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PubMed2003

A perfect correlate does not a surrogate make.

BACKGROUND: There is common belief among some medical researchers that if a potential surrogate endpoint is highly correlated with a true endpoint, then a positive (or negative) difference in potential surrogate endpoints between randomization groups would imply a positive (or negative) difference in unobserved true endpoints between randomization groups. We investigate this belief when the potential surrogate and unobserved true endpoints are perfectly correlated within each randomization group. METHODS: We use a graphical approach. The vertical axis is the unobserved true endpoint and the horizontal axis is the potential surrogate endpoint. Perfect correlation within each randomization group implies that, for each randomization group, potential surrogate and true endpoints are related by a straight line. In this scenario the investigator does not know the slopes or intercepts. We consider a plausible example where the slope of the line is higher for the experimental group than for the control group. RESULTS: In our example with unknown lines, a decrease in mean potential surrogate endpoints from control to experimental groups corresponds to an increase in mean true endpoint from control to experimental groups. Thus the potential surrogate endpoints give the wrong inference. Similar results hold for binary potential surrogate and true outcomes (although the notion of correlation does not apply). The potential surrogate endpoint would give the correct inference if either (i) the unknown lines for the two group coincided, which means that the distribution of true endpoint conditional on potential surrogate endpoint does not depend on treatment group, which is called the Prentice Criterion or (ii) if one could accurately predict the lines based on data from prior studies. CONCLUSION: Perfect correlation between potential surrogate and unobserved true outcomes within randomized groups does not guarantee correct inference based on a potential surrogate endpoint. Even in early phase trials, investigators should not base conclusions on potential surrogate endpoints in which the only validation is high correlation with the true endpoint within a group.

Endpoint Determination↗
PubMed2002

Statistics review 6: Nonparametric methods.

The present review introduces nonparametric methods. Three of the more common nonparametric methods are described in detail, and the advantages and disadvantages of nonparametric versus parametric methods in general are discussed.

Humans↗
PubMed2003

Telomerase activity and telomere length of peripheral blood mononuclear cells in SLE patients.

We evaluated the clinical significance of the telomerase activity and telomere length of peripheral blood mononuclear cells (PBMC) in systemic lupus erythematosus (SLE). PBMC were isolated from 55 patients with SLE and the telomerase activity was measured by TRAP assay. The telomere length of PBMC was also measured in 30 of these subjects. As a control group, 45 healthy adults with no particular clinical history were studied. The results were compared with clinical data. In patients with active SLE, the telomerase activity of PBMC was significantly increased compared with the control group. In patients with inactive SLE, the PBMC telomerase activity was not different compared with the controls in their 20s, 30s and 40s, but it was significantly increased compared with the controls in their 50s. In SLE patients, the telomerase activity of PBMC was significantly correlated with modified SLEDAI. The telomere length of PBMC in younger SLE patients tended to be shorter than that in the controls, but no difference was observed in older patients. The correlation coefficient between the telomerase activity and telomere length of PBMC in SLE patients was not significant. Abnormalities in the telomerase activity and telomere length observed in SLE patients are considered to be important findings for evaluation of the pathology of SLE.

Adolescent↗
PubMed1998

Influence of more extensive radiotherapy and adjuvant chemotherapy on long-term outcome of early-stage Hodgkin's disease: a meta-analysis of 23 randomized trials involving 3,888 patients. International Hodgkin's Disease Collaborative Group.

