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Biomedical subjects

H E Rockette

Publications and source records attributed to H E Rockette.

At least 19 recordsLinked to original sources
PubMed1995

Serum and urinary aluminium levels of workers in the aluminium industry.

We have measured serum aluminium and urinary aluminium/creatinine ratios in 235 aluminium workers and 44 controls to examine the association between occupational exposure to airborne aluminium and aluminium absorption. Serum and urine samples were taken before and after a 3- to 5-day work shift. Occupational exposure was estimated from aluminium measurements of respirable and total particulates in air. Median exposure values were 25 and 100 micrograms m-3, respectively. Serum aluminium and urinary aluminium/creatinine ratios did not change significantly during the shift; however, both pre-shift and post-shift serum aluminium and urinary aluminium/creatinine ratios were increased in the exposed group. Occupational exposure was associated with serum aluminium increments of 1.32 micrograms l.-1 (P = 0.01) pre-shift, and 0.96 micrograms l.-1) (P = 0.08) post-shift. Greater and more significant differences were seen between exposed and controls for the urinary aluminium/creatinine ratios [5.67 micrograms g-1 (P < 0.01) pre-shift; 8.01 micrograms g-1 (P < 0.01) post-shift]. Urinary aluminium/creatinine ratios were greater in plants with higher aluminium exposures. These results are consistent with the systemic absorption of aluminium from occupational exposure and suggest the presence of a sensitive uptake process for airway aluminium.

Aluminum↗
PubMed1995

Otitis media in a population of black American and white American infants, 0-2 years of age.

To determine the incidence of otitis media (OM) and the bacteriology of acute otitis media (AOM) in a clinic population of young children in Pittsburgh, 138 black infants and 60 white infants were followed from birth to 2 years of age, examined at monthly intervals and whenever an upper respiratory tract infection (URI) or OM intervened. By 24 months of age the cumulative incidence of episodes of AOM was 43% and 42%, and of episodes of middle-ear effusion (MEE) was 86% and 85% in black and white infants, respectively. The average rate of episodes of AOM was 0.41 and 0.39 and of episodes of MEE was 1.68 and 1.70 in black and white infants, respectively. Tympanocentesis was performed for episodes of AOM and the following organisms were isolated from black and white infants, respectively: Streptococcus pneumoniae 43% and 43% of episodes; Moraxella catarrhalis 24% and 24%; non-typable Haemophilus influenzae 18% and 24%; and Haemophilus influenzae type b 5% and 0%. In both black and white infants first born children had less ear disease. We found no difference in the incidence of otitis media during the first 2 years of life between black and white infants.

Acute Disease↗
PubMed1995

Imaging systems evaluation: effect of subtle cases on the design and analysis of receiver operating characteristic studies.

OBJECTIVE: Large-scale receiver operating characteristic (ROC) studies are expensive and time-consuming. If most of the difference in diagnostic accuracy occurs in a subset of subtle cases, considerable effort could be saved by restricting comparisons to this subset. We investigate the effect of subtle cases on diagnostic accuracy, the magnitude of error that can occur because of an imbalance of subtle cases in two groups, and the potential for sample size reductions if only subtle cases are used. METHODS: Data from a previous study of posteroanterior chest radiographs were reanalyzed separately for subsets of typical cases and subsets of subtle cases. Actually positive and actually negative cases were classified as subtle or typical and as difficult or easy for diagnosis of the specific abnormality. The area under the ROC curve (Az) was used as the measure of diagnostic accuracy. Pairwise comparisons were done among three techniques and for the detection of nodules and interstitial disease. RESULTS: The performance index (Az) was significantly (> or = 25%) lower for the subset of subtle cases as compared with the subset of typical cases. The difference in observer performance between two techniques was more often greater in the subset of subtle cases than in the subset of typical cases. CONCLUSION: The difference in diagnostic accuracy between the subset of typical cases and the subset of subtle cases is large enough that a difference in the proportion of subtle cases in two samples could result in clinically significant false differences in observer performance. Furthermore, the generally larger difference observed in the group of subtle cases suggests that sample sizes for some experiments could be reduced by 45-90% if the experiment were restricted to subtle cases.

