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Biomedical subjects

D W Bates

Publications and source records attributed to D W Bates.

At least 127 records · Page 7Linked to original sources
PubMed1994

A comparison of case definitions of chronic fatigue syndrome.

We compared three case definitions of chronic fatigue syndrome (CFS) applied to patients followed in CFS clinics at two institutions. All patients had debilitating fatigue without apparent etiology; patients with medical conditions associated with chronic fatigue and with major psychiatric disorders were stratified and presented separately. Patients were classified according to whether they met case definitions developed by a Centers for Disease Control and Prevention (CDC) Working Group, a British group, or an Australian group. When findings for 805 patients followed at the two clinics were combined, 61% met the CDC criteria, 55% met the British criteria, and 56% met the Australian criteria; these proportions were relatively similar at both sites. In addition, similar laboratory abnormalities were found for all case groups and for fatigued patients who met none of the three case definitions. These data suggest that more inclusive case definitions may be superior.

Adult↗
PubMed1994

SPECT imaging of the brain: comparison of findings in patients with chronic fatigue syndrome, AIDS dementia complex, and major unipolar depression.

OBJECTIVE: Chronic fatigue syndrome is an illness of unknown origin that begins abruptly with a flulike state and has symptoms suggesting both a chronic viral encephalitis and an affective disorder. We compared single-photon emission computed tomography (SPECT) scans of patients with chronic fatigue syndrome with those of patients with AIDS dementia complex and unipolar depression. SUBJECTS AND METHODS: We used 99mTc-hexamethylpropyleneamine oxime to examine 45 patients with chronic fatigue syndrome, 27 patients with AIDS dementia complex, and 14 patients with major unipolar depression. Scans of 38 healthy persons were used as controls. Comparison of regional defects between groups, as well as midcerebral uptake indexes (an objective measure of global radionuclide uptake), was performed by using analysis of variance with the Student-Newman-Keuls option. Correlation between the number of regional defects and the midcerebral uptake index was determined by using the Spearman rank-correlation test. RESULTS: Patients with AIDS dementia complex had the largest number of defects (9.15 per patient) and healthy patients had the fewest defects (1.66 per patient). Patients with chronic fatigue syndrome and depression had similar numbers of defects per patient (6.53 and 6.43, respectively). In all groups, defects were located predominantly in the frontal and temporal lobes. The midcerebral uptake index was found to be significantly lower (p < .002) in the patients with chronic fatigue syndrome (.667) and patients with AIDS dementia complex (.650) than in patients with major depression (.731) or healthy control subjects (.716). Also, a significant negative correlation was found between the number of defects and midcerebral uptake index in patients with chronic fatigue syndrome and AIDS dementia complex, but not in depressed patients or control subjects. CONCLUSION: These findings are consistent with the hypothesis that chronic fatigue syndrome may be due to a chronic viral encephalitis; clinical similarities between chronic fatigue syndrome and depression may be due to a similar distribution and number of defects in the two disorders.

AIDS Dementia Complex↗
PubMed1994

Computerized physician order entry and quality of care.

In automated physician order entry systems, physicians enter orders directly on the computer. Compared with manual systems, advantages are that orders are legible, transcription is eliminated, the writer can be identified, and orders can rapidly be routed to their destinations. But most importantly, physician order entry allows order checking and provision of decision support to the orderer in real time. Disadvantages are that systems developed to date have been slower than pen and paper and they represent a major process change so that implementation is time-consuming and requires patience both on the part of the users and the developers.

Boston↗
PubMed1994

A new knowledge structure for drug-drug interactions.

We developed a program to automatically screen patients' medication profiles for pairs of interacting drugs. Since some drug-drug interactions are indicated by changes in physiological parameters (e.g., ciprofloxacin and theophylline leading to an elevation of theophylline levels), the program considered the patients' relevant laboratory parameters prior to generating the alerts. We developed an editor to facilitate maintenance of the knowledge base. We evaluated the program for 3 weeks in two satellite pharmacies. The program reported 160 alerts of which 5 resulted in a change in the patients' therapies (one per 500 patient-days of care). These five interactions were potentially very serious. An additional 3 alerts led to changes in medication administration times. Subjectively, the program is well received and continues to be in routine clinical use.

Drug Interactions↗
PubMed1994

Impact of computerized physician order entry on physician time.

We examined the effect of computerized physician order entry on housestaff time use patterns, using time motion techniques. For both medical and surgical house officers, writing orders on the computer took about twice as long (p < 0.001), or 44 minutes for medical and 73 minutes for surgical house officers. Medical house officers recovered about half this time because some administrative tasks--e.g. looking for charts--were made easier. Within types of orders, sets of stereotyped orders took much less time with order entry, but one-time orders took longer. We have since developed strategies to make it easier to enter one-time orders.

