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PubMed1982

A signal-detection-theory measure of pitch shifts in sinusoids as a function of intensity.

Pitch shifts in sinusoids as a function of intensity result in systematic response biases and differences in performance in forced-choice frequency-discrimination tasks. Two approaches are described for converting these effects to a measure of pitch shift in Hz using standard signal-detection-theory assumptions. To illustrate these approaches, forced-choice frequency-discrimination data were obtained for three listeners at 250 and 4000 Hz, with six intensities from 40 to 90 dB SPL. The resulting pitch-shift estimates are in good agreement with adjustment data obtained from the same listeners. Collection and analysis of the forced-choice data can be greatly simplified by using an adaptive procedure. Pitch-shift estimates obtained in this way for two of the three listeners are in good agreement with the other estimates.

Adolescent↗
PubMed1997

Net effect of inoculum size on antimicrobial action of ampicillin-sulbactam: studies using an in vitro dynamic model.

To examine the predictable effect of inoculum size on the kinetics of the antimicrobial action of ampicillin-sulbactam, five TEM-1 beta-lactamase-producing Escherichia coli strains were studied in an in vitro dynamic model at two different initial inocula (N0S). All bacteria were exposed to ampicillin-sulbactam in a simulated system reflecting the pharmacokinetic profiles in human tissue after the administration of a single intravenous dose of ampicillin (2 g) plus sulbactam (1 g). Each strain was studied at low (4.0 to 5.2 log CFU/ml) and high (5.0 to 7.1 log CFU/ml) N0S. Despite pronounced differences in susceptibilities, the patterns of the killing curves observed with a given strain at different N0S were similar. As expected, viable bacterial counts increased with inoculum size. Striking visual contrasts in the respective curves for each organism were reflected by the area under the bacterial count-time curve (AUBC) but not by the difference between the N0 and the lowest bacterial counts (Nmin) at the nadir of the killing curve: the N0-associated changes in the AUBC on average were 75%, versus 2.5% for log N0--logNmin. To examine qualitative differences in antimicrobial effects at different N0S (i.e., the net effect of the inoculum), the difference in the high and low N0S was subtracted from each point on the killing curve obtained at the higher N0 for each strain. These adjusted curves were virtually superimposable on the observed killing curves obtained at the lower N0. Moreover, by using adjusted data, the AUBC values were similar at the two inocula, although slight (average, 11%) but systematic increases in the AUBC occurred at high N0S. Thus, there was only a weak net effect of inoculum size on the antibacterial effect of ampicillin-sulbactam. Due to similar slopes of the AUBC-log N0 plots, the antibacterial action at different N0S may be easily predicted by an approximate equation; the predicted AUBCs were unbiased and well correlated with the observed AUBCs (r = 0.997). Compiled data obtained with normalized AUBCs for different strains at different N0S yielded a positive correlation (r = 0.963) between the N0-normalized AUBC and the MIC of ampicillin-sulbactam. The adjustment and normalization procedure described might be a useful tool for revealing the net effect of the inoculum and to predict the inoculum effect if there are no qualitative differences in antimicrobial action at different inocula.

Ampicillin↗
PubMed1977

Self-concept and psychological adjustment differences between self-identified male transsexuals and male homosexuals.

Self-concept and adjustment data from anatomical males seeking sexual reassignment surgery were compared with that from a male homosexual group. Findings indicated that the homosexual group had a better self-image and was better adjusted than the sex change group. Other findings are presented that reinforce the view that the norm violations in homosexuality and transsexualism do not necessarily imply serious character damage.

Adaptation, Psychological↗
PubMedDate not supplied

Comparison of a family practice teaching service and a hospitalist model: costs, charges, length of stay, and mortality.