Humans↗
PubMed1995

Efficacy of 20- versus 10-day antimicrobial treatment for acute otitis media.

OBJECTIVE: The purpose of this trial was to determine whether 20 days of antimicrobial treatment is more efficacious than 10 days of treatment for acute otitis media (AOM) in clearing middle ear effusion and preventing recurrences of AOM, and whether changing to a beta-lactamase-stable antimicrobial agent after the initial 10-day treatment with amoxicillin for AOM is advantageous. METHODS: Children between 7 months and 12 years of age with AOM were randomly assigned to three treatment groups: (1) amoxicillin for days 1 through 10, then amoxicillin for days 11 through 20; (2) amoxicillin for days 1 through 10, then amoxicillin-clavulanate for days 11 through 20; and (3) amoxicillin for days 1 through 10, then a placebo for either amoxicillin or amoxicillin-clavulanate for days 11 through 20. Medication was dispensed in a double-blind manner. Children underwent tympanocentesis at entry and were re-examined on days 10, 20, 30, 60, and 90 after entry. RESULTS: Two hundred sixty-seven children entered the trial. At the 20-day visit, the percentages of children who were effusion free in the amoxicillin, amoxicillin-clavulanate, and placebo groups were 72.4%, 80.8%, and 52.5%, respectively. There was no statistically significant difference in the percentage of children who were effusion free between the amoxicillin and amoxicillin-clavulanate groups (95% confidence interval, -21.7, 4.9). Subsequent to the day 10 visit, the average proportions of time with middle ear effusion were not significantly different in the amoxicillin, amoxicillin-clavulanate, and placebo groups (0.29, 0.27, and 0.34, respectively), nor were there significant differences in the rates of recurrent episodes of AOM (0.56, 0.59, and 0.68, respectively). Regardless of treatment group, approximately 75% of children were effusion free at the time of their last visit. CONCLUSIONS: More children were effusion free by the day 20 visit if given antimicrobial treatment for 20 days rather than for 10 days, but this advantage was present for only a short time; by the end of the 90-day study period, the treatment groups were comparable with regard to effusion status. Recurrence of AOM during the study period was not prevented by the additional 10 days of treatment. Routine use of an additional 10-day course of antimicrobial treatment is therefore not recommended if a child is symptom free after the initial 10 days of treatment for AOM.

Acute Disease↗
PubMed1994

The role of thymidylate synthase expression in prognosis and outcome of adjuvant chemotherapy in patients with rectal cancer.

PURPOSE: We assessed the prognostic importance of the level of thymidylate synthase (TS) expression in patients with primary rectal cancer and whether, for Dukes' B and C cancer patients, the benefit of chemotherapy was associated with TS expression. PATIENTS AND METHODS: The level of TS expression in the primary rectal cancers of 294 of 801 patients enrolled on protocol R-01 of the National Surgical Adjuvant Breast and Bowel Project (NSABP) was immunohistochemically assessed with the monoclonal antibody TS 106. RESULTS: Forty-nine percent of patients whose tumors had low TS levels (n = 91) were disease free at 5 years compared with 27% of patients with high levels of TS (n = 203; P < .01). Moreover, 60% of patients with low TS levels were alive after 5 years compared with 40% of patients with high TS levels (P < .01). The level of TS protein was significantly associated with Dukes' stage (P < .01); patients with a more advanced Dukes' stage had a significantly higher level of TS. The level of TS expression remained prognostic for both disease-free survival (P < .01) and survival (P < .05) independent of Dukes' stage and other pathologic characteristics evaluated. Thirty-eight percent and 54% of patients with high TS levels (n = 71) were disease free and alive, respectively, after 5 years when treated with chemotherapy, compared with 17% and 31%, respectively, of similar patients when treated with surgery alone (n = 64) (P < .01). No difference was noted in disease-free survival (P = .46) or survival (P = .43) in patients with low TS levels. CONCLUSION: The expression of TS is an important independent prognosticator of disease-free survival and survival in patients with rectal cancer. Adjuvant fluorouracil (5-FU)-based chemotherapy demonstrated significant improvement in disease-free and overall survival for patients with high TS levels. Prospective studies measuring TS levels will be needed to understand further the role of TS as a prognosticator of survival and chemotherapeutic benefit.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

A comparative evaluation of cefaclor and amoxicillin in the treatment of acute otitis media.

