Between-reagent lot verification is a routine laboratory exercise in which a set of samples is te... more Between-reagent lot verification is a routine laboratory exercise in which a set of samples is tested in parallel with an existing reagent lot and a candidate reagent lot (before the candidate lot is committed to test patient samples). The exercise aims to verify and maintain consistency in the analytical performance of a test. We examined the limitations of a routine between-reagent lot verification procedure in detecting long-term analytical drift and looked for a more sensitive alternative. Via numerical simulations, we examined the statistical power of the current regression-based (weighted Deming regression) procedure for between-reagent lot verification in detecting proportional bias and constant bias. An alternative procedure applying the Student t-test to separately examine cumulative regression slopes and intercepts across multiple reagent lots was proposed and evaluated by numerical simulations. The regression-based procedure had poor statistical power in detecting proport...
The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists
* For consistency of reporting the same number of significant figures should be used for results ... more * For consistency of reporting the same number of significant figures should be used for results and reference intervals. * The choice of the reporting interval should be based on analytical imprecision (measurement uncertainty).
In this study we aimed to compare the reporting unit size used by Australian laboratories for rou... more In this study we aimed to compare the reporting unit size used by Australian laboratories for routine chemistry and haematology tests to the unit size used by learned authorities and in standard laboratory textbooks and to the justified unit size based on measurement uncertainty (MU) estimates from quality assurance program data.MU was determined from Royal College of Pathologists of Australasia (RCPA) - Australasian Association of Clinical Biochemists (AACB) and RCPA Haematology Quality Assurance Program survey reports. The reporting unit size implicitly suggested in authoritative textbooks, the RCPA Manual, and the General Serum Chemistry program itself was noted. We also used published data on Australian laboratory practices.The best performing laboratories could justify their chemistry unit size for 55% of analytes while comparable figures for the 50% and 90% laboratories were 14% and 8%, respectively. Reporting unit size was justifiable for all laboratories for red cell count, ...
ABSTRACT Pathology laboratories group some tests that they perform on their high throughput bioch... more ABSTRACT Pathology laboratories group some tests that they perform on their high throughput biochemistry analysers into profiles of tests that are associated with different organs (e.g. liver function tests—LFT). The components of these profiles are historic and often vary between different laboratories. This can lead to confusion and begs the question of what should be in a particular profile. In community medicine profiles may be used as screening tests but some of the components of the profiles may have low sensitivity and specificity and may produce both false positives and negatives. The LFT may include components which are poor liver function tests but are sensitive to fatty liver and hence elevations may cause unnecessary concern. Harmonisation of clinical chemistry reference intervals and units is occurring now so it is time to consider a similar process for components of a profile. A proposed list of analytes to be performed in the LFT profile is given.
The aim of this study was to evaluate whether the addition of red blood cell distribution width (... more The aim of this study was to evaluate whether the addition of red blood cell distribution width (RDW) improves the prognostic value of current intensive care unit (ICU) scoring systems, namely APACHE III. All patients admitted to a mixed ICU in Brisbane between June 2013 and July 2014 for whom RDW was available were included in the study. Analyses included descriptive statistics, linear regression correlation, and receiver operating characteristic (ROC) curves. The study included 708 patients for whom both ICU mortality prediction and RDW were available. In univariate analysis higher RDW values were associated with increased hospital mortality. Adding RDW to APACHE III increased the area under the ROC marginally (from 0.9586 to 0.9613). RDW was not correlated with C-reactive protein, white cell count, or patient's length of stay in ICU. RDW was an independent predictor of mortality. The addition of RDW to APACHE III improved its mortality prediction marginally. The underlying me...
One of the few and largest randomised controlled trials of point-of-care testing (PoCT) in genera... more One of the few and largest randomised controlled trials of point-of-care testing (PoCT) in general practice was conducted in Australia. This trial showed PoCT provided the same or better clinical effectiveness than central laboratory testing for HbA1c, urinary albumin/creatinine ratio, cholesterol and triglyceride measurements but not for the international normalised ratio (INR) or high-density lipoprotein (HDL) cholesterol. For most tests, however, testing in the central laboratory was more cost-effective than PoCT. One factor that contributed to the higher cost of PoCT was the considerable amount of resources devoted to training and monitoring the PoCT operators throughout the trial, many of whom were in remote locations.
