Search PubMed⌕ Search

Biomedical subjects

J A Hanley

Publications and source records attributed to J A Hanley.

At least 37 records · Page 2Linked to original sources
PubMed1999

The repeatability of three methods for measuring prospective patients' values in the context of treatment choice for end-stage renal disease.

In the context of the choice of treatment for end-stage renal disease (ESRD), three approaches to value assessment were examined for their repeatability over time within subjects. If formal decision analyses are to be used to advise patients about treatment choice, then repeatable value assessment methods, an essential component of such analyses, are needed. The methods assessed were standard gamble (SG), time trade-off (TTO), and visual analogue (VA). Sixty-six nephrology clinic patients were interviewed on two occasions, 10 days apart, by one of two interviewers. An information session was conducted 1 week before the first interview. Subjects were taught about the treatments using an information package developed expressly for the study and a video produced by a pharmaceutical company for use in this decision context. Patients differed widely in the values provided for the various treatments of ESRD, with responses that ranged across the entire scale (0 to 100). The repeatability of the three methods was poor, with the coefficients of repeatability (95% range of differences from one occasion to the next) observed as +/- 27.4 for SG, +/- 38.4 for TTO, and +/- 36.5 for VA. When subsets defined by characteristics that may have improved the repeatability were analyzed, the magnitude of the error did not vary substantially. The poor repeatability of these methods raises questions about their use for decision analyses applied to the individual context.

Adult↗
PubMed1999

Coding accuracy of hospital discharge data for elderly survivors of myocardial infarction.

OBJECTIVE: To assess the coding accuracy of primary and secondary discharge diagnoses in the Quebec hospital discharge database for elderly persons with myocardial infarction (MI). DESIGN: Retrospective chart review in a convenience sample of six Montreal hospitals. The diagnoses listed in the medical chart were compared with those listed in the hospital discharge database. For each subject, the Charlson comorbidity index was calculated twice, once based on the medical chart and again based on the hospital discharge database. PATIENTS: Subjects aged 65 years and over who had an MI coded as the primary discharge diagnosis in the hospital discharge database and who were discharged alive. MAIN RESULTS: For 234 MI survivors, the positive predictive value (ie, probability that a patient with MI reported in the hospital discharge database had an MI diagnosed by the discharging physician) for coding MI was 0.96 (95% CI 0.94, 0.98). Comorbid medical conditions and complications of the MI were under-reported in the hospital discharge database, which meant that the Charlson index based on the hospital discharge database was an average of 0.71 units lower than the Charlson index based on the medical chart. CONCLUSIONS: When studying survivors of MI by using hospital discharge databases, the advantages must be weighed against potential drawbacks in the quality of the information. Hospital discharge databases are almost as reliable as medical charts for identifying MI patients, but there is substantial under-reporting of comorbid medical conditions.

Aged↗
PubMed1998

Screening for prostate cancer: estimating the magnitude of overdetection.

BACKGROUND: No randomized controlled trial of prostate cancer screening has been reported and none is likely to be completed in the near future. In the absence of direct evidence, the decision to screen must therefore be based on estimates of benefits and risks. The main risk of screening is overdetection--the detection of cancer that, if left untreated, would not cause death. In this study the authors estimate the level of overdetection that might result from annual screening of men aged 50-70. METHODS: The annual rate of lethal screen-detectable cancer (detectable cancer that would prove fatal before age 85 if left untreated) was calculated from the observed prostate cancer mortality rate in Quebec; the annual rate of all cases of screen-detectable prostate cancer was calculated from 2 recent screening studies. RESULTS: The annual rate of lethal screen-detectable prostate cancer was estimated to be 1.3 per 1000 men. The annual rate of all cases of screen-detectable prostate cancer was estimated to be 8.0 per 1000 men. The estimated case-fatality rate among men up to 85 years of age was 16% (1.3/8.0) (sensitivity analysis 13% to 22%). INTERPRETATION: Of every 100 men with screen-detected prostate cancer, only 16 on average (13 to 22) could have their lives extended by surgery, since the prostate cancer would not cause death before age 85 in the remaining 84 (78 to 87).

