Persistent postoperative nonanginal pain after cardiac surgery

As the two principal research investigators, we are pleased that our large, long-term, multicentre study on persistent postcardiac surgery pain was published in CMAJ.1 However, we strongly take issue with the Editor’s comment in the April 15 print synopsis version regarding the data in the full-text article. We point out the editor’s misunderstanding referring to persistent preoperative nonanginal pain: “If the measurement scales were comparable, this suggests a great improvement from 6 months after surgery onward rather than a persisting problem.” We think that this merits a correction in CMAJ. Pain measurement before surgery related to an already existing persistent nonanginal pain from common health problems such as arthritis, headache or backache, while this study measured surgery-related pain that remained for about 10% of patients at two years later. As mentioned in our original manuscript, persistent postoperative pain was defined as pain that: first appeared after surgery, was not related to pain felt before surgery (e.g., anginal pain) or to other causes (e.g., infection, arthritis) and was present for at least three months.

Readers must not lose sight of the very important study findings supporting persistent pain as a potential consequence of this very common cardiac surgery. Patients with higher ratings for acute pain and related interference in daily functioning in the first week after surgery were more likely to report persistent postoperative pain at 2 years later. Cardiac surgeries rank among the most frequently performed interventions worldwide,2 and prevalence rates of long-term postoperative pain after these surgeries is substantial. Both clinicians and patients need to be informed of this potential consequence.

Unrelieved acute severe pain in the immediate postoperative period has been documented for decades and again in our study. The severity of persistent postoperative pain should be amenable to change. Future well-designed, carefully controlled studies are needed to determine whether persistent postoperative pain can be minimized or prevented.