Medical data mining: knowledge discovery in a clinical data warehouse.

Clinical databases have accumulated large quantities of information about patients and their medical conditions. Relationships and patterns within this data could provide new medical knowledge. Unfortunately, few methodologies have been developed and applied to discover this hidden knowledge. In this study, the techniques of data mining (also known as Knowledge Discovery in Databases) were used to search for relationships in a large clinical database. Specifically, data accumulated on 3,902 obstetrical patients were evaluated for factors potentially contributing to preterm birth using exploratory factor analysis. Three factors were identified by the investigators for further exploration. This paper describes the processes involved in mining a clinical database including data warehousing, data query and cleaning, and data analysis.

Pelvic examination instruction and experience: a comparison of laywoman-trained and physician-trained students.

PURPOSE: To evaluate medical student performances of pelvic examinations after completion of the obstetrics-gynecology (ob-gyn) clinical clerkship in order to compare the effectiveness of training by laywomen serving as both teachers and patients with the effectiveness of training by an attending physician as teacher, with a lay-woman serving only as the patient. The study also examined whether students were given additional training and opportunities for practice during their clinical clerkships in other disciplines. METHOD: Following completion of their ob-gyn clerk-ships in 1993 and 1994, a total of 81 students at two North Carolina medical schools answered a questionnaire eliciting demographic information, pelvic examination experience, and the content of the training they had received. The students then performed a pelvic examination on a standardized patient (SP). Their performances were evaluated by the SP using a 35-item scale, subdivided into technical and interpersonal skills. The data were analyzed by two-tailed t-tests, analysis of variance, and chi-square tests. RESULTS: The laywoman-trained students demonstrated better interpersonal skills than did the physician-trained students (p = .01). No significant difference was found in technical skills. Nearly one-fourth of the students reported that communication skills had not been taught during their ob-gyn clerkships. The students reported performing pelvic examinations often on their ob-gyn rotation but infrequently on other rotations. CONCLUSION: The authors recommend that teaching by laywomen be incorporated into the teaching of pelvic examinations and other aspects of a women's health curriculum. Interpersonal skills taught by laywomen in preclinical courses on pelvic examination may have a lasting effect that can be demonstrated after exposure to clinical clerkships. Clinical clerkships should then reinforce these skills.

Nonvisualization of the fetal gallbladder: frequency and prognostic importance.

PURPOSE: To assess the frequency of fetal gallbladder visualization through gestation and to determine the prognostic importance of nonvisualization. MATERIALS AND METHODS: Demonstration of the gallbladder was prospectively attempted in 578 consecutive second- and third-trimester obstetric ultrasound examinations. Data regarding gallbladder visualization were stratified into subgroups on the basis of estimated gestational age. Postnatal follow-up was performed in 80 fetuses with nonvisualization of the gallbladder. RESULTS: The gallbladder was seen on 477 of 578 (82.5%) fetal sonograms. The likelihood of gallbladder visualization increased with advancing gestational age, reaching a plateau of approximately 95% between 24 and 32 weeks. After 32 weeks, the frequency of visualization declined. Seventy-five of the 80 fetuses with nonvisualized gallbladders who underwent follow-up had normal outcomes. Except for one fetus with trisomy 21, all fetuses with abnormalities had relatively minor, non-life threatening problems that did not involve the gallbladder or biliary tract. CONCLUSION: Most fetuses with nonvisualization of the gallbladder have normal outcomes. The rate of nonvisualization of the fetal gallbladder is sufficiently high to undermine the utility of gallbladder visualization as a screen for fetal abnormality.

Fetal brain development of twins assessed in utero by ultrasound: implications for schizophrenia.

There is evidence that some forms of schizophrenia are due to alterations of in utero brain development. Given the concordance rate for schizophrenia in monozygotic twins is approx. 45%, it is not clear how a shared genetic predisposition for schizophrenia and a shared in utero environment might selectively lead to schizophrenia in one but not the other twin in a monozygotic twin pair. This study was undertaken to test the hypothesis that there is a difference in brain development between twins in a monozygotic twin pair that may contribute to the observed concordance rates for schizophrenia. Fetal ultrasound measures of brain (biparietal diameter, head circumference, ventricular width) and body size (femur length, abdominal circumference) obtained during the second trimester of fetal development were retrospectively analyzed in 41 monozygotic and 103 dizygotic twin pairs. In monozygotic twin pairs, there was a significant difference in measures of biparietal diameter, head circumference, and ventricular width, as well as in femur length and abdominal circumference, between twins. There was a similar difference in dizygotic twin pairs. These results indicate that in monozygotic twins, brain development is not identical. This difference in brain development may contribute to the observed concordance rates in monozygotic twins with schizophrenia.

