were quite different when different estimates of sigma(2)(i) were used in the logit model. The simulation study showed that the estimates of beta and tau(2) were less biased, and the 95 per cent CI coverage was closer to 95 per cent when the estimate of sigma(2)(i) was (macronp(1-macronp)n(i))(-1) rather than (circumflexp(i)(1-circumflexp)n(i))(-1). Finally, we showed that a simple regression analysis is not appropriate unless tau(2) is much larger than sigma(2)(i), or a robust variance is used.

Depletion of protein kinase Cepsilon in normal and scleroderma lung fibroblasts has opposite effects on tenascin expression.

OBJECTIVE: To determine whether the extracellular matrix protein tenascin-C (TN-C) is overexpressed in lung fibroblasts from systemic sclerosis (SSc) patients, the molecular mechanisms regulating TN-C secretion in SSc and normal lung fibroblasts, and how these processes might contribute to lung fibrosis in SSc patients. METHODS: TN-C secretion by SSc and normal fibroblasts was compared in vivo (in bronchoalveolar lavage [BAL] fluid) and in vitro (in culture medium). The ability of thrombin to induce TN-C was confirmed at both the protein and the messenger RNA (mRNA) level. The role of protein kinase Cepsilon (PKCepsilon) in the expression of TN-C was evaluated by determining the effects of thrombin on PKCepsilon levels and by directly manipulating PKCepsilon levels via the use of antisense oligonucleotides. RESULTS: BAL fluid from SSc patients contained high levels of TN-C, whereas that from normal subjects contained little or no TN-C. In vitro, SSc lung fibroblasts expressed much higher amounts of TN-C than did normal lung fibroblasts. Consistent with the idea that thrombin is a physiologic inducer of TN-C, thrombin stimulated TN-C mRNA and protein expression in both SSc and normal lung fibroblasts by a mechanism that required proteolytic cleavage of the thrombin receptor. Surprisingly, thrombin treatment and antisense oligonucleotide-mediated depletion of PKCepsilon indicated that TN-C expression is regulated via opposite signaling mechanisms in SSc and normal cells. In SSc lung fibroblasts, thrombin decreased PKCepsilon levels, and the decreased PKCepsilon induced TN-C secretion; in normal fibroblasts, thrombin increased PKCepsilon levels, and the increased PKCepsilon induced TN-C secretion. Normal and SSc lung fibroblasts also differed in the subcellular localization of PKCepsilon, both before and after thrombin treatment. CONCLUSION: These studies are the first to demonstrate that thrombin is a potent simulator of TN-C in lung fibroblasts and that PKCepsilon is a critical regulator of TN-C protein levels in these cells. Furthermore, our results indicate that both the regulation of PKCepsilon levels by thrombin and the regulation of TN-C levels by PKCepsilon are defective in SSc lung fibroblasts.

Bias in estimating association parameters for longitudinal binary responses with drop-outs.

This paper considers the impact of bias in the estimation of the association parameters for longitudinal binary responses when there are drop-outs. A number of different estimating equation approaches are considered for the case where drop-out cannot be assumed to be a completely random process. In particular, standard generalized estimating equations (GEE), GEE based on conditional residuals, GEE based on multivariate normal estimating equations for the covariance matrix, and second-order estimating equations (GEE2) are examined. These different GEE estimators are compared in terms of finite sample and asymptotic bias under a variety of drop-out processes. Finally, the relationship between bias in the estimation of the association parameters and bias in the estimation of the mean parameters is explored.

Testing for bias in weighted estimating equations.

It is very common in regression analysis to encounter incompletely observed covariate information. A recent approach to analyse such data is weighted estimating equations (Robins, J. M., Rotnitzky, A. and Zhao, L. P. (1994), JASA, 89, 846-866, and Zhao, L. P., Lipsitz, S. R. and Lew, D. (1996), Biometrics, 52, 1165-1182). With weighted estimating equations, the contribution to the estimating equation from a complete observation is weighted by the inverse of the probability of being observed. We propose a test statistic to assess if the weighted estimating equations produce biased estimates. Our test statistic is similar to the test statistic proposed by DuMouchel and Duncan (1983) for weighted least squares estimates for sample survey data. The method is illustrated using data from a randomized clinical trial on chemotherapy for multiple myeloma.