PURPOSE: To assess the effect of more extensive radiotherapy and of adjuvant combination chemotherapy on long-term outcome of early-stage Hodgkin's disease. METHODS: In a collaborative worldwide systematic overview, individual patient data were centrally reviewed on 1,974 patients in eight randomized trials of more versus less extensive radiotherapy and on 1,688 patients in 13 trials of radiotherapy plus chemotherapy versus radiotherapy alone. Crude mortality data on 226 patients in two other trials of chemotherapy were also reviewed. RESULTS: More extensive radiotherapy reduced the risk of treatment failure (resistant or recurrent disease) at 10 years by more than one third (31.3% v 43.4% failures; P < .00001), but there was no apparent improvement in overall 10-year survival (77.1 % v 77.0% alive). The addition of chemotherapy to radiotherapy halved the 10-year risk of failure (15.8% v 32.7%; P < .00001), with a small, nonsignificant improvement in survival (79.4% v 76.5% alive). This involved a reduction of borderline significance for deaths from Hodgkin's disease (12.3% v 15.4% dead at 10 years; P = .07), which was partly counterbalanced by a nonsignificant excess of deaths from other causes (12.4% v 10.0% 10-year risk). CONCLUSION: More extensive radiotherapy fields or the addition of chemotherapy to radiotherapy in the initial treatment of early-stage Hodgkin's disease had a large effect on disease control, but only a small effect on overall survival. Recurrences could be prevented by more extensive radiotherapy or by additional chemotherapy. However, if chemotherapy had not been given initially, recurrences were generally salvageable by re-treatment with chemotherapy. Hence, less intensive primary treatment--particularly a reduction in radiotherapy fields--appears to achieve similar survival rates as more intensive treatment, although more randomized evidence is needed to confirm this.

Antineoplastic Agents↗
PubMed1990

Systemic lymphoblastoid interferon therapy in chronic progressive multiple sclerosis. I. Clinical and MRI evaluation.

A randomized, double-blind, placebo-controlled, noncrossover trial determined the efficacy of lymphoblastoid interferon (IFN) in chronic progressive multiple sclerosis (CP MS). Fifty patients received 5 X 10(6) IU IFN subcutaneously daily for 6 months while 50 received placebo. After 2 years, there were no significant differences between the 2 groups based on clinical evaluations and quantitative MRI analysis of the brain, although a trend was observed in the IFN group. Clinically, the IFN group was worse at 1 and 3 months and improved at 6 to 18 months, when compared with the placebo group. Results of MRI evaluations of the brain at 6 months support this trend. This trend likely resulted from a subpopulation of 10 IFN-treated patients, characterized by a higher women:men ratio and a lower EDSS score at entry into the trial. We cannot recommend lymphoblastoid IFN as treatment for CP MS at this time.

Adult↗
PubMed2003

Genetic correlates of gene expression in recombinant inbred strains: a relational model system to explore neurobehavioral phenotypes.

Full genome sequencing, high-density genotyping, expanding sets of microarray assays, and systematic phenotyping of neuroanatomical and behavioral traits are producing a wealth of data on the mouse central nervous system (CNS). These disparate resources are still poorly integrated. One solution is to acquire these data using a common reference population of isogenic lines of mice, providing a point of integration between the data types. Recombinant inbred (RI) mice, derived through inbreeding of progeny from an inbred cross, are a powerful tool for complex trait mapping and analysis of the challenging phenotypes of neuroscientific interest. These isogenic RI lines are a retrievable genetic resource that can be repeatedly studied using a wide variety of assays. Diverse data sets can be related through fixed and known genomes, using tools such as the interactive web-based system for complex trait analysis, www.WebQTL.org. In this report, we demonstrate the use of WebQTL to explore complex interactions among a wide variety of traits--from mRNA transcripts to the impressive behavioral and pharmacological variation among RI strains. The relational approach exploiting a common set of strains facilitates study of multiple effects of single genes (pleiotropy) without a priori hypotheses required. Here we demonstrate the power of this technique through genetic correlation of gene expression with a database of neurobehavioral phenotypes collected in these strains of mice through more than 20 years of experimentation. By repeatedly studying the same panel of mice, early data can be re-examined in light of technological advances unforeseen at the time of their initial collection.

Animals↗
PubMed2003

Results after two years of non-operative treatment of occlusal surface in children with high caries prevalence.

