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Biomedical subjects

Robert C Hawkins

Publications and source records attributed to Robert C Hawkins.

13 recordsLinked to original sources
PubMed2006

B-type natriuretic peptide testing is associated with reduced cost in patients with secondary diagnosis of heart failure.

BACKGROUND: This study was designed to examine the effect of BNP use on resource utilization and clinical outcome in hospitalized patients with heart failure (HF). METHODS: Details of all (1788) hospital discharges over 12 months with ICD-9 code 428.x diagnosis were matched to the laboratory and echocardiography databases. Multiple linear regression and logistic regression analysis were performed using use of BNP testing, number of secondary diagnoses, sex, age, financial status, cardiology care, performance of echocardiography as dependent variables to predict length of stay, payable amount and discharge status in separate HF as primary and HF as secondary diagnosis groups. RESULTS: Use of BNP measurement was associated with an average $ Singapore 1305 (p=0.007) decrease in payable amount in patients with secondary diagnosis of HF when controlled for other variables. Its use was associated with reduced use of echocardiography in both primary (odds ratio: 0.04) and secondary (OR: 0.08) diagnosis groups. CONCLUSIONS: Use of BNP measurement was associated with reduced cost of hospitalization in patients with a secondary diagnosis of HF and with reduced use of echocardiography in heart failure patients. This suggests the potential of BNP measurement to reduce costs for the many patients whose multiple problems include HF.

Aged↗
PubMed2006

Over-reporting significant figures--a significant problem?

BACKGROUND: Excessive use of significant figures in numerical data gives a spurious impression of laboratory imprecision to clinicians. We describe reporting practices in 24 Asia-Pacific laboratories, assess whether these reporting formats and those used in the literature can be justified based on actual laboratory performance and outline how to choose the appropriate number of significant places. METHODS: Thirty-two laboratories in Asia-Pacific were surveyed as to their reporting practices for serum creatinine, ferritin, sodium and TSH. Imprecision data from the General Serum Chemistry program from the RCPA-AACB Quality Assurance Program (QAP) were used to assess whether the reporting unit magnitude implicitly suggested in Tietz, the RCPA Manual and the General Serum Chemistry program itself was justified. RESULTS: There was a 75% response rate to the survey, with laboratories generally reporting data using unjustifiable deciles. Unit sizes from the RCPA manual, Tietz and the RCPA-AACB QAP were not justified by the majority of laboratories in the RCPA-AACB QAP. CONCLUSIONS: The reporting unit size used by many laboratories is not justified by present laboratory performance using a 95% probability level. A consensus on appropriate reporting unit size is needed to encourage laboratories to change their present reporting formats.

Australia↗
PubMed2006

Effect of variability in assay bias and imprecision on external quality assessment bias and imprecision measures.

BACKGROUND: External quality assessment/proficiency testing programmes that report consensus means and coefficients of variations (CVs) are a potential source of information on assay bias and imprecision. This study examined the effect of variability in assay bias and imprecision on consensus means and CVs, using a computerized spreadsheet model. METHODS: A model with varying assay bias (mean and standard deviation) and assay imprecision (mean and standard deviation) was developed using a MS Excel 2003 spreadsheet with a macro to generate pseudo-random numbers from a Gaussian distribution. The means, standard deviations and CVs of these data points were considered to simulate the consensus measures reported in external quality assessment testing programmes. RESULTS: The simulated consensus CV was very sensitive to increases in assay bias variability, with greater effects at low levels of mean assay imprecision. Changes in assay imprecision variability had a much smaller effect on the simulated consensus CV, while the simulated consensus mean was relatively insensitive to any change in the other variables. CONCLUSION: Consensus imprecision measures from external quality assessment programmes are unreliable measures of assay imprecision. Consensus means are relatively unaffected by variability in assay bias and imprecision, and can be used as reliable measures of assay bias from a statistical standpoint.

Bias↗
PubMed2005

Evaluation of Roche Accu-Chek Go and Medisense Optium blood glucose meters.

