Familial hypercholesterolaemia with high triglycerides: A diagnostic challenge.

Combined or mixed hyperlipidaemia is characterised by hypercholesterolaemia together with high triglyceride concentrations. It is found in approximately 1 in 100 people in the United Kingdom. Most cases are secondary to an underlying condition such as the metabolic syndrome, diabetes mellitus (especially poorly controlled) or individuals with a high alcohol intake. Mixed hyperlipidaemia is also a feature of some primary hyperlipidaemia conditions such familial combined hyperlipidaemia (FCH) or type III hyperlipidaemia (dysbetalipoproteinaemia). One differential diagnosis for mixed hyperlipidaemia that can easily be overlooked is a patient with an underlying diagnosis of familial hypercholesterolaemia (FH) who also has a hypertriglyceridaemia due to any other cause. Those patients may have very high total and low-density lipoprotein cholesterol concentrations (LDL-C) with a moderately elevated triglyceride concentration. In this article, we report 4 cases of familial hypercholesterolaemia, confirmed by genetic testing, in patients initially presenting with hypertriglyceridaemia in addition to high total cholesterol and LDL-C. This article discusses the diagnostic challenges associated with this presentation and highlights the key role of directly measuring LDL-C to aid diagnosis in these specific situations.

'A case of autoimmune hepatitis associated with the PCSK9 inhibitor alirocumab'.

This is a case of a 61-year-old lady who presented to the lipid clinic with possible familial hypercholesterolaemia (Simon Broome Criteria). She was commenced on atorvastatin; however, 4 weeks later, she developed hepatitis, and therefore her atorvastatin was discontinued. Following that, her liver function tests normalized, and she was diagnosed with statin-induced hepatitis. Three years later, she was seen again in the lipid clinic with an uncontrolled lipid profile, and she was commenced on alirocumab, a Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) inhibitor. A few days later, she developed hepatitis, and subsequently, the alirocumab was discontinued. She underwent a liver biopsy, which confirmed that she had Autoimmune Hepatitis (AIH) with presumed superimposed drug injury. This is the first reported case of autoimmune hepatitis associated with alirocumab.

Limitations of glycated albumin standardization when applied to the assessment of diabetes patients.

OBJECTIVES: Glycated albumin (GA) has potential value in the management of people with diabetes; however, to draw meaningful conclusions between clinical studies it is important that the GA values are comparable. This study investigates the standardization of the Norudia Glycated Albumin and Lucica Glycated Albumin-L methods. METHODS: The manufacturer reported imprecision was verified by performing CLSI-EP15-A3 protocol using manufacturer produced controls. The Japanese Clinical Chemistry Reference Material (JCCRM)611-1 was measured 20 times to evaluate the accuracy of both methods. GA was also measured in 1,167 patient samples and results were compared between the methods in mmol/mol and %. RESULTS: Maximum CV for Lucica was ≤0.6 % and for Norudia ≤1.8 % for control material. Results in mmol/mol and % of the JCCRM611-1 were within the uncertainty of the assigned values for both methods. In patient samples the relative difference in mmol/mol between the two methods ranged from -10.4 % at a GA value of 183 mmol/mol to +8.7 % at a GA value of 538 mmol/mol. However, the relative difference expressed in percentage units ranged from of 0 % at a GA value of 9.9 % to +1.7 % at a GA value of 30 %. CONCLUSIONS: The results in mmol/mol between the two methods for the patient samples were significantly different compared to the results in %. It is not clear why patient samples behave differently compared to JCCRM611-1 material. Valuable lessons can be learnt from comparing the standardization process of GA with that of HbA1c.

A Cross-Sectional Study of Glomerular Hyperfiltration in Polycystic Ovary Syndrome.

