Brief PROMIS Assessment Screens for Frailty and Predicts Hospitalizations in Liver Transplant Candidates

BACKGROUND

Frailty is prevalent in patients with end-stage liver disease and predicts waitlist mortality, posttransplant mortality, and frequency of hospitalizations. The Liver Frailty Index (LFI) is a validated measure of frailty in liver transplant (LT) candidates but requires an in-person assessment.

METHODS

We studied the association between patient-reported physical function and LFI in a single-center prospective study of adult patients with cirrhosis undergoing LT evaluation from October 2020 to December 2021. Frailty was assessed with the LFI and 4-m gait speed. Patient-reported physical function was evaluated using a brief Patient-Reported Outcomes Measurement Information System (PROMIS) survey.

RESULTS

Eighty-one LT candidates were enrolled, with a mean model of end-stage liver disease-sodium of 17.6 (±6.3). The mean LFI was 3.7 (±0.77; 15% frail and 59% prefrail) and the mean PROMIS Physical Function score was 45 (±8.6). PROMIS Physical Function correlated with LFI ( r  = -0.54, P  < 0.001) and 4-m gait speed ( r  = 0.48, P  < 0.001). The mean hospitalization rate was 1.1 d admitted per month. After adjusting for age, sex, and model of end-stage liver disease-sodium, patient-reported physical function-predicted hospitalization rate ( P  = 0.001).

CONCLUSIONS

This study suggests that a brief patient-reported outcome measure can be used to screen for frailty and predict hospitalizations in patients with cirrhosis.

Personality Traits in Patients With Cirrhosis Are Different From Those of the General Population and Impact Likelihood of Liver Transplantation

BACKGROUND

Personality traits influence clinical outcomes in chronic diseases, but their impact in cirrhosis is unknown. We studied the personality of patients with cirrhosis undergoing liver transplant (LT) evaluation and determined their correlation to clinical outcomes.

METHODS

A multicenter' prospective study of adult patients undergoing LT evaluation was performed from January 2018 to October 2019. The "Big Five" personality traits of conscientiousness, extraversion, openness, neuroticism, and agreeableness plus agency were assessed with the Midlife Development Inventory Personality Scale and compared with the general population. Frailty was assessed with the Liver Frailty Index.

RESULTS

Two hundred sixty-three LT candidates were enrolled. Twenty-four percent had hepatitis C virus, 25% nonalcoholic steatohepatitis, and 25% ethyl alcohol (mean model for end-stage liver disease = 15.7). Compared with the general population, LT candidates had higher openness (3.1 versus 2.9; P < 0.001), extraversion (3.2 versus 3.1; P < 0.001), agreeableness (3.5 versus 3.4; P = 0.04), agency (2.9 versus 2.6; P < 0.001), neuroticism (2.2 versus 2.1; P = 0.001), and lower conscientiousness (3.3 versus 3.4; P = 0.007). Patients with higher conscientiousness were more likely to receive an LT (HR = 2.76; P = 0.003).

CONCLUSIONS

Personality traits in LT candidates differ significantly from the general population, with higher conscientiousness associated with a higher likelihood of receiving a transplant.

Post-Operative Severe Hyperbilirubinemia: A Case Report

Hyperbilirubinemia is commonly seen in medical practice. But what could be the highest level of bilirubin in an individual that is still an unanswered question. We came across to a 37 years old lady in October 2018 with hepaticolithiasis who underwent extended choledocholithotomy. Her preoperative serum bilirubin was within normal range. Post-operatively she developed cholangitis and from 3rd post-operative day onwards she developed severe hyperbilirubinemia, which was high as 70.47 mg/dl on the 6th post-operative day. Other causes of post-operative hyperbilirubinemia were excluded. She was managed conservatively for this hyperbilirubinemia and bilirubin level gradually reduced.

Development and performance assessment of new solar and fuel cell-powered oxygen generators and ventilators for COVID-19 patients

In this study, a new solar-based fuel cell-powered oxygenation and ventilation system is presented for COVID-19 patients. Solar energy is utilized to operate the developed system through photovoltaic panels. The method of water splitting is utilized to generate the required oxygen through the operation of a proton exchange membrane water electrolyser. Moreover, the hydrogen produced during water splitting is utilized as fuel to operate the fuel cell system during low solar availability or the absence of solar irradiation. Transient simulations and thermodynamic analyses of the developed system are performed by accounting for the changes in solar radiation intensities during the year. The daily oxygen generation is found to vary between 170.4 kg/day and 614.2 kg/day during the year. Furthermore, the amount of daily hydrogen production varies between 21.3 kg/day and 76.8 kg/day. The peak oxygen generation rate attains a value of 18.6 g/s. Moreover, the water electrolysis subsystem entails daily exergy destruction in the range of 139.9-529.7 kWh. The maximum efficiencies of the developed system are found to be 14.3% energetically and 13.4% exergetically.