BACKGROUND: We examined the analytical performance of two Roche Accu-Chek Go meters (reporting whole blood glucose) and two Medisense Optium meters (reporting plasma glucose) against laboratory plasma glucose measurement. METHODS: One hundred and twenty heparinized whole blood specimens were analyzed in duplicate on each of the four meters and compared to plasma glucose measurement on the Roche DP Modular system (glucose oxidase methodology). RESULTS: There was a significant difference in imprecision between the two Medisense meters (CV 3.7% and 4.9%), and between the Roche (CV 2.5% and 2.9%) and Medisense meters. The two Roche meters showed a consistent positive bias compared to the Modular, while the two Medisense meters over-read at low glucose concentrations and under-read at high glucose concentrations. Total error for the Roche meters averaged 10.8% and 8.9%, and for the Medisense meters averaged 12.5% and 15.6%, respectively. All results for all meters fell in error grid zones A and B. CONCLUSION: Neither meter met the ADA, CLIA or biological variation goals, although they came close to the NCCLS guideline. Neither meter reported plasma glucose equivalents. The Accu-Chek Go performed slightly better than the Optium meter, but the positive bias was puzzling and requires further explanation.

Blood Glucose↗
PubMed2005

Poor knowledge and faulty thinking regarding hemolysis and potassium elevation.

A questionnaire to assess knowledge of the expected elevation in serum K measurement with different grades of hemolysis was administered to medical technologists working in biochemistry laboratories, hospital physicians and nurses. The questions involved different grades of hemolysis (mild, 1.0, moderate, 2.5 and severe, 5.0 g/L) and different final K measurements (2.9, 4.0, 5.2 and 8.2 mmol/L). Subjects estimated the K concentration in a non-hemolyzed sample for each scenario. Adjustment values (difference between final hemolyzed K concentration and subject's response) were calculated. For the 132 respondees, the mean correct score was 1.7/12. Mean adjustment values were: mild, 0.43 mmol/L (K 2.9), 0.55 (4.0), 0.88 (5.2) and 1.53 (8.2); moderate, 0.85 (2.9), 0.92 (4.0), 1.33 (5.2) and 2.50 (8.2); and severe, 0.93 (2.9), 1.48 (4.0), 1.96 (5.2), 2.96 (8.2). Correct adjustments were: mild, 0.28; moderate, 0.70; and severe, 1.40 mmol/L. Healthcare staff overestimated the effect of hemolysis on potassium measurement and used an incorrect proportional adjustment approach to the problem. Such poor knowledge and faulty thinking could lead to diagnostic delays or misdiagnoses. There is potential for such faulty thinking in all areas of laboratory medicine, and laboratories should review their educational responsibilities and reporting practices in light of this.

Blood Chemical Analysis↗
PubMed2005

The Evidence Based Medicine approach to diagnostic testing: practicalities and limitations.

Evidence-Based Medicine (EBM) has become a popular approach to medical decision making and is increasingly part of undergraduate and postgraduate medical education. EBM follows four steps: 1. formulate a clear clinical question from a patient's problem; 2. search the literature for relevant clinical articles; 3. evaluate (critically appraise) the evidence for its validity and usefulness; 4. implement useful findings into clinical practice. This review describes the concepts, terminology and skills taught to attendees at EBM courses, focusing specifically on the approach taken to diagnostic questions. It covers how to ask an answerable clinical question, search for evidence, construct diagnostic critically appraised topics (CATs), and use sensitivity, specificity, likelihood ratios, kappa and phi statistics. It familiarises readers with the lexicon and techniques of EBM and allows better understanding of the needs of EBM practitioners.

Journal Article↗
PubMed2003

Age and gender as risk factors for hyponatremia and hypernatremia.

BACKGROUND: This study assesses gender and age as independent risk factors for hypo- and hypernatremia and describes the prevalence of hypo- and hypernatremia in different population groups. METHODS: Details of all serum Na results with accompanying patient demographics for 2 years were downloaded from the laboratory database into Microsoft Access for multiple logistic regression analysis using SPSS. Female gender and age <30 years were the reference groups. RESULTS: Data from 303577 samples on 120137 patients were available for analysis. Prevalence at initial presentation to a health care provider of Na<136, <116, >145, and >165 mmol/l were for acute hospital care patients: 28.2%, 0.49%, 1.43%, and 0.06%; ambulatory hospital care: 21%, 0.17%, 0.53%, and 0.01%; community care: 7.2%, 0.03%, 0.72%, and <0.01%. Age odds ratios rose with increasing age to 1.89 and 8.70 (Na<136 and <116 mmol/l) and 7.09 and 24.39 (Na>145 and >165 mmol/l, respectively) for age >81 years. Male gender was a mild risk factor for Na<136 mmol/l and was otherwise unimportant. CONCLUSIONS: Hyponatremia is a common but generally mild condition while hypernatremia is uncommon. Increasing age is a strong independent risk factor for both hypo- and hypernatremia. Gender is not an important risk factor for disturbances of serum Na concentration.

Adult↗