Aged↗
PubMed1998

Erythrocytosis after renal transplantation represents an abnormality of insulin-like growth factor-I and its binding proteins.

BACKGROUND: Secondary erythrocytosis is classically defined by an increase in erythropoietin (EPO) production. Despite increased levels of EPO often seen in secondary erythrocytosis, some of these forms such as that seen after renal transplantation remain undefined. Our group has recently investigated the in vivo function of insulin-like growth factor-I (IGF-I) in erythropoiesis both in humans and in a murine model of chronic renal failure. These data, and the recently recognized role of IGF-I in polycythemia vera, suggested that IGF-I might be involved in secondary erythrocytosis. METHODS: Renal transplant recipients who developed erythrocytosis after transplantation were compared to normal individuals and to renal transplant recipients without erythrocytosis. We measured fasting serum EPO and IGF-I in all three groups. Because binding proteins may modify IGF-I function, IGF-I-binding proteins (IGFBP) 1 and 3, major binding proteins of IGF-I, were also measured. RESULTS: Renal transplant recipients have significantly elevated serum of IGF-I and IGFBP3 compared to normal individuals. When transplant recipients with and without posttransplant erythrocytosis were compared, similar levels of IGF-I were found; however, the group with erythrocytosis had significantly elevated IGFBP1 and IGFBP3. No other significant differences including EPO levels were found between the groups. CONCLUSIONS: Erythrocytosis after renal transplantation represents an anomaly of both IGF-I and its major binding proteins. Further studies are under way to better define this dysregulation and determine whether IGF-I can play a more generalized role in secondary forms of erythropoiesis.

Adult↗
PubMed1998

Competing risk analysis of men aged 55 to 74 years at diagnosis managed conservatively for clinically localized prostate cancer.

CONTEXT: The appropriate therapy for men with localized prostate cancer is uncertain. Until results of clinical trials are available, men and their physicians need guidance. OBJECTIVE: To estimate survival based on a competing risk analysis stratified by age at diagnosis and histologic findings for men diagnosed as having clinically localized prostate cancer and who were managed conservatively. DESIGN: Retrospective cohort study. SETTING: Connecticut Tumor Registry. PATIENTS: A total of 767 men with localized prostate cancer diagnosed between 1971 and 1984, aged 55 to 74 years at diagnosis, either not treated or treated with immediate or delayed hormonal therapy, and followed up for 10 to 20 years after diagnosis. MAIN OUTCOME MEASURES: Estimates of the probability of dying from prostate cancer or other competing hazards. RESULTS: Men with tumors that have Gleason scores of 2 to 4, 5, 6, 7, and 8 to 10 face a 4% to 7%, 6% to 11%, 18% to 30%, 42% to 70%, and 60% to 87% chance, respectively, of dying from prostate cancer within 15 years of diagnosis depending on their age at diagnosis. CONCLUSIONS: Men whose prostate biopsy specimens show Gleason score 2 to 4 disease face a minimal risk of death from prostate cancer within 15 years of diagnosis. Conversely, men whose biopsy specimens show Gleason score 7 to 10 disease face a high risk of death from prostate cancer when treated conservatively, even when cancer is diagnosed as late as age 74 years. Men with Gleason score 5 or 6 tumors face a modest risk of death from prostate cancer that increases slowly over at least 15 years of follow-up.

Aged↗
PubMed1998

Three-dimensional computer-assisted analysis of sector biopsy of the prostate.

