Leprosy Mailing List – July 19, 2018
Ref.: (LML) Single-dose rifampicin chemoprophylaxis
From: Anujo Tiwari, Rotterdam, the Netherlands
Dear Pieter,
This is the email in response to the email sent by Joel Almeida (LML, July 15, 2018). I want to draw audience attention to some insights on the paper. Anuj Tiwari, Steaven Dandel, Rita Djupuri, Liesbeth Mieras and Jan Hendrik Richardus. Population-wide administration of single dose rifampicin for leprosy prevention in isolated communities: a three-year follow-up feasibility study in Indonesia. BMC Infectious Diseases 2018.18:324 https://doi.org/10.1186/s12879-018-3233-3
1. The study was mainly a feasibility study and was not designed to measure the efficacy of rifampicin. However, the odds ratio was reported to contribute in the external validity of chemoprophylaxis results presented in various papers.
2. The discussion section warned the readers to interpret results with caution as this was not an RCT, and leprosy cases were too few (n=10).
3. The results clearly states that "The odds ratio is 0.57 (95% CI: 0.16–2.03), indicating that the odds of having leprosy are lower in the exposed (SDR) than in the non-exposed (no SDR) group. Among the people screened during the third visit, there was an apparent reduction of leprosy of around 50% among those who had previously received SDR compared to those who had not." The results are comparable with COLEP study which stated "overall reduction in incidence of leprosy using a single dose of rifampicin in the first two years was 57% (95% confidence interval 33% to 72%)".
When odd ratio is 1 then there is no effect, and less than 1 indicates protective effect.
4. Nowhere in the paper, hypothesis testing was performed which provided the p value or significance. The p value in epidemiology is many times misleading, and experts recommend to avoid p values. Please follow the link to bring clarity about the p values and significance testing.
Fidler, F., Thomason, N., Cumming, G., Finch, S., & Leeman, J. (2004). Editors can lead researchers to confidence intervals, but can't make them think: Statistical reform lessons from medicine. Psychological Science, 15, 119-126.
Rothman KJ. Six persistent research misconceptions. J Gen Intern Med. 2014 Jul; 29(7):1060-4. PMID: 24452418 DOI: 10.1007/s11606-013-2755-z
Regards,
Anujo
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << editorlml@gmail.com
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