Use of the TDx-FLM assay in evaluating fetal lung maturity in an insulin-dependent diabetic population. The Diabetes and Fetal Maturity Study Group.

OBJECTIVE: To assess the usefulness of the recently introduced TDx-FLM assay in managing pregnant women with diabetes. METHODS: Participating institutions were recruited from the 1993 and 1994 Society of Perinatal Obstetricians Diabetes Special Interest Group meetings. Study patients consisted of insulin-dependent diabetic women who had undergone transabdominal amniocentesis with assay of the fluid by the TDx-FLM method. Pertinent data were requested concerning pregnancy and respiratory outcomes of the corresponding neonates. RESULTS: Data from 261 pregnancies at 13 institutions were collected. Eight of the 182 infants born within 4 days of amniocentesis developed respiratory distress syndrome (RDS); five of the eight infants with RDS required intubation, and all five had TDx-FLM values less than 70 mg of surfactant per gram of albumin. Three of the eight infants with RDS required hood oxygen only; two of these infants had TDx-FLM values at least 70 mg/g. Thirteen of 144 (9%) subjects who delivered within 4 days of amniocentesis and for whom a TDx-FLM assay and phosphatidylglycerol level were both reported had a TDx-FLM level of at least 70 mg/g and a negative phosphatidylglycerol result. No infant with this combination of results developed RDS. Fifteen of the 40 patients who delivered more than 4 days after amniocentesis, with both tests available, had TDx-FLM values at least 70 mg/g and were phosphatidylglycerol negative. CONCLUSION: In infants of diabetic mothers, TDx-FLM values at least 70 mg/g were not associated with RDS requiring intubation. The TDx-FLM assay may be useful in determining the best time of delivery for pregnant patients with diabetes, especially in a situation in which the TDx-FLM assay is mature and the phosphatidylglycerol result is immature.

Converting a legacy system database into relational format to enhance query efficiency.

The analysis of clinical data collected over time can provide important insight into the health care process. Unfortunately, much of the electronic clinical data that exists today is stored in legacy systems, making it difficult to access and share the information. An approach is needed to improve the accessibility of electronic data stored in legacy system databases. In this study, a legacy database is converted into a relational format in the personal computer environment. The impact of such a conversion on query performance is evaluated, and issues that need to be considered when converting a legacy system database are identified.

Fetal renal vein thrombosis, hydrops fetalis, and maternal lupus anticoagulant. A case report.

Hydrops fetalis with fetal renal vein thrombosis in a mother with antiphospholipid antibody syndrome detected post-partum suggests an underlying pathogenetic association that may provide new strategies for treatment of a lethal disorder.

hCG, progesterone, alpha-fetoprotein, and estradiol in the identification of ectopic pregnancy.

OBJECTIVE: To enhance the laboratory diagnosis of ectopic pregnancy by determining levels of hCG, progesterone, estradiol (E2), and alpha-fetoprotein (AFP). METHODS: Serum samples and medical records were retrospectively analyzed from 100 gynecologic patients for whom quantitative hCG determination had been ordered. Clinical data and levels of hCG, progesterone, E2, and AFP were examined by univariate and multivariate logistic analyses. RESULTS: Progesterone, hCG, and E2 were highest in viable pregnancies, whereas AFP tended to be higher in ectopic pregnancies. A single progesterone value could differentiate between ectopic and viable pregnancy in more than 80% of patients. The combination of all four biochemical markers predicted ectopic pregnancy with 98.5% specificity and 94.5% accuracy. Clinical diagnosis was less than 75% accurate. CONCLUSION: A combination of biochemical markers including hCG, progesterone, E2, and AFP can be superior to a single progesterone level or clinical evaluation in the diagnosis of ectopic pregnancy.

Prenatal events and the risk of subependymal/intraventricular haemorrhage in very low birthweight neonates.

