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Biomedical subjects

Peter S Bunting

Publications and source records attributed to Peter S Bunting.

9 recordsLinked to original sources
PubMed2006

Conflict between guideline methodologic quality and recommendation validity: a potential problem for practitioners.

BACKGROUND: It is not clear if good methodologic quality in current practice guidelines necessarily leads to more valid recommendations, i.e., those that are supported with consistent research evidence or, when evidence is conflicting or lacking, with sufficient consensus among the guideline development team. To help clarify this issue, we assessed whether there is a link between methodologic quality and recommendation validity in practice guidelines for the use of laboratory tests in the management of patients with non-small cell lung cancer (NSCLC). METHODS: We conducted a systematic review of data on laboratory tests in NSCLC published in English or in French within the last 10 years and retrieved 11 practice guidelines for the use of these tests. The guidelines were critically appraised and scored for methodologic quality and recommendation validity based on the Appraisal of Guidelines Research and Evaluation (AGREE) criteria and on the systematic review. RESULTS: Overall, these 11 guidelines had considerable shortcomings in methodologic quality and, to a lesser extent, in recommendation validity. Practice guidelines with the best methodologic quality were not necessarily the most valid in their recommendations, and conversely. CONCLUSIONS: Poor methodologic quality and lack of recommendation validity in laboratory medicine call for methodologic standards of guideline development and for international collaboration of guideline development agencies. We advise readers of guidelines to critically evaluate the methods used as well as the content of the recommendations before adopting them for use in practice.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

A reliable coding system to define screening prostate-specific antigen tests was developed in a case-control study.

OBJECTIVE: To establish the reliability of a coding system for screening and diagnostic prostate-specific antigen (PSA) testing from patient charts. STUDY DESIGN AND SETTING: Two investigators reviewed 448 chart abstractions from a population-based case-control study of PSA screening in the Toronto area. The tests evaluated for reliability were transrectal ultrasound (TRUS), digital rectal examination (DRE), and prostate-specific antigen (PSA). RESULTS: DRE results were found in 87%, PSA results in 65%, and TRUS results in 12% of the 749 charts. Interobserver agreement was 94% for DRE texture (kappa =.885), 95% for DRE asymmetry (kappa = .868), 85% for DRE physician interpretation (kappa = .698), 97% for final DRE result (kappa = .856), and 87% for TRUS (kappa = .769). Physician interpretation modified the final result in only 6.2% of DREs. Interobserver agreement for PSA coding was 91% (kappa = .787). Of PSA results, pure PSA screening with no symptoms of obstructive urination was found in 19%, symptomatic PSA screening in 46%, and diagnostic PSA testing in 35%. CONCLUSION: We have developed a practical and reliable coding system for TRUS, DRE, and PSA in the context of a case-control study of PSA screening.

Biomarkers, Tumor↗
PubMed2005

Reliability of point-of-care testing for glucose measurement in critically ill adults.

BACKGROUND: Glycemic control is increasingly being recognized as a priority in the treatment of critically ill patients. Titration and monitoring of insulin infusions involve frequent blood glucose measurement to achieve target glucose ranges and prevent adverse events related to hypoglycemia. Therefore, it is imperative that bedside glucose testing methods be safe and accurate. OBJECTIVE: To determine the accuracy and clinical impact of three common methods of bedside point-of-care testing for glucose measurements in critically ill patients receiving insulin infusions. DESIGN: Prospective observational study. SETTING: A 21-bed mixed medical/surgical intensive care unit of a tertiary care teaching hospital. PATIENTS: Thirty consecutive critically ill patients who were vasopressor-dependent (n = 10), had significant peripheral edema (n = 10), or were admitted following major surgery (n = 10). MEASUREMENTS: Findings from three different methods of glucose measurement were compared with central laboratory measurements: (1) glucose meter analysis of capillary blood (fingerstick); (2) glucose meter analysis of arterial blood; and (3) blood gas/chemistry analysis of arterial blood. Patients were enrolled for a maximum of 3 days and had a maximum of nine sets of measurements determined during this time. RESULTS: Clinical agreement with the central laboratory was significantly better with arterial blood analysis (69.9% and 76.5% for glucose meter and blood gas/chemistry analysis, respectively) than with capillary blood analysis (56.8%; p = .039 and .001, respectively). During hypoglycemia, clinical agreement was only 26.3% with capillary blood analysis and 55.6% and 64.9% for glucose meter and blood gas/chemistry analysis of arterial blood (p = .010 and <.001, respectively). Glucose meter analysis of both arterial and capillary blood tended to provide higher glucose values, whereas blood gas/chemistry analysis of arterial blood tended to yield lower glucose values. CONCLUSIONS: The magnitude of the differences in the glucose values offered by the four different methods of glucose measurement led to frequent clinical disagreements regarding insulin dose titration in the context of an insulin infusion protocol for aggressive glucose control.

