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Biomedical subjects

S L Hui

Publications and source records attributed to S L Hui.

At least 91 records · Page 5Linked to original sources
PubMed1985

The impact of reading on physicians' nonadherence to recommended standards of medical care.

In order to increase physicians' adherence to recommended standards of medical care and to examine factors presumed to contribute to such changes, we conducted a randomized, controlled trial using reading materials targeted to specific practice recommendations. Seventy-nine internal medicine residents completed baseline questionnaires stating their intentions to follow 13 common preventive care actions. They were randomly assigned to receive one of two different sets of readings covering these care actions. Thus, each physician was in the experimental group for one set of readings (A or B) while serving as a control for the other set. The impact of the reading was determined by: the physicians' knowledge of the recommended care actions detailed in the combined readings, their post-reading intentions, and clinical behavior when faced with patients having indications for the recommended actions. The 73 residents (92%) who read the material judged 39% of the information to be new and 72% useful. Residents had significantly better performance on the knowledge questions based on their own readings than did their control group peers for both sets of readings. For the Group A physicians, reading significantly (P less than 0.05) increased intentions to follow one of the seven clinical actions while Group B residents increased their intentions in three out of six. Step-wise multiple regression analyses were used to predict physicians' post-reading adherence to the recommended actions. For the Group A actions, pre-reading actions accounted for most of the variance in their post-reading actions.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Competence↗
PubMed1985

After-hours telephone access to physicians with access to computerized medical records. Experience in an inner-city general medicine clinic.

The authors examined the effect of after-hours telephone access to physicians and physician access to computerized medical records on hospitalizations and emergency room (ER) visits in an inner-city, adult, general medicine clinic. Patients were randomly assigned to a control (C) and two study groups (S1 and S2). Patients in study groups S1 and S2 had after-hours telephone access to physicians. Computerized medical records were accessible to physicians only for callers in study group S2. During the initial 18 months of study, only 7.6% of eligible patients called the after-hours service, a rate of 6 calls/1,000 patients/month (200 calls/1,849 patients/18 months). Repeated promotion of the service was subsequently undertaken, and 19.4% of the patients used the service during the final 12 months of study, a rate of 24.1 calls/1,000 patients/month (467 calls/1,616 patients/12 months). There were no significant differences in hospitalizations or ER visits among the control and two study groups.

Computers↗
PubMed1985

A prospective study of bone mass in patients with type I diabetes.

Sixty-nine patients with type I diabetes mellitus were followed for from 1-4 yr (mean, 3 yr). Their overall growth, as measured by height and weight, was normal; however, repeated measurements of their bone mass using photon absorptiometry and radiogrammetry showed that, relative to normal subjects, the patients had a persistent bone deficit throughout the course of the study. This deficit was not attributable to bone width, which was normal. On the average, the magnitude of the deficit did not change with time; furthermore, an individual's rate of change in bone mass deficit during the study was not correlated with the patient's glucose control, as measured by hemoglobin A-1 or fasting blood glucose levels. Initial levels of serum ionized calcium and magnesium were decreased in the patients with diabetes. During the study, the mean level of ionized calcium increased, but that of magnesium decreased further, compared to the initial values. In a group of 19 patients with newly diagnosed diabetes, bone mass was found to be significantly below normal among the girls, but not among the boys.

Adolescent↗
PubMed1985

Early menopausal changes in bone mass and sex steroids.

Eighty-four healthy perimenopausal and early postmenopausal women were divided into four groups: group A, those with slightly irregular menstrual periods and plasma FSH below 40 mIU/ml; group B, those with irregular periods and FSH above 40 mIU/ml; group C, those whose last menstrual period was within 1 yr of study; and, group D, those whose last menstrual period was between 12 and 55 months before the study. Plasma concentrations of estrone and estradiol progressively decreased in groups B, C and D compared to those in A in parallel with a decrease in the production rates, and FSH and LH were significantly increased. There was little change in the concentration of androstenedione or testosterone. Vertebral bone mass was significantly decreased in groups B, C, and D compared to that in A, and radial bone mass was decreased in group D. There was a significantly positive correlation between plasma estrone and estradiol and bone mass at both the radius and vertebra. Increased bone remodeling was suggested by increases in serum calcium and bone gla protein. These data suggest that bone loss, at least from the spine, may begin before menses cease and is correlated with decreases in estrogen production and increases in bone remodeling.

