One in five adults experienced chronic pain in 2016, and among those with a musculoskeletal disorder, that rate goes up to one in two, according to some estimates. At any given time, 100 million Americans are affected, leading to reduced quality of life and limited personal and work activities on most or all days, according to the CDC's National Health Interview Survey.
With so much suffering, accurate assessment of chronic pain can allow primary care physicians to possibly reduce the associated burdens, which can include suicide, said two experts.
Cindy McGeary, PhD, an associate professor at UT Health San Antonio in the department of psychiatry, and Don McGeary, PhD, vice chair for research in the department of rehabilitation medicine at UT Health San Antonio with cross appointments in the departments of psychiatry and family and community medicine, spoke about chronic pain as part of ACP CME 30.
The easiest part of distinguishing between acute and chronic pain is the duration, with the latter typically lasting 12 weeks or more, said Dr. Cindy McGeary. Another defining feature is goals of treatment. When you have acute pain, it's certainly realistic to expect that the pain will resolve, whereas with chronic pain, the goal is management.
“Now that doesn't mean that the patient needs to give up a goal of the pain abating,” she said. “What it means is while they're looking for options for pain abatement, they do need to ensure that they're doing things to be as active and functional in life as possible.”
The McGearys' talk outlined methods for evaluating pain in the primary care setting, focusing on those that are based on self-report, are in the public domain, can be completed by patients in the waiting room, and have diagnostic value during the clinical encounter. “The universe of assessment materials for chronic pain is actually pretty vast,” said Dr. Don McGeary.
History and physical exam
The history and physical examination is the primary assessment modality used for most patients seen for chronic pain, according to Dr. Cindy McGeary.
Dr. Don McGeary added that physical functioning should be considered not only at the time of the visit but premorbidly as well to learn how much it has changed from what patients were able to do in the past. This provides a sense of loss of function over time along with a sense of what functional targets might be in the future, he said.
Next is a functional analysis of pain that can include dimensions like location, duration, severity, and temporality.
“What we find is that chronic pain is not perfectly stable,” he said. “You'll either find fluctuations in chronic pain, or you'll find chronic pain that's punctuated by brief bouts of acute pain.”
As part of the history, include responsiveness to past treatments. “Identifying what they've done in the past that hasn't worked will help you build a preliminary armamentarium of treatment options that you can use or dismiss based on what they've done in the past,” he said.
One useful assessment method is a pain drawing. Templates can easily be found on Google, he said. Patients can put marks on the outline of a human body where they experience pain, associate those marks with a pain rating, and even use different lines and different shapes based on the character or quality of their pain, whether it's an electrical-like jabbing pain, a sharp stabbing pain, a burning pain, or a dull ache.
Pain intensity ratings
Dr. Don McGeary said although rating pain intensity on a numeric scale of 0 to 10 is common, research on its value is mixed.
“There are some individuals who have found that pain ratings are strongly correlated with other clinical outcomes, and they can be used as a valid tool for assessing pain, although others have suggested that the validity and reliability of the pain rating as a marker or an assessment of pain is actually quite poor,” he said.
Pain ratings are very valuable when a physician looks at multiple assessments over time and takes an average, he said. A single rating of a single point in time has limited validity and reliability because chronic pain changes over time.
“However, if you ask a patient to rate their pain across four different days in a week, and then average those pain ratings, the average actually is quite valid and reliable and goes a long way toward helping your treatment plan and really understand what the true nature of the pain is,” he said.
Dr. McGeary said he avoids asking patients to keep pain diaries or to self-report pain indefinitely.
“When you ask a patient to attend to any noxious stimulus for an extended period of time, they're going to be more bothered by that noxious stimulus,” he said. “I often tell my patients it's like asking you to listen to your partner's snore and think about how annoying that is. Do the pain ratings a few times so you can get a sense of what the course of their pain is. And then stop.”
One of the more commonly used measures is pain interference, or the extent to which pain interferes with aspects of a person's life. It's defined as a perceived disruption in daily activities, relationships, roles, and employment that's resulting from pain.
Ask patients specifically to what extent is pain interfering with their daily activities, Dr. McGeary said. He uses the PROMIS-PI (Patient-Reported Outcomes Measurement Information System Pain Interference), which includes 41 items as part of the pain interface, seven of which assess pain interference fairly thoroughly. It is available free of charge because it was developed by the federal government. Dr. McGeary said a free copy can be obtained online. “You can have your patients fill it out in the waiting room, it's very easy to score, and you'll have an instant interpretation.”
There are a number of other domains related to pain that physicians should assess, especially in a primary care encounter. Pain ratings are linked to emotional and psychosocial health and also strongly correlate with measures of depression and anxiety, as well as stress, including social stress. Suicide is also a concern, Dr. McGeary noted.
“Suicide risks are now increasingly being attended as problematic in chronic pain populations. It used to be thought that pain was actually protective of suicide,” he said. “Now we are increasingly seeing that chronic pain is a risk factor for suicide.”
One way of surveilling suicide risk is to give the patient a screening tool such as the Patient Health Questionnaire (PHQ)-9, which is in the public domain and can be accessed online. The questionnaire assesses a person's level of depression, and the ninth item screens for suicide, Dr. McGeary said. Anxiety, meanwhile, can be assessed with the seven-item Generalized Anxiety Disorder (GAD)-7 scale.
Other free, downloadable screening tools include the Pain Catastrophizing Scale, the Pain Self-Efficacy Questionnaire, and the Fear Avoidance Beliefs Questionnaire. “You can download them, have a patient fill them out in the waiting room, and there's very good scoring guidance that comes along with these measures,” he said.