Prevalence and risk factors related to poor outcome of patients with severe Plasmodium vivax infection: a systematic review, meta-analysis, and analysis of case reports.

Background: Plasmodium vivax rarely develops severe complications when compared to severe falciparum malaria. However, severe vivax malaria also needs urgent, intensive care and treatment as severe falciparum malaria. This systematic review aimed to explore pooled prevalence of severe vivax malaria and to identify factors related to poor outcome of patients who developed severe manifestation.

Methods: The systematic review conducted by two reviewers independently through searching of research publications related to severe P. vivax malaria in three databases including MEDLINE, Web of Science (ISI), and Scopus until October, 22 2019. The pooled prevalence of severe vivax malaria was achieved using STATA and RevMan 5 Software. Factors related to poor outcome of patients with severe vivax malaria were analyzed using SPSS 11.5 Software.

Results: Among 2615 research publications retrieved from three databases, 49 articles reporting on 42,325 severity cases were selected for calculating pooled prevalence. Seventy-six patients from case reports, case series, letter to editors, and research communications were collected to identify factors related to poor outcome of patients with severe vivax malaria. The results showed that severe anemia, jaundice, respiratory distress, impaired consciousness, and renal failure were the most common major manifestations of severe malaria guided by the World Health Organization (WHO) criterion. The meta-analysis indicated that severe malaria was less frequent in patient with P. vivax compared to those with P. falciparum (P -value < 0.00001, OR = 0.38, 95% CI = 0.25-0.56, I = 87%). In addition, thrombocytopenia, anemia, hepatitis, and severe thrombocytopenia were the most common minor complications. Analysis of cases indicated that convulsion, respiratory distress, renal failure, jaundice, anuria/oliguria, and complication during treatment impacted on longer hospital stays compared to other severe complications (P-value < 0.05). Respiratory distress was frequently found after first treatment with anti-malarial drugs (P-value = 0.002). Renal failure was frequently found before treatment with anti-malarial drugs (P-value = 0.016). Mean days of fever and higher pulse rates at presentation were predictors of poor outcome among patients with severe vivax malaria (P-value < 0.05).

Conclusions: Severe anemia was the most common major manifestation of P. vivax malaria guided by the WHO criterion. Severe anemia was found less frequently in patients with P. vivax than those with P. falciparum. Renal failure, jaundice, anuria/oliguria, and complication during treatment along with, mean days of fever and higher pulse rates at presentation might be predictors of poor outcome of patients with severe vivax malaria.