Adult↗
PubMed1985

Multivariate slope ratio assay with repeated measurements.

A method is given for analyzing a slope ratio assay in which a test drug is compared with a standard drug, two or more response variates being measured on each subject at each of several successively increased drug doses. The method requires all subjects to receive the same number of doses, all subjects on the same drug to receive the same doses, the ratio of corresponding doses of the two drugs to be constant over the successive increases, and response variables to be measured only once on each subject at each dose with no missing data allowed. The technique is also applicable when doses are randomly assigned, provided there is no carry-over effect between doses. For each of the J response variates, the relative potency of the test drug with respect to the standard is defined and estimated in the usual way; a 100(1-alpha)% confidence region is then obtained for the vector of the J relative potencies. A procedure is given for testing the equality of some or all of the J relative potencies; an estimator of a common relative potency is obtained by a standard multivariate least squares method. A common relative potency is of interest because the multiple outcome variables are often different indicators of a general physiologic response. The procedures in the paper are illustrated by a simple example concerning the effects of two anesthetics on children.

Analysis of Variance↗
PubMed1985

Bone mass in normal children and young adults.

The growth of bone mass in the radius of children from age 6 on was studied in Indiana and Wisconsin. Growth curves describing change in bone mass, bone width, body height and weight were fitted separately to the data of males and females in the two states. Statistically significant differences between states were found in almost all growth measurements in both sexes. Refined growth curves with standard deviations were generated separately for the two states. When adjusted for age and bone width, Wisconsin subjects always had higher mean bone mass than Indiana subjects. Thus researchers should exercise caution when using published normative values established elsewhere.

Adolescent↗
PubMed1985

Cisplatin plus 5-FU for the treatment of adenocarcinoma of the colon.

Cisplatin plus 5-FU appears to have significant additive activity in various tumors, such as head and neck carcinoma and esophageal cancer. A partial explanation for this may be drug synergism, which has been noted in the L1210 leukemia model. Based on these data, a prospective trial of weekly bolus 5-FU (15 mg/kg) and cisplatin (60 mg/m2) given every 3 weeks was initiated at Indiana University. Forty-one patients, of whom 38 are fully evaluable for response, were treated with these two drugs. Ten partial and one complete response (complete + partial response rate = 29%) were observed in the 38 evaluable patients. Thirteen additional patients had stable disease for greater than or equal to 3 months. The median durations of remission and survival time were 6 and 10.3 months, respectively. Myelosuppression was unusually severe, with granulocyte counts less than 1000/mm3 in 65% of patients, including four patients with granulocyte count nadirs less than 100/mm3. Three patients developed granulocytopenic fever, with two drug-related deaths (sepsis, hyperosmolar coma). Nearly all patients had nausea and vomiting, but this was not a treatment-limiting toxic effect in any patient. Although this combination suggests a higher response rate than usually seen with bolus iv 5-FU in colon cancer, a trial comparing 5-FU alone or with cisplatin to determine whether true synergy exists is currently underway.

Adenocarcinoma↗
PubMed1984

Androgen and estrogen dynamics in women with vertebral crush fractures.

Using constant infusions of [3H]androgen/[14C]estrogen we measured metabolic clearance and production rates and aromatization of androgens to estrogens in post-menopausal women with vertebral crush fractures and compared these results to similar measurements in a similar population of post-menopausal women who did not have vertebral crush fractures. The mean +/- SEM values for the metabolic clearance rates of testosterone and estrone, 220 +/- 10 and 880 +/- 50 1/day per m2, were significantly less in the crush fracture group than the respective mean values in the control group, 280 +/- 15 and 1110 +/- 70 1/day per m2. The mean concentration of estradiol was higher in the crush fracture group, 18 +/- 2 pg/ml, compared to that in the control group, 13 +/- 1 pg/ml. However, for the crush fracture group the mean blood production rates of both androstenedione, 0.7 +/- 0.1 mg/day, and testosterone, 56 +/- 9 micrograms/day, were significantly less than the respective values in the control group, 1.2 +/- 0.2 mg/day and 115 +/- 15 micrograms/day. The production rates for estrone and estradiol were not different for the two groups. In addition the mean value for the fraction of adrostenedione converted to testosterone ( [rho]A, T BB) was lower in the crush fracture, 0.030 +/- 0.002 compared to the control group, 0.041 +/- 0.004. Thus the amount of biologically available androgen is less in the vertebral crush fracture group than in the control group. However, since these measurements represent an isolated point temporally removed from major changes in bone morphology, their exact relationship to the crush fracture and osteoporotic process remains uncertain.

