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Biomedical subjects

R W Baker

Publications and source records attributed to R W Baker.

At least 37 records · Page 2Linked to original sources
PubMed1997

An evaluation of 'rapid review' as a method of quality control of cervical smears using the AxioHOME microscope.

One method of quality control which has recently been recommended by professional bodies in the UK is the 'rapid review' method. This involves the microscopic 30 s review of all negative cervical smears with the intention of flagging potential missed abnormalities. Although it has been suggested that rapid review is better than 10% random rescreening of negative smears, the efficiency and efficacy of this method of quality control have not been thoroughly evaluated. We have used the AxioHOME system, which can record the area of a slide covered and the screening time, to investigate slide coverage during rapid review quality control, as performed by 15 cytoscreeners and MLSOs reviewing a test set of 22 slides each. The test set comprised 18 negative slides, three positive slides, and one unsatisfactory slide. We have recorded two distinct methods of rapid review in use amongst cytotechnologists, the step method and the whole slide method. The data show that rapid review takes longer on average than the recommended 30 s, the mean screening times being 76 s and 82 s for the step and whole slide methods, respectively. Abnormal smears were missed on three of 15 occasions by the step method (sensitivity 80%, positive predictive value 85%), and on seven of 30 occasions by the whole slide method (sensitivity 76.6%, positive predictive value 45%). However, the 95% confidence intervals were wide (57.7-90.7% for the step method, and 51.9-95.7% for the whole slide method). Analysis of scanning tracks and screening rates shows significant flaws in the methodology of rapid review. Abnormal cells were not identified, although dyskaryotic cells were included in the scanning track on nine occasions, seven using the whole slide method and two using the step method. On one occasion (using the step method) abnormal cells were not identified because they were not included in the scanning track. Further research is in progress to determine optimal methods of rapid review, and whether the rapid review technique is as effective as automated screening systems for quality assurance in cytology.

False Negative Reactions↗
PubMed1997

Assessing slide coverage by cytoscreeners during the primary screening of cervical smears, using the AxioHOME Microscope system.

We have used the HOME Microscope system to examine the screening patterns of cytotechnologists who undertake the primary screening of cervical smears, in order to measure accuracy of screening against screening time, slide coverage, and mean screening rate. Twelve cytotechnologists engaged routinely on cervical screening volunteered for this study. They were asked to perform primary screening of 10 test slides under normal laboratory conditions in the normal way. Slide coverage and screening time were recorded on the HOME system. Slide maps were prepared and the results analysed. The exercise demonstrated that all primary screeners fail at some point to scan the whole of the slide during primary screening. The maps produced by the HOME system clearly demonstrated that 5 different types of error can occur that lead to incomplete coverage of the slide. Mean slide coverage was 84%, and some individuals averaged only 66% coverage. The results show that there is a major problem in the education of some individual cytotechnologists in slide coverage. This could be rectified by the incorporation of a HOME system into every training centre, and the establishment of a protocol for assessment of slide coverage in competence examinations. Furthermore, the exercise has shown that even those individuals who normally attain a good standard of slide coverage would be able to improve slide coverage given access to the daily use of a HOME Microscope, or a system with equivalent screening/reviewing functionality.

Clinical Laboratory Techniques↗
PubMed1996

Predictive value of eosinophilia for neutropenia during clozapine treatment.

BACKGROUND: Myelotoxicity continues to hinder the widespread use of clozapine in the United States. It has been theorized that eosinophilia predicts later agranulocytosis and that agranulocytosis occurs due to an immunologic mechanism. Our study compares the rates of these dyscrasias in clozapine-treated patients and a control group. METHOD: Forty-one patients taking clozapine and 29 patients taking haloperidol were monitored for a period of 6 months. Rates of eosinophilia and neutropenia were compared between the two treatment groups. RESULTS: Treatment-emergent eosinophilia occurred frequently in both haloperidol- and clozapine-treated patients. No significant difference was seen between groups in the incidence of eosinophilia and neutropenia. CONCLUSION: We find no statistical difference between the rates of eosinophilia or neutropenia in haloperidol- and clozapine-treated patients. This study does not support the use of eosinophilia as a reliable predictor of neutropenia.

Adult↗
PubMed1996

The treatment of clozapine-associated agranulocytosis with granulocyte colony-stimulating factor (G-CSF).

During a 5-year period, 6 patients with clozapine-associated agranulocytosis who received granulocyte colony-stimulating factor (G-CSF) were compared with 5 subjects who did not receive this treatment. Seven patients were asymptomatic, and the weekly leukocyte count alone indicated agranulocytosis. The average duration of agranulocytosis was not significantly different between the treated and untreated groups (6.5 vs. 6.6 days), though the treated group had a significantly shorter average duration of hospitalization (8.2 vs. 13.5 days). G-CSF administration was well tolerated, and no adverse effects were noted. Incidentally noted was the recent addition of ranitidine (with the potential for bone marrow toxicity) to clozapine for 2 patients. Currently, weekly white cell and differential counts remain the main tools for detecting incipient or occurring agranulocytosis. Until efficacy studies prove otherwise, G-CSF administered soon after the diagnosis of clozapine-associated agranulocytosis may shorten the duration of hospitalization and thus prove cost-effective.

Adult↗
PubMed1996

Obsessive-compulsive symptoms in schizophrenia: a comparison of olanzapine and placebo.

The antipsychotic drug olanzapine is similar to clozapine and risperidone in potent serotonergic antagonism. We assessed obsessive-compulsive symptoms during olanzapine treatment because these symptoms have been reported during risperidone and clozapine treatment. Obsessions and compulsions were measured in 25 subjects with schizophrenia before and after a 6-week double-blind trial comparing two olanzapine doses to placebo. At baseline, 8 subjects had mild or moderate obsessions, and 6 had mild compulsions. There was no significant difference in the course of obsessive-compulsive symptoms among the three treatment groups. We found that olanzapine did not appear to cause obsessive-compulsive symptoms in patients with schizophrenia. Our sample size, the dose and duration of olanzapine treatment, and assessment methods limit the extent to which this finding can be generalized. Though emerging obsessive-compulsive symptoms have been reported for 13 clozapine-treated and 2 risperidone-treated patients with schizophrenia, this phenomenon has not yet been demonstrated in a controlled study.

Adult↗
PubMed1995

Assessment of changes in both weight and frequency of use of medications for the treatment of gastrointestinal symptoms among clozapine-treated patients.

Clozapine has an unusual profile of adverse effects; among them, gastrointestinal (GI) side effects are important management concerns. The charts of patients in a state hospital who received clozapine for at least 3 months were reviewed. We compared the pre- and post-clozapine weights and changes in frequency and intensity of use of drugs prescribed for gastrointestinal symptoms for each subject (n = 99). There were statistically significant increases in the use of antacids (p < 0.02) and both bulk and non-bulk laxatives (p < 0.05, p < 0.03). Seventy-three percent of patients gained weight, of whom 27% gained over 10% body weight. This study confirms clozapine's association with weight gain, constipation, and upper GI symptoms. The literature concerning weight gain, and the mechanisms underlying GI adverse effects were reviewed.

Adult↗
PubMed1995

Clozapine use in female geriatric patients with psychoses.

This study was undertaken to evaluate the clinical response of geriatric patients with psychoses to the atypical neuroleptic drug, clozapine. Records of patients over 60 years of age (n = 12, all female) who had received clozapine over a 30-month period from selected hospitals in Western Pennsylvania were reviewed. Among the six patients who were rapidly titrated (300 mg/day in 3 weeks), none are currently receiving clozapine, while four patients who received a slower titration and lower dosage (range, 25 mg/day to 300 mg/day; mean, 150 mg/day) remain clinically improved on stable doses of clozapine. Postural hypotension affected seven patients, and was the reason for discontinuation of clozapine in five patients. One patient experienced nonfatal agranulocytosis, and one subject experienced leukopenia. One patient died from causes unrelated to clozapine. This retrospective study suggests both a low-dose and slow-titration strategy for initiating clozapine among elderly patients, similar to the use of other psychotropic drugs in the elderly, as well as close attention to postural hypotension, agranulocytosis, and drug interactions.

Aged↗
PubMed1994

The prevalence of akathisia in patients receiving stable doses of clozapine.

BACKGROUND: Akathisia is a common side effect of traditional neuroleptic drugs and is associated with medication refusal and impulsive behavior. While our previous experience indicates that clozapine is effective in treating persistent akathisia, two controlled studies indicate vastly different prevalence rates of akathisia (7% vs. 40%) in patients receiving clozapine. METHOD: We used the Barnes Rating Scale for Drug-Induced Akathisia to estimate the prevalence of akathisia in patients receiving stable doses of clozapine alone (N = 29) in a state hospital. Measurements were also made of manifest psychopathology (Brief Psychiatric Rating Scale) and tardive dyskinesia (Abnormal Involuntary Movement Scale). RESULTS: Two patients (6.8%) receiving clozapine were rated as having akathisia. Only 4 (28.6%) of the 14 subjects with a history of moderate-to-severe tardive dyskinesia on traditional neuroleptic drugs continued to show current evidence of tardive dyskinesia, and in 10 patients (71.4%) there was no evidence of the syndrome (p < .002). In the 4 subjects with tardive dyskinesia there was amelioration to a milder form of the syndrome. There were no new cases of tardive dyskinesia among clozapine-treated subjects. CONCLUSION: These data support the low prevalence of akathisia in patients receiving stable doses of clozapine monotherapy. There is further support that clozapine has an ameliorating effect on tardive dyskinesia associated with traditional neuroleptic drugs. These and other data indicate the need for a controlled trial of clozapine in patients experiencing persistent and disabling akathisia on traditional neuroleptic drugs.

Adult↗