We thank Xue et al1 for their interest and comments regarding our article entitled “Impact of Neuraxial Preservative-Free Morphine in Vaginal Delivery on Opiate Consumption and Recovery: A Randomized Control Trial”2 where we found a benefit to administering epidural morphine after vaginal delivery. Xue et al1 had some questions regarding our methodology and presentation of our results that we want to address. They questioned our morphine milligram equivalent (MME) conversation factors for oral and intravenous (IV) hydromorphone. We do not believe there is a uniformly accepted conversion and investigators use slightly different approaches. The source they cite3 includes a table that reports the conversion factor for oral hydromorphone as 5. However, this table was adapted from 2 sources4,5 that report a range of 4 to 6 as acceptable conversion factors. We chose a conversion factor of 4 based on our clinical experience that is routinely used by our acute pain service.
There were also questions in regard to our outcome variables. Xue et al wrote that opioid consumption is not patient-centered by itself and “cannot imply any patient benefit unless this is matched with improved pain control or decreased side effects…” We agree with the authors that clinical outcomes are critical to demonstrate benefit, which is why we also assessed the obstetric quality of recovery score (OBS-QOR10), breast-feeding success, and the Edinburgh Postnatal Depression Score (EPDS) for each patient. The OBS-QOR10 is a validated scoring tool that is patient-reported and quantitatively assesses the quality of recovery postpartum.6 The outcomes that are measured are included in Table 5 in the original article. The authors also questioned the clinical significance that we found in regard to pain scores since most had a score ≤3. We would contend that a pain score of 3, though classified by some as mild pain, is clinically significant and is not necessarily an acceptable level of pain depending on the patient. If we can reduce the pain level after vaginal delivery with epidural morphine we believe this is valuable especially since it is associated with few side effects.
Lastly, Xue et al queried why we did not report our secondary outcomes of total opioid consumption until discharge and total opioid consumption through week 1 of discharge. We appreciate the question and indeed this was initially included in the manuscript, but the journal reviewers recommended removing that data from Table 4. We found that MME from 24 hours after delivery to discharge was 0 [0–0] for the placebo group and 0 [0–0] for the treatment group, P = .291. Furthermore, we found the MME as outpatient up to 6 weeks was 0 [0–0] in the placebo and 0 [0–0] in the treatment, P = .657.
We thank you again for your thoughtful comments and hope our study and comments from other research groups will stimulate further studies about postpartum pain control to improve the parturient experience.
Benjamin Hyers, MD
Department of Anesthesiology, Perioperative, and
Pain Medicine
Icahn School of Medicine at Mount Sinai
New York, New York
Yaakov Beilin, MD
Department of Anesthesiology, Perioperative, and
Pain Medicine
Icahn School of Medicine at Mount Sinai
New York, New York
Daniel Katz, MD
Department of Anesthesiology, Perioperative, and
Pain Medicine
Icahn School of Medicine at Mount Sinai
New York, New York
daniel.katz@mountsinai.org