Glomerular hyperfiltration (GH) has been reported to be higher in women with polycystic ovary syndrome (PCOS) and is an independent risk factor for renal function deterioration, metabolic, and cardiovascular disease. The aim of this study was to determine GH in type A PCOS subjects and to identify whether inflammatory markers, markers of CKD, renal tubule injury markers, and complement system proteins were associated. In addition, a secondary cohort study was performed to determine if the eGFR had altered over time. In this comparative cross-sectional analysis, demographic, metabolic, and proteomic data from Caucasian women aged 18-40 years from a PCOS Biobank (137 with PCOS, 97 controls) was analyzed. Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement was undertaken for inflammatory proteins, serum markers of chronic kidney disease (CKD), tubular renal injury markers, and complement system proteins. A total of 44.5% of the PCOS cohort had GH (eGFR ≥ 126 mL/min/1.73 m2 (n = 55)), and 12% (n = 17) eGFR ≥ 142 mL/min/1.73 m2 (super-GH(SGH)). PCOS-GH women were younger and had lower creatinine and urea versus PCOS-nonGH. C-reactive protein (CRP), white cell count (WCC), and systolic blood pressure (SBP) were higher in PCOS versus controls, but CRP correlated only with PCOS-SGH alone. Complement protein changes were seen between controls and PCOS-nonGH, and decay-accelerator factor (DAF) was decreased between PCOS-nonGH and PCOS-GSGH (p < 0.05). CRP correlated with eGFR in the PCOS-SGH group, but not with other inflammatory or complement parameters. Cystatin-c (a marker of CKD) was reduced between PCOS-nonGH and PCOS-GSGH (p < 0.05). No differences in tubular renal injury markers were found. A secondary cohort notes review of the biobank subjects 8.2-9.6 years later showed a reduction in eGFR: controls -6.4 ± 12.6 mL/min/1.73 m2 (-5.3 ± 11.5%; decrease 0.65%/year); PCOS-nonGH -11.3 ± 13.7 mL/min/1.73 m2 (-9.7 ± 12.2%; p < 0.05, decrease 1%/year); PCOS-GH (eGFR 126-140 mL/min/17.3 m2) -27.1 ± 12.8 mL/min/1.73 m2 (-19.1 ± 8.7%; p < 0.0001, decrease 2%/year); PCOS-SGH (eGFR ≥ 142 mL/min/17.3 m2) -33.7 ± 8.9 mL/min/17.3 m2 (-22.8 ± 6.0%; p < 0.0001, decrease 3.5%/year); PCOS-nonGH eGFR versus PCOS-GH and PCOS-SGH, p < 0.001; no difference PCOS-GH versus PCOS-SGH. GH was associated with PCOS and did not appear mediated through tubular renal injury; however, cystatin-c and DAF were decreased, and CRP correlated positively with PCOS-SGH, suggesting inflammation may be involved at higher GH. There were progressive eGFR decrements for PCOS-nonGH, PCOS-GH, and PCOS-SGH in the follow-up period which, in the presence of additional factors affecting renal function, may be clinically important in the development of CKD in PCOS.

Using nephropathy as an outcome to determine the HbA1c diagnostic threshold for type 2 diabetes.

OBJECTIVE: The hemoglobin A1c (HbA1c) diagnostic threshold for type 2 diabetes (T2D) of 6.5 % (48 mmol/mol) was based on the prevalence of retinopathy found in populations not known to have T2D. It is unclear if nephropathy has a similar HbA1c threshold, partly because it is a rarer complication of early diabetes. This cohort study investigated a very high diabetes prevalence population to determine if a better diagnostic HbA1c value can be established for predicting nephropathy rather than retinopathy in subjects without T2D. METHODS: The urine albumin:creatinine ratios (UACRs) of 2920 healthy individuals from the Qatar Biobank who had an HbA1c ≥ 5.6 %. were studied. Nephropathy was defined as a UACR≥30 mg/g and its prediction by HbA1c was assessed using cut-points ranging from 5.7 to 7.0 % to dichotomize high from low HbA1c. RESULTS: Although there was a significant trend for an increased prevalence of abnormal UACR as the HbA1c threshold increased (p < 0.01), significance was due mostly to subjects with HbA1c ≥ 7.0 % (53 mmol/mol). The odds ratios for abnormal UACR were similar over the 5.7-6.9 % HbA1c threshold range, with a narrow odds ratio range of 1.2-1.6. Utilizing area-under-receiver-operating characteristic curves, no HbA1c threshold <7.0 % was identified as the best predictor of nephropathy. CONCLUSION: Even in a population with a high prevalence of known and unknown diabetes, no HbA1c threshold <7.0 % could be found predicting an increased prevalence of nephropathy. This means there is not a requirement to change the existing retinopathy-based HbA1c threshold of 6.5 % to also accommodate diabetes nephropathy risk.

