Utility of point-of-care haemoglobin measurement in the HemoCue-B haemoglobin for the initial diagnosis of anaemia

Measurement of haemoglobin (Hb) concentration provides a reliable indication of the presence and severity of anaemia. However, other laboratory parameters are usually requested as well, leading to an increase in socio-sanitary costs. Accordingly, this study was undertaken to ascertain the reliability of point-of-care Hb determination with the portable photometer HemoCue-B haemoglobin (HBH) and to evaluate its utility for the initial diagnosis of anaemia. Hb was measured (x3) in 20 venous blood samples diluted with saline (v/v; 1 : 0, 2 : 1, 1 : 1, 2 : 1 and 3 : 1) to obtain a wide range of Hb and in venous and capillary blood samples from 247 primary health care patients. All HBH results were compared with those yielded by the reference cell counter Pentra 120 Retic (ABX). In diluted samples, Hb values obtained with either method were not significantly different (ABX-HBH, -0.01 +/- 0.32 g/dl; 95% CI, -0.04 to 0.028 g/dl) and showed an excellent Pearson's coefficient of correlation (r = 0.992; P < 0.01). HBH provides accurate values if at least 4 mul of blood is loaded into the cuvette. There were no significant differences between Hb measured in venous (v) and capillary (c) blood samples in primary care patients. Eighteen anaemic patients were detected by ABX measurements (7.3%; 15 female/3 male), 18 by HBHv (specificity, 100%; sensitivity, 100%) and 25 by HBHc (eight false positives; one false negative; specificity, 94.4%; sensitivity, 96.5%). Compared with ABX, HBH provides accurate and precise measurements for a wide range of Hb and its use in primary health care seems to be a good method for the initial diagnosis of anaemia.     

Evaluation of capillary haemoglobin determination for anaemia screening in blood donation settings

BackgroundAn accurate assessment of hemoglobin (Hb) values before donation is unavoidable for safeguarding donors’ safety and fulfilling the current specifications of Hb content in blood bags. This study was hence aimed to compare a finger-prick method for Hb measurement in capillary blood with Hb assessment in venous blood using a hematological analyser.ResultsA significant overestimation was found with HemoCue compared to UniCel DxH800, but the correlation between methods was significant (comprised between 0.600 and 0.759; all p<0.01) and the bias always lower than the quality specifications. The prevalence of Hb values below the gender-specific thresholds for blood donation was also not significantly different (p=0.186).DiscussionIt can hence be concluded that the finger-prick method evaluated is a safe and reliable means for screening blood donors.     

ICSH recommendations for the measurement of haemoglobin F

Measurement of the Haemoglobin F in red cell haemolysates is important in the diagnosis of δβ thalassaemia, hereditary persistence of fetal haemoglobin (HPFH) and in the diagnosis and management of sickle cell disease. The distribution of Hb F in red cells is useful in the diagnosis of HPFH and in the assessment of feto-maternal haemorrhage. The methods of quantifying Hb F are described together with pitfalls in undertaking these laboratory tests with particular emphasis on automated high-performance liquid chromatography and capillary electrophoresis.     

Capillary and venous haemoglobin levels in blood donors: a 42‐month study of 36 258 paired samples

Background EU law requires a haemoglobin of ≥ 12·5 g/dl for women or ≥ 13·5 g/dl for men at the time of donation. As capillary and venous haemoglobin values may differ in the same subject, we examined whether a capillary haemoglobin level of 12·0 g/dl for women or 13·0 g/dl for men, is equivalent to a venous haemoglobin level of ≥ 12·5 g/dl and ≥ 13·5 g/dl, respectively, to avoid unnecessary loss of blood donations. Methods Over a continuous 42‐month period, 36 258 paired capillary and venous samples were taken from 25 762 females and 10 496 males, when the capillary haemoglobin was < 12·5 g/dl and < 13·5 g/dl respectively. Results Venous haemoglobin levels were higher than capillary levels, with a mean difference of 1·07 g/dl (SD 0·68 g/dl), range ?2·2 to +3·25 g/dl for men (P < 0·001), and a mean difference of 0·67 g/dl (SD 0·65 g/dl), range ?2·5 to +5·4 g/dl for women (P < 0·001). The difference for the three consecutive winters was 0·78 g/dl (SD 0·081 g/dl) for females and 1·26 g/dl (SD 0·162 g/dl) for males and for the three consecutive summers was 0·56 g/dl (SD 0·089 g/dl) for females and 0·88 g/dl (SD 0·134 g/dl) for males: P < 0·001. Conclusions Capillary haemoglobin levels of 12·0–12·5 g/dl in healthy females or 13·0–13·5 g/dl in healthy males are substantively equivalent to venous haemoglobin levels of ≥ 12·5 and ≥ 13·5 g/dl for women and men respectively. This finding has permitted an additional 32 990 blood units to be collected over the period of the study, a gain of 9·4%.     

