Background: The aim of this study was to determine whether a conclusion could be obtained through meta-analysis of the published trials on the relative efficacy of rifampicin and doxycycline versus streptomycin and doxycycline or another tetracycline (SD).
Methods: The comparative and randomized trials identified by a search in the reference data base MEDLINE from 1967 to 1992 and through manual review of the articles cited in these studies or other reviews were included. The evaluation of quality was performed by a standardized scale. The differences in efficacy were expressed as odds ratio and the results were contrasted by the Mantel-Haenszel method. Heterogenicity was graphically analyzed by the Woolf method with an adjustment being made for small subgroups. The confidence intervals were calculated for each trial and for the combined data by the Cornfield method.
Results: Six trials including 581 patients of whom 544 were considered evaluable were analyzed. In the RD treatment group 261 (242 valid) patients were included with 268 (253 valid) being included in the SD group. Five cases of initial therapeutic failure were observed in each group without significant differences. The secondary effects described were very variable. Nonetheless no secondary effects obliging discontinuation of treatment were presented in the RD group with only one in the SD group with no differences between the two groups. Recurrences were presented in 5% and 39% in the RD group and in 0 and 17% in the SD group. In total 37 (16%) in the former group and 13 (5%) in the latter group. The Mantel-Haenszel odds ratio with respect to recurrence was 3.81 (CI 95%, 1.82-8.17; p = 0.00009). The total number of cures was 196 (81%) in the RD group and 232 (92%) in the SD group (Mantel-Haenszel odds ratio 0.36; CI 95%, 1.19-0.64; p = 0.0004). The inclusion of the quality index of the trials did not modify the statistical significance achieved.
Conclusions: In human brucellosis the treatment of rifampicin and doxycycline presents a greater number of recurrence and lower number of cure than the classical treatment with streptomycin and tetracycline drugs.