The effects of prenatal factors on the risk of subependymal and/or intraventricular brain haemorrhage in very low birthweight (VLBW) neonates were studied. Data were collected on 201 consecutively born VLBW neonates without major congenital anomalies, who were born at a regional obstetric referral centre. Brain haemorrhage was identified by cranial ultrasound examinations. The reliability of these examinations (concordance among readers' interpretations) was assessed and found to be moderate (kappa = 0.47 for the finding of subependymal haemorrhage (SEH); kappa = 0.50 for the finding of intraventricular haemorrhage (IVH)). Prenatal factors were more strongly associated with IVH than with SEH. In univariable analyses, maternal pre-eclampsia, multiple gestation and maternal treatment with betamethasone were associated most strongly with a decreased risk of haemorrhage whereas labour and vaginal delivery were associated most strongly with an increased risk. These associations remained in a multivariable analysis which included prenatal events (maternal illnesses, fetal presentation and obstetrical interventions), as well as gestational age, birthweight, gender, treatment with assisted ventilation, and the occurrence of pneumothorax. Further aetiological study of the effects of prenatal factors could provide information useful in preventing SEH/IVH.

Acute childbirth morbidity: its measurement using hospital charges.

OBJECTIVES: An analytic descriptive analysis of acute childbirth morbidity was carried out at Duke University Medical Center, comparing patients delivered by primary cesarean section with those delivered vaginally. STUDY DESIGN: All primary cesarean deliveries and vaginal deliveries from July 1, 1981, through June 30, 1986, were combined with maternal and infant charge data. A total of 7256 patients were analyzed. A description of the charges for the associated diagnoses was carried out. A morbidity index was used to identify differences in predicted median hospital charges with 95% confidence intervals. RESULTS: The ratio of mean primary cesarean delivery to mean vaginal delivery total charges was 2.5:1. The magnitude of the mean hospital charges was inversely related to the frequency of the indication with the lowest charges associated with dystocia and the highest with multiple pregnancy. Antepartum risk factors (increased maternal age, patient referral) were associated with increases in maternal and infant morbidity as measured by the morbidity index. Chronic maternal hypertension resulted in decreased maternal morbidity but increased infant morbidity when primary cesarean delivery was used. Although preterm delivery was associated with large increases in charges, it was not significantly altered by using primary cesarean delivery. Risk factors associated with the management of abnormalities of labor were associated with decreases in maternal and infant morbidity when primary cesarean delivery was used. CONCLUSION: Analysis of acute childbirth morbidity, as measured by hospital charges, showed marked variation of diagnosis and risk-specific charges for patients delivered by primary cesarean section.

Alloimmune thrombocytopenia may be associated with systemic disease.

Adverse outcome was encountered in a case of neonatal alloimmune thrombocytopenia after in utero platelet transfusion. This may have resulted from generalized systemic vascular endothelial damage, because several cell types, including umbilical endothelial cells, have been shown to contain surface molecules similar to the receptor containing the PlA1 antigen.

Interpretations of nonstress tests by obstetric nurses.

Five 20-minute nonstress-test strips were mailed to 1,000 members of NAACOG--the organization for obstetric, gynecologic, and neonatal nurses. The individuals were selected systematically from NAACOG's 10 districts. For the 412 (41%) respondents, at least 84% of the answers concurred on each of the five strips. The majority opinion was taken to be the correct answer. Concurrence with the majority was independent of clinical experience, clinical training, and the extent of present nonstress-test responsibilities. The same five strips were interpreted by obstetricians in a previously reported survey. On a two-point, reactive-nonreactive scale, the sample of obstetric nurses' degree of agreement differed significantly from the sample of physicians' degree of agreement (92 versus 98%) on only one strip.

Use of the fibrin D-dimer in screening for coagulation abnormalities in preeclampsia.

Plasma from pregnant women with preeclampsia was screened for the D-dimer, a degradation product specific for crosslinked fibrin, using a monoclonal antibody (DD-3B6), latex-bead agglutination assay (DIMERTEST). Seventy-nine of 204 (38.7%) of the preeclamptic women and none of 88 healthy non-preeclamptic women were positive for the D-dimer. Presence of the D-dimer correlated consistently with elevated fibrin(ogen) degradation products, detectable fibrin monomer, and platelet count less than or equal to 100 x 10(9)/L, with a 93.0% sensitivity overall for abnormalities of the same. Among D-dimer-positive women, 66.7% had fibrin(ogen) degradation products less than 10 micrograms/mL, 60.3% had no detectable fibrin monomer, and 82.0% had platelets greater than 100 x 10(9)/L. When compared with D-dimer-negative preeclamptic women, D-dimer-positive women had significantly higher blood pressures prompting delivery, greater proteinuria, more abnormal liver function tests, and higher serum creatinine and blood urea nitrogen. In addition, they had a greater risk of cesarean section (49.4 versus 34.4%), premature delivery (58.2 versus 20.0%), low birth weight (54.5 versus 20.3%), low Apgar scores, and an abnormally high ratio of female to male offspring (1.72 versus 0.93). Testing for the fibrin D-dimer may be useful in early screening and follow-up for preeclamptic coagulopathy, and may also help to define the subset of patients with severe disease.

