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PubMed2006

Concentration of the most-cited papers in the scientific literature: analysis of journal ecosystems.

BACKGROUND: A minority of scientific journals publishes the majority of scientific papers and receives the majority of citations. The extent of concentration of the most influential articles is less well known. METHODS/PRINCIPAL FINDINGS: The 100 most-cited papers in the last decade in each of 21 scientific fields were analyzed; fields were considered as ecosystems and their "species" (journal) diversity was evaluated. Only 9% of journals in Journal Citation Reports had published at least one such paper. Among this 9%, half of them had published only one such paper. The number of journals that had published a larger number of most-cited papers decreased exponentially according to a Lotka law. Except for three scientific fields, six journals accounted for 53 to 94 of the 100 most-cited papers in their field. With increasing average number of citations per paper (citation density) in a scientific field, concentration of the most-cited papers in a few journals became even more prominent (p<0.001). Concentration was unrelated to the number of papers published or number of journals available in a scientific field. Multidisciplinary journals accounted for 24% of all most-cited papers, with large variability across fields. The concentration of most-cited papers in multidisciplinary journals was most prominent in fields with high citation density (correlation coefficient 0.70, p<0.001). Multidisciplinary journals had published fewer than eight of the 100 most-cited papers in eight scientific fields (none in two fields). Journals concentrating most-cited original articles often differed from those concentrating most-cited reviews. The concentration of the most-influential papers was stronger than the already prominent concentration of papers published and citations received. CONCLUSIONS: Despite a plethora of available journals, the most influential papers are extremely concentrated in few journals, especially in fields with high citation density. Existing multidisciplinary journals publish selectively most-cited papers from fields with high citation density.

Journal Impact Factor↗
PubMed2003

Physiological approaches to the prediction of drug-drug interactions in study populations.

The prediction of metabolic drug-drug interactions should include quantitative attributes, such as variability in the study populations, and the results should be presented in terms of probability and uncertainty. The simple algebraic equations used to calculate one mean value for the extent of drug-drug interaction are adequate for qualitative or semi-quantitative risk assessment. However, truly quantitative predictions continue to fail. The success of drug-drug interaction predictions requires understanding of the relationship between drug disposition and quantifiable influential factors on the change in systemic exposure. The complex interplay of influential factors, including variability estimates, on successful prediction of drug interaction have not been systematically examined. Therefore, physiologically relevant models of metabolic drug-drug interaction will likely play increasingly important roles in improving quantitative predictions and in the assessment of the influential factors underlying the interactions. The physiologically-based approach, with stochastic considerations, offers a powerful alternative to the empirical calculation of mean values. In addition to quantitative estimation of the interaction for assessing probability of risk, a reasonably validated predictive model is useful for prospective optimization of study designs. As a consequence, the definitive clinical trial would yield more meaningful information to support dosing recommendations. This review focuses on illustrating the importance of an integrated approach to building useful models for prediction of metabolism-based drug-drug interactions in human subjects.

Animals↗
PubMed2001

Judgments of grammaticality of Japanese bitransitive sentences with a differing number of arguments.

This study explored the linguistic intuition of Japanese speakers when they judged the grammaticality of isolated simple bitransitive sentences. The role of the number of arguments and the manner of presenting sentences-whether or not the number of arguments increased across judgment trials-in determining the judged grammaticality was examined. Findings showed that the speakers tended to judge even sentences lacking arguments as grammatical. A direct object was most influential in determining judged grammaticality, an indirect object next most influential, and a subject least influential. The manner of presenting sentences had an almost negligible effect. The findings suggest that speakers' judgments of sentences are graded as contrasted to linguists' judgments. Osgood's Naturalness Principle of 1980 was interpreted as providing a good explanation for the findings.

Adolescent↗
PubMed2001

Prognostic factors of hyperglycemic hyperosmolar nonketotic state.