BACKGROUND AND OBJECTIVES: One third of our nation's health care costs are incurred in the hospital. This study compares the inpatient outcomes between a family practice teaching service (FPTS) and a hospitalist group in the same suburban community hospital. METHODS: All patients discharged by the hospitalist group or the FPTS between April 1998 and June 1999 were included for study if they had one of the 10 most frequent principal diagnoses on discharge. The outcomes compared between the groups were length of stay, mortality, total charges, laboratory charges, radiology charges, and direct costs. Student's t test, chi-square, and analysis of variance were used to compare the outcomes, after adjusting data for severity of illness. RESULTS: Mean severity of illness for the FPTS patients was 2.42 and for the hospitalist patients was 2.26, with higher scores indicating greater severity of illness. After adjusting for severity of illness, there were no differences between the two groups of physicians for total charges, laboratory charges, radiology charges, direct costs, length of stay, or mortality rates. CONCLUSIONS: This study failed to demonstrate a statistically significant difference in the use of hospital resources between a family practice residency teaching service and a hospitalist team. Given the outcomes measured in this community teaching hospital, the residency teaching service appears to be a financially competitive model for delivery of inpatient care.

Analysis of Variance↗
PubMed2002

Relationship between fibromyalgia features and smoking.

OBJECTIVE: The objective of this study was to examine a possible relationship between smoking and fibromyalgia features among 233 female patients with fibromyalgia syndrome. METHODS: Data on clinical and psychological features were collected by a protocol. Smoking status was evaluated by a question inquiring about the packs of cigarettes smoked per day. Differences between the smokers and non-smokers were tested by Mann Whitney U test. To adjust data for age and education, a partial correlation test was used. A p value of < or = 0.01 was accepted as the level of significance. RESULTS: Fifty-one patients (21.9%) smoked. After adjustment for age and education, significantly positive relationship was found between smoking and pain, patient global severity, functional disability, and numbness. There was no difference between smokers and non-smokers for fatigue, morning fatigue, sleep difficulties, tender points (TP), depression, anxiety and stress. CONCLUSIONS: Smokers reported significantly more pain, numbness, patient global severity, and functional difficulties than non-smokers. There was no significant difference between smokers and non-smokers for fatigue and TP.

Adult↗
PubMed2006

Constructing intervals for the intracluster correlation coefficient using Bayesian modelling, and application in cluster randomized trials.

Studies in health research are commonly carried out in clustered settings, where the individual response data are correlated within clusters. Estimation and modelling of the extent of between-cluster variation contributes to understanding of the current study and to design of future studies. It is common to express between-cluster variation as an intracluster correlation coefficient (ICC), since this measure is directly comparable across outcomes. ICCs are generally reported unaccompanied by confidence intervals. In this paper, we describe a Bayesian modelling approach to interval estimation of the ICC. The flexibility of this framework allows useful extensions which are not easily available in existing methods, for example assumptions other than Normality for continuous outcome data, adjustment for individual-level covariates and simultaneous interval estimation of several ICCs. There is also the opportunity to incorporate prior beliefs on likely values of the ICC. The methods are exemplified using data from a cluster randomized trial.

Bayes Theorem↗
PubMed2006

Risks of mortality and morbidity from worldwide terrorism: 1968-2004.

Worldwide data on terrorist incidents between 1968 and 2004 gathered by the RAND Corporation and the Oklahoma City National Memorial Institute for the Prevention of Terrorism (MIPT) were assessed for patterns and trends in morbidity/mortality. Adjusted data analyzed involve a total of 19,828 events, 7,401 "adverse" events (each causing >or= 1 victim), and 86,568 "casualties" (injuries), of which 25,408 were fatal. Most terror-related adverse events, casualties, and deaths involved bombs and guns. Weapon-specific patterns and terror-related risk levels in Israel (IS) have differed markedly from those of all other regions combined (OR). IS had a fatal fraction of casualties about half that of OR, but has experienced relatively constant lifetime terror-related casualty risks on the order of 0.5%--a level 2 to 3 orders of magnitude more than those experienced in OR that increased approximately 100-fold over the same period. Individual event fatality has increased steadily, the median increasing from 14% to 50%. Lorenz curves obtained indicate substantial dispersion among victim/event rates: about half of all victims were caused by the top 2.5% (or 10%) of harm-ranked events in OR (or IS). Extreme values of victim/event rates were approximated fairly well by generalized Pareto models (typically used to fit to data on forest fires, sea levels, earthquakes, etc.). These results were in turn used to forecast maximum OR- and IS-specific victims/event rates through 2080, illustrating empirically-based methods that could be applied to improve strategies to assess, prevent, and manage terror-related risks and consequences.

