Diurnal variation in intraocular pressure.
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Analysis of Variance↗
Biomedical subjects
R F Woolson
Publications and source records attributed to R F Woolson.
The risk of hepatitis B transmission from health care workers to patients in a hospital setting--a prospective study.
A prospective study was designed to determine the risk of hepatitis B transmission from health care deliverers to patients in the hospital setting. Six chronic carriers of hepatitis B were identified: 2 surgeons, 1 dialysis nurse, 1 pediatric ICU nurse, 1 pharmacist and 1 orderly. Three of the six were HBeAg-positive. Two of the HBeAG-positive chronic carriers also had circulating hepatitis B virus DNA and accounted for approximately two-thirds of the total patient contacts. Two hundred thirteen patients were exposed 450 times to these six hepatitis B carrier staff without evidence of hepatitis B acquisition over a 6-month follow up. One-hundred nineteen control patients, exposed 789 times to noncarrier health care deliverers, were also negative. Another 33 patients were exposed to three additional individuals who were in the prodrome of acute hepatitis B: an intensive care nurse, a dental hygienist and a medical student. These patients showed no evidence of hepatitis B during 6 months of follow-up, nor did 25 separate control patients. Thus, 246 patients were exposed a total of 483 times to nine health care personnel who had either acute or chronic hepatitis B. No evidence of hepatitis B transmission was found. One-hundred forty-four controls revealed similar results after 814 exposures. Based on the number of exposures to chronic carriers alone, the risk of hepatitis B transmission is estimated to be less than 1%.(ABSTRACT TRUNCATED AT 250 WORDS)
Carrier State↗
Mantel-Haenszel statistics and direct standardization.
This paper demonstrates that the Mantel-Haenszel chi-square statistic may be employed to test the equality of two directly standardized rates. For certain epidemiological applications, this eliminates the need for special computer programs to contrast two directly standardized rates. Furthermore, since the weights are determined entirely by the data there is the advantage of avoiding the selection of an external standard population. Data analysts who compare two groups of rates with the Mantel-Haenszel chi-square statistic may view this statistic as a comparative measure of two directly adjusted rates.
Age Factors↗
Propranolol in the treatment of anxiety neurosis.
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Administration, Oral↗
Effects of errors in a multicenter medical study: preventing misinterpreted data.
Large research projects offer significant advantages for research, but they pose special data quality problems. Data gathered in such projects may contain a greater absolute number of mistakes because of the people collecting data, the complexity of data processing, and the collation required. We wanted to learn from the types and frequencies of errors encroaching on data in a multicenter field trial, and to assess the effects of these errors had they passed through. We used extensive error trapping while processing 688 forms from seven sites in the field trial. Snapshots of the dataset were taken at several points in the process, before and after checking and correcting. We discovered 2.4% of the received data to be mistaken. These errors would have affected the data's reliability, decisions based on the study, and possibly the choice of analysis. Almost all of the mistakes were made at the time of measurement and may be related to raters' perceived importance of the variables. We found that communication and education effectively reduced the number of mistakes and their impact on the study over the course of the field trial. While an estimate of the overall error rate is important, the number of mistakes, in general, is only imperfectly related to the errors' effects on the study's results. Our results also suggest that statistical models that treat mistakes as simple independent events can be misleading.
Bias↗
Chlorinated drinking water and bladder cancer: effect of misclassification on risk estimates.
Data are presented from the Iowa portion of the National Bladder Cancer Case-Control Study demonstrating the effect of misclassification on depressing odds ratio estimates for years of exposure to chlorinated drinking water and bladder cancer. Four methods (METHODS 1 through 4) of quantifying chlorination exposure with sequentially decreasing degrees of misclassification are presented for the 268 bladder cancer cases and 658 population-based controls fulfilling criteria for inclusion in this study. Twenty-eight other risk factors for bladder cancer were considered along with chlorinated drinking water exposure estimated by METHOD 4. Stepwise regression models included as significant factors cigarette smoking (p less than .001), chlorination exposure (p = .038), and irradiation to the pelvic area (p = .040). Replacement of chlorinated drinking water exposure estimated by METHOD 4 with any of the remaining three methods resulted in models that included cigarette smoking and irradiation to the pelvic area, but not chlorination exposure. Thus, misclassification of chlorination exposure signified the difference between observing and not observing an association with bladder cancer.
Adult↗
Self-reported postwar injuries among Gulf War veterans.
OBJECTIVE: From September 1995 to May 1996, the authors conducted a telephone survey of Iowa military personnel who had served in the regular military or activated National Guard or Reserve during the Gulf War period. To assess the association between military service in a combat zone and subsequent traumatic injury requiring medical consultation, the authors analyzed veterans' interview responses. METHODS: Using data from the larger survey, the authors compared rates of self-reported postwar injuries requiring medical consultation in a sample of Iowa Gulf War veterans to the rates in a sample of Iowa military personnel who served at the same time, but not in the Persian Gulf. RESULTS: Of 3695 veterans, 605 (16%) reported a traumatic injury in the previous three months requiring medical consultation. Self-reported injuries were associated with service in the Persian Gulf (odds ratio 1.26; 95% confidence interval 1.02, 1.55). CONCLUSION: This finding is consistent with the results of earlier studies of traumatic injury mortality rates among war veterans.
Adult↗
Maintenance of clinical skills: a study of full-time physician teachers.
The ways in which full-time physician teachers of family medicine maintain their clinical skills were examined. A questionnaire survey of 500 randomly sampled physician teachers was conducted to examine their practice profile, both ambulatory and inpatient, and opinions as to the value of various activities in maintaining their clinical skills. Overall response rate was 84.4%, but only the responses of full-time teachers (69.6%) were used. Teachers spend 2.4 half days per week providing direct patient care and 3.1 half days per week supervising residents. Approximately 90% attend on an inpatient family medicine service, while about 60% admit and manage patients by themselves. A minimum of 2.3 half days per week of providing direct patient care was felt to be necessary to maintain clinical skills. Direct patient care was felt to be the single most important activity in maintaining clinical skills. While statistical differences among residency types existed, the faculty of the various types of residency programs had very similar practice profiles and opinions as to the maintenance of their clinical skills.
Clinical Competence↗