Donor quality of life after living donor liver transplantation: a review of the literature

Living donor liver transplantation (LDLT) provides a source for transplant in the setting of the deceased donor organ shortage. Seeing as living donors do not derive any medical benefit from the procedure, fully understanding the impact of donation on donor health-related quality of life (HRQOL) is essential. A systematic search of the MEDLINE database was performed from 2008–2020, using relevant Medical Subject Headings. Articles were evaluated for study design, cohort size and follow-up time and excluded if they contained significant methodological flaws. A total of 43 articles were included: 20 (47%) were cross-sectional and 23 (53%) were longitudinal. The mean number of donors per study was 142 (range:8–578) with follow-up ranging from 12–132 months. Forty-two unique HRQOL metrics were implemented across the 43 studies, the majority of which were questionnaires. Of the 31 studies that used the Medical Outcomes Study Short Form 36 questionnaire, 9.1% of donors reported physical QOL did not return to pre-LDLT levels for at least 2 years after donation. Mental QOL remained stable or improved after LDLT, with mean mental composite scores increasing from 50 to 52 at 3 months post-LDLT in one study. The predicted probability of poor sexual desire decreased at 1-year post-LDLT (male: 0.08, female: 0.26) relative to pre-LDLT (male: 0.44, female: 0.76; P<0.001) and three months post-LDLT (male: 0.35, female 0.69; P=0.001). Forty percent of donors found LDLT to be financially burdensome at 3 months and 19% at 2 years post-LDLT. Female gender and obesity were consistent predictors of worse HRQOL. Laparoscopy-assisted donor hepatectomy was associated with shorter hospitalizations than open donor hepatectomy (10.3 vs. 18.3 days, P=0.02). No studies used the National Institutes of Health Patient Reported Outcomes Measurement Information System (PROMIS) measures of HRQOL. Our review demonstrates that LDLT can have a long-lasting negative impact on physical QOL in 9.1% of donors and can cause both sexual dysfunction and significant financial strain. Future studies should consider using standardized and extensively validated patient reported outcomes measures, such as PROMIS, in order to directly compare outcomes across studies and gain further insight into the impact of LDLT on D-HRQOL.

Development and analysis of a new renewable energy-based industrial wastewater treatment system

In this research study, a new solar energy-based integrated system is developed for treating industrial brine wastewater. An integrated solar-powered evaporation and membrane-based water treatment technique is utilized. Both forced convection as well as falling film evaporators are incorporated to treat high-concentration rejected brine. The system performance is assessed through a comprehensive thermodynamic investigation at varying operating parameters. The energetic performance is evaluated to vary from 12.5% to 15.9% across the year. Furthermore, the peak efficiency in terms of exergy is found to be 11.1%. Also, the membrane-based wastewater treatment subsystem is found to entail an energetic performance of 73.3% and an exergetic performance of 34.6% in terms of efficiencies. Moreover, an energetic performance of 15.4% and an exergetic performance of 2.9% is found for the evaporation-based subsystem. The exergy destructions in each system component are evaluated and the power generation subsystem is determined to have the highest exergy destruction rate of 15.4 MW. To investigate the effects of varying design parameters and operating conditions on the system performance, several parametric studies are also performed.

A THz graphene metasurface for polarization selective virus sensing

We propose a novel method to exploit chirality of highly sensitive graphene plasmonic metasurfaces to characterize complex refractive indexes (RI) of viruses by detecting the polarization state of the reflected electric fields in the THz spectrum. A dispersive graphene metasurface is designed to produce chiral surface currents to couple linearly polarized incident fields to circularly polarized reflected fields. The metasurface sensing sensitivity is the result of surface plasmon currents that flow in a chiral fashion with strong intensity due to the underlying geometrical resonance. Consequently, unique polarization states are observed in the far-field with the ellipticity values that change rapidly with the analyte's RI. The determination of bimolecular RI is treated as an inverse problem in which the polarization states of the virus is compared with a pre-calculated calibration model that is obtained by full-wave electromagnetic simulations. We demonstrate the polarization selective sensing method by RI discrimination of three different types of Avian Influenza (AI) viruses including H1N1, H5N2, and H9N2 is possible. Since the proposed virus characterization method only requires determination of the polarization ellipses including its orientation at monochromatic frequency, the required instrumentation is simpler compared to traditional spectroscopic methods which need a broadband frequency scan.

