Post-op Complications: Are They Related to Post-op Pain?

The Connection Between Postoperative Pain and Complications

In a recent report, van Boekel and colleagues^[1] provide helpful information to clarify this relationship. Their retrospective study included all patients (N = 1014) who underwent different types of surgery in a Dutch hospital from 2012 to 2015, with general surgery, orthopedics, and urology comprising the major subgroups.

The authors reviewed complications (overall complication rate, 34%) and patient-reported pain levels and found that the risk for complications increased as pain levels rose. Compared with patients who reported the lowest level of pain, patients with moderate pain had about a two-fold greater risk for complications (P = .005), and patients reporting the highest level of pain had a nearly threefold greater risk for complications (P < .001). The pain-complication link was generally similar in the various surgical subgroups.

How do these results compare with previous studies? A report based on 211,231 operations performed on patients in the US Veterans Administration system found postoperative pain to be a strong factor leading to readmission and unplanned visits to the emergency departments.^[2]

In another, highly cited study of 411 older patients treated for hip fracture, the authors concluded that improved pain control could shorten hospital length of stay and perhaps improve overall functional results.^[3] By contrast, Liu and Wu^[4] reviewed 38 studies, including 18 meta-analyses and eight randomized controlled trials, and concluded that there was insufficient evidence to link postoperative analgesia to a lower incidence of postoperative complications.

What Makes It so Difficult to Conclude That Pain Control Reduces Complications?

One of the major problems associated with pain studies is that pain is a patient-reported measure and, unlike a characteristic such as hypertension, pain does not lend itself to objective measurement. Every patient has his or her individual pain threshold. One patient may report severe pain, whereas another, more stoic patient may regard the same stimulus as mild or moderate pain. In addition, many of the published reports do not include prior opioid use by patients or measure opioid use during the postoperative period.

Another question common to all of the reports studying the relationship between postoperative pain and complications is whether better control of pain (ie, increased use of pain medication) would have resulted in a reduction in the number of complications. It is difficult to visualize a randomized trial designed to provide a satisfactory answer to this question, so we can only speculate that more attention to pain control would lower the complication rate.

An additional problem associated with pain studies is the possibility that some complications may be caused by pain relief medications. Opioid use is known to be associated with constipation and also with nausea—two of the listed complications in the recent Dutch study.

Adding to the complexity is the current alarming spike in opioid-associated deaths, which now exceed deaths related to motor vehicle crashes. Opioid-associated deaths also have been a factor leading to a recent decline in US life expectancy. Overprescribing opioid drugs has been associated with an increasing prevalence of opioid addiction.

Focus on Controlling Pain, In Any Case

Within the past few decades, several technical innovations have played a major role in reducing postoperative pain. For example, laparoscopic surgery with much smaller abdominal incisions is less painful than traditional open abdominal surgery, and endovascular procedures for the replacement of the aortic valve are much less painful and require fewer narcotics compared with traditional open procedures.

Would any other nonanesthetic measures potentially reduce postoperative pain? One study found that preoperative smoking cessation resulted in reduced pain after lung surgery compared with pain levels in patients who continued to smoke.^[5] This provides an additional reason to urge patients to stop smoking before surgery.

This brief review of the pain-postoperative complication issue provides some evidence that better control of pain may result in fewer postoperative complications. A much stronger, unquestioned reason for better pain control is simply that, on humanitarian grounds, patients should not be made to endure unreasonable levels of pain following surgery. Surgeons and their patients can agree on this point without having to assess any available evidence.

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