Performance of renin assays in selecting fludrocortisone dose in children with adrenal disorders.

Children with salt-wasting adrenal insufficiency are managed with glucocorticoid and mineralocorticoid replacement. Measurement of renin activity or concentration alongside blood electrolyte levels is used to monitor the adequacy of mineralocorticoid replacement. Our unit changed from using renin activity to renin concentration and carried out a service review to assess whether this influenced decision-making for fludrocortisone dosing. In total, 50 measurements of plasma renin activity and 50 of renin concentration were analysed on separate cohorts before and after the assay change, with values standardised to multiples of the upper limit of normal (MoU) to allow comparison between assays. We were more likely to increase the fludrocortisone dose for a raised renin concentration than a raised renin activity. The renin concentration MoU was more strongly related to plasma sodium (negatively) and 17α-hydroxyprogesterone (17α-OHP) (positively) than the renin activity MoU. Using a MoU cut-off of 1.5, a decision to increase the dose of fludrocortisone was more likely to be made when using the renin concentration assay compared with the activity assay. Using a cut-off of 40 nmol/L for 17α-OHP, a decision not to change the fludrocortisone dose when 17α-OHP was <40 was more likely when using the renin concentration assay. For both assays, a plasma sodium <140 mmol/L was more likely to lead to a fludrocortisone dose increase, and most likely for the renin concentration assay. Overall, the decision to adjust fludrocortisone dose in this cohort of children with adrenal insufficiency was better supported by the biochemical parameters when based on renin concentration results and clinical status.

Assay error detection when using common quality control targets across multiple instruments: An analysis using simulated and real-world data.

BACKGROUND: Clinical laboratories frequently implement the same tests and internal quality control (QC) rules on identical instruments. It is unclear whether individual QC targets for each analyser or ones that are common to all instruments are preferable. This study modelled how common QC targets influence assay error detection before examining their effect on real-world data. METHODS: The effect of variable bias and imprecision on error detection and false rejection rates when using common or individual QC targets on two instruments was simulated. QC data from tests run on two identical Beckman instruments (6-month period, same QC lot, n > 100 points for each instrument) determined likely real-world consequences. RESULTS: Compared to individual QC targets, common targets had an asymmetrical effect on systematic error detection, with one instrument assay losing detection power more than the other gained. If individual in-control assay standard deviations (SDs) differed, then common targets led to one assay failing QC more frequently. Applied to two analysers (95 QC levels and 45 tests), common targets reduced one instrument's error detection by ≥ 0.4 sigma on 15/45 (33%) of tests. Such targets also meant 14/45 (31%) of assays on one in-control instrument would fail over twice as frequently as the other (median ratio 1.62, IQR 1.20-2.39) using a 2SD rule. CONCLUSIONS: Compared to instrument-specific QC targets, common targets can reduce the probability of detecting changes in individual assay performance and cause one in-control assay to fail QC more frequently than another. Any impact on clinical care requires further investigation.

The effectiveness of blood glucose and blood ketone measurement in identifying significant acidosis in diabetic ketoacidosis patients.

BACKGROUND: Patients with diabetic ketoacidosis (DKA), a potentially fatal complication of type 1 diabetes, have hyperglycemia, ketonemia and metabolic acidosis. Blood glucose and blood ketone results are often used to triage patients with suspected DKA. This study aimed to establish how effective blood glucose and blood ketone (beta-hydroxybutyrate, BOHB) measurements are in identifying patients with significant acidosis and sought to validate existing diagnostic BOHB thresholds. METHODS: Initial Emergency Department results on 161 presumptive DKA episodes in 95 patients (42 F, 53 M, age range 14-89 years) containing a complete dataset of D (glucose), K (BOHB) and A (Bicarbonate [HCO3] and pH) results. RESULTS: Blood glucose correlated poorly with BOHB (r = 0.28 p = 0.0003), pH (r= -0.25, p = 0.002) and HCO3 (r= -0.17, p = 0.04). BOHB, though better, was still limited in predicting pH (r = -0.44, p < 0.0001) and HCO3 (r = -0.49, p < 0.0001). A HCO3 of 18mmol/L equated to a BOHB concentration of 4.3mmol/L, whilst a HCO3 of 15mmol/L equated to a BOHB of 4.7mmol/L. Of the 133 of 161 events with HCO3 < 18mmol/L, 22 were not hyperglycemic (> 13.9mmol/L, n = 8), ketonemic (≤ 3mmol/L, n = 9) or either (n = 5). CONCLUSIONS: The commonly employed BOHB diagnostic cutoff of 3mmol/L could not be verified. Since acid-base status was poorly predicted by both glucose and BOHB, this highlights that, regardless of their results, pH and/or HCO3 should also be tested in any patient suspected of DKA.

