Although apheresis may be a useful adjunct treatment for patients with babesiosis, or loiasis with a microfilarial count >8000/mL prechemotherapy, the data does not support routine use of apheresis in cases of severe Plasmodium falciparum malaria, according to a study published in the Journal of Infection.
Apheresis, the removal of a specific component of a patient’s blood, with the remainder being returned to the patient, has been used as adjunctive treatment of severe P falciparum malaria and babesiosis, and, prior to chemotherapy for patients with loiasis. To investigate the effectiveness and safety of apheresis in these conditions, investigators performed a systematic review of studies involving patients treated with apheresis for severe falciparum malaria, babesiosis, or loiasis, published between January 1969 and March 2018. Researchers conducted a search of the CINAHL, EMBASE, MEDLINE, and PUBMED databases. Efficacy end points were specific to each disease, and safety end points were the number and type of complications and adverse events due to apheresis.
Among a total of 67 publications that met the inclusion criteria; 36 were studies on malaria (70 participants), 17 on babesiosis (22 participants) and 14 on loiasis (34 participants). The publications included case reports, case series, and cohort studies; no randomized controlled trials were identified. Investigators considered potential publication bias to be high.
Because many malaria studies did not report parasite counts immediately pre- or post-red cell exchange (RCE) and rarely documented the timing of drug administration relative to apheresis, it is possible that the median 80% (interquartile range [IQR], 68.4-90) reduction in parasitemia per apheresis procedure may overestimate efficacy. Further, the clinical improvements observed following plasmapheresis may be the result of other potential benefits of apheresis, such as removal of toxins and cytokines, thus improving the overall prognosis. The complete recovery seen in 65/70 (92.9%) of patients in the analysis was notable, given that patients with malaria who are treated with apheresis are commonly more unwell, as evidenced by a higher Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) 2 score (26 vs 17) and a higher initial median parasitemia (46.5% vs 7.3%), compared with patients not treated using apheresis. Adverse events and complications were rare.
Patients with babesiosis included in this review more frequently demonstrated severe disease, evidenced by a median pre-apheresis parasitemia of 20.25%, compared with the median levels of 7.6%-15.1% commonly seen in other studies. All but 1 patient identified in this review had identifiable immunosuppression risk factors, and 4 of 22 patients died. In regards to the safety of RCE for patients with severe babesiosis, no RCE-related adverse events were reported. The low mean pre-apheresis hemoglobin level of 7.6 g/dL (standard deviation 2.2 g/dL) suggested that the procedure was safe and well tolerated, even in patients with low hemoglobin levels.
In cases where apheresis is conducted to reduce microfilarial load in patients with loiasis, the researchers found a median parasitemia reduction of 51.7% (IQR, 28.9-70.8%) across all procedures where both pre- and post-apheresis procedure data are available. Though they emphasized that it cannot be assumed that this reduction is solely the result of apheresis, because of the diurnal variation and the potential for microfilariae to migrate from the periphery, researchers concluded that apheresis is likely to be a significant contributing factor.
Despite limitations, such as the low sample sizes and the unavailability of randomized controlled trials for analysis, investigators concluded, “Existing data suggests that apheresis may be a useful adjunct to chemotherapy in the treatment of patients hospitalised for Babesia, and prior to chemotherapy in loiasis with microfilarial count >8000 parasite/mL on the basis of reduction of parasite counts, but there are no clear clinical benefits. Our review does not currently support the use of apheresis in patients with severe P falciparum malaria.”
Odedra A, Lalloo DG, Kennedy G, Llewellyn S, McCarthy JS. Safety and effectiveness of apheresis in the treatment of infectious diseases: A systematic review [published online October 14, 2019]. J Infect. doi: 10.1016/j.jinf.2019.09.014