BACKGROUND: To delineate the prognostic factors of patients suffering from hyperglycemic hyperosmolar nonketotic state (HHNK) in Taiwan. METHODS: We reviewed the charts of patients who had been admitted to the Division of Endocrinology and Metabolism of Kaohsiung Veterans General Hospital from 1992 to 1998 due to HHNK. General and clinical data were collected. The influential factors for prognosis were determined. RESULTS: One hundred and nineteen patients fulfilling the criteria of HHNK were included in our study. The mean age was 67.8 +/- 11.7 years with male predominance. Twenty-nine patients died which produced a fatality rate of 24.4%. Eighty-six (72.3%) cases occurred in patients with known diabetic history, while another thirty-three (27.7%) occurred in patients with no diabetic history. Most patients received oral antidiabetic drugs before HHNK episodes. The patients who died had shorter length of inpatient stay than did survivors. The leading precipitating factor was infection (57.1%), followed by poor compliance of medication (21.0%) and undiagnosed diabetes (10.9%). Fifty patients (42%) had a history of stroke. The risk factors for death included precipitation of HHNK by infection and low Glasgow coma scale (GCS) on admission. Old age itself did not contribute to death. Severity of hyperglycemia or hyperosmolarity was also not an important prognostic factor. Multiple logistic regression revealed that low GCS on admission was the most influential factor of leading to death. Most of the patients who died did so due to underlying precipitating factors. CONCLUSIONS: Neither age nor osmolarity, but underlying precipitating factors and state of consciousness were the most influential factors affecting the prognosis of HHNK.

Adult↗
PubMed2003

[Compliance of medical treatment in primitive glaucoma open angle].

INTRODUCTION: Compliance to medical treatment expresses the patient's perception of the disease and the treatment prescribed by the doctors. Lack of compliance endangers chronic glaucoma care, which explains the importance it has been given these last years. The objectives of this survey were to evaluate the compliance of adult patients suffering from primary open angle glaucoma to discover the influential factors. MATERIALS AND METHODS: We conducted a survey at the ophthalmology clinic of Le Dantec Hospital from January 1997 to May 1998 among 31 adults being treated for primary open angle glaucoma. An indirect evaluation of the patients' compliance was made on the basis of a questionnaire after examination of their medical files. It was deemed good, average, or bad depending on: regularity of the patient's visits to the doctors, regularity of the treatment, respect of the doctor's prescription and the prescribed times for taking the medicine. The Chi square independence test was used to study the influence of the following factors: age, sex, residence, socioeconomic status, duration of symptom progression, level of instruction, counseling, and treatment. RESULTS: The patients' mean age was 60.5 years. Compliance was deemed good for 29% of the total cases, average for 32.3%, and bad for 38.7%. Only factors such as the regular visits to the doctor, the regularity of the treatment, and respect of the doctor's prescription and the prescribed times for taking the medicine were found to be influential (p<0.05). CONCLUSION: The medical treatment of primary open angle glaucoma, whether temporary or permanent, with a maximum of efficacy and a minimum of side-effects requires good compliance on the part of the patient. This compliance in turn requires a good doctor-patient relationship based on effective repeated counseling to educate patients, help them understand the disease, and act on the influential factors.

Adult↗
PubMed2005

A factors influencing applicant selection of entry-level physical therapist education programs in the United States.

Physical therapist education programs must compete for qualified applicants due to a nationwide reduction in the applicant pool. To develop successful recruitment strategies, faculty members need information on factors influencing applicant selection of a program. The purpose of this study was to analyze factors influencing selection of an entry-level physical therapist education program. Survey subjects were students enrolled in the first professional year of an accredited entry-level physical therapist education program. A survey instrument was developed based on the literature and interviews with physical therapist students and faculty members. Results of pilot studies to determine face and content validity were acceptable. Stratified random cluster sampling was applied to select 66 entry-level physical therapy programs from an available population of 150 of the 199 accredited programs. Forty-nine programs were not included in the population for various reasons. Using a five-point Likert scale, subjects rated the influence of 51 items on their selection of a specific physical therapist education program. The overall return rate was 70.4% (1,250 surveys returned). Data were analyzed by response frequency. Four factors were selected as "very influential" by 50% or more of the subjects: degree offered, accreditation status, perception of educational quality, and program atmosphere. Additional factors selected by 45% or more of respondents as "very influential" were pass rate on licensing examination, marketability of degree, student/faculty ratio, and small class size. Factors rated "not influential" by 50% or more of subjects included ethnic, cultural, and gender issues. Since 1998, the physical therapy profession has experienced changes in entry-level degree requirements, practice requirements, and employment opportunities, resulting in increased competition for qualified applicants to education programs. The information gained in this study may assist faculty in the development of recruitment strategies.

Accreditation↗
PubMed1981

Possible factors influencing immunoglobulin A concentration in swine colostrum.

The immunoglobulin (Ig) A concentration in swine colostrum was determined by the single radial immunodiffusion method, using 157 samples collected from the same number of farm-raised sows in the Yamaguchi Prefecture of Japan during 1976 and 1977. The mean IgA value was 12.26 +/- 3.30 mg/ml, and the maximum and minimum values were 28.14 mg/ml and 5.63 mg/ml, respectively. To determine factors influencing the IgA concentration in swine colostrum, the following items were analyzed in the present study: season, district, breed, number of parturitions, udder section from which samples were collected, kind of feed, vaccinations of swine (erysipelas live-organism vaccine, hog cholera live-virus vaccine, Japanese encephalitis live-virus vaccine, and transmissible gastroenteritis live-virus vaccine), type of farming, and number of sows raised on a farm. Relationships between the IgA concentration in swine colostrum and each of these 12 items were analyzed. Of the 12 items, breed and number of parturitions were the most influential on the IgA concentration in colostra of farm-raised sows. Season, district, and vaccination with transmissible gastroenteritis live-virus vaccine were moderately influential. Udder section, kind of feed, vaccinations of swine (erysipelas live-organism vaccine, hog cholera live-virus vaccine, and Japanese encephalitis live-virus vaccine), type of farming, and number of farm-raised sows were slightly influential. The multiple correlation coefficient obtained was 0.5887 (P greater than 0.05).

Animal Feed↗
PubMed1981

Possible factors influencing the immunoglobulin M concentration in swine colostrum.

The immunoglobulin (Ig) M concentration in swine colostrum was determined by the single radial immunodiffusion method, using 157 samples collected from the same number of farm-raised sows in Yamaguchi Prefecture of Japan during 1976 and 1977. The mean IgM value was 4.16 +/- 1.11 mg/ml, and the maximum and minimum values were 7.74 mg/ml and 1.50 mg/ml, respectively. To elucidate the possible factors influencing the IgM concentration in swine colostrum, the following 12 items were surveyed in the present study: season, district, breed, age, udder section (mamma) from which colostral samples were collected, kind of feed, 4 vaccinations (swine erysipelas live-organism vaccine, hog cholera live-virus vaccine, Japanese encephalitis live-virus vaccine, and transmissible gastroenteritis live-virus vaccine), type of farming, and number of sows raised on a farm. Relationships between the IgM concentration in swine colostrum and each item were analyzed. Of the 12 items, 3 items--season, breed, and vaccination of swine erysipelas live-organism vaccine--were the most influential on the IgM concentration in colostra of farm-raised sows. Five items--district, age, kind of feed, vaccination with transmissible gastroenteritis live-virus vaccine, and number of sows raised on a farm--were moderately influential. The remaining items--udder section, vaccinations with hog cholera live-virus vaccine and Japanese encephalitis live-virus vaccine, and type of farming--were poorly influential. The multiple correlation coefficient obtained here was 0.5605 (P greater than 0.05).

Age Factors↗
PubMed1994

Cues to action in prostate cancer screening.

PURPOSES/OBJECTIVES: To describe factors that cue men of all ages to participate in prostate cancer screening programs and to explore the relationship of age to the rating of the cues. DESIGN: Exploratory survey. SETTING: A large community prostate cancer screening program in the Midwest. SAMPLE: 127 men (mean = 66.3 years of age) who participated in community prostate screening. METHODS: Subjects completed and returned by mail the 13-item Prostate Screening Follow-Up Questionnaire developed, piloted, and refined by the investigator for measuring the rating of the cues to action. MAIN OUTCOME MEASURES: Results of the rating of each cue to action, selected demographic variables, and comparison of the cue ratings by age group. FINDINGS: Appointment scheduling, reminder cards, a friend/family member with cancer, and newspaper promotion were perceived by the sample as most influential in their decision to have prostate cancer screening. No practical significant differences in cue ratings were found between the two age groups: 70 years of age and older and less than 70 years of age. CONCLUSION: Reminder cards, specific appointments, and newspaper promotion should be used when structuring community prostate cancer screening programs. Men who have a friend or family member with cancer may be more likely to participate in screening activities. IMPLICATIONS FOR NURSING PRACTICE: By incorporating influential cues to action into their everyday practice, nurses can be instrumental in reaching the population of men who are at risk for prostate cancer. Strategies for promoting prostate cancer screening should include: educating patients and family members about prostate cancer screening guidelines, using specific influential promotional practices when setting up prostate screening programs, and networking with seniors programs in the community.

Adult↗
PubMedDate not supplied

Course and prognosis of 132 patients with diabetic non ketotic hyperosmolar state.

One hundred and thirty two episodes of diabetic non ketotic hyperosmolar states were studied after a prospective schedule of treatment was designed. The admission data, the prognostic factors and their outcome were analyzed. Initial high osmolarity, urea and sodium plasma levels and low plasma pH were related to the admission level of consciousness (p < 0.01). High glucose, osmolarity, urea and sodium plasma levels at entry were related to the admission level of dehydration (p < 0.01). In multivariate regression analysis, osmolarity was the most influential variable in both the level of consciousness and the admission level of dehydration (p < 0.0001). Twenty two patients died (16.9%). Septic shock was the most frequent cause of death (31%) and mortality was higher in patients with cardiovascular disease (acute myocardial infarction or stroke) as the precipitating factor for diabetic hyperosmolar state (p < 0.002). Older age, low blood pressure, low sodium, pH and bicarbonate plasma levels, and high urea plasma levels were related to mortality (p < 0.01). In multiple regression analysis, urea was the most influential mortality risk factor (p < 0.0118). Non survivors received higher doses of insulin than survivors (p < 0.01). All these data suggest that it is not the hyperosmolarity itself, but the hemodynamical state of the patients, which is the most influential factor on the prognosis of a diabetic hyperosmolar state.

Age Factors↗
PubMed1993

Factors affecting cure at depths within light-activated resin composites.

When confronted with all the variables that are influential in maximizing the cure in light-activated resin composites, a practitioner may require information that ranks the relative importance of these parameters, so that clinical time can be best utilized. The purpose of this study was to determine simultaneously the relative impact of filler type (hybrid or microfill), composite shade (universal or gray), exposure duration (20, 40, 60 and 80 seconds) and source intensity (800, 578, 400 and 233 mW/cm2) on the extent of cure in light-activated composite at selected depths (top surface, 1, 2, and 3 mm) of a simulated restoration. Thin wafers of composite (P-50 and Silux Plus) were made between a cured composite underlay and varying thicknesses of cured overlay to obtain a wafer that reproduced the curing environment within a cylinder of composite. The monomer conversion of each specimen was obtained by infrared spectroscopic techniques. Analysis of variance was used to determine the significance of factors contributing to the cure of composite at each thickness of overlay used. At the surface, filler type, exposure duration and resin shade predominated as the most influential factors respectively. At 1 mm depth, the order of influential factors were exposure duration, filler type and source intensity. At depths of 2 mm and more, the overwhelming influences on cure were related solely to source intensity and exposure duration. Resin shade and filler type exerted minimal influence at these depths.

Analysis of Variance↗
PubMed1998

A graduating medical school class evaluates their educational experience.

OBJECTIVE: To determine how graduating medical students perceive instructional settings, materials, and teachers as to importance or influence upon their education and how they would change curriculum and allocate educational resources based on their experience. MATERIALS AND METHODS: One hundred thirty-nine graduating medical students at the University of Wisconsin, Madison were offered five dollars to complete and return the survey. Students were asked to rate the importance or influence (1 = most important or influential, 5 = least important or influential) of more than forty educational settings, materials, teachers, and which aspects of the curriculum should be emphasized or preserved when educational resources become more limited. Open-ended responses were also allowed. Ratings were analyzed determining a mean and standard deviation. One way analysis of variance was used to determine whether there were differences among groups. When statistically significant differences existed, the Tukey HSD test was used to compare subsets of the group. In the only group with a dissimilar number of responders, T tests were used for comparison. RESULTS: Sixty-four of 139 (46%) surveys were correctly completed and returned. Students rated the most important and influential parts of their education as experiences in years 3 and 4 of medical school. The most highly rated group of teachers were resident physicians (mean rating = 1.64, F (df = 343) = 12.55, p < .0001) during years 3 and 4 of medical school, followed by full time clinical faculty in years 3 and 4 (mean = 1.78), full time basic science faculty in years 1 and 2 (mean = 1.98), community physicians in years 3 and 4 (mean = 2.15), and teaching assistants in years 1 and 2 (mean = 2.75). Students rated the preservation of teaching efforts in years 1 and 2 (mean = 3.06), developing objective structured clinical examinations (mean = 3.21), and administering "board type" end of course examinations (mean = 3.42), as the lowest priority items for receiving educational resources. Coordination of the basic science and clinical years of medical school (mean = 2.03), problem based learning (mean = 2.08) and preserving teaching effort of years 3 and 4 clinical faculty (mean = 2.09) were the highest priorities for receiving resources. Open-ended comments indicated years 1 and 2 should be condensed and coordinated with years 3 and 4, making learning more clinically oriented. CONCLUSIONS: Students at the end of their medical school education at the University of Wisconsin rate the clinical portions of their training as most important to their medical education and residents as their most important teachers. When asked how best to change medical education, their most common responses were to 1) make years 1 and 2 more clinically oriented, both by including patient care earlier and more often during those years, 2) take the repetitiveness out of the years 1 and 2 curriculum and 3) prepare students for years 3 and 4 with transitional classes.

Attitude of Health Personnel↗
PubMed2003

Lung cancer screening with helical computed tomography in older adult smokers: a decision and cost-effectiveness analysis.

CONTEXT: Encouraged by direct-to-consumer marketing, smokers and their physicians are contemplating lung cancer screening with a promising but unproven imaging procedure, helical computed tomography (CT). OBJECTIVE: To estimate the potential benefits, harms, and cost-effectiveness of lung cancer screening with helical CT in various efficacy scenarios. DESIGN, SETTING, AND POPULATION: Using a computer-simulated model, we compared annual helical CT screening to no screening for hypothetical cohorts of 100 000 current, quitting, and former heavy smokers, aged 60 years, of whom 55% were men. We simulated efficacy by changing the clinical stage distribution of lung cancers so that the screened group would have fewer advanced-stage cancers and more localized-stage cancers than the nonscreened group (ie, a stage shift). Our model incorporated known biases in screening programs such as lead time, length, and overdiagnosis bias. MAIN OUTCOME MEASURES: We measured the benefits of screening by comparing the absolute and relative difference in lung cancer-specific deaths. We measured harms by the number of false-positive invasive tests or surgeries per 100 000 and incremental cost-effectiveness in US dollars per quality-adjusted life-year (QALY) gained. RESULTS: Over a 20-year period, assuming a 50% stage shift, the current heavy smoker cohort had 553 fewer lung cancer deaths (13% lung cancer-specific mortality reduction) and 1186 false-positive invasive procedures per 100 000 persons. The incremental cost-effectiveness for current smokers was $116 300 per QALY gained. For quitting and former smokers, the incremental cost-effectiveness was $558 600 and $2 322 700 per QALY gained, respectively. Other than the degree of stage shift, the most influential parameters were adherence to screening, degree of length or overdiagnosis bias in the first year of screening, quality of life of persons with screen-detected localized lung cancers, cost of helical CT, and anxiety about indeterminate nodule diagnoses. In 1-way sensitivity analyses, none of these parameters was sufficient to make screening highly cost-effective for any of the cohorts. In multiway sensitivity analyses, a program screening current smokers was $42 500 per QALY gained if extremely favorable estimates were used for all of the influential parameters simultaneously. CONCLUSION: Even if efficacy is eventually proven, screening must overcome multiple additional barriers to be highly cost-effective. Given the current uncertainty of benefits, the harms from invasive testing, and the high costs associated with screening, direct-to-consumer marketing of helical CT is not advisable.

Aged↗
PubMed1984

Decision-making, professional discipline, and program affiliation: selection of an inpatient treatment alternative.

Used a hypothetical case history to examine the clinical decision-making of a group of 75 mental health practitioners representing the disciplines of alcohol/drug counseling, nursing, psychiatry, psychology, and social work. The variables of professional discipline, program affiliation, work setting, and influential case history items were studied in relation to clinicians' selection of an inpatient treatment alternative. All clinicians, including para-professionals, performed similarly in that they followed an internally consistent process of reasoning in identifying influential case history items and using them in decision-making. Program affiliation and work setting had no biasing effect on decision-making, and only social workers showed a clear indication of a "set" related to their professional discipline. The implications of these findings for multi-disciplinary settings are discussed.

Adult↗
PubMed2006

Factors influencing inclusion of patients with malignancies in clinical trials.

Participation in clinical trials remains low and is a central issue in oncology. The authors identified, through a systematic review, 75 papers published up to August 2004 that report barriers to recruitment of patients in clinical trials. These barriers range from patient preference and concern about information/consent to clinical problems with protocols. Strategies to overcome barriers on the part of patients and clinicians are needed and should be carefully evaluated. Thirty-three (44%) papers reported factors related to patients as influencing the inclusion of patients, 28 (37%) reported clinician's related factors, and 37 (49%) other factors from either specific groups of patients (30 papers, 40%) and/or other scopes (13 papers, 17%). No differences in prevalence were found between papers dedicated to hematologic malignancies and solid tumors. Factors related to clinicians as influential were more frequently reported before 1995 (70%) than thereafter (25%; P = 0.0009). Reporting specific groups of patients as influential was more frequent in North American articles (50%) than in others (14%, P = 0.008). Patients' barriers included mostly patient preference (12 papers), concern about information and/or consent (11 papers), worry about uncertainty (7 papers), and/or relationship with medical team (7 papers). Concerning clinicians, incompatibility of protocol with normal practice (nine papers), problems in complying with the protocol (eight papers), and/or consent procedure (eight papers) were the most reported factors. The remaining factors mostly relied on specific groups of patients (30 papers), notably age of patients (18 papers) and/or minority population (11 papers, all from the USA). Strategies to overcome these barriers are needed and should be carefully evaluated.

Clinical Trials as Topic↗
PubMed2001

Depression in Singapore: failure to demonstrate an age effect on clinical features.

