Reply to Drs Rowley and Emamdee

To the Editor: W e read with interest the work by Shariat et al. The attempt to increase our knowledge of analgesia for hip arthroplasty is commendable; however, we have noted some debatable statistics and questionable methodology, which may cast doubt on the conclusion and summary of this article. The study protocol describes visual analog scale scoring for pain assessment; however, the article refers solely to the numeric rating scale 11 (NRS-11) score. This could easily be a typographical error in the study protocol; if, however, it is not, then the substitution of NRS-11 (in the article) for visual analog scale (in the study protocol) is questionable. The interchangeability of these 2 scoring systems has been controversial in the past. Indeed, such interchangeability has been questioned specifically for postoperative orthopedic patients. The NRS-11 data in this article are presented as continuous (numerical) data, data that can be represented on a number line. Clearly, one patient’s NRS score of 8, say, is not twice as much pain as his NRS score of 4. Similarly, a patient’s perception of a score of 6, for example, is not the same as another patient’s score of 6. Is it therefore wise to consider NRS scores as a continuous variable? Finally, we noted that the authors wanted a “... mean NRS approximately 8–9 for the SB group” and pain intensity ranged up to 10 in each group (for up to 30 minutes postblock). Assuming a pain score of 10 is not an instantaneous event, to have a patient with a pain score of 10 up to 30 minutes after a hip arthroplasty seems a long timewithout giving supplemental analgesia (apart from the patient controlled analgesia morphine and fascia iliaca block), all in the name of a randomized control trial.