Androgens↗
PubMed1984

Reminders to physicians from an introspective computer medical record. A two-year randomized trial.

We developed a computer-stored medical record system containing a limited set of the total clinical data base--primarily diagnostic studies and treatments. This system responds to its own content according to physician-authored reminder rules. To determine the effect of the reminder messages generated by 1490 rules on physician behavior, we randomly assigned practitioners in a general medicine clinic to study or control groups. The computer found indications for six different actions per patient in 12 467 patients during a 2-year study: 61 study group residents who received computer reminders responded to 49% of these indications; 54 control group residents, to only 29% (p less than 0.0001). Preventive care (occult blood testing, mammographic screening, weight reduction diets, influenza and pneumococcal vaccines) was affected. The intentions of the study group to use a given action for an indication predicted their response to the indications (p less than 0.03, r2 = 0.33). The intentions of the control residents did not.

Computers↗
PubMed1984

Curve fitting for repeated measurements made at irregular time-points.

In longitudinal studies of human populations, it is often not feasible to measure all subjects at the same time-points. This precludes the use of classical methods of curve fitting for repeated measurements. When the total interval of follow-up is short for all subjects in the study, an intraclass correlation matrix is assumed for the measurements on each subject. An estimation procedure based on iteratively reweighted least squares is described. The model is then generalized to incorporate covariables, with little modification in the estimation procedure. The proposed method is applied to data from a longitudinal study of bone mass in postmenopausal women.

Aged↗
PubMed1982

A prospective study of change in bone mass with age in postmenopausal women.

For the first time a model for age-related bone loss has been developed from prospective data utilizing a new weighted least squares method. Two hundred and sixty-eight Caucasian women ranging in age from 50 to 95 were studied. A quadratic function best fit the data, and correcting for body weight and bone width reduced variance. The derived equation is: bone mass = (0.6032) (bone width) (cm) + (0.003059) (body weight) (kg) - (0.0163) (age - 50) + (0.0002249) (age - 50)2. Analysis of cross-sectional data on 583 Caucasian women of similar age showed a quadratic function with very similar coefficients. This quadratic function predicts an increase in bone mass after age 86, therefore 42 women over age 70 who had been followed for at least 2.5 yr were identified to test for this effect. of these, 13 had significantly positive regression coefficients of bone mass on age, and rate of change in bone width was positive in 40 of 42 individuals, of which 5 were significant. Since photon absorptiometry measures net changes on all bone envelopes, the most likely explanation for the observed changes is an early exponential loss of endosteal bone which ultimately slows or perhaps stops. There is a positive balance on the periosteal envelope which only becomes apparent in later years when the endosteal loss stops. These new statistical methods allow the development of models utilizing data collected at irregular intervals. The methods used are applicable to other biological data collected prospectively.

Aged↗
PubMed1982

Correlation between serum antichlamydial antibodies and tubal factor as a cause of infertility.

Although salpingitis frequently produces tubal damage and infertility, many women with tubal factor as a cause of their infertility do not have a clinical history of salpingitis. In order to investigate whether or not some such cases might be due to subclinical chlamydial infections, we measured antichlamydial antibodies in the serum of 172 women consecutively undergoing evaluation for infertility. Only 16 (9.3%) had a prior history of salpingitis. Sixty-one (35%) had antichlamydial antibodies (S+), and of these 75% had tubal factor as a sole or contributing cause of their infertility, versus 28% of the seronegative (S-) women (x2 - 34, P less than 0.001). There was no association between chlamydial seropositivity and any infertility factor other than tubal factor in multivariant analyses. Subclinical infections with Chlamydia trachomatitis may be a major cause of tubal infertility in the United States, and chlamydial serologic studies may be useful in identifying the subset of infertile women likely to have tubal factor.

Adult↗
PubMed1980

Estimating the error rates of diagnostic tests.

It is often required to evaluate the accuracy of a new diagnostic test against a standard test with unknown error rates. If the two tests are applied simultaneously to the same individuals from two populations with different disease prevalences, then assuming conditional independence of the errors of the two tests, the error rates of both tests and the true prevalences in both populations can be estimated by a maximum likelihood procedure. Generalizations to several tests applied in several populations are also possible.

Clinical Laboratory Techniques↗
PubMed1977

Lung function, respiratory disease, and smoking in families.

Respiratory symptoms, disease and lung function were studied in 376 families with 816 children who participated in a survey in three USA towns. Parental smoking had no effect on children's symptoms and lung function. Also, there was no evidence that passive smoking affected either lung function or symptoms of adults. There was no association between prevalence of self-reported cough and/or phlegm in parents and their children. There was a highly significant association between the prevalence of wheeze in parents and their younger children, for whom parents reported this symptom. Wheeze in children was also significantly associated with a parental history of asthma, and lung function was lower in children with a family history of asthma. Even after accounting for height, weight, age, sex and race, children's lung function correlated significantly with parents' lung function. However, the contribution of familial factors (i.e., parents' lung function, smoking, and history of asthma) to children's lung function is small compared to the effects of height, weight and age.

Adolescent↗
PubMedDate not supplied

Estimating the incidence of dementia from two-phase sampling with non-ignorable missing data.

Two-phase sampling designs have been used in the field of psychiatry to estimate prevalence and incidence of a rare disease such as dementia and Alzheimer's disease. In a longitudinal study on dementia, since the repeated two-phase sampling is conducted several years after the baseline wave, some subjects may die before the follow-up wave, thus their disease status prior to death is missing. There are reasons to suggest that the missing due to death is non-ignorable. Estimation of disease incidence from longitudinal dementia study has to appropriately adjust for data missing by death as well as the sampling design used at each study wave. In this paper we adopt a selection model approach to model the missing data by death and use a likelihood approach to derive incidence estimates. A modified EM algorithm is used to deal with data from sampling selection. The non-parametric jack-knife variance estimator is used to derive variance estimates for the model parameters and the incidence estimates. The proposed approaches are applied to data from the Indianapolis-Ibadan Dementia Study.

Black or African American↗
PubMedDate not supplied

Spacing of follow-up waves in incidence studies.

Longitudinal studies of dementia are often undertaken to estimate the incidence of dementia and to identify incident cases for the study of risk factors measured on the entire cohort at baseline. The power of these analyses is determined primarily by the number of demented cases identified. Increasing the number of waves of evaluation of the cohort in a given time period increases the yield of demented cases but it also increases the cost of the study. This paper provides a method for estimating dementia incidence in the presence of mortality and loss to follow-up. It also assesses the trade-off between the cost (as measured by the number of re-evaluations) and the yield of incident dementia cases so that longitudinal studies of dementia can be designed optimally in the future.

Aged↗
PubMedDate not supplied

Using clinical data to predict abnormal serum electrolytes and blood cell profiles.

OBJECTIVE: To identify clinical predictors of five abnormalities on the serum electrolyte panel and two abnormalities on the blood cell profile, to study which data elements carried predictive information, and to measure the predictive accuracy and stability of the resulting predictive equations. DESIGN: Prospective data collection from a computerized medical database supplemented by data entered by physicians who ordered outpatient tests into microcomputers. Equations were derived during an eight-month period and later validated twice in the same setting. SETTING: Academic primary care practice affiliated with a county hospital. PATIENTS AND PARTICIPANTS: Patients were mostly black women; physicians were full-time academic general internists and medical residents. MEASUREMENTS AND MAIN RESULTS: There were 6,570 electrolyte and blood cell profile panels ordered during the equation derivation period. The mean receiver operating characteristic (ROC) curve area for the seven equations was 0.849. For the 4,977 tests ordered during ten months of prospective validation, the mean ROC curve area was only 3% less. For three equations, ROC curve areas were lower for patients with unscheduled visits than for those with scheduled visits (p less than 0.05). Except for two equations involving abnormalities with very low prevalences, the equations were also well calibrated. Prior results for the abnormality being considered were the strongest predictors, followed by other laboratory results, diagnoses, and the physicians' estimate of the probability that the test would be abnormal. CONCLUSIONS: Clinical data can accurately predict abnormal results of common outpatient laboratory tests. Computers can help find the necessary data and produce estimates of risk.

Blood Cells↗