Characteristics of a rapid,point‐of‐care lateral flow immunoassay for the diagnosis of sickle cell disease

Sickle cell disease (SCD) is a common and life‐threatening hematological disorder, affecting approximately 400,000 newborns annually worldwide. Most SCD births occur in low‐resource countries, particularly in sub‐Saharan Africa, where limited access to accurate diagnostics results in early mortality. We evaluated a prototype immunoassay as a novel, rapid, and low‐cost point‐of‐care (POC) diagnostic device (Sickle SCAN?) designed to identify HbA, HbS, and HbC. A total of 139 blood samples were scored by three masked observers and compared to results using capillary zone electrophoresis. The sensitivity (98.3–100%) and specificity (92.5–100%) to detect the presence of HbA, HbS, and HbS were excellent. The test demonstrated 98.4% sensitivity and 98.6% specificity for the diagnosis of HbSS disease and 100% sensitivity and specificity for the diagnosis of HbSC disease. Most variant hemoglobins, including samples with high concentrations of HbF, did not interfere with the ability to detect HbS or HbC. Additionally, HbS and HbC were accurately detected at concentrations as low as 1–2%. Dried blood spot samples yielded clear positive bands, without loss of sensitivity or specificity, and devices stored at 37°C gave reliable results. These analyses indicate that the Sickle SCAN POC device is simple, rapid, and robust with high sensitivity and specificity for the detection of HbA, HbS, and HbC. The ability to obtain rapid and accurate results with both liquid blood and dried blood spots, including those with newborn high‐HbF phenotypes, suggests that this POC device is suitable for large‐scale screening and potentially for accurate diagnosis of SCD in limited resource settings. Am. J. Hematol. 91:205–210, 2016. © 2015 Wiley Periodicals, Inc.     

Blood haemoglobin declines in the elderly: implications for reference intervals from age 70 to 88

The objective was to determine whether Hb declines in healthy elderly men and women and if this influences health-related reference intervals. A representative population sample, comprising 30% of all 70-yr-old subjects in a Swedish city with 420,000 inhabitants (n = 1148, participation rate 85%), was followed at 1-5-yr intervals for 18 yr within a longitudinal population study. Age-related changes in Hb were calculated after exclusion of non-healthy probands and by multivariate analyses in the total study group. Mean Hb declined between age 70 and 88 from 149 to 138 g/L in men (annual decline 0.69 g/L, p = 0.000), and from 139 to 135 g/L in women (annual decline 0.06 g/L, n.s.). Healthy men declined from 152 to 141 g/L (annual decline 0.53 g/L, p = 0.038), for women from 140 to 138 g/L (annual decline 0.05 g/L, n.s.). Age and body mass index correlated, in multivariate analysis, independently to Hb in both men and women, as did variables indicating a non-healthy state. Epidemiological decision limits for anaemia declined for men from 128 to 116 g/L, for women from 118 to 114 g/L. Anaemia, thus defined, occurred in 3.2 to 9.7% of the subjects, whereas 28.3% of the 88-yr-old men had anaemia according to the WHO definition. In conclusion, there is a significant age-related decline in Hb from age 70 to 88 among healthy men, and a less pronounced decline among women. This justifies the use of lower epidemiological decision limits for anaemia of about 115 g/L for both men and women from age 80-82.     

Relationship between haemoglobin and haematocrit in the definition of anaemia

Introduction Anaemia is the most frequent haematological disorder in childhood. The notion that defines naemia does not change throughout life, although parameters used for its evaluation show significant variations during childhood. Haematocrit (Hct) (%) is usually defined as three times the value of haemoglobin (Hgb) (g/dl), while the clinical definition of anaemia is related to either an abnormal Hct or Hgb value. Objective To evaluate the agreement between Hgb and Hct values in the definition of anaemia, the relationship between these two parameters and their age‐dependence. Methods The Hct and Hgb paired values from children aged 2–18 months from Ifakara (Tanzania) and children aged 1–4 years from Manhiça (Mozambique) were analysed. Haematological determinations of the Manhiça samples were done using a KX‐21N cell counter (Kobe, Japan) and Ifakara samples were analysed in a semiautomatic cell counter (Sysmex F800 microcell counter, TOA Medical Electronics, Kobe, Japan). The κ‐statistic was used to calculate the agreement between anaemia definitions in each group. Crude and multivariate relationship between Hct and Hgb levels were analysed by linear regression model estimation. The age‐dependence of the crude ratio (Hct/Hgb) was analysed using linear regression models and fractional polynomials. Results The prevalences of mild and moderate anaemia as defined by Hgb levels in the Manhiça group were 61% and 6%, respectively, and 41% and 2% by Hct. In the Ifakara group these were 74% and 10%, respectively, by Hgb and 42% and 3% by Hct, respectively. Agreement between mild and moderate anaemia definitions made up from Hgb or from Hct levels were from fair to moderate. Hct levels decreased with age for high Hgb levels, whereas they increased for low Hgb levels. The classification of cases is improved when higher age‐related cut‐off values for Hct are used. The crude relationship between Hct and Hgb levels was significantly different from 3, and this was modified by age. The evaluation of the age‐dependence ratio (Hct/Hgb) showed a non‐linear relationship with an asymptotic trend to 3. Conclusions Measurement of haematocrit count is easy and can be performed in most rural health care centres. However, the corresponding Hgb levels cannot be derived with an acceptable accuracy using the value 3 as a conversion factor. Furthermore, the commonly assumed ‘equivalent’ cut‐off points for anaemia definitions need to be re‐evaluated.     