Between-reagent lot verification is a routine laboratory exercise in which a set of samples is te... more Between-reagent lot verification is a routine laboratory exercise in which a set of samples is tested in parallel with an existing reagent lot and a candidate reagent lot (before the candidate lot is committed to test patient samples). The exercise aims to verify and maintain consistency in the analytical performance of a test. We examined the limitations of a routine between-reagent lot verification procedure in detecting long-term analytical drift and looked for a more sensitive alternative. Via numerical simulations, we examined the statistical power of the current regression-based (weighted Deming regression) procedure for between-reagent lot verification in detecting proportional bias and constant bias. An alternative procedure applying the Student t-test to separately examine cumulative regression slopes and intercepts across multiple reagent lots was proposed and evaluated by numerical simulations. The regression-based procedure had poor statistical power in detecting proport...
The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists
* For consistency of reporting the same number of significant figures should be used for results ... more * For consistency of reporting the same number of significant figures should be used for results and reference intervals. * The choice of the reporting interval should be based on analytical imprecision (measurement uncertainty).
In this study we aimed to compare the reporting unit size used by Australian laboratories for rou... more In this study we aimed to compare the reporting unit size used by Australian laboratories for routine chemistry and haematology tests to the unit size used by learned authorities and in standard laboratory textbooks and to the justified unit size based on measurement uncertainty (MU) estimates from quality assurance program data.MU was determined from Royal College of Pathologists of Australasia (RCPA) - Australasian Association of Clinical Biochemists (AACB) and RCPA Haematology Quality Assurance Program survey reports. The reporting unit size implicitly suggested in authoritative textbooks, the RCPA Manual, and the General Serum Chemistry program itself was noted. We also used published data on Australian laboratory practices.The best performing laboratories could justify their chemistry unit size for 55% of analytes while comparable figures for the 50% and 90% laboratories were 14% and 8%, respectively. Reporting unit size was justifiable for all laboratories for red cell count, ...
ABSTRACT Pathology laboratories group some tests that they perform on their high throughput bioch... more ABSTRACT Pathology laboratories group some tests that they perform on their high throughput biochemistry analysers into profiles of tests that are associated with different organs (e.g. liver function tests—LFT). The components of these profiles are historic and often vary between different laboratories. This can lead to confusion and begs the question of what should be in a particular profile. In community medicine profiles may be used as screening tests but some of the components of the profiles may have low sensitivity and specificity and may produce both false positives and negatives. The LFT may include components which are poor liver function tests but are sensitive to fatty liver and hence elevations may cause unnecessary concern. Harmonisation of clinical chemistry reference intervals and units is occurring now so it is time to consider a similar process for components of a profile. A proposed list of analytes to be performed in the LFT profile is given.
The aim of this study was to evaluate whether the addition of red blood cell distribution width (... more The aim of this study was to evaluate whether the addition of red blood cell distribution width (RDW) improves the prognostic value of current intensive care unit (ICU) scoring systems, namely APACHE III. All patients admitted to a mixed ICU in Brisbane between June 2013 and July 2014 for whom RDW was available were included in the study. Analyses included descriptive statistics, linear regression correlation, and receiver operating characteristic (ROC) curves. The study included 708 patients for whom both ICU mortality prediction and RDW were available. In univariate analysis higher RDW values were associated with increased hospital mortality. Adding RDW to APACHE III increased the area under the ROC marginally (from 0.9586 to 0.9613). RDW was not correlated with C-reactive protein, white cell count, or patient's length of stay in ICU. RDW was an independent predictor of mortality. The addition of RDW to APACHE III improved its mortality prediction marginally. The underlying me...
One of the few and largest randomised controlled trials of point-of-care testing (PoCT) in genera... more One of the few and largest randomised controlled trials of point-of-care testing (PoCT) in general practice was conducted in Australia. This trial showed PoCT provided the same or better clinical effectiveness than central laboratory testing for HbA1c, urinary albumin/creatinine ratio, cholesterol and triglyceride measurements but not for the international normalised ratio (INR) or high-density lipoprotein (HDL) cholesterol. For most tests, however, testing in the central laboratory was more cost-effective than PoCT. One factor that contributed to the higher cost of PoCT was the considerable amount of resources devoted to training and monitoring the PoCT operators throughout the trial, many of whom were in remote locations.
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Papers by Tony Badrick