Background: Following splenectomy there is an increased risk of severe and fatal bacterial and parasitic infections, however the risk of Plasmodium vivax malaria is unknown. The aim of this study was to quantify the Plasmodium species-specific risks of malaria and other clinical outcomes following splenectomy in patients attending two hospitals in southern Papua, Indonesia.
Methods: Records of all patients attending Mitra Masyarakat Hospital between 2004 and 2013 were reviewed to identify those who had undergone splenectomy. The subsequent risks of specific clinical outcomes within 12 months for splenectomized patients were compared to non-splenectomized patients from their first recorded admission to hospital. A cohort of 11 patients from an adjacent hospital were followed prospectively from their day of splenectomy and post-splenectomy outcomes were reported by descriptive statistics.
Results: Of the 162,966 patients attending Mitra Masyarakat hospital during the study period, 67 underwent splenectomy. Compared to 10,707 controls with comparable characteristics, splenectomized patients were at 5-fold higher rate of representing with malaria within 12 months (Adjusted Hazard Ratio (AHR)=5.0 [95%CI: 3.4-7.3], p<0.001). The rate was greater for P. vivax (AHR=7.8 [95%CI: 5.0-12.3], p<0.001) compared to P. falciparum (AHR=3.0 [95%CI: 1.7-5.4], p<0.001). Splenectomized patients were also at greater risk of being admitted to hospital for: any cause (AHR=1.8 [95%CI: 1.0-3.0], p=0.037), diarrheal illness (AHR=3.5 [95%CI: 1.3-9.6], p=0.016) or pneumonia (AHR=2.8 [95%CI: 0.9-8.8], p=0.085). In the prospective cohort, 64% (7/11) of splenectomy patients returned with symptomatic microscopy-confirmed malaria, 5 with P. vivax and 2 with P. falciparum, none severe.
Conclusions: Splenectomy is associated with a high risk of malaria and this is more apparent with P. vivax than P. falciparum. Eradication of P. vivax hypnozoites using primaquine (radical cure) and subsequent malaria prophylaxis is warranted in patients following splenectomy in malaria-endemic areas, particularly in the early post-operative period.