Establishing Pragmatic Analytical Performance Specifications for Blood Beta-Hydroxybutyrate Testing.

BACKGROUND: Currently, no authoritative guidelines exist recommending the analytical performance specification (APS) of blood beta-hydroxybutyrate (BOHB) testing in order to meet the clinical needs of patients. This study has applied existing diabetic ketoacidosis (DKA) BOHB diagnostic thresholds and the recommended rates of fall in BOHB concentrations during DKA treatment to establish pragmatic APSs for BOHB testing. METHODS: Required analytical performance was based on 2 clinical requirements: (a) to reliably distinguish between non-adjacent DKA BOHB diagnostic categories of <0.6, 0.6 to 1.5, 1.6 to 2.9, and ≥3 mmol/L, and (b) to be assured that a measured 0.5 mmol/L reduction in BOHB indicates the true concentration is at least falling (meaning >0 mmol/L decline). RESULTS: An analytical coefficient of variation (CV) of <21.5% could reliably distinguish all non-adjacent diagnostic categories with >99% certainty, assuming zero bias. In contrast, within-day CVs of 4.9%, 7.0%, and 9.1% at 3 mmol/L BOHB were required to assure truly falling ketone concentrations with 99% (optimal), 95% (desirable), and 90% (minimal) probability, respectively. These CVs are larger at lower BOHB concentrations and smaller at higher concentrations. CONCLUSIONS: Reliable tracking of changes in BOHB during DKA treatment largely drives the requirement for analytical performance. These data can be used to guide minimal, desirable, and optimal performance targets for BOHB meters and laboratory assays.

Factors influencing the derivation and clinical application of blood calcium adjustment equations.

BACKGROUND: Laboratories are recommended to use patient data to derive their local adjusted calcium (adjCa) equation, using numerous criteria to exclude patients with potential calcium metabolism abnormalities. It is not known which, if any, of the exclusions influence the final equation formula, or to what extent. This study investigated the effect using fewer exclusions has on adjCa equations and on patient results when compared to a reference equation. METHODS: A reference ACB adjCa equation was derived from the total calcium and albumin pairs of 1305 individuals who, from an initial 22,906 adults, met recommended criteria (excluding abnormalities in either calcium, albumin, creatinine, magnesium, ALP or ALT, and specific clinical areas). This reference equation was compared to seven alternatives derived using fewer criteria, including one with no exclusions. All equations were applied to a validation cohort (n=19,640) to determine their effect on adjCa results and on categorizing patients into hypo-, normo- or hypercalcaemia. RESULTS: Most alternative adjCa equations, including the one without any exclusions, showed no statistical (p < 0.05) difference in their slope or intercept compared to the ACB reference. Nor did any of the validation cohort have a clinically significantly different adjCa result (>5% and >0.1 mmol/L different) when applying an alternative rather than the reference equation. Additionally, no alternative equation changed the kappa categorization of the validation population's calcium status. CONCLUSIONS: When deriving adjCa equations, most exclusion criteria have little influence on the equation or patient results, including using none at all. This knowledge could simplify deployment of local equations.

Progressive loss of corneal nerve fibers is associated with physical inactivity and glucose lowering medication associated with weight gain in type 2 diabetes.