OBJECTIVES: To assess the relationship between tumor volume, gland volume, number of sectors submitted to biopsy, and prostatic biopsy detection rate. METHODS: Using a three-dimensional mathematical model of the prostate, we assessed detection rates achieved with 4-, 6-, 8-, 10-, and 12-sector biopsies for glands ranging from 20 to 100 cc and peripheral zone tumors ranging from 0.3 to 1.4 cc. RESULTS: Quadrant and sextant biopsy approaches only yielded from 6.2% to 13.4% and 8.6% to 18.3%, respectively, of lesions in a 40-cc gland. Conversely, 10- and 12-sector approaches yielded, respectively, from 19.8% to 48.8% and 25.4% to 62% of lesions for the same gland size. When assessed according to the density of sampling, one biopsy core used for every 1 .5 to 3.5 cc of prostatic tissue detected 42.5% of 0.5-cc lesions. For the same lesion size, the density of sampling per biopsy core was then decreased to intervals extending from 3.6 to 7.5 cc, 7.6 to 12.5 cc, and 12.6 to 25 cc. These sampling density intervals yielded, respectively, 25.0%, 15.8%, and 9.8% detection rates. CONCLUSIONS: On the basis of our results, a gland volume-based biopsy algorithm is likely to result in improved detection of clinically significant prostate cancer.

Biopsy↗
PubMed1998

Aeroallergens and work-related respiratory symptoms among office workers.

OBJECTIVE: We sought to determine the association between office workers' respiratory tract symptoms and immediate skin test reactions with exposure to fungal and house dust mite aeroallergens at their work sites. METHODS: An initial prevalence survey was conducted among 1102 full-time workers in six mechanically ventilated, air-conditioned, nonindustrial buildings in downtown Montreal. Detailed environmental measures of 214 subjects' work sites were determined. Half of the workers reported frequent work-related respiratory tract symptoms on the initial survey. Participants simultaneously underwent allergy skin prick testing and completed a second self-administered questionnaire. RESULTS: Contaminant levels were low and not associated with symptoms in the great majority of workers. For approximately 17% of workers, symptoms were associated with exposure to total concentrations of house dust mite allergen greater than 1 microg/gm floor dust (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.3, 19.5]) or to detectable airborne Alternaria allergens in their offices (OR, 3.3; 95% CI, 1.2, 9.4 and in the ventilation system supplying their offices (OR, 3.9; 95% CI, 1.6, 9.6). Workers with positive skin test reactions to Alternaria extract were exposed at their work site to airborne Alternaria allergen (OR, 4.4; 95% CI, 1.4, 14.5) and cited significantly more respiratory symptoms on both questionnaires. Detection of airborne Alternaria allergen at work sites was significantly associated with detection in the ventilation system (OR, 4.0; 95% CI, 1.4,10.9); this was in turn associated with lower efficiency filters. CONCLUSIONS: Potentially avoidable exposure to aeroallergens accounted for symptoms in a small subgroup of office workers with frequent work-related respiratory tract symptoms.

Adult↗
PubMed1997

Use of physician services among family caregivers of elderly persons with dementia.

It is well known that there is an excess of physical and psychological health problems among family caregivers of elderly persons with Alzheimer's disease and other dementias. The objective of this study was to determine whether the higher level of morbidity translates into a higher level of medical care utilization. Data from a previously completed longitudinal study of caregivers for elderly persons with dementia were merged with data on physician visits obtained from the computerized records of the Quebec Health Insurance Board. Utilization of physician care (adjusted for age, sex, number of chronic diseases, and depression) was no higher for family caregivers of elderly patients with Alzheimer's disease and other dementias than for comparable family members of older persons without dementia. The annual cost of physician care was almost identical among caregivers and noncaregivers. However, the pattern of utilization for the two groups was somewhat different: there was a significantly higher frequency of physician utilization among caregivers for services billed by psychiatrists and internal medicine specialists. In multivariate analysis, physician utilization was significantly associated with having more than one chronic condition and with increased age. Future studies should focus on determining whether caregivers neglect their own health care needs as a result of the exigencies of the caregiving role.

Adult↗
PubMed1997

Extension of receiver operating characteristic analysis to data concerning multiple signal detection tasks.

