Rate of False Deferral and False Pass of Prospective Blood Donors Screened by Copper Sulphate Gravimetric Method at Hossana Blood Bank, Hossana, South Ethiopia
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Date
2016-07
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Addis Ababa University
Abstract
Background: The primary responsibility of a blood transfusion service (BTS) is to provide a
safe, sufficient and timely supply of blood and blood products so as to ensure that blood donation
causes no harm to the donor. The Copper Sulphate (CuSO4) screening test has been found to
erroneously include anemic people and exclude eligible people and its performance is not well
studied in poor settings like Ethiopia.
Objectives: To determine the rate of false deferral and false pass of prospective blood donors
screened by the copper sulphate gravimetric test from April to June 2016 at Hossana blood
bank, Ethiopia..
Methods: A cross- sectional study was carried out from April to June 2016 in Hossana blood
bank. Blood sample from 422 voluntary donors were collected and analyzed by CuSo4
gravimetric test and automated hematology analyzer (Cell-dyn 1800). The data was entered in
Epi-Data 3.1 and analyzed by SPSS 20 and interpreted accordingly. P value less than 0.05 was
considered as statistically significant. Agreement between the two methods was determined
using the Kappa coefficient.
Result: The overall deferra1 rate was 20.1% by the reference method and varies by blood
collection site for the copper sulphate method (15.4% and 16.8% using capillary and whole
blood, respectively). False pass rates were 9.2% and 7.6% and false fail rates were 4.5% and
4.3% using capillary and venous blood samples, respectively. The CuSo4 method using capillary
blood sample had sensitivity of 94.4%, specificity 54.1%, PPV 89.1% and NPV 70.8%, while
using venous blood sample it gave sensitivity of 94.7%, specificity 62.4%, PPV 90.9% and NPV
74.6%. The CuSo4 method had moderate with Kappa value of 0.53, (95% CI, 0.425-0.625,
P<0.01) and substantial (Kappa value of 0.61, 95% CI (0.507 to 0.698), (P<0.01.) level of
agreement with the reference method using capillary and venous blood samples, respectively.
Conclusion: The high rate of false pass warrants the search for an alternative simple method to
replace the old copper sulphate method. Until replaced, CuSO4 method which moderately
agrees with the reference method can be retained as a primary screening tool by applying strict
quality control method.
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Keywords
False Deferral, False Pass