A Rare Case of Insulinoma: A Case Report

Insulinoma is a rare variety of endocrine neoplasm and is usually benign, solitary, and small in size. The hallmark of this disorder is high endogenous insulin secretion resulting in development of symptoms of hypoglycemia. Insulinomas account for 60% of islet cell tumors (ICT) of the pancreas. Ninety percent (90%) of the insulinomas measure less than 2cm. Early localization of the disease is essential to prevent lethal hypoglycemia. Here we report a case of insulinoma in a 28 year old female who subsequently underwent distal pancreatectomy with splenectomy on February 2017 in Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh.

Cardiac Progenitor Cells Enhance Neonatal Right Ventricular Function After Pulmonary Artery Banding

BACKGROUND

C-kit⁺ cardiac progenitor cells (CPCs) have been shown to be safe and effective in large-animal models and in an early-phase clinical trial for adult patients with ischemic heart disease. However, CPCs have not yet been evaluated in a preclinical model of right ventricular (RV) dysfunction, which is a salient feature of many forms of congenital heart disease.

METHODS

Human c-kit⁺ CPCs were generated from right atrial appendage biopsy specimens obtained during routine congenital cardiac operations. Immunosuppressed Yorkshire swine (6 to 9 kg) underwent pulmonary artery banding to induce RV dysfunction. Thirty minutes after banding, pigs received intramyocardial injection into the RV free wall with c-kit⁺ CPCs (1 million cells, n = 5) or control (phosphate-buffered saline, n = 5). Pigs were euthanized at 30 days postbanding.

RESULTS

Banding was calibrated to a consistent rise in the RV-to-systemic pressure ratio across both groups (postbanding: CPCs = 0.76 ± 0.06, control = 0.75 ± 0.03). At 30 days postbanding, the CPCs group demonstrated less RV dilatation and a significantly greater RV fractional area of change than the control group (p = 0.002). In addition, measures of RV myocardial strain, including global longitudinal strain and strain rate, were significantly greater in the CPCs group at 4 weeks relative to control (p = 0.004 and p = 0.01, respectively). The RV free wall in the CPCs group demonstrated increased arteriole formation (p < 0.0001) and less myocardial fibrosis compared with the control group (p = 0.02).

CONCLUSIONS

Intramyocardial injection of c-kit⁺ CPCs results in enhanced RV performance relative to control at 30 days postbanding in neonatal pigs. This model is important for further evaluation of c-kit⁺ CPCs, including long-term efficacy.

A study on gender-related differences in laboratory characteristics of dengue fever

Studies have reported significant gender-related differences in serological tests for detection of NS1 antigen and IgM antibody used for diagnosing dengue fever. However, no such study has been undertaken in India though dengue fever is endemic in this country. Therefore, this study was planned to study the association of serological findings with gender in 700 patients suspected to be suffering from dengue fever in the Indian setting. Haematological parameters of seropositive patients were also studied. Seropositivity and haemorrhagic findings were significantly associated with the female gender. Positive NS1 antigen and IgM antibody results were significantly associated with females and males, respectively.

Intracoronary Stem Cell Delivery to the Right Ventricle: A Preclinical Study

Clinical protocols for stem cell-based therapies are currently under development for patients with hypoplastic left heart syndrome. An ideal cell delivery method should have minimal safety risks and provide a wide distribution of cells to the nonischemic right ventricle (RV). However, the optimal strategy for stem cell delivery to the RV has yet to be explored in a preclinical model, necessary for a hypoplastic left heart syndrome trial. Human c-kit⁺ cardiac stem cells (CSCs) were delivered to healthy Yorkshire swine through the proximal right coronary artery with a stop and reflow technique. The effect of premedication with antiarrhythmic (AA) medications in this model was retrospectively reviewed, with the primary outcome of survival 2 hours after infusion. A group underwent CSC delivery to the RV without prophylactic AA medication (no AA, n = 7), whereas the second group was premedicated with a loading dose and intravenous infusion of amiodarone and lidocaine (AA, n = 13). Cardiac biopsies were obtained from each chamber to ascertain the biodistribution of CSCs. Survival was significantly greater in the prophylactic AA group compared with the group without AA (13/13 [100%] vs 1/7 [14.3%], P < 0.0001). Cardiac arrest during balloon inflation was the cause of death in each of the nonmedicated animals. In the premedicated group, 9 (69.2%) pigs experienced transient ST segment changes in the precordial leads during CSC delivery, which resolved spontaneously. Most c-kit⁺ CSCs were distributed to lateral segments of the RV free wall, consistent with the anatomical course of the right coronary artery (lateral RV, 19.2 ± 1.5 CSCs/field of view vs medial RV, 10.4 ± 1.3 CSCs/field of view, P < 0.0001). Few c-kit⁺ CSCs were identified in the right atrium, septum, or left ventricle. Prophylactic infusion of AA enhances survival in swine undergoing intracoronary delivery of human c-kit⁺ CSCs to the RV. Additionally, intracoronary delivery results in a limited biodistribution of c-kit⁺ CSCs within the RV. Human clinical protocols can be optimized by requiring infusion of AA medications before cell delivery.

