LABORATORY PROCEDURES AND QUALITY CONTROL
All analyses were carried out according to Standard Operating Procedures (SOPs) set by Sonic Healthcare. All results were routinely checked by the dedicated Quality Control (QC) laboratory technicians and clinically significant results were notified to the laboratory pathologist. Method coefficient of variations (CVs) were obtained by an appropriate internal QC programme for each machine based on the measurement of biomarker concentrations around the clinical laboratory cut-offs. Further information about the laboratory test method, analysing instrument and internal quality control CVs is available in Excel spreadsheet format in the Downloads page of this product.
Clinically significant results
As part of the ethics approval granted by the Australian Government Department of Health and Ageing Departmental Ethics Committee (DEC), the ABS had a mechanism in place with Sonic Healthcare ensuring that participants and/or their nominated doctor were notified of critical or clinically significant results. Further information about Sonic Healthcare’s laboratory reference ranges is available in Excel spreadsheet format in the Downloads page of this product. Values within these ranges were considered to be clinically ‘normal’, while those outside were treated as clinically significant
Internal Quality Control
Internal Quality Control (IQC) processes were conducted to monitor the performance of the methods and machines used to analyse the blood and urine samples and identify any analytical errors in the AHS test results. The DHM laboratory performed daily quality control runs on their methods and analysing machines using laboratory and commercial reference controls. The IQC results for each AHS test were compared to target (mean) values and target standard deviations (SDs). Imprecision was measured using the IQC results for each AHS test by comparing average coefficient of variation (CV) over two measured Quality Control (QC) levels from each test against published analytical goals. Each test was categorised as meeting Optimal, Desirable or Minimum goals over the period of the survey according to the Westgard rules. IQC values are assessed against an acceptable range and samples were re-analysed if any of the Westgard rules had been violated.
External Quality Assurance
An External Quality Assurance (EQA) system assesses the overall performance of the laboratory and conducts method comparisons between laboratory test results. Whilst conducting this assessment, the EQA authority can identify problems with certain methods.
Royal College of Pathologists of Australasia
DHM subscribes to the External Quality Assurance Program (EQAP) that is run by the Royal College of Pathologists of Australasia (RCPA). During the period of analysing the NHMS results, DHM received blind samples of varying concentration from RCPA at regular frequencies throughout the calendar year. These samples are analysed with the results sent back to RCPA and compared against other laboratories across Australia and New Zealand. RCPA distributes reports to all participating laboratories annually reporting mean values for test methods, inter laboratory measurements of precision and details of laboratory bias. DHM were forthcoming in providing their RCPA EQAP reports to the ABS thus ensuring confidence in the analytical methods and machines used to report the results for the NHMS. As part of Sonic Healthcare’s EQA summary report from the RCPA, there were no outliers within any of the analyte results.
Vitamin D Standardization Program
The Vitamin D Standardization Program (VDSP) was designed to internationally standardise the Vitamin D analytical method, which was established by the National Institute of Health (NIH) Office of Dietary Supplements (ODS), in collaboration with the Centers for Disease Control and Prevention (CDC) and the National Institute for Standards and Technology (NIST), to test the international differences and similarities in serum 25-hydroxyvitamin D [25(OH)D] distributions.1 The AHS is one of eight participating National Surveys in the VSDP, and is using the Liquid Chromatography with tandem Mass Spectrometry (LC-MS/MS) method to measure vitamin D, which is referred to as the ‘gold standard’2 analytical method.
1 National Institute of Health (NIH) Office of Dietary Supplements, ODS Vitamin D Initiative, <http://ods.od.nih.gov/Research/VitaminD.aspx#vdsp>, Last accessed 11/12/2013.
2 Grebe SKG and RJ Singh 2011, LC-MS/MS in the Clinical Laboratory – Where to From Here?, Clinical Biochemistry Reviews, <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3052391/>, Last accessed 11/12/2013.