OBJECTIVES: Studies comparing older and younger depressed patients have variably identified differing and similar clinical feature patterns, an inconsistency requiring clarification and explanation. If influential, age may have a true phenotypic effect or be a secondary influence reflecting depressive sub-type differences. If age is primarily influential, then, after controlling for depressive sub-type differences its effect should impact on clinical features - even in non-western regions. METHODS: We therefore undertook a study in Singapore, comparing 42 elderly and 28 younger patients of a Singapore psychiatric hospital, and with the diagnostic sub-type profile similar across the age-based groups. RESULTS: Despite the elderly group being some 35 years older, both at first episode and when surveyed, and having a distinctly higher rate of physical disorders, few clinical differences were identified. While the elderly group reported a less severe depressed mood and more 'somatic' symptoms, analyses indicated that such differences were accounted for by education and language factors, and were compatible with the view that Chinese subjects historically report depression more 'somatically'. CONCLUSION: We conclude that, in a non-western, largely Chinese sample of depressed patients, few differences in the phenotypic expression of depression were identified, perhaps reflecting similar distributions of depressive sub-types across the groups, an issue which may have muddied interpretation of western studies.

Adolescent↗
PubMed2005

Detection of epithelial ovarian cancer using 1H-NMR-based metabonomics.

Currently available serum biomarkers are insufficiently reliable to distinguish patients with epithelial ovarian cancer (EOC) from healthy individuals. Metabonomics, the study of metabolic processes in biologic systems, is based on the use of (1)H-NMR spectroscopy and multivariate statistics for biochemical data generation and interpretation and may provide a characteristic fingerprint in disease. In an effort to examine the utility of the metabonomic approach for discriminating sera from women with EOC from healthy controls, we performed (1)H-NMR spectroscopic analysis on preoperative serum specimens obtained from 38 patients with EOC, 12 patients with benign ovarian cysts and 53 healthy women. After data reduction, we applied both unsupervised Principal Component Analysis (PCA) and supervised Soft Independent Modeling of Class Analogy (SIMCA) for pattern recognition. The sensitivity and specificity tradeoffs were summarized for each variable using the area under the receiver-operating characteristic (ROC) curve. In addition, we analyzed the regions of NMR spectra that most strongly influence separation of sera of EOC patients from healthy controls. PCA analysis allowed correct separation of all serum specimens from 38 patients with EOC (100%) from all of the 21 premenopausal normal samples (100%) and from all the sera from patients with benign ovarian disease (100%). In addition, it was possible to correctly separate 37 of 38 (97.4%) cancer specimens from 31 of 32 (97%) postmenopausal control sera. SIMCA analysis using the Cooman's plot demonstrated that sera classes from patients with EOC, benign ovarian cysts and the postmenopausal healthy controls did not share multivariate space, providing validation for the class separation. ROC analysis indicated that the sera from patients with and without disease could be identified with 100% sensitivity and specificity at the (1)H-NMR regions 2.77 parts per million (ppm) and 2.04 ppm from the origin (AUC of ROC curve = 1.0). In addition, the regression coefficients most influential for the EOC samples compared to postmenopausal controls lie around delta3.7 ppm (due mainly to sugar hydrogens). Other loadings most influential for the EOC samples lie around delta2.25 ppm and delta1.18 ppm. These findings indicate that (1)H-NMR metabonomic analysis of serum achieves complete separation of EOC patients from healthy controls. The metabonomic approach deserves further evaluation as a potential novel strategy for the early detection of epithelial ovarian cancer.

Adenocarcinoma, Clear Cell↗
PubMed1992

A note on last case influence using the partial likelihood approach under heavy censoring.

The Cox proportional hazards model always treats the last observation in a time ordered data set as an inexact survival time. In certain situations this can lead to this observation always having a low case influence and consequently never being highlighted by a case influence analysis. Thus an influential value can become non-influential by a miscalculation of survival time and this, in turn, can affect conclusions of an analysis based on statistical significance (P-values).

Bias↗