Should hyperbaric oxygen be used to treat the pregnant patient for acute carbon monoxide poisoning? A case report and literature review.

Carbon monoxide (CO) is the leading cause of death due to poisoning. Although uncommon, CO poisoning does occur during pregnancy and can result in fetal mortality and neurological malformations in fetuses who survive to term. Uncertainty arises regarding the use of hyperbaric oxygen (HBO) as a treatment for the pregnant patient because of possible adverse effects on the fetus that could be induced by oxygen at high partial pressures. While the dangers of hyperoxia to the fetus have been demonstrated in animal models, careful review of animal studies and human clinical experience indicates that the short duration of hyperoxic exposure attained during HBO therapy for CO poisoning can be tolerated by the fetus in all stages of pregnancy and reduces the risk of death or deformity to the mother and fetus. A case is presented of acute CO poisoning during pregnancy that was successfully treated with HBO. Recommendations are suggested for the use of HBO during pregnancy.

Changing rates of cesarean delivery: the Duke experience, 1978-1986.

There was a steady increase in the yearly cesarean delivery rate, from 14.0 to 24.8%, between July 1, 1978 and June 30, 1986 at Duke University Medical Center; this was associated predominantly with an increase in the rate of primary cesarean deliveries. The three most frequent major diagnoses associated with primary cesarean delivery changed significantly over the study period. Fetal compromise became the most commonly associated diagnosis (from third), dystocia second (from first), and maternal disease third (from second). The categories of fetal positional abnormalities (fourth), abnormalities of placentation (fifth), and multiple pregnancy (sixth) did not change in rank. Primary cesarean delivery patients were compared with patients who delivered vaginally using odds ratios, prevalence, and population-attributable fractions. The risk factors of nulliparity, gestational age less than 37 weeks, late decelerations, and referral had the largest impact on the primary cesarean rate. Decreases in rates related to an increased tolerance of abnormalities of labor were overshadowed by the effects of increased concerns related to fetal health.

Expectant management of abdominal pregnancy. A report of two cases.

In two recent consecutive cases of abdominal pregnancy the diagnosis was made at 18 weeks' gestation, and the patients refused immediate surgery and elected to maintain the pregnancy until fetal viability developed. Both patients were managed expectantly with continuous antepartum hospitalization. Fetal assessment was by serial ultrasound assessment of growth and amniotic fluid volume and by nonstress testing. Planned operative delivery was accomplished at 28 1/2 weeks and 33 weeks' gestation. In the second case the diagnosis was confirmed by magnetic resonance imaging. That fetus was also assessed with umbilical artery Doppler flow studies. Despite significant morbidity, both the mothers and infants are alive and well.

Management decisions after nonstress testing.

Evaluation of patient management after the utilization of a specific diagnostic test has been difficult to interpret from retrospective studies. Specifically, the impact of the interpretation of the diagnostic study, the environment where the test is performed, and the biases of the physician have been difficult to separate. In this study, agreement on first-choice management decisions by a national sample of obstetricians blinded to specific clinical information, based on interpretations of five nonstress tests, was low (kappa = 0.24 +/- 0.02). The response "evaluate for delivery" was significantly different between "reactive" and "nonreactive" interpretations. There was better management agreement among those respondents with more experience with nonstress testing; those from larger hospitals; and those who practiced at universities, HMOs, and military hospitals. The attitudes of individual respondents as measured by the first-choice goals of the test did not significantly influence overall management agreement. Reliability of management was less among physicians aged 50-59 years. There was no obvious national consensus regarding management following nonstress testing.

Interpretation of nonstress tests.

Five nonstress tests were interpreted by a national sample of obstetricians blinded to specific patient clinical data. The 169 questionnaires suitable for analysis showed that the reliability of the test interpretation, as measured by the kappa statistic, decreased with increasing number of categories of interpretation. Kappa values for two, three, and five categories of interpretation were 0.60, 0.39, and 0.36, respectively. The middle values in the three- and five-category methods of interpretation had very low levels of reliability. Kappa values as related to the age of the respondent or measurements of experience showed relatively small changes in reliability of interpretation.