Invasive infections and sickle-cell disease

Abstract

The burden of disease caused by bacterial infections in patients with sickle-cell disease has long been neglected. Meenakshi Ramakrishnan and colleagues emphasise the scarcity of data for the association between sickle-cell disease and invasive bacterial disease in Africa. However, four of the seven studies included in this metaanalysis were from Kinshasa, Democratic Republic of the Congo (formerly Zaire). Although the reviewers present these as independent studies, the same data are shared in these reports. The fi rst study by Eeckles and colleagues, published in 1967, included data for blood and cerebrospinal fl uid (CSF) infections, recorded from 1959 to 1966. The second study, by Lontie and colleagues published in 1973, included data for CSF samples collected from 1959 to 1972. The third study, by Omanga published in 1981, from the same clinics as the fi rst and second studies, included data for all types of invasive infections; the investigators do not mention dates of sample collection. In a fourth study by Omanga published in 1989, data were collected from 1964 to 1985. This study reported 69 patients with sicklecell disease and bacteraemia. At least 14 of these 69 patients also had positive CSF cultures. A fi fth study, published in 1977 (not included in Ramakrishnan and colleagues review), also by Omanga and colleagues, examined meningitis in 47 patients with sicklecell disease, nine of whom also had positive blood cultures. These CSF samples were collected from 1964 to 1974. Because Eeckles and colleagues’ 1967 study, reported 45 patients with sickle-cell disease, few new cases are likely to have been added in the last study published in 1989 (confl ict in the Democratic Republic of the Congo meant microbiology laboratories might not have been functional). The combined odds ratios for bacterial infections calculated in Ramakrishnan and colleagues’ study therefore included duplicate, triplicate, and perhaps quadruplicate data. This fact clearly shows the need for a more careful analysis of this published work, but more importantly, the need for new studies to accurately establish the relative burden of disease in patients with sickle-cell disease in Africa.