Dieulafoy's lesion: an overview

Dieulafoy's lesion accounts for 1-5.8% of cases of acute upper GI bleeding. The two largest retrospective series, both from North America, found Dieulafoy's lesion as the source of hemorrhage in 1.9% and 1.2% of all endoscopies performed for acute GI bleeding. In the prospective study of Chung et al., Dieulafoy's Lesion was found in 3.4% of all patients with acute GI bleeding referred to their unit. The Dieulafoy's Lesion accounted for up to 40% of all causes of nonvariceal upper GI bleeding not caused by gastric or duodenal ulceration or esophageal varices in the prospective study of Matsui et al. In the study of Schmulewitz and Bailli, colonic Dieulafoy's Lesion were only found in 0.09% of all colonoscopies performed for lower GI bleeding. The actual incidence of both upper and lower GI bleeding from Dieulafoy's Lesion is likely higher than estimated because the diagnosis remains difficult. Recent advances in endoscopy have led to an increased detection of Dieulafoy's lesions. Initial GI endoscopy is effective in diagnosing up to 70% of patients. Several endoscopies may be required with 6% of patients, requiring three or more to establish the diagnosis. Angiography and/or red cell scanning can be used when endoscopy fails to diagnose a doubtful case. There is no definite unique policy for the treatment of Dieulafoy's lesions. Therapeutic endoscopy remains the first line of treatment option for controlling the bleeding while angiography is considered as a valuable alternative. Surgical intervention is kept for failure cases where it should be guided by preoperative localization. The mortality rate has decreased dramatically from 80% to 8.6% in recent times due to advancement in both diagnostic and therapeutic tools.

Ventral free oral mucous membrane graft for bulbar urethral stricture

The use of oral mucous membrane graft onlay urethroplasty represents the most widespread method of bulbar urethral stricture repair. We investigated the short term result of oral mucous membrane graft placed on the ventral surface for management of bulbar urethral stricture. Patients with Bulbar urethral stricture of any length, infection free urinary tract and informed consent for oral mucosa harvesting and urethroplasty were selected for study. We enrolled 108 cases of bulbar urethral stricture patients from January 2004 to July 2009. The mean ± SD preoperative maximum flow rate of 5.2 ± 2.6 ml/sec and mean ± SD PVR 87 ± 58.3 ml were treated by substitution urethroplasty with oral mucous membrane by a single surgical team in a private hospital. Causes of stricture were trauma 26(24.1%), infection 58(53.7%), catheter induced 8(7.4%), post TURP 11(10.2%) and unknown 5(4.6%). Oral mucous membrane was harvested from the cheek or from the inner side of lower lip. Defect of the urethra displayed by longitudinal ventral urethrotomy and the graft was sutured over the edges of the incised urethral mucosa over a 14 Fr latex Foley's catheter. Spongiosum tissue was closed over the graft. Pericatheter urethrogram was performed in all cases to check for the anastomotic leakage and the Catheter was removed after 2 weeks of the procedure. After removal of catheter uroflowmetry & ultrasound scan of bladder were performed to estimate the maximum flow rate and post voidal residue. The patient was followed-up every 3 months with uroflowmetry & ultrasonography. The median (range) age of the patients was 32(21-72) years. Mean follow up period was 36 months (range 12-54). Mean ± SD stricture length was 3.7 ± 2.6 cm. The overall success rate was 91.7%. Mean ± SD flow rate was 23 ± 4.2 ml/sec, mean ± SD post void residue was 25 ± 15.5 ml and patient quality of life (QOL) was excellent in almost all patients. Overall complications were seen in 9(8.3%) cases. Of which, restricture occurred in 6 patients; periurethral fistulae seen in 2 cases and per urethral bleeding in 1 patient. No significant complications were observed at the donor site. Oral numbness and mild discomfort complained by 67.6% patients which were managed by reassurance only. In our experience ventral placement of oral mucous membrane graft along with spongioplasty is a very easy procedure with very encouraging short term result.