Hospital Information Systems↗
PubMed1993

Prevalence of fatigue and chronic fatigue syndrome in a primary care practice.

BACKGROUND: Our goals were to determine the prevalence of unusual, debilitating fatigue and the frequency with which it was associated with the chronic fatigue syndrome (CFS) or other physical or psychological illness in an outpatient clinic population. METHODS: We prospectively evaluated a cohort of 1000 consecutive patients in a primary care clinic in an urban, hospital-based general medicine practice. The study protocol included a detailed history, physical examination, and laboratory and psychiatric testing. RESULTS: Five patients who came because of CFS studies were excluded. Of the remaining 995, 323 reported fatigue, and 271 (27%) complained of at least 6 months of unusual fatigue that interfered with their daily lives. Of the 271, self-report or record review revealed a medical or psychiatric condition that could have explained the fatigue in 186 (69%). Thus, 85 (8.5%) of 995 patients had a debilitating fatigue of at least 6 months' duration, without apparent cause. Of these patients, 48 refused further evaluation, and 11 were unavailable for follow-up; 26 completed the protocol. Three of the 26 were hypothyroid, and one had a major psychiatric disorder. Of the remaining 22 patients, three met Centers for Disease Control and Prevention criteria for CFS, four met British criteria, and 10 met the Australian case definition. The point prevalences of CFS were thus 0.3% (95% confidence interval [CI], 0% to 0.6%), 0.4% (95% CI, 0% to 0.8%), and 1.0% (95% CI, 0.4% to 1.6%) using the Centers for Disease Control and Prevention, British, and Australian case definitions, respectively. These estimates were conservative, because they assumed that none of the patients who refused evaluation or were unavailable for follow-up would meet criteria for CFS. CONCLUSIONS: While chronic, debilitating fatigue is common in medical outpatients, CFS is relatively uncommon. Prevalence depends substantially on the case definition used.

Adult↗
PubMed1993

Physician reporting compared with medical-record review to identify adverse medical events.

OBJECTIVE: To assess the effectiveness of housestaff physician reporting as a method for identifying adverse events on a medical service and to compare the physician reporting mechanism with a retrospective record review mechanism. SETTING: Medical service of an urban, university-affiliated teaching hospital. DESIGN: Concurrent physician reporting mechanism using the hospital electronic mail system compared with a retrospective record review using a screening mechanism followed by structured, implicit physician review of the record. PATIENTS: All 3146 admissions to the medical service from 13 November 1990 to 14 March 1991. RESULTS: The housestaff physician reporting method identified nearly the same number (89) of adverse events as did the record review (85). However, the two methods identified only 41 of the same patients (kappa = 0.52). No statistically significant clinical or socioeconomic differences occurred between the patients identified as having had an adverse event, using the two reporting methods (physician versus record review). The housestaff did report statistically more preventable adverse events (62.5% compared with 32%; P = 0.003). The physician reporting mechanism was also less costly (approximately $15,000 compared with $54,000). CONCLUSION: An adverse event identification strategy based on physician self-referral uncovers as many adverse events as does a record review and is less costly. In addition, physician-identified events are more likely to be preventable and, thus, are targets for quality improvement.

Adolescent↗
PubMed1993

Incidence and preventability of adverse drug events in hospitalized adults.

OBJECTIVE: To evaluate the incidence and preventability of adverse drug events (ADEs) and to determine the yield of several strategies for identifying them. DESIGN: Prospective cohort study. SETTING: Seven units, including two medical, two surgical, and two obstetric general care units and a coronary intensive care unit in an urban tertiary care hospital. PATIENTS: All patients on these units over a 37-day period (2,967 patient-days). INTERVENTION: None. METHODS: Events were identified in three ways: 1) logs were placed on each unit and satellite pharmacy for nurses and pharmacists to record incidents; 2) a research nurse solicited reports of incidents twice daily on each unit; and 3) the nurse reviewed all charts at least daily. Incidents were classified by two independent reviewers as ADEs or potential ADEs. RESULTS: The rate of drug-related incidents was 73 in 2,967 patient-days; 27 incidents were judged ADEs, 34 potential ADEs, and 12 problem orders. Fifty different drugs were involved. Physicians were primarily responsible for 72% of the incidents, with the remainder divided evenly between nursing, pharmacy, and clerical personnel. Of the 27 ADEs, five were life-threatening, nine were serious, and 13 were significant. Fifteen (56%) of the 27 were judged definitely or probably preventable. Incidents were discovered about equally often from the logs and by chart review. However, when the incidents in which an ADE was present were compared with the remainder of incidents, the authors found that 67% (18 of 27) of the ADEs were identified only by chart review (p < 0.001), and physicians were more often judged responsible than other personnel (p < 0.001). CONCLUSIONS: The authors conclude that ADEs are not infrequent, often preventable, and usually caused by physician decisions. In this study, solicited reporting by nurses and pharmacists was inferior to chart review for identifying ADEs, but was effective for identifying potential ADEs. Optimal prevention strategies should cover many types of drugs and target physicians' ordering practices.