RATIONALE AND OBJECTIVES: When receiver operating characteristic (ROC) studies involve multiple detection tasks in the same patient, the correlations among the within-patient interpretations and the shortage of patients raise several analytic challenges. The authors propose methods for both parametric and nonparametric analysis of this type of data. METHODS: First, they computed one accuracy statistic for each task. Then one jackknife "pseudovalue" was calculated for each task and each patient. Then, they formed a summary index from the accuracy statistics and calculated the standard error of this summary index on the basis of the observed correlations among the jackknife pseudovalues. The method was extended to comparisons of two diagnostic systems and illustrated by using data from a clinical study. RESULTS AND CONCLUSION: This approach can be used with rating or quantitative data and with any index of accuracy, whether calculated parametrically or nonparametrically.

Angiography↗
PubMed1997

Proper receiver operating characteristic analysis: the bigamma model.

RATIONALE AND OBJECTIVES: The standard binormal model is the most commonly used model for fitting receiver operating characteristic rating data; however, it sometimes produces inappropriate fits that cross the chance line with degenerate data sets. The authors proposed and evaluated a proper constant-shape bigamma model to handle binormal degeneracy. METHODS: Monte Carlo samples were generated from both a standard binormal population model and a proper constant-shape bigamma model in a series of Monte Carlo studies. RESULTS: The results confirm that the standard binormal model is robust in large samples with no degenerate data sets and that the standard binormal model is not robust in small samples because of degenerate data sets. CONCLUSION: A proper constant-shape bigamma model seems to solve the problem of degeneracy without inappropriate chance line crossings. The bigamma fitting model outperformed the standard binormal fitting model in small samples and gave similar results in large samples.

Decision Making↗
PubMed1997

Sampling variability of nonparametric estimates of the areas under receiver operating characteristic curves: an update.

RATIONALE AND OBJECTIVES: Several methods have been proposed for calculating the variances and covariances of nonparametric estimates of the area under receiver operating characteristic curves (AUC). The authors provide an explanation of the relationships between them and illustrate the factors that determine sampling variability. METHODS: The authors investigated the algebraic links between two methods, that of "placements" and that of "pseudovalues" based on jackknifing. They also performed a numerical investigation of the comparative performance of the two methods. RESULTS: The "placement" method has a simple structure that illustrates the determinants of the sampling variability and does not require specialized software. The authors show that the pseudovalues used in the jackknife method are directly linked to the placement values. CONCLUSION: Because of the close link, borne out in a numeric investigation of the sampling variation, and because of the ease of computation, the choice between the two methods can be based on users' preferences. For indexes other than the AUC, however, the use of pseudovalues holds greater promise.

Area Under Curve↗
PubMed1996

The use of the 'binormal' model for parametric ROC analysis of quantitative diagnostic tests.

The binormal model is widely used for parametric receiver operating characteristic (ROC) analyses of data concerning the accuracy of medical diagnostic tests. Empirical evaluation of the performance of this model in the face of departures from binormality has been limited to interpretations of radiology-type examinations recorded on a rating scale. This paper extends the investigation to the performance of the model with biochemical and other tests recorded on an interval scale. In order to describe non-binormal pairs of distributions, a useful standardized graphical display is developed; this display also illustrates several features of ROC curves. We consider non-binormal pairs of distributions with or without a monotone likelihood ratio and show that by transformation of the underlying scale, one can make many such pairs resemble closely the binormal model. These findings justify Metz's use of the binormal model in the 'LABROC' software for ROC analyses of laboratory type data even when the raw data may 'look' decidedly non-Gaussian.

Diagnostic Imaging↗
PubMed1996

Reducing the lifetime risk of cancer from spinal radiographs among people with adolescent idiopathic scoliosis.