AIMS/INTRODUCTION: Limited studies have identified risk factors linked to the progression of diabetic peripheral neuropathy (DPN) in type 2 diabetes. This study examined the association of risk factors with change in neuropathy measures over 2 years. MATERIALS AND METHODS: Participants with type 2 diabetes (n = 78) and controls (n = 26) underwent assessment of clinical and metabolic parameters and neuropathy using corneal confocal microscopy (CCM), vibration perception threshold (VPT), and the DN4 questionnaire at baseline and 2 year follow-up. RESULTS: Participants with type 2 diabetes had a lower corneal nerve fiber density (CNFD), branch density (CNBD), and fiber length (CNFL) (P ≤ 0.0001) and a higher VPT (P ≤ 0.01) compared with controls. Over 2 years, despite a modest reduction in HbA1c (P ≤ 0.001), body weight (P ≤ 0.05), and LDL (P ≤ 0.05) the prevalence of DPN (P = 0.28) and painful DPN (P = 0.21) did not change, but there was a significant further reduction in CNBD (P ≤ 0.0001) and CNFL (P ≤ 0.05). CNFD, CNBD, and CNFL decreased significantly in physically inactive subjects (P < 0.05-0.0001), whilst there was no change in CNFD (P = 0.07) or CNFL (P = 0.85) in physically active subjects. Furthermore, there was no change in CNFD (P = 0.82), CNBD (P = 0.08), or CNFL (P = 0.66) in patients treated with glucose lowering medication associated with weight loss, whilst CNBD (P = 0.001) decreased in patients on glucose lowering medication associated with weight gain. CONCLUSIONS: In participants with type 2 diabetes, despite a modest improvement in HbA1c, body weight, and LDL there was a progressive loss of corneal nerve fibers; except in those who were physically active or on glucose lowering medication associated with weight loss.

Efficacy and Safety of PCSK9 Monoclonal Antibodies in Patients With Diabetes.

PURPOSE: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are novel drugs that have proven efficacy in improving cardiovascular outcomes. Roles for the PCSK9 molecule in metabolic pathways beyond LDL receptor processing and cholesterol homeostasis are well established. PCSK9 genetic variants associated with lower LDL-C levels correlate with a higher incidence of type 2 diabetes (T2DM), calling into question the appropriateness of these drugs in patients with T2DM and those at high risk of developing diabetes, and whether cardiovascular benefit seen with PCSK9 inhibitors might be offset by resultant dysglycemia. The purpose of this review was to examine the role of PCSK9 protein in glucose homeostasis, the impact of PCSK9 inhibition in relation to glucose homeostasis, and whether some of the cardiovascular benefit seen with PCSK9 inhibitors and statins might be offset by resultant dysglycemia. METHODS: Comprehensive literature searches of electronic databases of PubMed, EMBASE, and OVID were conducted by using the search terms hyperlipidaemia, PCSK9, diabetes, and glucose as well as other relevant papers of interest collected by the authors. The retrieved papers were reviewed and shortlisted most relevant ones. FINDINGS: Genetically determined lower circulating LDL-C and PCSK9 concentrations may have an incremental effect in increasing T2DM incidence, but any perceived harm is outweighed by the reduced risk of atherosclerotic cardiovascular disease achieved through lower lifetime exposure to LDL-C. PCSK9 monoclonal antibodies are effective and safe in patients with T2DM and those at high risk of developing it. The number-needed-to-treat to prevent one atherosclerotic cardiovascular disease event in the FOURIER (Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk) study in the subgroup with diabetes is significantly lower than for those without. Therefore, T2DM or being at high risk to develop it should not be a reason to avoid these agents. The safety of PCSK9 inhibition in relation to glucose homeostasis may depend on the method of inhibition and whether it occurs in circulation or the cells. Data from experimental studies and randomized controlled trials suggest no detrimental effect of PCSK9 monoclonal antibodies on glucose homeostasis. More data and large randomized controlled studies are needed to assess the impact of other methods of PCSK9 inhibition on glucose homeostasis. IMPLICATIONS: PCSK9monoclonal antibodies markedly reduce LDL-C and consistently reduce cardiovascular mortality in patients with and without diabetes. Current evidence does not suggest an adverse effect of PCSK9 monoclonal antibodies on glycemic parameters.

Controversies Around the Measurement of Blood Ketones to Diagnose and Manage Diabetic Ketoacidosis.

