Analysis of "Capillary and Venous Blood Glucose Accuracy in Blood Glucose Meters Versus Reference Standards: The Impact of Study Design on Accuracy Evaluations".

The article by Macleod and coauthors outlines an accuracy study of two blood glucose monitoring systems (BGMSs) against glucose-oxidase- and hexokinase-based assays showing how the reference/comparison method and inappropriate sample comparisons can affect accuracy conclusions. The dangers of independent institutions producing inappropriate conclusions when the methodology used for product regulatory or registration accuracy requirements is not according to best practice are stressed. The authors highlight several important aspects of a multistep accuracy evaluation protocol. However, it is essential that anyone undertaking or reporting BGMS accuracy studies should have a clear understanding of each and every protocol point, best practice, and how each can influence accuracy conclusions. Claims against regulatory accuracy criteria should be made only if the detailed specified protocol design and analysis is followed.

Measurement of C-reactive protein, procalcitonin and neutrophil elastase in saliva of COPD patients and healthy controls: correlation to self-reported wellbeing parameters.

BACKGROUND: Saliva is increasingly promoted as an alternative diagnostic bio-sample to blood; however its role in respiratory disease requires elucidation. Our aim was to investigate whether C-reactive protein (CRP), procalcitonin (PCT) and neutrophil elastase (NE) could be measured in unstimulated whole saliva, and to explore differences between COPD patients and controls with normal lung function. We also determined the relationship between these salivary biomarkers and self-reported COPD-relevant metrics. METHODS: Salivary CRP, PCT and NE levels were measured at each of 3 visits over a 14-day period alongside spirometry and a daily self-assessment dairy in 143 subjects: 20 never-smokers and 25 smokers with normal spirometry; 98 COPD patients [GOLD Stage I, 16; Stage II, 32; Stage III, 39; Stage IV, 11]. Twenty-two randomly selected subjects provided simultaneous blood samples. RESULTS: Levels of each salivary biomarker could distinguish between the above cohorts. Significant differences remained for salivary CRP and NE (p < 0.05) following adjustment for age, gender, sampling time, gum disease and total co-morbidities; but not for BMI except for salivary NE, which remained higher in smokers compared to non-smokers and stable COPD subjects (p < 0.001). Patients with acute COPD exacerbations had a median increase in all 3 salivary biomarkers (p < 0.001); CRP: median 5.74 ng/ml, [interquartile range (IQR) 2.86-12.25], PCT 0.38 ng/ml, [IQR 0.22-0.94], and NE 539 ng/ml, [IQR 112.25-1264]. In COPD patients, only salivary CRP and PCT levels correlated with breathing scores (r = 0.14, p < 0.02; r = 0.13, p < 0.03 respectively) and sputum features but not with activities of daily living. Salivary CRP and PCT concentrations strongly correlated with serum counterparts [r = 0.82, (95% CI: 0.72-0.87), p < 0.001 by Spearman's; and r = 0.53, (95% CI: 0.33-0.69), p < 0.006 respectively]; salivary NE did not. CONCLUSIONS: CRP, PCT and NE were reliably and reproducibly measured in saliva, providing clinically-relevant information on health status in COPD; additionally NE distinguished smoking status. All 3 salivary biomarkers increased during COPD exacerbations, with CRP and PCT correlating well with patient-derived clinical metrics. These results provide the conceptual basis for further development of saliva as a viable bio-sample in COPD monitoring and exacerbation management.

Assessing the quality of publications evaluating the accuracy of blood glucose monitoring systems.

Many studies determine the performance of blood glucose monitoring (BG) systems. Correct evaluation is, however, complex, and apparent contradiction of results creates confusion. This study aimed to provide an overview of frequently made errors and to develop easy-to-use checklists to verify the quality of such studies. Building on the work from Mahoney and Ellison and subsequent re-evaluation, study designs of accuracy studies were assessed, and best practice and internationally accepted norms were determined. Key issues were collated, and two simplified checklists were developed: one for the assessment of analytical accuracy studies and a second for guidance with studies assessing the influence of interferences. The checklists have been used in a feasibility study with 20 representative studies selected from a literature search between 2007 and 2012. This check revealed that limitations in the designs and methods of studies assessing the performance of BG systems are common. The use of the accuracy checklist with the 20 representative studies showed that only 20% were in agreement with most of the issues deemed important and that 40% showed clear nonconcordance with ISO 15197. The use of the interference checklist showed that only 50% of the publications were in good agreement with the quality checks. In agreement with previous studies, which concluded many evaluations are performed poorly and present questionable conclusions, the use of these checklists demonstrated that few publications adhered to international guidelines and recommendations. Taking this into consideration, it becomes obvious that the publications must be examined in more detail to establish their quality and the validity of conclusions drawn.