Abstract P77: Reduced Inflammatory Response with a Novel Cardiopulmonary Bypass Circuit: A Prospective Randomized Evaluation

BACKGROUND: The detrimental effects of inflammation following cardiopulmonary bypass (CPB) result in poor postoperative outcomes in patients undergoing heart surgery. A novel CPB circuit (Admiral, Eurosets, Italy) with its inner surface coated with a proprietary phosphorylcholine coating was hypothesized to elicit a reduced inflammatory response compared to a conventional CPB circuit.

METHODS: Patients undergoing isolated aortic valve surgery were enrolled in a prospective study and either assigned to Admiral group (Admiral, n=15) or the conventional CPB group (Dideco, n=15). The Admiral oxygenator reduces priming volumes, decreases membrane surface area and incorporates a cell-saver selectively filtering the blood collected through mediastinal cavity before re-transfusion into the patient. The conventional CPB circuit used was a Dideco D903 Avant with an open cardiotomy reservoir. Clinical data and biochemical parameters were measured postoperatively, during CPB and at 1, 18, 36, 48 and 72 hours, respectively.

RESULTS: Preoperative demographics such as age (68.2±10.4 vs. 70.9±10), Euroscore (6.8±2.3 vs. 6.2±1.1) as well as others did not differ between Admiral and Dideco groups, respectively. The CPB time (Admiral=104±30 vs. Dideco=99±17 minutes, p=NS), aortic cross clamp time (Admiral=73.2±17.5 vs. Dideco=73.8±19 minutes, p=NS) and the incidence of perioperative complications were also comparable. There was a significant decrease in the Admiral group with respect to inflammatory response, assessed by means of D-dimer (Admiral=1332.3±953.9 vs. Dideco=2791.9±1740.7, p=0.02), CRP (Admiral=169.1±164.8 vs. Dideco=57.1±39.3, p=0.04), IL-6 (Admiral=11.8±12.5 vs. Dideco=26.5±24.9, p=0.02) and TNF-a (Admiral=29±28.7 vs. Dideco=45.5±23.6, p=0.03).

CONCLUSIONS: Although no considerable difference was detected in terms of peri-operative outcomes, the Admiral oxygenator did result in a significant reduction of inflammatory markers in immediately postoperative course primarily due to its enhanced biocompatibility. More powerful studies may yield potentially incremental benefits with Admiral oxygenator in future.

Multiple imputation compared with some informative dropout procedures in the estimation and comparison of rates of change in longitudinal clinical trials with dropouts

Statistical analysis based on multiple imputation (MI) of missing data when analyzing data with missing observations is gaining popularity among statisticians because of availability of computing softwares; it might be tempting to use MI whenever data is missing. An important assumption behind MI is the "ignorability of missingness." In this paper, we demonstrate the use of MI in conjunction with random effects models and several other methods that are devised to handle nonignorable missingness (informative dropouts). We then compare the results to assess sensitivity to underlying assumptions. Our focus is primarily to estimate and compare rates of change (of a primary variable). The application dataset has a high dropout rate and has features to suggest informativeness of the dropout process. The estimates obtained under random effects modeling with multiple imputation were found to differ substantially from those obtained by methods devised to handle informative dropouts.

Random-effects regression analysis of correlated grouped-time survival data

Random-effects regression modelling is proposed for analysis of correlated grouped-time survival data. Two analysis approaches are considered. The first treats survival time as an ordinal outcome, which is either right-censored or not. The second approach treats survival time as a set of dichotomous indicators of whether the event occurred for time periods up to the period of the event or censor. For either approach both proportional hazards and proportional odds versions of the random-effects model are developed, while partial proportional hazards and odds generalizations are described for the latter approach. For estimation, a full-information maximum marginal likelihood solution is implemented using numerical quadrature to integrate over the distribution of multiple random effects. The quadrature solution allows some flexibility in the choice of distributions for the random effects; both normal and rectangular distributions are considered in this article. An analysis of a dataset where students are clustered within schools is used to illustrate features of random-effects analysis of clustered grouped-time survival data.

Linear structural equation model in analyzing quality-of-life-data from clinical trials

Assessment of quality of life (QOL) in clinical trials becomes a challenging task from the viewpoint of clinical biostatistics. The responses of the items for measuring QOL indices usually vary widely from patient to patient and from time to time. Measurement errors might be present in the responses of the items, and they might be correlated. Hence, in analyzing QOL data, the usual assumption that there are no measurement errors in responses is too liberal. Because the QOL indices are likely to be correlated, separate analysis of each index might not be efficient from the point of view of statistical methodology. We apply linear structural equation modeling (LISREL) in assessing the QOL data obtained from a clinical trial. A basic premise of the LISREL approach is that the abstract concepts (latent constructs) that are not directly measurable can be studied. LISREL is a statistical procedure for conceiving and testing structural hypotheses that cannot be tested adequately with other statistical procedures. It allows us to specify relations between unobserved and observed variables while controlling for measurement errors and correlations among both the measurement errors and the latent constructs.