The impact of birth weight on the racial disparity of end-stage renal disease.

PURPOSE: Blacks have a high rate of end-stage renal disease (ESRD) and low birthweight (LBW) than whites. LBW has been associated with ESRD. The purpose of this study was to assess impact of LBW on the racial difference in ESRD.METHODS: Patients born in SC after 1950 and diagnosed with ESRD between 1991-1996 were identified from the ESRD registry. Birth weight was compared for 858 black and 372 white patients and 2460 controls matched for age, sex, and race. LBW was defined as birthweight <2500 g.RESULTS: Among patients with ESRD, mean birthweight was lower in blacks than whites (3179 vs 3367 g, p < 0.001). LBW was more common in blacks than whites with ESRD (13.9 vs 7.5%, p = 0.02). The risk ratio for LBW among ESRD patients was 1.4 (95% C.I. 1.1 to 1.8) for blacks and 1.5 (95% C.I. 0.9 to 2.5) for whites. The population attributable risk (PAR) for ESRD due to LBW was greater for blacks than whites (33.6 vs 4.2 per 100,000).CONCLUSIONS: Birthweights were lower and LBW was more common among blacks than whites with ESRD. Moreover, LBW contributed more to the PAR of ESRD in blacks than whites. Thus, LBW may contribute to the greater risk for ESRD in African Americans than Caucasians. This preliminary study indicates that further research on the link between LBW and ESRD could be instructive in understanding the racial health disparities.

Racial, age, and rural/urban disparity in cervical cancer incidence.

PURPOSE: High mortality rates of cervical cancer among black women have been observed for several decades in the Southeast. The purpose of this study is to assess the factors associated with this geographic and racial enigma, and to see if incidence is consistent with mortality.METHODS: Using the Savannah River Regional Health Information System (SRRHIS), a 5-year cancer registry from 1991-1995, incidence rates were calculated and compared to rates from Surveillance, Epidemiology, and End Results (SEER). The rates per 100,000/year were analyzed by race, rural/nonrural, and age (<45 and >/=45).Rates are similar between SRRHIS and SEER except in the case of black women over the age of 45. These women in rural SRRHIS have 1.66 times the incidence rate compared to those in nonrural SRRHIS and 1.97 times the rate of rural SEER.RESULTS:Table 1CONCLUSIONS: The results of the study suggest that the incidence of cervical cancer in the region is consistent with the mortality rates. The age-group with the highest rates are black women over 45 in rural areas, suggesting the need to target this group to reduce the racial disparity in cervical cancer.

Possible relationship between birth weight and cancer incidence among young adults.

PURPOSE: Fetal and early life events have been associated with diseases that develop later in life. Low birth weight and the adult onset of hypertension, coronary heart disease, cerebrovascular disease, and non-insulin dependent diabetes have been identified. As well, associations with breast, ovarian, and prostate cancer to high birth weight have been found. An assessment of birth weight and cancer incidence was conducted in a cohort of black and white residents under the age of 46 years.METHODS: Cases were obtained from the Savannah River Region Health Information System cancer registry incident cases (1991-1995) and were limited to South Carolinians born in 1950 and later. Controls were obtained from birth certificate records by choosing the next two records after a cancer case record that matched on year of birth, race, and sex. Results were obtained for 117 cancer cases and 238 controls.RESULTS: After examining the birth distribution, the births were split into two groups based on mean birth weight among controls (3215 grams). Conditional logistic regression (CLR) showed that individuals with higher birth weights (> = 3215 g) were 1.65 (95% CI = 1.03-2.64) times more likely to be cancer cases than those with lower birth weights. When weights were categorized into 500 g increments, a CLR Score statistic showed there was a significant trend (p = 0.0006) of increasing proportion of cancer cases with increasing birth weight. Eight out of the eight cases of lymphoma had birth weights greater than 3579 g.CONCLUSIONS: The results of this preliminary study suggest that cancer incidence among the young may be associated with higher birth weights. One possible reason for this finding, which requires further investigation, might be that larger infants are exposed to higher levels of hormones and/or growth factor than smaller infants in utero that might increase the risk of certain cancers later in life. This may be suggestive of possible environmental factors affecting early growth. These findings support the need for additional study of this association.