The aim of this study was to describe the 2-year results of an individualized treatment program designed to control occlusal caries in erupting first permanent molars. The sample consisted of 145 five-to-six-year-old students divided into a control group (n = 71) and a test group (n = 74). All test children received a biannual basic preventive program and a recall system according to individual disease activity. The basic program consisted of 3 (March) and 2 (August) sessions of oral hygiene orientation and toothbrushing with fluoride gel. The analysis of the baseline and 1-2-year data showed a significant reduction in the number of active lesions in the test group. In the control group, there were initially 70 active lesions and after two years 68 surfaces remained with disease and 24 surfaces had been filled. The children in the test group had 80 surfaces with active lesions initially and after two years only 3 surfaces with disease remained. From the 15 cavitated lesions, only 5 surfaces needed to be filled. This program showed that care of erupting teeth on an individualized basis can control occlusal caries.

Cariostatic Agents↗
PubMed2001

Nasometric values for normal nasal resonance in the speech of young Flemish adults.

OBJECTIVE: The purpose of this study was to obtain normative nasalance scores for adult subjects speaking the Flemish language. Additional objectives of the study were to determine if speaker sex played a role in differences in nasalance scores and if significantly different nasalance scores existed for Flemish compared with other languages or dialects. DESIGN: Nasalance scores were obtained while young Flemish adults read three standard nasalance passages. These passages were an oronasal passage (a text that contained the same approximate percentage of nasal consonants as found in the standard Dutch speech), an oral passage (a text that excluded nasal consonants), and a nasal passage (a reading text loaded with nasal consonants). PARTICIPANTS: Subjects included 58 healthy young Flemish adults with normal oral and velopharyngeal structure and function, normal hearing levels, normal voice characteristics, and normal resonance and articulation skills. METHODS: The Nasometer (model 6200) was used to obtain nasalance scores for the three reading passages. These three reading passages were designed specifically for use with the nasometer. The nasalance data were analyzed for sex dependence, using Student's t test for each reading passage. This same test was used for comparison of our data with data of other languages. RESULTS: Normative nasalance data were obtained for the oronasal text (33.8%), the oral text (10.9%), and the nasal text (55.8%). Female speakers exhibited significantly higher nasalance scores than male speakers on the passages containing nasal consonants (normal text, p = .001; nasal text, p = .042). Furthermore, statistically significant cross-linguistic nasality differences were observed. The English and Spanish languages were found to have more nasalance than the Flemish language. For the North Dutch and Flemish languages, this cross-linguistic phenomenon was absent. CONCLUSION: These normative nasalance scores for normal young adults speaking the Flemish language provide important reference information for Flemish cleft palate teams. Sex-related differences and cross-linguistic differences were shown.

Adult↗
PubMed2001

Nasalance measures in Cantonese-speaking women.

OBJECTIVES: To establish and evaluate stimulus materials for nasalance measurement in Cantonese speakers, to provide normative data for Cantonese-speaking women, and to evaluate session-to-session reliability of nasalance measures. PARTICIPANTS AND SETTING: One hundred forty-one Cantonese-speaking women with normal resonance who were students in the Department of Speech and Hearing Sciences, University of Hong Kong. PROCEDURES: Participants read aloud four speech stimuli: oral sentences, nasal sentences, an oral paragraph (similar to the Zoo Passage), and an oral-nasal paragraph (similar to the Rainbow Passage). Data were collected and analyzed using the Kay Nasometer 6200. Data collection was repeated for a subgroup of speakers (n = 28) on a separate day. Nasalance materials were evaluated by using statistical tests of difference and correlation. RESULTS: Group mean (standard deviation) nasalance scores for oral sentences, nasal sentences, oral paragraph, and oral-nasal paragraph were 16.79 (5.99), 55.67 (7.38), 13.68 (7.16), and 35.46 (6.22), respectively. There was a significant difference in mean nasalance scores for oral versus nasal materials. Correlations between stimuli were as expected, ranging from 0.43 to 0.91. Session-to-session reliability was within 5 points for over 95% of speakers for the oral stimuli but for less than 76% of speakers for the nasal and oral-nasal stimuli. CONCLUSIONS: Standard nasalance materials have been developed for Cantonese, and normative data have been established for Cantonese women. Evaluation of materials indicated acceptable differentiation between oral and nasal materials. Two stimuli (nasal sentences and oral paragraph) are recommended for future use. Comparison with findings from other languages showed similarities in scores; possible language-specific differences are discussed. Session-to-session reliability was poorer for nasal than oral stimuli.

Adolescent↗
PubMed2001

Nasal morphology and shape parameters as predictors of nasal esthetics in individuals with complete unilateral cleft lip and palate.

OBJECTIVE: The purpose of this study was to assess the ability of shape parameters of nasal morphology to predict esthetics in individuals with complete unilateral cleft lip and palate (CUCLP). METHODS: This retrospective study involved 28 patients with repaired CUCLP. Nostril morphology was analyzed using nose casts and a video-imaging technique. Calculated shape parameters included area, perimeter, centroid, angle of the principal axis, major and minor moments of area, anisometry, bulkiness, lateral offset, and three-dimensional internostril angles. Esthetics was assessed using a panel of six orthodontists who rated nasal esthetics from frontal, lateral, basal, and three-quarters view slides and from nose casts. Correlations between esthetics and the shape parameters were completed using the entire group as well as using two statistically determined subsets: those with the best and those with the worst esthetics. RESULTS: Nasal esthetics was related to only the perimeter and bulkiness parameter ratios. Symmetry of the perimeters between the right and left nostrils positively correlated with better esthetics using the entire sample group while symmetry of bulkiness between the right and left nostrils positively correlated with better esthetics using both the entire sample group and the best and worst subsets. CONCLUSIONS: Only perimeter and bulkiness showed positive correlations with nasal esthetics. The group of parameters used to assess nostril morphology had neither significant correlation with-nor predictive power for-esthetics. Thus, an assessment of the entire nasal surface topography in three dimensions needs to be completed and assessed with respect to predictability of nasal esthetics.

Adolescent↗
PubMed2001

Dentocraniofacial morphology of 12 Japanese subjects with unilateral cleft lip and palate with a severe Class III malocclusion: a cephalometric study at the pretreatment stage of surgical orthodontic treatment.

OBJECTIVE: The present study clarifies the dentocraniofacial morphology of patients with cleft lip and palate (CLP) with severe Class III malocclusion prior to surgical orthodontic treatment. METHODS: The sample was 12 Japanese male subjects with repaired complete unilateral CLP (surgical CLP group; 21.2 +/- 1.92 years in mean age). Two sets of patients without CLP Class III malocclusion, consisting of 19 male subjects treated by surgical orthodontic treatment (surgical Class III group; 23.4 +/- 6.35 years in mean age) and 14 male subjects treated by nonsurgical orthodontic treatment (nonsurgical Class III group; 18.7 +/- 3.49 years in mean age) were used as controls. Analyses were performed using lateral and posteroanterior (P-A) cephalograms. RESULTS: (1) The surgical CLP group showed significantly smaller values for overjet, SNA angle, and inclination of the maxillary incisor as compared with those of the surgical and nonsurgical Class III controls. The values of SNB, mandibular effective length, and ramus height in the surgical CLP group were significantly smaller than those of the surgical Class III group but were similar to those of the nonsurgical Class III group. (2) The mandible and the upper and lower dental arches deviated laterally toward the cleft side. The displacement of the mandible was correlated with that of the maxilla. These results show that CLP patients who required surgical orthodontic treatment had a characteristic dentocraniofacial morphology, compared to controls without CLP with Class III malocclusion.