APACHE↗
PubMed2005

Screening with prostate specific antigen and metastatic prostate cancer risk: a population based case-control study.

PURPOSE: Screening of asymptomatic men with prostate specific antigen (PSA) remains a controversial issue. There is limited evidence that screening is effective in reducing mortality from prostate cancer. In the current study we determined if screening with PSA reduces the risk of metastatic prostate cancer. MATERIALS AND METHODS: We conducted a population based case-control study among the residents of Metropolitan Toronto and 5 surrounding counties in Ontario, Canada. Data were obtained from 236 cases of metastatic prostate cancer and 462 controls randomly sampled from the source population and frequency matched to cases for age and area of residence. History of PSA testing, digital rectal examination, symptoms and other data were obtained from medical records and a self-administered questionnaire. The association between PSA screening and metastatic prostate cancer was measured by the Mantel-Haenszel odds ratio stratified by exposure observation time and other potential confounding factors. RESULTS: In asymptomatic men, the frequency of PSA screening as determined from medical records was significantly lower among the cases compared with the controls (odds ratio 0.65, 95% confidence interval 0.45 to 0.93). The odds ratio was 0.52 (0.28 to 0.98) in men 45 to 59 years old and 0.67 (0.41 to 1.09) in those 60 to 84 years old. CONCLUSIONS: In this case-control study screening of asymptomatic men with PSA was associated with a significantly reduced risk of metastatic prostate cancer. The results need to be confirmed in randomized controlled trials.

Aged↗
PubMed2004

Has there been a change in practice of screening for prostate cancer with prostate-specific antigen in Ontario?

OBJECTIVE: To determine whether there has been a change in the rate of screening in Ontario in 2002 compared to 1995. METHODS: A questionnaire was mailed to 520 physicians, associated with PSA records selected randomly from the database of a large community laboratory. Physicians were asked to consult their records as to the reasons for PSA testing. RESULTS: There were 285 usable responses from 520 mailings (response rate 55%), mostly (91%) from family or general practice. Reasons for testing, expressed as proportions of responses, were as follows (this study, 1995 study and P value for the differences): screening for prostate cancer (74%, 63%; P = 0.059), diagnosis of urinary symptoms (30%, 40%; P = 0.027), follow-up of a medical procedure or drug therapy (14%, 32%; P = 0.001), confirmation of a previous PSA result (14%, 6%; P = 0.015) and other reasons (7%, 8%; P = 0.73). Of those records with screening as one reason for testing, 80% vs. 66% (P = 0.003) indicated it was the only reason; 86% vs. 73% (P = 0.003) indicated that it was part of a routine examination, and 54% vs. 64% (P = 0.052) indicated that the test was requested by the patient. CONCLUSION: These findings are consistent with increased screening for prostate cancer with PSA.

Adult↗
PubMed2003

Effect of a controlled feedback intervention on laboratory test ordering by community physicians.