Databases, Factual↗
PubMed1996

Comparison of long-term survival between hemodialysis and peritoneal dialysis.

We have reviewed the literature and our own center's results for patients on long-term continuous ambulatory peritoneal dialysis (CAPD) in comparison to results for patients on hemodialysis (HD). Contrary to recent American data showing one-year survivals to be worse on CAPD, the Canadian Registry and other studies show no significant difference in survivals on the two methods. Results are also conflicting for diabetics. Insufficient adjustments for age and case-mix variations are probably the most important causes for differences. For the general population, personal Cox-adjusted data show no difference between CAPD and HD up to ten-year follow-up, with very close curves for the adults and non-significant differences for the elderly. Old elderly (> 75 years) have better survival on CAPD in the first years of treatment. Dropout, which is higher on CAPD, decreases with age, and the patient retention on CAPD is worse than on HD for all patients, except the old elderly, for whom it is similar. These data were obtained in patients receiving a standard treatment, modified in order to give a more adequate dialysis dose only in recent years. The results of a prospective three-year study on the effect of nutritional [serum albumin and transferrin, normalized protein catabolic rate (PCRN), and subjective global assessment of malnutrition] and adequacy indices [Kt/V, creatinine clearance (Ccr), residual renal function] on patient survival on CAPD and HD are reported. Survival was not different for the two methods. Using the Cox analysis, nutritional indices did not affect survival whereas adequacy indices did. The effect of low serum albumin on survival was referable to the predialysis nutritional state. The similar survivals obtained on CAPD and HD, with Kt/V more or less than 1.0/treatment for HD and 1.7/week for CAPD, support the "peak concentration hypothesis" of Keshaviah et al. Survival in different groups of patients with different Kt/V and Ccr shows that the adequate dose on CAPD is Kt/V between 1.96 and 2.03 and Ccr > or = 70 L/week. A group of 26 patients who remained on CAPD treatment for more than eight years was also studied. Patient age and predialysis comorbidity were the most important factors affecting survival. Patients surviving longest had > 3 g/dL of serum albumin, > 0.8 g/kg/day of PCRN, a Kt/V > 1.6, and a weekly Ccr > 54L/week.

Adolescent↗
PubMed1979

Social interaction and life satisfaction: an empirical assessment of late-life patterns.

Problems of social and psychological adjustment in later life have been examined by numerous investigators. Some have found positive relationships between social interaction and personal adjustment, while others have found interaction and adjustment to be unrelated. The purpose of the research reported here was to examine how different ways of measuring interaction may affect its relationship with personal adjustment. Data were obtained in interviews with 218 noninstitutionalized persons aged 70 and older. Findings indicate that both the number of persons interacted with, and the frequency of this interaction, are of little importance for the adjustment of older people. We suggest that the quality, rather than quantity, of social interaction is crucial to understanding adaptations to old age.

Aged↗
PubMed1997

Perceptions of control, physical exercise, and psychological adjustment to breast cancer in South African women.

Psychological adjustment and locus of control were measured in 257 South African women both with and without breast cancer. Adjustment was defined as positive affect, negative affect, the balance between the two, satisfaction with various domains of life, and an overall sense of well-being. Health locus of control was measured separately for internal, external, and chance loci. The instrument's reliability was comparable to that reported for U.S. norms. The women with breast cancer reported significantly lower affect and had lower internal and higher external and chance perceptions of control. The more invasive the surgical treatment, the greater the negative impact on adjustment. Data suggested that using written instructions to stress the importance of exercise to rebuild arm strength immediately following the surgery had a long-lasting positive impact on affect. Side of intervention was also related to psychological adjustment. Significant differences across racial groups were found for both adjustment and health locus of control.

Activities of Daily Living↗
PubMed1987

AIDS in Europe: current trends and short-term predictions estimated from surveillance data, January 1981-June 1986.