The measurement of blood ketones in preference to urine ketones has become a well-established tool in the diagnosis and management of diabetic ketoacidosis (DKA). However, there remains considerable disparity between diabetes guidelines regarding if, how, and when this test should be used. While recent guidelines now mainly emphasize blood measurement, several issues nonetheless remain. Many laboratories still measure blood ketones using a semiquantitative test that does not measure the predominant ketone, ß-hydroxybutyrate (BOHB), which may hinder patient management. Even when BOHB is measured, the evidence for cutoffs used in DKA diagnosis or exclusion is limited, while its use in gauging severity, treatment progress, and resolution is not fully clear. Lastly, although employing point-of-care meters instead of a laboratory for BOHB measurement brings undoubted benefits, this approach has its own challenges. This article provides a perspective on these topics to complement current recommendations and to suggest how future research may improve its use in the DKA context.

Reducing neonatal phlebotomy blood losses through the accurate calculation of minimum test volume requirements.

BACKGROUND: Repeated phlebotomy for laboratory diagnostic testing is a known cause of iatrogenic anaemia and in critically ill neonates often leads to blood transfusion being required. This study has developed a spreadsheet clinical decision support tool to allow neonatal staff to determine the true minimum blood volume required to analyse groups of blood tests and modelled its potential benefit compared with the existing system in use. METHODS: The tool calculates the minimum blood volume accounting for novel factors including the current patient haematocrit for plasma/serum samples, instrument minimum test and dead volumes (including those where shared) and sharing of samples within/between laboratory departments. A year of neonatal unit laboratory requests were examined comparing the volumes and containers of blood recommended by the hospital information system with both the amount actually collected by staff and that recommended by the tool. RESULTS: A total of 463 patients had 8481 blood draws for 23,899 tests or test profiles over the year. The hospital information system recommended collecting 11,222 mL of blood into 18,509 containers, while 17,734 containers were actually received (10,717 mL if fully filled). The tool recommended collecting 4915 mL of blood into 15,549 containers. CONCLUSIONS: This tool allows neonatal intensive care unit staff to objectively determine the minimum blood volume required for a combination of tests and is generalizable between laboratory instruments. Compared with the hospital information system, use of the minimum blood volume clinical decision support tool could maximally reduce the volume of blood collected from this neonatal unit by more than a half. Neonatal intensive care unit staff had apparently already gone some way to determining their own minimum volumes required.

The retinopathy-derived HbA1c threshold of 6.5% for type 2 diabetes also captures the risk of diabetic nephropathy in NHANES.

AIM: To determine if an HbA1c diagnostic threshold of less than 6.5% (<48 mmol/mol) could be identified based on a urinary albumin-creatinine ratio (UACR) of 30 mg/g or higher in subjects not known to have diabetes. METHODS: A UACR was measured for 20 158 participants in the 2011-2018 nationally representative cross-sectional National Health and Nutrition Examination Surveys (NHANES; cycles 7-10 inclusive). RESULTS: There was a significant trend for an increasing risk with a UACR of 30 mg/g or higher across increasing HbA1c categories (P < .0001). This trend was mainly attributable to the high prevalence of raised UACR in the 7.0% or higher HbA1c subgroup of subjects not previously diagnosed with diabetes. None of the odds ratios in the lower HbA1c subgroups versus the HbA1c subgroup of less than 5.0% reached significance. There were racial/ethnic differences in UACR risk (P < .0001), with White and Black subjects exhibiting little increased risk (vs. HbA1c <5.0%) until they reached an HbA1c of 7.0%, while Asian and Hispanic subjects showed some increased, but non-significant, risks at lower HbA1c levels. Maximizing the area under receiver operating characteristic curves from logistic regressions predicted an ideal HbA1c threshold of 5.8%, but there was little variation in area from 5.5% to 7.0%. CONCLUSION: A clinically useful diagnostic threshold below 6.5% for HbA1c for elevated UACR risk was not identified, with an increased risk only obvious at an HbA1c of 7.0% or higher. Thus, the retinopathy-derived HbA1c threshold of 6.5% also captures the risk of diabetic nephropathy in NHANES.

Diagnosing type 2 diabetes using Hemoglobin A1c: a systematic review and meta-analysis of the diagnostic cutpoint based on microvascular complications.