In an earlier study of 214 children with acute otitis media (AOM) randomly assigned to a 14-day course of either cefaclor or amoxicillin, 55.7% of cefaclor-treated subjects were effusion-free compared with 41.2% of amoxicillin-treated subjects at the end of treatment. The present study was conducted to determine whether, in a 1-year period, subjects treated with cefaclor for each episode would have middle ear effusion for significantly less time than those treated with amoxicillin for each episode. One hundred fifty-seven subjects with AOM were enrolled. No statistically significant differences were found between the cefaclor-treated and amoxicillin-treated groups in number of subjects effusion-free immediately after first treatment (47.9% vs. 42.3%, respectively), average percent of time with effusion (22.2% vs. 23.4%, respectively), or in rate of new episodes of AOM (3.05 vs. 3.26, respectively). We conclude that there is no clinically significant advantage to the use of cefaclor rather than amoxicillin as the routine first line drug in the treatment of AOM.

Acute Disease↗
PubMed1992

The use of continuous and discrete confidence judgments in receiver operating characteristic studies of diagnostic imaging techniques.

Virtually all receiver operating characteristic (ROC) studies of medical imaging methods have involved data collected on a discrete confidence-rating scale, though in principle ROC studies can be conducted with either discrete or continuous scales. Continuous scales provide potential advantages in medical applications of ROC analysis, but the possible dependence of ROC results on the kind of scale used in an observer-performance experiment has not been investigated empirically. The authors conducted a multi-observer ROC study in which radiologists read abdominal computed tomography (CT) examination results displayed on a workstation with a high-resolution video monitor. Ninety-five examinations were evaluated by five radiologists who reported their confidence concerning the presence of abdominal masses on a conventional five-category discrete scale and, in a separate reading session, on a continuous subjective-probability scale. ROC analysis showed no statistically significant difference between the detection accuracies (Az) achieved with the two scales by any reader. Accuracies averaged over all readers were identical with the two scales. The results of this study suggest that discrete or continuous scales often can be used interchangeably in image-evaluation studies. However, the authors recommend continuous scales for routine use in radiologic ROC studies because of their potential advantages in some situations.

Confidence Intervals↗
PubMed1992

Efficacy of myringotomy with and without tympanostomy tubes for chronic otitis media with effusion.

In a previous trial involving 109 children with chronic otitis media with effusion of at least a 2 months' duration that had been unresponsive to medical treatment, we compared the efficacy of myringotomy with tube insertion, myringotomy alone and no surgical intervention with regard to time with middle ear effusion, hearing status and other indices over a 3-year period. Because interpretation of the results was rendered difficult by certain complexities of study design, the present trial with a revised protocol was carried out in an additional group of 111 children. As in the previous trial, myringotomy with tube insertion resulted in less time with effusion and better hearing than did either myringotomy alone or no surgery. However, acute and chronic otorrhea and tympanic membrane perforation developed not uncommonly after tube insertion. Myringotomy alone offered no advantage over no surgery regarding the percent of time with effusion or the number of episodes of acute otitis media. Currently for children with long-standing middle ear effusion, we recommend either watchful waiting with periodic hearing assessment or myringotomy with tube insertion, individualizing the recommendation for each child.

Child↗
PubMed1992

Efficacy of antimicrobial prophylaxis and of tympanostomy tube insertion for prevention of recurrent acute otitis media: results of a randomized clinical trial.

