Medium-term course and outcome of schizophrenia depicted by the sixth-month subtype after an acute episode.

BACKGROUND/PURPOSE: The intermediate course of schizophrenia is a complex intertwined with the heterogeneity of the illness. This article attempts to simplify this complexity using a hypothetical tripartite based on the profile of symptoms at 6 months after acute treatment. METHODS: This is a prospective 5-year follow-up study including 163 schizophrenic inpatients in northern Taiwan comparing patients' demographic data at index admission, scores on the Positive and Negative Syndrome Scale (PANSS) for schizophrenia and social function scale measured at admission, 6-month follow-up, and annually, and scores on a neuropsychologic test battery measured approximately 5 years after recruitment. RESULTS: Patients were grouped into three subtypes based on their sixth-month symptomatology by Generalized Association Plots, designated as remitted (RM), persistent delusion/hallucination (PDH), and markedly blunting (MB) groups. These three subtypes presented with similar positive symptom profiles at recruitment, yet during follow-up, the PDH group tended to maintain the highest risk of having worse clinical symptomatology, social functioning, and neuropsychologic functioning, and the RM was the best outcome group. CONCLUSION: This three-subtype model provides a practical reference to predict medium-term outcomes by the subject's response to acute treatment and serves as a model to sort out part of the heterogeneous nature of schizophrenia that still should be examined by further psychopharmacological, neurobiological, and genetic studies.

On ROC analysis with nonbinary reference standard.

Statistical methods for the evaluation of the accuracy of diagnostic tests usually assume a binary true disease status. However, this assumption may not be realistic in practical settings in which "disease" is defined by dichotomizing continuous or ordinal categorical measures using a pre-specified threshold value. In this paper, we focus on the analysis of studies in which both the diagnostic test and the reference standard are reported as continuous measures. We propose a semiparametric model for estimating the sensitivity, specificity, and the ROC curve as functions of reference standard thresholds. Under suitable order restrictions on the mean of the test result variable, fitting is done via two alternative approaches: isotonic regression and monotone smoothing splines. The model provides the basis to assess the effect of varying reference standard threshold on the performance of a diagnostic test. An example to evaluate the ability of the maximal SUV-lean (standardized uptake value normalized to lean body mass) in predicting axillary node involvement in women diagnosed with breast cancer is presented.

Anti-diabetic properties of three common Bidens pilosa variants in Taiwan.

Bidens pilosa L. var. radiata (BPR), B. pilosa L. var. pilosa (BPP), and B. pilosa L. var. minor (BPM) are common variants of a plant often used as a folk remedy for diabetes in Taiwan. However, the three variants are often misidentified and little is known about their relative anti-diabetic efficacy and chemical composition. In this paper, we have first developed a method based on GC-MS and cluster analysis with visualization to assist in rapidly determining the taxonomy of these three Bidens variants. GC-MS was used to determine the chemical compositions of supercritical extracts, and differences and similarities in the variants were determined by hierarchical cluster analysis. Next, the HPLC profiles of the methanol crude extracts in the Bidens plants and evaluated anti-diabetic effects of methanol crude extracts were compared, as well as three polyacetylenic compounds of the Bidens plants using db/db mice. Single-dose and long-term experiments showed that the BPR extract had higher glucose-lowering and insulin-releasing activities than extracts from the other two variants, and that cytopiloyne was the most effective pure compound among the three polyacetylenic compounds. BPR extract and cytopiloyne also significantly reduced the percentage of the glycosylated hemoglobin A1c in db/db mice. Besides, both animal studies and HPLC analysis demonstrated a good correlation between anti-diabetic efficacy of the Bidens extracts and the particular polyacetylenes present.

How do Mothers, Fathers, and Friends Influence Stages of Adolescent Smoking?

Parent and friend influences may differentially promote or deter adolescent smoking at discrete stages. Drawing from national (Add Health) data, a partial proportional odds ordinal regression model was utilized to examine the multivariate influence of parent and friend variables and their interactions on transitions across smoking stages (Never Smokers, Experimenters, Intermittent, Regular/Established) separately for mother-child pairs (N = 15,983) and father-child pairs (N = 1,142). Friend smoking status was by far the strongest predictor across smoking stages. Gender differences indicated males with one or more daily smoking friends are at higher risk for regular smoking relative to females. Fathers' smoking status had a direct effect on teen smoking across all stages, whereas mothers' smoking was significant in influencing which stage of smoking teens exhibited. Moreover, maternal smoking status had an indirect effect by moderating the association between teen smoking and the closeness of the mother-teen relationship. Mothers who smoke were found to have a stronger impact on the transition to regular smoking compared to mothers who do not smoke regardless of the number of smoking friends the teen reports. Results have implications for stage-matched and family-based prevention and intervention programs.

The predictive receiver operating characteristic curve for the joint assessment of the positive and negative predictive values.

Binary test outcomes typically result from dichotomizing a continuous test variable, observable or latent. The effect of the threshold for test positivity on test sensitivity and specificity has been studied extensively in receiver operating characteristic (ROC) analysis. However, considerably less attention has been given to the study of the effect of the positivity threshold on the predictive value of a test. In this paper we present methods for the joint study of the positive (PPV) and negative predictive values (NPV) of diagnostic tests. We define the predictive receiver operating characteristic (PROC) curve that consists of all possible pairs of PPV and NPV as the threshold for test positivity varies. Unlike the simple trade-off between sensitivity and specificity exhibited in the ROC curve, the PROC curve displays what is often a complex interplay between PPV and NPV as the positivity threshold changes. We study the monotonicity and other geometric properties of the PROC curve and propose summary measures for the predictive performance of tests. We also formulate and discuss regression models for the estimation of the effects of covariates.

Exercise participation after diagnosis of breast cancer: trends and effects on mood and quality of life.

Individuals treated for cancer often experience higher levels of emotional distress than the general population. Previous research has shown that exercise can have an ameliorating effect on these problems. This 12-month prospective longitudinal study investigated mood, quality of life, cancer-related symptoms, and exercise behavior of 69 women who had completed treatment for Stage 0-2 breast cancer. We studied the natural progression of exercise participation after cancer treatment. Effects on mood, quality of life, and cancer-related symptoms were assessed after controlling for demographic variables, disease variables, social support, and baseline values to test the hypothesis that women who exercised were more likely to report better mood, higher quality of life, and fewer cancer-related symptoms. Results indicated that women did not increase their exercise participation over time and that overall mean minutes of exercise participation were below recommended levels. Baseline demographic predictors of exercise participation included younger age, having a spouse or partner, increased time since diagnosis, higher social support, and higher depression. Exercise participation was associated with improved physical functioning, but not overall mood or cancer-related symptoms. We discuss implications of these findings towards the well-being of breast cancer survivors.