Non-invasive assessment of rejection in pediatric transplant patients: serologic and echocardiographic prediction of biopsy-proven myocardial rejection.

BACKGROUND: Cardiac allograft rejection is a multifocal immune process that is currently assessed using biopsy-guided histologic classification systems (International Society for Heart and Lung Transplantation). Cardiac troponin T and I are established serologic markers of global myocyte damage. The use of load-independent measures of contractility have also been shown to accurately assess the presence of ventricular dysfunction. Little is known about their utility in accurately predicting rejection in the pediatric age group. We undertook the present study to compare rejection grade with echocardiographic and serologic estimates of transplant rejection-related myocardial damage. METHODS: We compared histologic rejection grades (0 to 4) with patient characteristics, echocardiographic measurements, catheterization measurements, and biochemical markers for 86 evaluations in 37 transplant recipients at Children's Hospital. RESULTS: In univariate analyses, biopsy scores correlated (p < 0.05) inversely with left ventricular systolic function (shortening fraction) and contractility (stress velocity index, SVI), and directly with mitral E-wave amplitude. In multivariate analyses, lower contractility and higher mitral E-wave amplitude remained significantly (p < or = 0.01) associated with rejection (SVI, p = 0.002, odds ratio = 0.393; E wave, p = 0.0002, odds ratio = 228). Most rejection episodes were associated with elevation of biochemical markers of myocardial injury. Although troponin I was weakly associated with differences between rejection grades (p = 0.034), troponin T, creatine kinase-MB fraction, and C-reactive protein did not differ with biopsy-rejection scores. Serum markers had a poor predictive capacity for biopsy-detected rejection. Troponin T and I did correlate with increased left ventricular wall thickness and mass. CONCLUSION: Progressively depressed left ventricular contractility and diastolic function are found with worsening pediatric heart transplant rejection-biopsy score; however, sensitive and specific serum markers do not correspond to the degree of active myocardial injury. The use of echocardiographic measures of contractility is associated with a specificity of 91.8% but low sensitivity of 66.7%. Overall we found poor concordance between serum markers and grade of rejection. It is unclear whether myocardial injury as assessed by serum markers, echocardiography, or histologic scoring is more important for assessment of acute rejection or long-term outcome, but it does not appear that serum and tissue markers of rejection can be used interchangeably.

Analysis of dichotomous outcome data for community intervention studies.

Community intervention trials are becoming increasingly popular as a tool for evaluating the effectiveness of health education and intervention strategies. Typically, units such as households, schools, towns, counties, are randomized to receive either intervention or control, then outcomes are measured on individuals within each of the units of randomization. It is well recognized that the design and analysis of such studies must account for the clustering of subjects within the units of randomization. Furthermore, there are usually both subject level and cluster level covariates that must be considered in the modelling process. While suitable methods are available for continuous outcomes, data analysis is more complicated when dichotomous outcomes are measured on each subject. This paper will compare and contrast several of the available methods that can be applied in such settings, including random effects models, generalized estimating equations and methods based on the calculation of 'design effects', as implemented in the computer package SUDAAN. For completeness, the paper will also compare these methods of analysis with more simplistic approaches based on the summary statistics. All the methods will be applied to a case study based on an adolescent anti-smoking intervention in Australia. The paper concludes with some general discussion and recommendations for routine design and analysis.