The modes of transmission of human immunodeficiency virus (HIV) are now well understood. Although HIV transmission through blood transfusion accounts for only a small proportion of new infections, its efficiency is [is greater than] 90%. However, as the risk of HIV transmission through blood transfusion depends on the prevalence of infected individuals in the donor population, the possibility of such transmission can be minimized by selecting donors at low risk for HIV infection and by screening the donated blood for HIV antibodies. It is also important to ensure the appropriate use of blood and blood products in order to avoid unnecessary transfusions and exposure of recipients to the risk of transfusion-transmitted disease.
The choice of a suitable screening test depends on the objectives of the screening, the sensitivity and specificity of available tests, and the prevalence of HIV infection in the donor population. Certain strategies have been recommended by WHO[2,7]. For the purpose of transfusion safety, for all prevalences, it is recommended that all blood donations be tested with one highly sensitive assay, e.g. enzyme-linked immunosorbent assay (ELISA). A reactive serum sample is considered HIV-positive and a non-reactive one, HIV-negative. All positive units (on the basis of one test) are discarded.
As for other laboratory procedures, it is essential to introduce an effective quality assurance programme covering inspection of specimens, maintenance of equipment, the choice of assay, record-keeping, and verification of results. Such a quality assurance programme is an essential part of achieving the transfusion of a safe unit of blood. Quality assurance in HIV testing also minimizes the wastage of blood units based on false-positive results.
Materials and methods
Quality assurance programmes for HIV screening were analysed during routine annual inspection of 11 blood transfusion centres in Delhi, India. The 10 parameters studied are described in Fig. 1-10. A pre-tested closed-type questionnaire with a weighted scoring system was used for the evaluation. Weights assigned to elements of the various parameters are detailed in Fig. 1-10. For each parameter, all the centres were graded according to score, as follows: 76-100%, excellent; 51-75%, good; 26-50%, fair; and [is less than] 25%, poor. Overall performance [is greater than] 50% was considered satisfactory.
Standardized sample collection and handling (Fig. 1). Sample collection and handling were good in three centres and fair in eight centres. None scored excellent and one, poor.
Adherence to recommended technical procedure (Fig. 2). Adherence to recommended technical procedure was good in three centres and fair in five. Two centres scored excellent and one, poor. In particular, preservation and use of reconstituted reagents was a cause for concern.
Use of standard operating procedure (Fig. 3). Seven centres did not use any standard operating procedure; one laboratory's use was fair, while three centres were excellent.
Proper use of reagents (Fig. 4). Use of reagents was good in two centres and fair in three. One centre scored excellent and five, poor. Eight centres did not pay adequate attention to checking the sensitivity and specificity of the reagents employed.
Laboratory record-keeping (Fig. 5). Record-keeping was good in three centres and fair in three others. Two centres scored excellent and three, poor. Only two centres employed a computerized record-keeping system. Laboratory worksheets did not uniformly mention the type, the batch and the lot number, and the expiry date of the test kit used.
Proper handling of HIV-positive blood units (Fig. 6). Handling and disposal of HIV-positive blood units were good in five centres and fair in two centres; three centres scored excellent and one, poor. Such units were not always labelled clearly in nine centres. …