Malaria-related hospitalizations in the US: The disease and economic burden, and risk factors for severe and fatal malaria
Although malaria has been eliminated from the US since the early 1950s, about 1,500 cases of malaria are reported in the US every year. Few studies have comprehensively quantified the disease and economic burden of malaria in the US, and the domestic impact has not been well described. Epidemiological study of malaria using hospital data has rarely been explored, and can supplement the findings from current nationwide surveillance system data to elucidate the malaria disease and economic burden. Identification of predictors of increased costs and severe malaria may be useful in developing targeted interventions.
Discharge records for malaria-related hospitalizations from the 2000-2012 Nationwide Inpatient Sample (NIS) were examined. In chapter 1, the disease burden was quantified by examining the frequencies and population rates of malaria-related hospitalization by demographics, infecting species, clinical, financial, institutional, geographic, and seasonal characteristics. Trends over the period in the counts of malaria cases by different patient characteristics were assessed using negative binomial regression. In chapter 2, the economic burden was quantified by examining the mean and total hospital days, hospital charges, and hospital costs for malaria-related hospitalizations by demographics, species, clinical, financial, geographic, and institutional characteristics. Trends and potential predictors for hospital charges and costs were identified using linear regression. Trends and potential predictors for length of stay were identified using negative binomial regression. In chapter 3, a subset analysis on severe malaria cases was conducted, and the frequencies and population rates of severe malaria-related hospitalizations by demographics, species, clinical, financial, geographic, and institutional characteristics were examined. Trends in the rates of severe malaria hospitalizations over the study period were assessed by negative binomial regression. Multiple logistic regression models were used to identify potential predictors for severe disease (cerebral malaria, acute respiratory distress [ARDS], severe anemia, renal failure, or jaundice) and death among those with malaria-related hospitalizations.
From 2000-2012, there were an estimated 19,189 malaria-related hospitalizations (4.95 per 1 million population) in the US, including 147 in-hospital deaths and 3,888 severe malaria cases. On average, malaria patients were hospitalized for 4.39 days with charges of $25,116. From 2000-2012, malaria-related hospitalizations accounted for 84,213 hospital days, $151,825,389 in total hospital costs, and $470,102,584 in total charges. The most frequent malaria complication was renal failure (40.5%), followed by severe anemia (34.6%), ARDS (19.9%), cerebral malaria (18.7%), and jaundice (15.4%). P. falciparum accounted for the majority of malaria- and severe malaria-related hospitalizations. Malaria-related hospitalizations occurred disproportionately among patients who were male, Black, or aged 25-44 years. After controlling for potential confounders, older age was associated with higher odds of severe malaria, ARDS, severe anemia, and renal failure. Males had higher odds of developing renal failure and jaundice, while females had higher odds of developing severe anemia and ARDS. HIV infection was associated with increased odds of severe malaria. Having severe malaria was associated with a longer length of stay. Older age, severe malaria, HIV infection, and longer lengths of stay were associated with higher charges and costs. Mean charges increased significantly over the study period. Patients with a malaria diagnosis were more often hospitalized in the Middle Atlantic and South Atlantic census divisions, urban teaching, private not-for-profit, and large bed size hospitals. Malaria patients who were self-payers or had Medicaid were at increased odds of having renal failure, compared to those with Medicare.
This dissertation demonstrates that malaria imposes a substantial disease and economic burden in the US, and underscores the need for improved primary and secondary prevention measures, especially among high-risk groups.