To determine the efficacy of amoxicillin prophylaxis and of tympanostomy tube insertion in preventing recurrences of acute otitis media, we randomized 264 children 7 to 35 months of age who had a history of recurrent otitis media but were free of middle ear effusion to receive either amoxicillin prophylaxis, bilateral tympanostomy tube insertion or placebo. The average rate of new episodes per child year of either acute otitis media or otorrhea was 0.60 in the amoxicillin group, 1.08 in the placebo group and 1.02 in the tympanostomy tube group (amoxicillin vs. placebo, P less than 0.001; tubes vs. placebo, P = 0.25). The average proportion of time with otitis media of any type was 10.0% in the amoxicillin group, 15.0% in the placebo group and 6.6% in the tympanostomy tube group (amoxicillin vs. placebo, P = 0.03; tubes vs. placebo, P less than 0.001). At the 2-year end point, the rate of attrition was 42.2% in the amoxicillin group, 45.5% in the placebo group and 26.7% in the tympanostomy tube group. Adverse drug reactions occurred in 7.0% of the amoxicillin group and persistent tympanic membrane perforations developed in 3.9% of the tympanostomy tube group. The observed degree of efficacy of amoxicillin prophylaxis and of tympanostomy tube insertion must be viewed in light of the fact that study subjects proved not to have been at as high risk for acute otitis media as had been anticipated and in view of the differential attrition rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Biostatistics in otolaryngology journals.

Clinical research depends on biostatistics to form meaningful inferences from uncertain data. We performed a cross-sectional analysis of clinical research in otolaryngology journals to identify trends in statistical usage and determine the statistical aptitude expected of journal readers. Statistical content and study design were assessed for 1262 articles from 1969, 1979, and 1989. General trends toward an increasing use of inferential statistics and stronger study designs were observed. The number of analytic and experimental studies employing inferential statistics has risen from 20 (31%) in 1969 to 145 (65%) in 1989. Although familiarity with only five statistical techniques gave access to 90% of current articles, this study suggests that the level of statistical expertise demanded of both researchers and readers will continue to increase.

Bibliometrics↗
PubMed1991

Comparative efficacy of erythromycin-sulfisoxazole, cefaclor, amoxicillin or placebo for otitis media with effusion in children.

We randomly assigned children with otitis media with effusion to receive either erythromycin-sulfisoxazole, cefaclor, amoxicillin or placebo for a 2-week period, primarily to determine whether either erythromycin-sulfisoxazole or cefaclor would have greater short term efficacy than that found previously for amoxicillin, and secondarily to supplement earlier data on outcomes in placebo-treated subjects. Interim analyses showed no statistically significant (P less than 0.05) differences between the three antimicrobial treatment groups in the primary outcome measures, i.e. the prevalence of middle-ear effusion 2 and 4 weeks after entry, and indicated that postulated differences favoring the erythromycin-sulfisoxazole and cefaclor groups over the amoxicillin group were unlikely to be found even if the originally calculated sample size were attained. Subject accrual was therefore terminated. Final analysis showed no significant between-group differences in other outcome measures as well. In antimicrobial vs. placebo comparisons neither erythromycin-sulfisoxazole nor cefaclor gave more favorable outcomes than placebo, whereas more children were effusion-free in the amoxicillin group than in the placebo group at 2 weeks (31.6% vs. 14.1%, P = 0.007), but not at 4 weeks. We conclude that when antimicrobial treatment for otitis media with effusion is deemed advisable, neither erythromycin-sulfisoxazole nor cefaclor should replace amoxicillin as first line treatment.

Amoxicillin↗
PubMed1991

Statistical issues in carcinogenic risk assessment.

Considerable progress has been made on the development of a variety of analytical methods to aid in the carcinogenic risk associated with exposure to both occupational and environmental agents. Although the development of these methods has been accompanied by consideration of many statistical issues, there are many areas where additional effort could be directed if these analytical methods are to provide the most appropriate interpretation of risk. These issues include methods of combining multiple studies to obtain an overall risk estimate, the robustness of the statistical model, methods of selection among competing models, an assessment of the effect of different measures of exposure on the estimated dose-response relationship, and development of surveillance methodology. These issues are discussed, and productive areas of future research are indicated.

Carcinogens, Environmental↗
PubMed1991

Amoxicillin or myringotomy or both for acute otitis media: results of a randomized clinical trial.