Adolescent↗
PubMed2001

The dental health and caries-related microflora in children with craniosynostosis.

OBJECTIVE: To compare levels of dental caries, bacterial dental plaque, gingivitis, enamel defects, and caries-related microflora in children with and without craniosynostosis. STUDY GROUP: Fifty-seven children with craniosynostosis and their matched controls. OUTCOME MEASURES: The decayed, missing, and filled teeth and surfaces in both the deciduous (dmfs and dmft) and the permanent dentition (DMFS and DMFT). The plaque and gingivitis scores and developmental enamel defects were also recorded. The caries-related microflora was sampled using an alginate swab and the prevalence of Streptococcus mutans and Lactobacillus and Candida species were recorded. RESULTS: The dmfs (p <.02) and dmft (p <.01) were significantly greater in the control children. The plaque score for the deciduous dentition only (p <.02) and also the gingivitis score for the permanent teeth only (p <.008) in the craniosynostosis group were significantly greater. The total aerobic bacterial count (p <.004), anaerobic count (p <.002), and Candida count (p <.05) were significantly greater in the control group. The proportion of S. mutans both as a percentage of the total anaerobic count (p <.04) and the total streptococcal count (p <.05) was significantly greater in the control group.

Acrocephalosyndactylia↗
PubMed2002

Cephalometric analysis in submucous cleft palate: comparison of cephalometric data obtained from submucous cleft palate patients with velopharyngeal competence and incompetence.

OBJECTIVE: The purpose of this study was to investigate the relationship between craniofacial and nasopharyngeal morphology and velopharyngeal function in submucous cleft palate. DESIGN AND PATIENTS: Fifty-two lateral cephalometric radiographs of 46 submucous cleft palate (SMCP) patients with velopharyngeal competence (24 patients) and incompetence (22 patients) at 4 and 7 years of age were studied. The patients had not received any surgical or orthodontic treatment prior to cephalography being performed. RESULTS: Significant differences were found between cephalometric variables (N-Ba, N-S-Ba angle) in children with velopharyngeal competence and incompetence. However, the results of our study showed that cephalometric data alone are not useful for predicting velopharyngeal function and can not serve as an absolute prognostic indicator. CONCLUSION;There are many factors that can influence velopharyngeal function in SMCP patients. Cephalometric data did not demonstrate a strong relationship to velopharyngeal function.

Age Factors↗
PubMed2002

Nonsyndromic cleft lip with or without cleft palate in China: assessment of candidate regions.

OBJECTIVE: Although Asians have the highest birth prevalence of oral-facial clefts, the majority of gene mapping studies of cleft lip with or without cleft palate (CL/P) have been in European or American Caucasians. Therefore, the objective of this study of Chinese families was to evaluate linkage and association between CL/P and 10 genetic markers in five chromosomal regions that have shown positive results in Caucasians. SETTING: Families were ascertained through nonsyndromic CL/P surgical probands from hospitals throughout Shanghai, China. PARTICIPANTS: Study participants included 671 individuals from 60 families with two or more members affected with oral-facial clefts. Of the 671 total individuals, 145 were affected. RESULTS: Ten markers from chromosomes 2, 4, 6, 17, and 19 were assessed (TGFA, MSX1, D4S194, D4S175, F13A1, GATA185H, D17S250, D17S579, D19S49, APOC2). LOD scores were calculated between each of the 10 markers and CL/P as well as model-free statistics of linkage (SimIBD) and association (TDT). None of the markers showed significantly positive LOD scores with CL/P. A significantly positive result (p =.01) was seen using SimIBD for APOC2 on chromosome 19, and a positive TDT result (p =.004) was obtained for D19S49, near APOC2. CONCLUSIONS: This is the first gene mapping study of CL/P in China. These results indicate that most of the genetic regions with positive results in Caucasian families may not be involved in CL/P found in China, although there is some positive evidence for the candidate region on chromosome 19.

Alleles↗