The application of Poisson random-effects regression models to the analyses of adolescents' current level of smoking

BACKGROUND

In school-based smoking prevention research, it is still debatable whether parents or peers are most influential to maintained smoking among adolescents. As a result, this study examines the effects of parental and peer approval of smoking on adolescents' current levels of smoking.

METHODS

Poisson random-effects regression models were used to assess the effects of parental and peer approval of smoking on adolescents' (n = 913) current level of smoking.

RESULTS

Results of these analyses indicate that a stronger relationship between parental approval of smoking and current level of smoking was found for female adolescents than for male adolescents. Conversely, a stronger relationship between peer approval of smoking and current level of smoking was found for male adolescents than for female adolescents. With respect to race, the influence of parental approval of smoking on adolescents' current level of smoking was generally more pronounced for minority adolescents, relative to white adolescents. However, the influence of peer approval of smoking on current level of smoking was strongest for white adolescents and was less strong for black, Hispanic, and Asian adolescents.

CONCLUSION

The findings of this study demonstrated that the effects of parental and peer approval of smoking on adolescents' current levels of smoking were varied by gender and race. These differential effects may have some implication for the development of future school-based smoking prevention and cessation programs.

Characteristics of inconsistent respondents who have "ever used" drugs in a school-based sample

This study examines the predictors of inconsistent responses from adolescents to questions about whether they ever used alcohol, cigarettes, and marijuana. Male adolescents had significantly higher rates of inconsistent responses than female adolescents. Black and Hispanic adolescents had significantly higher rates of inconsistent responses regarding ever using alcohol and cigarettes (only for Black) than White adolescents. The subjects' living status and academic achievements were significant predictors of inconsistent responses regarding ever using marijuana. Thus, these results are consistent with the notion that inconsistent responses may bias the estimation of the prevalence of ever using drugs in multivariate analyses.

A comparison of the random-effects pattern mixture model with last-observation-carried-forward (LOCF) analysis in longitudinal clinical trials with dropouts

The last-observation-carried-forward imputation method is commonly used for imputting data missing due to dropouts in longitudinal clinical trials. The method assumes that outcome remains constant at the last observed value after dropout, which is unlikely in many clinical trials. Recently, random-effects regression models have become popular for analysis of longitudinal clinical trial data with dropouts. However, inference obtained from random-effects regression models is valid when the missing-at-random dropout process is present. The random-effects pattern-mixture model, on the other hand, provides an approach that is valid under more general missingness mechanisms. In this article we describe the use of random-effects pattern-mixture models under different patterns for dropouts. First, subjects are divided into groups depending on their missing-data patterns, and then model parameters are estimated for each pattern. Finally, overall estimates are obtained by averaging over the missing-data patterns and corresponding standard errors are obtained using the delta method. A typical longitudinal clinical trial data set is used to illustrate and compare the above methods of data analyses in the presence of missing data due to dropouts.

Patterns of use of smokeless tobacco and the unidimensional model of drug involvement

The present study tested whether smokeless tobacco (ST) fits a unidimensional model of drug involvement and tried to locate ST along the dimension that underlies drug use. The latent trait analysis was employed to quantify drug involvement in a sample of high school students. Analyses showed that although ST use fits the unidimensional model of drug involvement, the place of ST use along the continuum of drug involvement is not stable and differs by gender and ethnicity. Particularly for males, ST use is likely to be preceded by soft drug use and followed by hard drug use; for females, however, ST use is closely associated with hard drug use. The analyses also revealed that the fit of the unidimensional model and the location of ST use along the dimension vary with different ethnic groups.

Factors affecting attrition in a longitudinal smoking prevention study

BACKGROUND

In longitudinal smoking prevention studies, a difficulty in evaluating treatment effects is understanding whether bias is associated with those who do not complete the study. This study presents the significant predictors of attrition and suggests how to reduce attrition bias in evaluating program effects.

METHODS

Survival analysis methods were used to assess factors associated with attrition at different time points of the study.