AIMS: Diabetic microvascular complications of retinopathy, nephropathy and neuropathy may occur at hemoglobin A1c levels (HbA1c) below the 6.5% (48 mmol/mol) diagnostic threshold. Our objective was to assess the validity of the HbA1c diagnostic cutpoint of 6.5% based upon published evidence of the prevalence of retinopathy, nephropathy and neuropathy as markers of diabetes. METHODS: Data Sources PubMed, Embase, Cochrane, Scopus and CINAHL from 1990-March 2019, grey literature sources. Study Selection All studies reported after 1990 (to ensure standardized HbA1c values) where HbA1c levels were presented in relation to prevalence of retinopathy, nephropathy or neuropathy in subjects not known to have diabetes. Data Extraction Studies were screened independently, data abstracted, and risk of bias appraised. Data Synthesis Data were synthesized using HbA1c categories of < 6.0% (< 42 mmol/mol), 6.0-6.4% (42-47 mmol/mol) and ≥ 6.5% (≥ 48 mmol/mol). Random-effects meta-analyses were conducted for retinopathy, nephropathy and neuropathy prevalence stratified by HbA1c categories. Random-effects multivariable meta-regression was conducted to identify predictors of retinopathy prevalence and sources of between-study heterogeneity. RESULTS: Pooled mean prevalence was: 4.0%(95% CI: 3.2-5.0%) for retinopathy, 10.5% (95% CI: 4.0-19.5%) for nephropathy, 2.5% (95% CI: 1.1-4.3%) for neuropathy. Mean prevalence when stratified for HbA1c < 6.0%, 6.0-6.4% and ≥ 6.5% was: retinopathy: 3.4% (95% CI: 1.8-5.4%), 2.3% (95% CI: 1.6-3.2%) and 7.8%(95% CI: 5.7-10.3%); nephropathy: 7.1% (95% CI: 1.7-15.9%), 9.6% (95% CI: 0.8-26.4%) and 17.1% (95% CI: 1.0-46.9%); neuropathy: 2.1% (95% CI: 0.0-6.8%), 3.4% (95% CI: 0.0-11.6%) and 2.8% (95% CI: 0.0-12.8%). Multivariable meta-regression showed HbA1c ≥ 6.5% (OR: 4.05; 95% CI: 1.92-8.57%), age > 55 (OR: 3.23; 95% CI 1.81-5.77), and African-American race (OR: 10.73; 95% CI: 4.34-26.55), to be associated with higher retinopathy prevalence. Marked heterogeneity in prevalence estimates was found across all meta-analyses (Cochran's Q-statistic p < 0.0001). CONCLUSIONS: The prevalence of nephropathy and moderate retinopathy was increased in subjects with HbA1c values ≥ 6.5% confirming the high specificity of this value for diagnosing T2DM; however, at HbA1c < 6.5% retinopathy increased at age > 55 years and, most strikingly, in African-Americans, suggesting there may be excess microvascular complication prevalence (particularly nephropathy) in individuals below the diabetes diagnostic threshold.

Using clinical guidelines to assess the potential value of laboratory medicine in clinical decision-making.

INTRODUCTION: It is often quoted that 70% of clinical decisions are based on laboratory results, but the evidence to substantiate this claim is lacking. Since clinical guidelines aim to document best-practice decision making for specific disease conditions, inclusion of any laboratory test means that the best available evidence is recommending clinicians use it. Cardiovascular disease (CVD) is the world's most common cause of mortality, so this study reviewed all CVD guidelines published by five national/international authorities to determine what proportion of them recommended laboratory testing. MATERIALS AND METHODS: Five leading CVD guidelines were examined, namely the European Society of Cardiology (ESC), the UK National Institute for Health and Clinical Excellence (NICE), the American College of Cardiology (ACC), the Australian Heart Foundation (AHF) and the Cardiac Society of Australia and New Zealand (CSANZ). RESULTS: A total of 101 guidelines were reviewed. Of the 33 individual ESC guidelines relating to CVD, 24/33 made a direct reference to the use of clinical laboratory tests in either diagnosis or follow-up treatment. The same applied to 15/20 of NICE guidelines, 24/32 from the ACC and 15/16 from the AHF/CSANZ. Renal function and blood count testing were the most recommended (39 and 26 times), with lipid, troponin and natriuretic peptide measurement advocated 25, 19 and 19 times respectively. CONCLUSIONS: This study has shown that laboratory testing is advocated by between 73% and 94% of individual CVD guideline recommendations from five national/international authorities. This provides an index to assess the potential value of laboratory medicine to healthcare.