European AIDS surveillance data, reported to the World Health Organization (WHO) Collaborating Centre on AIDS, Paris by 30 June 1986, have been analysed statistically to assess current trends and to provide short-term predictions. Reported case numbers were first adjusted to allow for the estimated time delays between diagnosis and reporting. The adjusted data (cases per half-year of diagnosis) were then fitted using exponential functions over selected time intervals to monitor and compare the evolution of the epidemic in individual countries and in the European Community (EC) as a whole. Predictions to mid-1988 were made by extrapolation. Results are presented for the EC and for the following individual countries: Belgium, Denmark, France, Federal Republic of Germany, Italy, The Netherlands, Spain, Sweden, Switzerland and the United Kingdom.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Genetic and environmental sources of QT interval variability in Israeli families: the kibbutz settlements family study.

QT interval prolongation not attributed to long QT syndromes is reported to be associated with increased risk of sudden and nonsudden cardiac death. Genetic and environmental determinants of QTc interval were investigated in an unselected free living population sample of 80 kindreds residing in kibbutz settlements in Israel. The sample included 214 males and 227 females aged 15-97 years. There was a significant familial aggregation of adjusted QT interval levels, as indicated by inter- and intraclass correlation coefficients significantly different from zero. Complex segregation analysis applied to the sex- and age-adjusted data was not conclusive and heterogeneous etiologies for individual differences were suggested. There was evidence for a single recessive locus (q = 0.173) with a major effect in addition to polygenic effects (h2 = 0.41) that explained the mixture of distributions. In parallel, a nontransmitted environmental major factor in addition to polygenic effects that explained the adjusted variation in QTc could not be rejected. Similar results were obtained upon the adjustment for sex, age, and environmental covariables. The major factor, either genetic or environmental, and polygenic-loci accounted for about 20 and 33% of the adjusted QTc variation, respectively. Furthermore, sex, age, measured environmental covariables, the unmeasured major factor, and the unmeasured polygenes could account for 63% of the variation of QTc in these families. Our data provide evidence for a major factor, either genetic or environmental, in addition to a polygenic background, influencing QT interval levels in a population-based sample of pedigrees.

Adolescent↗
PubMed1985

Why me? Attributions and adjustment by cancer patients and their mates at two stages in the disease process.

This research investigated how cancer patients at early and advanced stage disease (N = 73) and their mates (N = 39) attributed causality for the disease, their levels of adjustment and the relationship between attributions and adjustment. Data were collected through semi-structured home interviews. Results indicated that the largest numbers of individuals cited chance as the cause of the cancer, although many reported that they had not asked themselves the question, 'Why me?'. Adjustment measures indicated, in general, more similarities than differences between groups. Attributions were not significant predictors of adjustment. It is suggested that not making strong causal attributions may be adaptive for cancer patients and their families.

Adaptation, Psychological↗
PubMed2003

Immunologic memory in Haemophilus influenzae type b conjugate vaccine failure.

AIMS: To compare the convalescent antibody response to invasive Haemophilus influenzae type b (Hib) disease between conjugate vaccine immunised and unimmunised children, to look for evidence of priming for immunologic memory. METHODS: Unmatched case-control study in the UK and Eire 1992-2001 and Victoria, Australia 1988-1990. A total of 93 children were identified as having invasive Hib disease following three doses of conjugate vaccine in infancy through post licensure surveillance throughout the UK and Eire; 92 unvaccinated children admitted to an Australian paediatric hospital with invasive Hib disease were used as historical controls. Convalescent serum was taken for measurement of Hib antibody concentration, and clinical information relating to potential disease risk factors was collected. The geometric mean concentrations of convalescent Hib antibodies were compared between immunised and unimmunised children, using raw and adjusted data. RESULTS: Hib conjugate vaccine immunised children had higher serum Hib antibody responses to disease (geometric mean concentration (GMC) 10.81 microg/ml (95% CI 6.62 to 17.66) than unimmunised children (1.06 microg/ml (0.61 to 1.84)) (p < 0.0001). However, following adjustment for the significant confounding influences of age at presentation and timing of serum collection, a difference persisted only in children presenting with meningitis (vaccinated GMC 3.78 microg/ml (2.78 to 5.15); unvaccinated GMC 1.48 microg/ml (0.90 to 2.21); p = 0.003). CONCLUSIONS: Higher antibody responses to invasive Hib disease in vaccinated children with meningitis reflect priming for immunologic memory by the vaccine. Although a majority of children in the UK are protected from Hib disease by immunisation, the relative roles of immunologic memory and other immune mechanisms in conferring protection remain unclear.