RESULTS

Results of the analysis indicate that those who drop out tend to be of lower academic achievement, have lower tobacco and health knowledge, and have lower social influence/resistance skills knowledge, and are more likely to be smokers and to be marijuana users. Blacks are more likely to drop out than the other ethnic groups. Gender is not a significant predictor for dropout. The dropout rates among the treatment conditions are significantly different.

CONCLUSIONS

The findings of this study demonstrate that attritions in longitudinal smoking prevention studies are not at random. By considering the characteristics of dropouts, one can reduce attrition bias using available procedures and can take appropriate strategies for reducing dropout rates in future smoking prevention studies.

Intraclass correlation estimates in a school-based smoking prevention study. Outcome and mediating variables, by sex and ethnicity

Most school-based smoking prevention studies employ designs in which schools or classrooms are assigned to different treatment conditions while observations are made on individual students. This design requires that the treatment effect be assessed against the between-school variance. However, the between-school variance is usually larger than the variance that would be obtained if students were individually randomized to different conditions. Consequently, the power of the test for a treatment effect is reduced, and it becomes difficult to detect important treatment effects. To assess the potential loss of power or to calculate appropriate sample sizes, investigators need good estimates of the intraclass correlations for the variables of interest. The authors calculated intraclass correlations for some common outcome variables in a school-based smoking prevention study, using a three-level model-i.e., students nested within classrooms and classrooms nested within schools. The authors present the intraclass correlation estimates for the entire data set, as well as separately by sex and ethnicity. They also illustrate the use of these estimates in the planning of future studies.

The patterns and predictors of smokeless tobacco onset among urban public school teenagers

This study describes the patterns and predictors of smokeless tobacco (ST) use in a large sample of urban public school students in Los Angeles and San Diego. The use of ST is more common among men than women and among Caucasians than African Americans, Hispanics, and others. Approximately 20% of the male respondents and 5% of the female respondents reported use of ST at least once, and 10.1% of male students and 3.1% of female students who had never tried ST by seventh grade started to use it by eighth grade. Among Caucasians, about 30% of boys reported trying ST at least once and 13.7% of those who had never used ST by seventh grade initiated experimentation by eighth grade. These data are used to examine the family, peer, and intrapersonal predictors of ST onset. The family risk factors for ST onset include living with a single parent, parent-child conflicts, and parental alcohol use. The peer risk factors for ST use include peer drug use and activities with friends, such as parties and participation in sports. The intrapersonal risk factors include poor grades in school, risk taking, and stress. The study also shows that those who use cigarettes, alcohol, or marijuana are at higher risk of using ST and vice versa. This study supports a problem-prone behavior perspective of ST use and cigarette smoking. We suggest that both products be targeted because the same programs are likely to apply to both products to counteract problem-prone type variables. Medical Subject Headings (MeSH): tobacco, smokeless chewing tobacco, adolescent behavior.

The television, school, and family smoking prevention and cessation project. VIII. Student outcomes and mediating variables

BACKGROUND

This paper presents the student outcomes of a large-scale, social-influences-based, school and media-based tobacco use prevention and cessation project in Southern California.

METHODS

The study provided an experimental comparison of classroom delivery with television delivery and the combination of the two in a 2 x 2 plus 1 design. Schools were randomly assigned to conditions. Control groups included "treatment as usual" and an "attention control" with the same outcome expectancies as the treatment conditions. Students were surveyed twice in grade 7 and once in each of grades 8 and 9. The interventions occurred during grade 7.

RESULTS

We observed significant effects on mediating variables such as knowledge and prevalence estimates, and coping effort. The knowledge and prevalence estimates effects decayed partially but remained significant up to a 2-year follow-up. The coping effort effect did not persist at follow-ups. There were significant main effects of both classroom training and TV programming on knowledge and prevalence estimates and significant interactions of classroom and TV programming on knowledge (negative), disapproval of parental smoking, and coping effort. There were no consistent program effects on refusal/self-efficacy, smoking intentions, or behavior.

CONCLUSIONS

Previous reports demonstrated successful development and pilot testing of program components and measures and high acceptance of the program by students and parents. The lack of behavioral effects may have been the result of imperfect program implementation or low base rates of intentions and behavior.