A total of 536 infants and children with acute otitis media were randomly assigned to one of six consistent year-long regimens involving the treatment of nonsevere episodes with either amoxicillin or placebo, and severe episodes with either amoxicillin, amoxicillin and myringotomy, or, in children aged 2 years or older, placebo and myringotomy. Nonsevere episodes had more favorable outcomes in subjects assigned to treatment with amoxicillin than with placebo, as measured by the proportions that resulted in initial treatment failure (3.9% vs 7.7%, P = .009) and the proportions in which middle-ear effusion was present at 2 and 6 weeks after onset (46.9% vs 62.5%, P less than .001; and 45.9% vs 51.5%, P = .09, respectively). In subjects whose entry episode was non-severe, those assigned to amoxicillin treatment had less average time with effusion during the succeeding year than those assigned to placebo treatment (36.0% vs 44.4%, P = .004), but recurrence rates of acute otitis media in the two groups were similar. In the 2-year-and-older age group, severe episodes resulted in more initial treatment failures in subjects assigned to receive myringotomy alone than in subjects assigned to receive amoxicillin with, or without, myringotomy (23.5% vs 3.1% vs 4.1%, P = .006). In the study population as a whole, severe episodes in subjects assigned to receive amoxicillin alone, and amoxicillin with myringotomy, had comparable outcomes. It is concluded that children with acute otitis media should routinely be treated with amoxicillin (or an equivalent antimicrobial drug). The data provide no support for the routine use of myringotomy either alone or adjunctively.

Acute Disease↗
PubMed1990

Effect of two rating formats in multi-disease ROC study of chest images.

ROC methodology has been expanded in recent years to include multi-disease experiments. To accommodate these changes, different rating formats, general or disease specific, can be used. No experimental data are available concerning the possible effects of the rating format on the results of these studies. We performed a multi-observer, multi-disease study in which 196 chest images were rated using a format where each disease was evaluated individually and one in which the cases were evaluated without scoring a specific disease. The results indicate that for our data set, the overall assessment of accuracy was not significantly affected by the study format used. Thus, in spite of the difficulties in selecting appropriate controls and the necessity of reassessing sample size considerations, the disease-specific format appears to produce an assessment of accuracy equivalent to that produced by the general format. This equivalence permits the use of the disease-specific approach since it more closely simulates the readers' true environment and is more appropriate for comparing imaging systems that may have a relative accuracy that is disease specific.

Diagnosis, Differential↗
PubMed1990

Effect of observer instruction on ROC study of chest images.

Receiver-operating characteristic (ROC) analysis has been used in many medical imaging applications during the past decade. In order to ensure that reader-confidence ratings are analyzable (well distributed to meet convergence requirements of curve-fitting algorithms) and meaningful (limit extrapolation of the data), many investigators train readers specifically for this purpose. No experimental data are available concerning the possible effects of such training on the results of ROC studies. We performed a multi-observer, multi-disease study in which 300 chest images were rated by four radiologists before and after they were trained to provide well-distributed confidence ratings. The results indicate that for our data set, reader and disease-specific accuracy was not significantly affected by the training process for interstitial disease and pneumothoraces. However, the accuracy of two readers was significantly affected for the detection of nodules (P less than 0.05), and the overall accuracy of one reader was significantly affected for the classification of normal versus abnormal images (P less than 0.01). Thus, in spite of the difficulties associated with the performance of ROC studies in a free-reading environment, one should carefully consider the possible effects of any intervention on the results prior to conducting ROC studies.

Humans↗
PubMed1990

Practical issues of experimental ROC analysis. Selection of controls.

Receiver operating characteristics (ROC) analysis has been used in many medical imaging applications during the past decade. With the recent expansion of the ROC methodology to multi-disease studies, several reports have begun to address both the theoretical and experimental design issues associated with such studies. While the appropriate selection, classification, and verification of actually positive cases is carefully addressed in the literature, similar considerations are rarely given to the selection of actually negative controls for these studies. In this paper, theoretical considerations and experimental data are provided to demonstrate the significance of this very issue.

Case-Control Studies↗