Age Factors↗
PubMed1993

Cesarean section to reduce perinatal transmission of human immunodeficiency virus. A metaanalysis.

OBJECTIVE: Individual epidemiologic investigations into the association between type of delivery and perinatal HIV transmission have been suggestive but inconclusive. Metaanalysis was used in an attempt to establish if there is, at present, adequate evidence concerning the effectiveness of cesarean section in reducing vertical HIV transmission rates. METHODS: The MEDLINE data retrieval system and other sources were used to identify studies containing data on the relationship between type of delivery and vertical HIV transmission. No randomized control trials were located. Six cohort studies identified were included in the metaanalysis. Crude and, in the only study in which these were available, adjusted data were extracted and pooled. RESULTS: The overall weighted risk of perinatal HIV infection was 20.2% and 14.0% after vaginal and cesarean delivery, respectively. Pooling data of all studies showed a statistically significant difference of HIV perinatal transmission rates between cesarean and vaginal delivery (odds ratio 0.65; 95% CI, 0.43 to 0.99; P = 0.044) (Random effects model: DerSimonian and Laird method). Approximately 16 (95% CI, 76 to 9) HIV-infected women must deliver by cesarean in order to prevent 1 case of HIV perinatal infection. CONCLUSIONS: Results of this study show that performing elective cesarean section in HIV-infected women is potentially an effective procedure. However, the nonexperimental nature of the available studies leads us to conclude that randomized control trials are indicated before setting specific guidelines for mode of delivery in HIV-infected women.

Bias↗
PubMed1976

Life tables with concomitant information.

A regression model for the analysis of survival data adjusting for concomitant information is developed. The model presented can lead to the log linear exponential model (Glasser [1967]) and the life table regression model of Cox [1972]. In addition, the model described can be used to analyze data from the commonly employed actuarial life table. A discussion of the special case where one is comparing two survival curves is presented. The methods developed are illustrated using data from a clinical trial investigating treatments for lung cancer.

Biometry↗
PubMed1991

Is the Canadian health care system more effective at expenditure control than previously thought? A reply to Peter Coyte.

In an article published by the Journal of Public Health Policy (Summer 1990), Peter C. Coyte argues that it is not empirically valid to say that the introduction of universal medical insurance in Canada successfully contained the growth in the share of society's resources devoted to the health care industry. During the period under consideration, both Canada and the United States witnessed several major policy changes in the provision and regulation of health services. Coyte's decision to apply a simple time trend to the data assumes away these changes, especially the introduction of universal medical insurance in Canada in 1971, whose influence on health expenditures is itself the primary subject of inquiry of this paper. We conclude that both the unadjusted and the adjusted data suggest that the Canadian universal health system has been a resounding success economically, once the appropriate periodization is applied to the data, reflecting the institutional and policy changes that took place. Finally, we propose suggestions for future research with respect to measuring resource usage in the Canadian and U.S. health care systems.

Canada↗
PubMed2004

How health policy and health services researchers are compensated: analysis of a nationwide salary survey.

The membership of Academy Health, a professional organization, was invited to complete an anonymous Web-based survey in 2002. Responses were received from 1,140 of 2,633 surveyed (43 percent). Fifty-six percent worked in academic institutions or teaching hospitals, 34 percent in the private sector or foundations, and 10 percent in government. Most (96 percent) had at least one advanced degree, and the diversity of educational backgrounds was pronounced. The median annual salary was $99,000. Salaries were highest in the private sector, followed by academic and government settings. There were large regional variations, with higher salaries in the Mid-Atlantic and New England regions. Adjusted data suggested these higher regional salaries were inadequate to compensate for higher local cost of living. Among academic respondents, nonadjusted salaries increased with advancing faculty job titles, but this seniority effect was inconsistent across geographic regions. Junior faculty salaries, when adjusted for cost of living, were more similar across regions than salaries at the full professor level.

Adult↗