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A new review summarises existing evidence gaps regarding when blood transfusions should be carried out for visceral leishmaniasis patients. The review is published in Transactions of the Royal Society of Tropical Medicine and Hygiene.

© © Salahaldeen Nadir, World Bank

Visceral leishmaniasis (VL) is the most severe of the three forms of leishmaniasis and is fatal without treatment. A blood transfusion is an important aspect of patient management but currently the trigger to carry out the procedure is poorly understood.

The 2010 World Health Organization (WHO) technical report on leishmaniasis suggests undertaking transfusion in patients with severe anaemia. Transfusion may also be indicated in cases of acute blood loss due to invasive procedures such as splenic aspiration. Despite the importance of transfusion in the management of VL patients, the actual practice in clinical trials is poorly reported and remains largely unclear.

Researchers used the IDDO VL clinical trials library and accessed 160 studies between 1980–2021. A total of 16 studies, with 3,459 patients, included a description of blood transfusion.  The review found the number of patients receiving a transfusion was explicitly reported in only 10 studies and of the 2,421 patients enrolled, 217 underwent transfusion. Of the 217 patients, for 58, transfusion occurred before the start of treatment for VL, in 46 it was during the treatment/follow-up phase, and for 113 patients the time was not mentioned.

Transfusion was initiated solely based on haemoglobin (Hb) measurement in nine studies, combining Hb measurement with an additional condition (epistaxis/poor health/clinical instability) in three studies, and the criteria was not mentioned in four studies. Hb threshold range for triggering transfusion was 3-8 g/dL.

One of the study authors Dr Prabin Dahal said: “We found data regarding blood transfusion in the treatment of VL remains largely unreported. In particular, the risk-benefit of transfusion practices in VL case management couldn’t be gauged from existing studies. Our research demonstrates the need for the research community to adopt a standardised methodology to generate and report transfusion related data. This type of data could help in assessing the impact of transfusion triggers on treatment outcomes.”

Prof Ahmed Musa, a globally recognised expert on visceral leishmaniasis from the University of Khartoum, Sudan said: “Patients with VL who require blood transfusion have low concentrations of cellular blood elements mainly red blood cells and plasma proteins including clotting factors. So, they commonly present with high-output heart failure or pending failure, bleeding and peripheral oedema due to low oncotic pressure of the blood and fatigue due to low oxygen tension at the tissue level leading to metabolic acidosis. Blood transfusion prevents the above-mentioned complications and can possibly accelerate the cure of visceral leishmaniasis. The selection of patients for blood transfusion is critical and should not depend on the level of haemoglobin only. This is because some patients adapt with low haemoglobin levels. This review provides an important evidence towards the need for incorporating clinical parameters as a part of transfusion trigger”.

Read the full paper: