Prednisone Plus Chloroquine Versus Chloroquine for the Treatment of Hyper-reactive Malarial Splenomegaly in Papua New Guinea: a Randomized Open-label Trial

Hyper-reactive malarious splenomegaly (HMS) is a known chronic autoimmune complication in areas where malaria is endemic. Patients with HMS complain most commonly of abdominal swelling or pain from the enlarged spleen and the condition is defined using clear clinical and laboratory criteria. HMS appears benign in most patients when seen first but if untreated, it leads to severe anaemia and also acute bacterial infections. There is familiar and ethnic clustering suggesting genetic basis. High prevalence rates have been reported in certain areas of Papua New Guinea, and Venezuela, and HMS is also common in parts of sub-Saharan Africa, including Sudan and Ghana.

The treatment of HMS is still empirical since no randomized trials have been done so far. Long term anti-malarial chemoprophylaxis is deemed the mainstay of therapy, but the optimal drug-regimen and duration are unknown. Three to six months may pass before a response is observed, and relapses may occur when therapy is discontinued.

On the basis of the observed benefit in experimental studies, glucocorticoids have been used for severe hyper-reactive malarial splenomegaly in various case reports. Because these cases had a favourable outcome and the drug tolerability was good, prednisone has become an attractive therapeutic option for this disease. Central to the pathophysiology of HMS is the overproduction of Immunoglobulin M due to a functional CD8 T-cell defect and the consequent expansion and activation of B lymphocytes. Glucocorticoids may have an immediate effect due to inhibition of the sequestration of immunoglobulin coated red blood cells by the mononuclear phagocyte system and a later effect due to glucocorticoid-induced inhibition of antibody synthesis. We aim to assess the efficacy of chloroquine after prednisone-induction therapy compared to chloroquine alone in the treatment of adult patients with newly diagnosed hyper-reactive malarial splenomegaly.