BACKGROUND: Most studies of interventions to reduce laboratory test utilization have occurred in academic hospital settings, used historical controls, or have had short post intervention follow-up. Interventions with the greatest impact use multiple approaches, are repeated regularly, include comparisons with physician peers, and have a personal approach. We determined whether laboratory test utilization by community physicians could be reduced by a multifaceted program of education and feedback. METHODS: We identified 200 physicians who ordered the largest number of common laboratory tests during 1 year in a nonhospital, commercial community (reference) laboratory. They were assigned to intervention and control groups (100 each). Intervention physicians were visited individually up to three times by laboratory representatives over a 2-year period. At each visit, educational material and the physician's personal laboratory test utilization data were presented and discussed briefly in general terms, with the latter compared with utilization data for the physician's peers. Overall test utilization rates 1 year before, during, and 2 years after the intervention were measured using population-based databases. Time-series analysis was used to determine the effect of the intervention on laboratory test utilization. RESULTS: The two groups began with similar test utilization: control group, 4.06 x 10(6) tests in 1.48 x 10(6) visits (2.73 tests/visit); intervention group, 3.90 x 10(6) tests in 1.41 x 10(6) visits (2.77 tests/visit). During the 2-year intervention, intention-to-treat analysis showed that utilization decreased significantly in the intervention group compared with the controls [relative reduction of 7.9% (P <0.0001); absolute reduction of 0.22 tests/visit (95% confidence interval, 0.20-0.24)]. This difference persisted until the end of study observation, or more than 2 years after the intervention ended. CONCLUSION: A multifaceted education and feedback strategy can significantly and persistently decrease laboratory utilization by practicing community physicians.

Clinical Laboratory Techniques↗
PubMed2002

Screening for prostate cancer with prostate-specific antigen: beware the biases.

BACKGROUND: The evidence relating to the use of prostate-specific antigen (PSA) as a screening test is a highly controversial, as demonstrated by the lack of agreement among experts. There may be biases associated with various studies. ISSUES: The main controversy is the relatively high prevalence of prostate cancer (PC) found at autopsy compared with the relatively low death rate from the disease. The lack of modifiable risk factors has led to early detection as a strategy to reduce mortality, as there is evidence for a significant burden of disease. Important issues are the accuracy of current screening tests, some attempts to improve on them, and whether there are good prognostic markers. The consequences of PSA testing (usually further testing including biopsy) and outcomes of treatment are presented in terms of mortality and morbidity; quality of life (QOL) must also be considered. Also important are the benefits from, and the difficulties associated with the "informed choice" approach to PSA screening. CONCLUSION: There is evidence to suggest that biases can have a significant impact on the utility of PSA as a screening test for PC.

Age Factors↗
PubMed2002

Intraindividual variation of PSA, free PSA and complexed PSA in a cohort of patients with prostate cancer managed with watchful observation.

OBJECTIVE: To determine the intraindividual variation of prostate-specific antigen (PSA) isoforms in prostate cancer patients managed conservatively with watchful observation. METHODS: Patients with favorable clinical parameters (stage T1b-T2b N0 M0, Gleason score </= 7, and PSA </= 15) were recruited to participate in a watchful observation program. Specimens were drawn for measurement of total (tPSA), free (fPSA) and complexed (cPSA) prostate-specific antigen isoforms. Total biologic variation and between-day analytical variation were used to calculate intraindividual variation. RESULTS: Total variation for each isoform and two ratios were not greatly affected by the time window for measurements in the interval 6 months to 2.7 yr. Analytical variation made only a small contribution to the total biologic variation. Intraindividual variation for a 1-yr time interval for tPSA, fPSA, cPSA and the ratios of fPSA and cPSA to tPSA was, respectively, 21.6, 19.3, 25.4, 20.0 and 13.1%. The amount of change required for a significant difference between two readings (with 95% confidence) was, respectively, 59.8, 53.4, 70.4, 55.3 and 36.2%. CONCLUSIONS: There is a significantly higher intraindividual variation of cPSA (25.4%), and a significantly lower intraindividual variation of the ratio cPSA to tPSA (13.1%) compared to the other individual PSA isoforms and to the ratio of fPSA to tPSA. The amount of change required for a significant difference between two concentrations is large for all variables studied, but the lowest is the ratio of cPSA to tPSA (36.2%). These results have significance for diagnosis and monitoring of patients with prostate cancer.

Cohort Studies↗