Adult↗
PubMed1992

Rapid classification of positive blood cultures. Prospective validation of a multivariate algorithm.

OBJECTIVE: To develop and validate a model predicting whether a positive blood culture represents a true positive or a contaminant in hospitalized patients, using only information available when the initial culture result becomes available. DESIGN: Prospective cohort study with derivation and validation sets. SETTING: Urban tertiary care hospital. PATIENTS: Clinical data were collected within 24 hours of the initial culture from a random sample of inpatients who had blood cultures performed, and data from the episodes in which growth was reported were included. There were 219 episodes in the derivation set and 129 episodes in the validation set. MAIN OUTCOME MEASURE: True bacteremia. Reviewers blinded to potential clinical predictors and initial laboratory results classified 115 (53%) of the episodes in the derivation set and 57 (44%) of the episodes in the validation set as true positives. RESULTS: Independent multivariate predictors of bacteremia were organism type, days until the blood culture became positive, multiple positive cultures, and clinical risk score. These factors were used to develop a model stratifying patients into four risk groups. In the derivation set's lowest-risk group, 92% (65/71) of positives represented contaminants, and in the highest-risk group, 97% (86/89) of positives represented true positives. In the validation set, the misclassification rates were 14% (8/59) in the low-risk group, and 11% (5/44) in the high-risk group. These two groups together comprised 76% of all episodes. CONCLUSION: This model can help clinicians quantify the likelihood that a given positive blood culture represents a true positive when the laboratory first calls, which may be helpful in subsequent decision making.

Adult↗
PubMed1991

Contaminant blood cultures and resource utilization. The true consequences of false-positive results.

To determine whether contaminant blood cultures increase resource utilization, we studied charge and length of stay data for episodes in which blood cultures were obtained from hospitalized adults. Compared with 1097 negative episodes, 94 false-positive episodes were associated with increased subsequent length of stay (median, 12.5 vs 8 days) and subsequent total charges (median, $13,116 vs $8731), pharmacy charges (median, $1456 vs $798), and laboratory charges (median, $2057 vs $1426). In multivariate analyses, contaminants were independently correlated with 20% and 39% increases in total subsequent laboratory charges and intravenous antibiotic charges, respectively. Thus, the true costs of contaminants may greatly exceed those of the test itself. Identifying patients at very low risk of bacteremia and attention to sterile technique may reduce costs by decreasing the frequency of contaminants.

Adult↗
PubMed1990

Predicting bacteremia in hospitalized patients. A prospectively validated model.

OBJECTIVE: To develop and validate a model for the prediction of bacteremia in hospitalized patients, and to identify subgroups of patients with a very low likelihood of bacteremia in whom a positive blood culture has a low positive predictive value. DESIGN: Prospective cohort study with clinical data on 1516 episodes collected from a random sample of all patients who had blood cultures done at one institution. SETTING: Urban, tertiary care hospital. PATIENTS: Derivation set: 1007 blood culture episodes sampled from all blood cultures done on patients at Brigham and Women's Hospital between October 1988 and February 1989. Validation set: 509 episodes, May 1989 to June 1989. The unit of evaluation was the episode, defined as a 48-hour period beginning after a blood culture was drawn. MEASUREMENTS AND MAIN RESULTS: True- and false-positive rates of blood cultures in the derivation set as assessed by independent reviewers were 7% (74 of 1007) and 8% (81 of 1007), respectively. Independent multivariate predictors of true bacteremia were temperature of 38.3 degrees C or higher, presence of a rapidly (less than 1 month) or ultimately (less than 5 years) fatal disease; shaking chills; intravenous drug abuse; acute abdomen on examination; and major comorbidity. In the low-risk group, defined by absence of these predictors, the misclassification rate of the model in the derivation set was 1% (4 of 303), and a positive blood culture had a positive predictive value of only 14% for true bacteremia. The model also identified a high-risk subset in which 16% (41 of 264) of episodes represented true bacteremia. The model was prospectively validated in 509 additional episodes, and the misclassification rate in the low-risk group was 2% (3 of 155). INTERVENTIONS: None. CONCLUSION: These findings provide a means of stratifying hospitalized patients according to their risk for bacteremia. If prospectively validated in other settings, this model may be helpful when deciding whether or not to do blood cultures or start antibiotic therapy and, when evaluating a positive blood culture, to determine whether or not it is a true-positive.

Adult↗
PubMed1989

Health and metabolic responses of young calves housed at -30 degrees C to -8 degrees C.