STUDY DESIGN: Data from a retrospective cohort study of people with adolescent idiopathic scoliosis were combined with information on full-spinal radiographs to estimate contemporary x-ray doses and lifetime risks for development of cancer. OBJECTIVES: To project the lifetime risk for development of cancer from diagnostic radiographs for people with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Although a twofold excess risk for breast cancer has been reported for women treated for scoliosis between 1925 and 1965, information on the cancer risks associated with scoliosis management today is sparse. Specifically, there is a lack of up-to-date information on the number of spinal radiographs taken, the organ-specific x-ray doses from current radiographic techniques, and the projected cancer risks. METHODS: The cohort consisted of subjects with adolescent idiopathic scoliosis who were referred to the scoliosis clinic of a large pediatric hospital between 1965 and 1979 in Montreal, Quebec, Canada. Based on radiographic equipment and practices implemented in 1982, organ-specific x-ray doses to the thyroid gland, female breast, respiratory organs, digestive organs, and bone marrow were calculated using Monte Carlo methods. These doses were incorporated into a life table procedure to calculate theoretic lifetime cancer risks. For all organs except the thyroid gland, dose-response models from the United States National Academy of Sciences Fifth Committee on the Biological Effects of ionizing Radiation were used. For thyroid cancer, a risk model was derived from a study of thyroid cancer incidence after x-ray treatment for tinea capitis. RESULTS: The average number of spinal radiographs was 12 for women (80% anteroposterior or posteroanterior) and 10 for men (78% anteroposterior or posteroanterior). Cumulative x-ray doses were in general higher in adolescents who were referred as younger teenagers than at later ages, and doses increased with the size of the spinal curve. Depending on the age at referral and curve size, the total excess lifetime cancer risks were calculated to range from 42 to 238 cases per 100,000 women and 14 to 79 cases per 100,000 men. For subjects who underwent surgery (those exposed to the highest doses), the lifetime number of cancer cases over and above background was almost as great as the number of thyroid cancers that would occur in the absence of radiation exposure. If the anteroposterior view was replaced by the posteroanterior view, a three- to sevenfold reduction in cumulative doses to the thyroid gland and the female breast would be achieved, yielding three- to fourfold reductions in the lifetime risk of breast cancer and a halving of the lifetime risk of thyroid cancer. CONCLUSIONS: The cancer risks from full-spinal radiographs for scoliosis are not negligible and can be reduced from one half to three quarters if the anteroposterior view is replaced with the posteroanterior view.

Adolescent↗
PubMed1996

Diagnostic accuracy of technologies used in low back pain assessment. Thermography, triaxial dynamometry, spinoscopy, and clinical examination.

STUDY DESIGN: A prospective blind study compared three new technologies to assess back pain. OBJECTIVE: To assess the diagnostic accuracy and comparability of thermography, triaxial dynamometry, and spinoscopy in the assessment of recent onset work-related low back pain. SUMMARY OF BACKGROUND DATA: The role of these technologies in assessing patients with low back pain is unproved. METHODS: Forty-one patients with low back pain and 46 control subjects were assessed by each technology and by two clinical examiners blind to clinical status. Twenty patients were trained to simulate a healthy back without low back pain, and 50% of the control subjects were trained to simulate the presence of a low back pain disorder. Each technology was interpreted on two occasions by each of two readers. RESULTS: Thermography performed significantly worse than did triaxial dynamometry, spinoscopy, and clinical examination. The diagnostic accuracy of the last three was similar, and inter-rater comparability did not differ significantly. Among simulators, the diagnostic accuracy of triaxial dynamometry and spinoscopy was significantly higher than that of clinical examination, although considerable inaccuracy remained in assessing individual subjects. CONCLUSIONS: The diagnostic accuracy of thermography in recent onset low back pain does not support its use. Among those simulating normality or low back pain, triaxial dynamometry and spinoscopy have greater diagnostic accuracy than does a single clinical evaluation. However, for an individual, the inaccuracy that remains limits the use of triaxial dynamometry or spinoscopy for diagnosis in recent onset low back pain.