Evaluation of the WHO Haemoglobin Colour Scale for diagnosis of anaemia in children and pregnant women as used by primary health care nurses and community health workers in western Kenya

OBJECTIVES: To evaluate the diagnostic accuracy of the WHO Haemoglobin Colour Scale (HCS) for anaemia in three groups of children aged 2 months to 2 years (sick children, those visiting an immunization clinic and a community-based random sample of children) and a sample of pregnant women. METHODS: Finger-prick blood samples were taken from all consenting participants. Haemoglobin (Hb) levels from the HCS were compared with results from a HemoCue portable haemoglobinometer. Sensitivity, specificity and positive and negative predictive values for the HCS were calculated. RESULTS: A total of 457 sick children, 336 children visiting immunization clinics, 454 children from the community at large and 643 pregnant women participated. The prevalence of anaemia (Hb<11 g/dl) in these groups was 87%, 79%, 74% and 52%, respectively. The prevalence of severe anaemia (Hb<7 g/dl) was 24%, 11%, 10% and 2%, respectively. The sensitivity of the HCS for anaemia ranged from 60% to 79% and specificity from 59% to 94%. The sensitivity of the HCS for severe anaemia ranged from 24% to 63% and the specificity from 97% to 100%. Through use of the HCS, the proportion of sick, anaemic children visiting peripheral health facilities diagnosed and treated for anaemia would increase from 3% to 65%. CONCLUSIONS: In an area with high prevalence of anaemia among sick children, use of the HCS has the potential to significantly increase the proportion of sick, anaemic children who are diagnosed with anaemia and given appropriate treatment. Further evaluations of the effect of the use of the HCS on treatment practices at the health facility level are required.     

A simple and inexpensive point‐of‐care test for hepatitis B surface antigen detection: serological and molecular evaluation

Early identification of chronic hepatitis B is important for optimal disease management and prevention of transmission. Cost and lack of access to commercial hepatitis B surface antigen (HBsAg) immunoassays can compromise the effectiveness of HBV screening in resource‐limited settings and among marginalized populations. High‐quality point‐of‐care (POC) testing may improve HBV diagnosis in these situations. Currently available POC HBsAg assays are often limited in sensitivity. We evaluated the NanoSign^® HBs POC chromatographic immunoassay for its ability to detect HBsAg of different genotypes and with substitutions in the ‘a’ determinant. Thirty‐seven serum samples from patients with HBV infection, covering HBV genotypes A–G, were assessed for HBsAg titre with the Roche Elecsys HBsAg II quantification assay and with the POC assay. The POC assay reliably detected HBsAg at a concentration of at least 50 IU/mL for all genotypes, and at lower concentrations for some genotypes. Eight samples with substitutions in the HBV ‘a’ determinant were reliably detected after a 1/100 dilution. The POC strips were used to screen serum samples from 297 individuals at risk for HBV in local clinical settings (health fairs and outreach events) in parallel with commercial laboratory HBsAg testing (Quest Diagnostics EIA). POC testing was 73.7% sensitive and 97.8% specific for detection of HBsAg. Although the POC test demonstrated high sensitivity over a range of genotypes, false negatives were frequent in a clinical setting. Nevertheless, the POC assay offers advantages for testing in both developed and resource‐limited countries due to its low cost (0.50$) and immediately available results.     

Innovative technologies for point‐of‐care testing of viral hepatitis in low‐resource and decentralized settings

According to the Global Burden of Diseases, chronic viral hepatitis B and C are one of the most challenging global health conditions that rank among the first causes of morbidity and mortality worldwide. Low‐ and middle‐income countries are particularly affected by the health burden associated with HBV or HCV infection. One major gap in efficiently addressing the issue of viral hepatitis is universal screening. However, the costs and chronic lack of human resources for using traditional screening strategies based on serology and molecular biology preclude any scaling‐up. Point‐of‐care tests have been deemed a powerful potential solution to fill the current diagnostics gap in low‐resource and decentralized settings. Despite high interest resulting from their development in recent years, very few point‐of‐care devices have reached the market. Scaling down and automating all testing steps in 1 single device (eg, sample preparation, detection and readout) is indeed challenging. But innovations in multiple disciplines such as nanotechnologies, microfluidics, biosensors and synthetic biology have led to the creation of chip‐sized laboratory systems called “lab‐on‐a‐chip” devices. This review aims to explain how these innovations can overcome technological barriers that usually arise for each testing step while developing integrated point‐of‐care tests. Point‐of‐care test prototypes rarely meet the requirements for mass production, which also hinders their large‐scale production. In addition to logistical hurdles, legal and economic constraints specific to the commercialization of in vitro diagnostics, which have also participated in the low transfer of innovative point‐of‐care tests to the field, are discussed.