Differential influence of parental smoking and friends' smoking on adolescent initiation and escalation of smoking

Smoking-related behaviors and attitudes of significant others (especially friends and parents) are among the most consistent predictors of adolescent smoking. However, theorists remain divided on whether the behaviors of significant others influence adolescent smoking directly or indirectly, and the relative influence of parental and peer smoking on adolescents' own smoking is still a matter of debate. In addition, little research has examined the role of significant others' behavior on different stages of smoking onset. In particular, not much information is available regarding gender and ethnic differences in social influences on smoking behavior. We use structural equation modeling to address these issues. Different theoretical perspectives from cognitive-affective theories (Ajzen 1985; Ajzen and Fishbein 1980) and social learning theories (Akers et al. 1979; Bandura 1969, 1982, 1986) have been integrated into a structural model of smoking influence. The results show that friends' smoking affects adolescent initiation into smoking both directly and indirectly, whereas parental smoking influences smoking initiation only indirectly. The data also show that friends' and parents' smoking affect smoking escalation only indirectly. In general, friends' smoking has a stronger effect on adolescents' smoking behavior, particularly on initiation. Multiple group comparisons of the structural models predicting smoking initiation among males and females reveal that parental approval of smoking plays a significant mediating role for females, but not for males. Comparisons of Whites, Blacks, Hispanics, and other ethnic groups reveal that there are some significant differences in the pathways of friends' influences among the four groups.

Preparation and Properties of a Glycerolatocalcium Complex

The synthesis of a glycerolatocalcium complex has been achieved by heating precipitated calcium hydroxide and glycerol to above 180�C in a microwave oven. The complex has the formula C3H6CaO3, and therefore it appears to have a molecular structure similar to that of the cobalt and zinc analogues. X-Ray powder and single-crystal data are consistent with the complex having an orthorhombic unit cell with a 6.420 �0.006, b 7.930 � 0.010, c 8.967 � 0.010 � and volume of 456.51 � 0.69 � 3. Experiments in vivo (rats) and in vitro were conducted to demonstrate the transdermal permeation that occurred after topical application of this complex. The experiments were aimed at delivering therapeutic amounts of calcium by the transdermal route.

Percutaneous absorption of steroids: relative contributions of epidermal penetration and dermal clearance

The permeation of triamcinolone, hydrocortisone, prednisolone, corticosterone, triamcinolone acetonide, testosterone, and betamethasone-17-valerate through excised human stratum corneum was quantified. The time course of permeation could be adequately described by a simple diffusion model suggesting that shunt transport may not be important. The disappearance of these steroids from aqueous solutions applied to human and rat dermis was also monitored. The concentrations of unbound steroid in the viable epidermis appeared to be mainly related to the blood perfusion rate in the dermis and, more importantly, to the lipophilicity of the steroid. The most lipophilic steroids penetrated the human epidermis at the fastest rates but are cleared from the viable epidermis at rates comparable to those found for more polar steroids.

Iontophoretic transport of weak electrolytes through the excised human stratum corneum

The effect of iontophoresis on the rate of permeation of a number of therapeutically active weak acids and bases through excised human stratum corneum has been examined, over a range of pH values. It has been shown that the amount of ionized drug species present in the drug solution is an important factor in the delivery of acids and bases by this route and that the molecular weight of the drug does not influence the rate of delivery by iontophoresis.

The effect of iontophoresis and vehicle pH on the in-vitro permeation of lignocaine through human stratum corneum

The effect of iontophoresis and the pH of aqueous vehicles on the rate and extent of permeation of lignocaine through excised human stratum corneum was investigated. In the absence of iontophoresis, the rate of penetration was greatest at the higher pH values where lignocaine exists mainly in the unionized form; iontophoresis was most effective at the lower pH values where lignocaine is mainly ionized. At pH 3.4, and 5.2, the flux increased during iontophoresis, by approximately 8.5 and 4 times, respectively, relative to that occurring without iontophoresis. The present results suggest that some weak electrolytes which show poor percutaneous penetration may be administered topically using iontophoresis provided the drug is kept in a highly ionized form.

Physical factors affecting microencapsulation by simple coacervation of gelatin

Gelatin has been coacervated at 60 degrees C using sodium sulphate. Interfacial tensions between coacervate and supernatant liquid, coacervate and two oils (with and without one of two drugs, clofibrate and chlormethiazole) and supernatant liquid and the oils (+/- drug) have been measured by a drop volume technique, in the presence and absence of one of three surfactants, cetrimide, sodium lauryl sulphate and hexadecyltrimethylammonium lauryl sulphate (double salt). Spreading coefficients calculated from tensions indicate that coacervate should spread readily over oil droplets in presence of double salt, less readily with cetrimide and spreading is unlikely in the presence of sodium lauryl sulphate. The sign of the charge on coacervate droplets and oil droplets was identified under different conditions and showed coacervate droplets and oil droplets have opposite charges except in the presence of sodium lauryl sulphate. Microcapsules were prepared using cetrimide or 'double salt' as emulsifier and release of drug measured. Those prepared with 'double salt' released more slowly than those prepared with cetrimide.