Adult↗
PubMed1996

Socioeconomic status and lung function among primary school children in Canada.

We examined the relationship of lung function level to socioeconomic status (SES) using a cross-sectional design among 989 primary school children selected from 18 Montreal schools and studied between April 1990 and November 1992. Information on each child's health, demographics, home exposure to tobacco smoke, pets, and cooking and heating fuel used in the child's home was collected by questionnaire. Spirometry was performed at school. Parental occupation was used to establish SES. After adjusting for personal, familial, and environmental factors, in boys but not in girls, FEV1 and FVC were progressively larger in higher categories of SES (p < 0.001 for linear trend). After taking into account the effect of multiple comparisons and adjusting for personal, familial, and environmental factors, boys from families in the lowest category of SES were found to have an FEV1 lower by 8.2% (95% CI, -13.8 to -2.1) and an FVC lower by 8.1% (95% CI, -13.4 to -2.6) when compared with the most advantaged. These results provide evidence that socioeconomic status, independent of common indoor exposures, is a risk factor for lower FEV1 and FVC among boys.

Canada↗
PubMed1995

The comparison of injury severity instrument performance using likelihood ratio and ROC curve analyses.

BACKGROUND: The relative merits of injury severity instruments are often difficult to determine because the statistical techniques, study populations, and outcomes used in trauma research tend to obscure rather than elucidate differences in performance. OBJECTIVE: To describe the advantages of likelihood ratio and receiver operator characteristic (ROC) curve analyses and to demonstrate them using study populations and outcomes that facilitate instrument discrimination. MATERIALS AND METHODS: Previously published data on the performance of the "Injury Severity Score" and of four triage instruments in the prediction of mortality; paired comparison of two instruments in a previously unpublished trauma registry dataset; use of likelihood ratio and ROC analyses. MEASUREMENTS AND MAIN RESULTS: In a comparison of triage instruments this study clearly showed that CRAMS, PHI, and RTI, which contain nonphysiological information, have higher performance levels than the Revised Trauma Score (RTS), which is restricted to physiological information. Absolute performance gains of these instruments over the RTS ranged from 5.9% to 43.5%. This study also noted that the ISS performs equally well for blunt and penetrating trauma, and affirms concerns about the adequacy of its performance. CONCLUSIONS: Likelihood ratio and ROC curve analyses demonstrate differences in injury severity instrument performance that were obscured by less rigorous methods of comparison.

Humans↗
PubMed1994

Health of family members caring for elderly persons with dementia. A longitudinal study.

OBJECTIVE: To estimate the change in depression and physical symptoms during a 1-year period in a group of caregivers for elderly persons with dementia and in a group of comparison participants. DESIGN: Cohort study with a comparison group. SETTING: Outpatient geriatric assessment unit and ophthalmology service in an acute care hospital. PARTICIPANTS: 218 close family members of a consecutive sample of patients with dementia and patients having cataract surgery were interviewed to obtain a baseline assessment. Of these, 86 caregivers (family members of patients with dementia) and 95 comparison participants (family members of patients with cataracts) were interviewed again approximately 1 year later. MAIN OUTCOME MEASURES: Center for Epidemiologic Studies depression scale and Aday and Andersen's 24-item physical symptom checklist. RESULTS: For the Center for Epidemiologic Studies depression score, the difference between caregivers and comparison participants with respect to change during the 1-year study period was 2.1 (95% CI, 1.0 to 5.2); for physical symptoms, the difference was 0.4 (CI, -0.3 to 1.1). A higher level of behavioral disturbance in the patients with dementia at time 1 and institutionalization of the patient between time 1 and time 2 were predictive of worsening caregiver depression and physical symptoms during the study period. The magnitude and direction of changes in caregiver health varied considerably. CONCLUSIONS: Overall mean changes in depression and physical symptoms during 1 year were small. The observed variability in the individual response to the caregiving situation suggests that future research should focus on the identification of salient prognostic factors.

Aged↗