A zero event rate is also given value in the meta-analysis calculation. The raw metric data are standardized across all the studies and then subjected to pooling. 1 A meta-analysis considers not only the number of events, or evident event rates, but also the number of subjects in the study to evaluate the “weight” and effect size. Methods for meta-analysis use a weighted average of the results, in which the larger trials have more influence than the smaller ones. The results from studies with a small number of subjects carry a lesser significance than do those from studies with a larger number of patients. A simple arithmetic average of the results from all the included studies would be erroneous. We understand the concerns raised due to this.Ī meta-analysis aims at systematically distilling and connecting data from different studies in order to formulate an overall opinion regarding a given topic. Yet the event rate quoted against this study in Fig. 3C and E), which were indicated to be 0.071, when the study did not report any cases of in-procedure nausea/vomiting or paresthesia. The questions in point 3 relate to the event rates for in-procedure nausea/vomiting (Fig. in our article.įirst, we would like to address point 3. We appreciate the interest shown by Schreglmann et al. However, as with other scientific endeavors, their validity depends on the accurate and meticulous execution of all necessary steps involved, and thus, the following of publication standards and guidelines is nice but ultimately pointless if primary data are not handled adequately. Meta-analyses are powerful scientific tools used to condense findings from individual studies in an accessible way, and their popularity is hence increasing steadily. We would also like to express our concerns with the use of a funnel plot for the evaluation of publication bias when only 8 studies were included in order for such a test to give valid results, it has been argued that at least 30 studies of sufficient power would be necessary, and its interpretation should therefore be done with caution. Additional minor inaccuracies-for example, in stating the age of our study participants inconsistently and incorrectly twice (Table 1 and text)-add to these concerns.Įven without cross-checking the accuracy of data points derived from all other included publications, one wonders about the validity of the authors’ results, although overall their conclusions might be similar to those reported in other publications. We are also uncertain why our quality of life data, as measured by the standard Quality of Life in Essential Tremor (QUEST) tool and stated in the abstract, were omitted from the analysis. 6) Finally, “persisting limb weakness” at 3 months after the intervention was reported in Table 4, although we did not report any paresis. 3D and F suggest that ataxia persisted at 3 and 12 months (event rates stated as 0.333 and 0.071, respectively), although our study stated that signs of ataxia “resolved within 3 months.” 5) Relatedly, we only reported a maximum follow-up of 6 months. 3C and E suggest the occurrence of paresthesia (event rates stated as 0.071), although we did not report this. 3) Figure 3B suggests the occurrence of in-procedure nausea/vomiting and Fig. 2) In-procedure complications were reported for 5 patients (Table 3), although our publication reported them in only 4 patients. However, we found several relevant factual errors in the representation of data from one of our publications 3 cited in this work, 2 which unfortunately casts a shadow on the overall analysis: 1) Our study was cited as retrospective when in fact it had been performed in a prospective manner. We are delighted to see such work, as the subject is of course of interest and significance, and its timing germane now that a number of relevant studies have been published. 2 on magnetic resonance–guided focused ultrasound (MRgFUS) ablations for treating tremor ( Mohammed N, Patra D, Nanda A: A meta-analysis of outcomes and complications of magnetic resonance–guided focused ultrasound in the treatment of essential tremor. TO THE EDITOR: We read with interest the meta-analysis by Mohammed et al.