Re: Associations between Burkitt’s Lymphoma among Children in Malawi and Infection with HIV, EBV and Malaria: Results from a Case-Control Study
Adamson S. Muula
Department of Community Health, University of Malawi College of Medicine and Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, North Carolina

The article by Mutalima et al(1) published recently in this journal is certainly an important contribution to global health and opens up possibilities for new thinking on the prevention (both primary and secondary) of Burkitt’s lymphoma. If HIV infection is a ‘causative factor’ of this common childhood lymphoma in Eastern and Southern Africa, it would also be important to study if HIV infection may have a role in the disease’ recurrence following treatment, and overall poor treatment outcomes.
With regard the Mutalima et al’s study (1), the authors reported that “Cases were more likely than controls to be HIV positive (Odds ratio (OR)) = 12.4, 95% Confidence Interval (CI) 1.3 to 116.2, p = 0.03).” The confidence limit ratio (CLR), although not reported in the paper, is 89.4 (upper confidence limit divided by the lower confidence limit). If we were to be concerned about precision (3,4) and although there are no ‘hard and fast’ rules in interpreting CLRs, many researchers would consider a CLR value in excess of 10 as manifestation of an imprecise effect estimate. There may be agreement therefore that the effect of HIV on Burkitt’s lymphoma as reported by Mutalima et al (1) is highly imprecise. An imprecise estimate casts a shadow on the ‘confidence’ that may have on the findings of a study. A future study with a large sample size, although expensive, is desperately warranted.
On a minor note however, the authors reported, that “Sixty-eighty percent of infants living alongside Lake Malawi were found to be infected with Plasmodium falciparum by the age of 10 month” (4). It is not very clear to me why the reference by Slutsker et al (4) was used as if the situation may be similar currently when that study was reported in 1996 (almost 12 years ago). We can only speculate that the authors intended to suggest that the malaria situation along Lake Malawi has little changed. This suggestion obviously may or may not be true. I would have preferred a more guarded approach that was obvious in the paper.
Competing interests
I have no competing interests to declare.
References

1. Mutalima N, Molyneux E, Jaffe H, Kamiza S, Borgstein E, et al. Associations between Burkitt Lymphoma among Children in Malawi and Infection with HIV, EBV and Malaria: Results from a Case-Control Study. PLoS ONE. 2008;3:e2505.
2. Poole C. Beyond the confidence interval. Am J Public Health 1987; 77: 195–199.
3. Poole C. Confidence intervals exclude nothing. Am J Public Health 1987; 77: 492–493.
4. Slutsker L, Khoromana C, Hightower A, Macheso A, Wirima J, et al. (1996) Malaria infection in infancy in rural Malawi. Am J Trop Med Hyg 55: 71–76.