Newborn, male, Holstein calves, were continuously housed for three weeks in calf hutches at 17 degrees C or in a thermal environment which varied rhythmically on a daily basis either between -20 degrees C and -8 degrees C (experiment A) or between -30 degrees C and -18 degrees C (experiment B). Compared to warm-housed calves, cold-housed calves in experiment A had metabolic rates which were significantly higher (p less than 0.001) in a standing position but which were not significantly different (p less than 0.05) in a recumbent position. Recumbent and standing cold-housed calves in experiment B had an increased (p less than 0.05) metabolic rate compared to warm-housed controls. Heat loss was less (p less than 0.05) for recumbent cold-housed calves in experiment B than for standing calves in a thermoneutral environment. Localized subcutaneous hemorrhages of hindlimbs were a consistent necropsy finding among all cold-housed calves. Average daily gains of cold-housed calves were not significantly different from warm-housed controls. Clinical, physiological and pathological findings indicated that cold treatments used in the present study did not cause serious harm to calves. It was concluded that calves housed in properly managed hutches are remarkably cold tolerant.

Animals↗
PubMed1989

Thermal insulation of young calves exposed to cold.

Tissue, external and whole animal insulation values were determined for 12 newborn male Holstein calves continuously housed for two weeks in hutches within environmental chambers in which temperature was maintained at a constant 17 degrees C (three calves) or cycled on a daily basis either between -20 degrees and -8 degrees C (three calves) or between -30 degrees and -18 degrees C (six calves). Three of the six calves at the coldest temperature were outfitted with an insulated coat. The insulated coat provided calves a 52% increase in total insulation. Tissue insulation of cold-housed calves increased 37.2% over the first two weeks of life. It was concluded that the capacity for vasoconstriction improved with age. External insulation did not change significantly except during the first week in cold-housed calves without insulated coats. External insulation values were five to eight times those of tissue insulation values for all treatment groups. This indicated that insulation of structures external to the skin (hair, bedding, ground, etc.) provided most of the insulation for calves.

Animals↗
PubMed1988

Evaluation of the stable fly (Stomoxys calcitrans) as a vector of enzootic bovine leukosis.

Experiments reported here were directed at 2 questions: (1) Can the stable fly (Stomoxys calcitrans) transmit enzootic bovine leukosis? (2) Could early viremia augment the probability of transmission by this insect? In one vector experiment, calves and bovine leukemia virus (BLV)-infected cows were housed with and without stable flies. The calves were monitored serologically during a 3-month postexposure period, using the agar gel immunodiffusion test. All fly-infested and fly-free calves remained BLV-seronegative. For a second vector experiment, donor calves, newly injected with blood from BLV-infected cows with high virus expression, were tethered alternately between uninoculated, weaned BLV-seronegative calves. These groups were housed with or without flies in 2 replicate trials. The inoculated calves from the first replicate seroconverted at 16 and 23 days after inoculation; the inoculated calves from the second replicate seroconverted at 11, 16, 16, and 37 days after inoculation. All uninoculated calves remained BLV-seronegative. In a manual transmission experiment, 50 unfed stable flies were allowed to complete a meal on each of 3 BLV-seronegative calves after feeding on a BLV-seropositive cow with high (42%) virus expression. One control calf was injected with blood from the cow. Seroconversion occurred in the control calf and 1 calf on which flies were given access. A scanning electron microscopic study was made of the everted and closed mouth parts of the stable fly. Given the lymphocyte count in blood from the cow used in the manual vector transmission experiment, it was calculated that 3,950 mouth part volumes would be necessary to transmit BLV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Subspecialty differences in responding to patient death--comparing cardiologists with oncologists.

Cardiac deaths are more likely to be unanticipated than cancer deaths by patients, their families, and their physicians. We hypothesized that differing physician attitudes toward dying patients may affect the degree of expectation of death. To evaluate differences in attitudes and behaviors among subspecialists, we surveyed a randomly selected population of California subspecialists; 44 of 136 (32%) of cardiologists and 91 of 167 (55%) of oncologists responded. Oncologists experienced three times as many deaths as cardiologists and reported having discussed code status more often with patients who died. Cardiologists' patients' deaths were more often unexpected and occurred more frequently in intensive care units. In addition, their patients were more likely to be given cardiopulmonary resuscitation. Oncologists reported being more comfortable dealing with dying patients and having less desire to avoid them. When presented with patient scenarios, however, cardiologists' and oncologists' responses were similar when discussing and estimating prognosis and likelihood of successful therapy.

Attitude to Death↗
PubMed1979

Calculation of ventilation needs for confined cattle.

Fundamental to maintaining a healthy environment in a mechanically ventilated livestock building is a continuous flow of air, with at least 4 exchanges per hour to remove moisture and aerosol contaminants. A correctly designed fresh air intake system is mandatory for uniform air distribution. Proper insulation is essential. Supplemental heat may be required to permit continuous ventilation while maintaining an ambient temperature suitable for preserving animal health.

Air↗