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Approaching Pain Variability in Patients With Fibromyalgia Improves Outcomes

February 5, 2017
Responding to differences in pain intensity, pain unpleasantness, fatigue, depressed mood, and anxiety in patients with fibromyalgia by clustering symptoms may inform the best approach to pain treatment.

Interviews with Roland Staud, MD, and Don Goldenberg, MD

The variability in chronic pain symptoms between patients and within the same patient confounds the treatment process.1 Despite these known variations, most studies assessing chronic pain-related conditions have relied on patient recall or self-reporting at a single point in time point; this may not accurately reflect the complex nature of pain as experienced by most patients.

With regard to fibromyalgia (FM), evidence pooled from several studies examining these patients found that lower daily fatigue was associated with within-person increases in positive affect.6 However, the actual influence that fluctuations in daily symptoms may have on health outcomes has not been well-studied. The authors questioned whether an improved understanding these fluctuations, which may affect the clinical course of pain and disease-associated symptoms, might help optimize pain management. 

Roland Staud, MD, FACP, a research professor at the University of Florida Health in Gainsville, and colleagues, examined the intra- and inter-individual variability in pain, mood, and fatigue in patients with fibromyalgia (FM).1 Three clusters emerged, suggesting that the existence of FM subgroups based on variability in pain.1

Clustering symptoms in patients with fibromyalgia helps improve pain management outcomes

Variability in Pain Experience May Be Predictive of Patients Outcomes

Variability in pain symptoms has been linked to depression, poor health, lower quality of life and higher daily pain intensity.2-4 And pain-related problems such as poor sleep quality and a negative outlook also influence pain fluctuations.5

A total of 256 subjects with FM were recruited and evaluated. All participants met the American College of Rheumatology Criteria for FM and completed psychosocial questionnaires. Participants completed daily symptom ratings for a minimum of two weeks using an automated phone line to report their overall clinical pain intensity, pain unpleasantness, fatigue, depressed mood and anxiety on a scale of 0-100. The Short Form Health Survey (SF-36) was used to measure health status and quality of life.6 The Pennebaker Inventory of Limbic Languidness (PILL) was used to assess the frequency of physical symptoms and sensations associated with the tendency to exhibit hyper-vigilance to somatic stimuli.7

Using hierarchical linear modeling, inter- and intra-individual variability of daily ratings of pain, pain unpleasantness, fatigue, depressed mood, and anxiety were assessed.1

The researchers determined that higher levels of pain were associated with greater fluctuations in symptomatology, such as fatigue, pain unpleasantness, and depressed mood,1 according to results published in The Journal of Pain.

“The findings of greatest interest related to the predictability that variations of pain, mood, and fatigue appeared to have on pain itself in these patients,” Dr. Staud told Practical Pain Management.

Variation in Fibromyalgia Symptoms Predicted Pain Intensity and Fatigue

Differences between and within persons for daily ratings of pain intensity, pain unpleasantness, fatigue, depressed mood, and anxiety were estimated using multilevel null models.1 Most of the variability in FM symptoms was due to differences between persons in their average levels, but day-to-day variation within persons was also statistically significant (range 23-35%).1

“The question we were specifically looking for was pain intensity over time, which decreased,” Dr. Staud said. Using time as a predictor of each FM symptom, linear decreases were seen in pain intensity (b = -0.17, P =0.005) and fatigue (b = -0.17, P = 0.01).1

When looking at both unadjusted and final multilevel models, all mean-level predictors were associated with daily pain intensity (ie, pain unpleasantness, fatigue, depressed mood and anxiety all had P < 0.001).1 Symptom increases were associated with higher levels of pain intensity at the within-person level for all predictors except anxiety. Similarly, all mean-level predictors were associated with daily fatigue in the unadjusted analysis. However, in assessing the effects of other variables only mean pain intensity (P < 0.01) and anxiety (P < 0.001) were significant predictors of fatigue. Within-person results had significant associations between all predictors for daily fatigue.1

The authors used Cluster Analysis to find empirically derived classifications based on variability profiles.1  “Based on studies that we and others have seen on resilience, we wanted to know if individuals with high variability in symptoms have higher function, and therefore potentially better quality of life, compared with people with lower variability,” Dr. Staud said.

They found three clusters: 1

  • Cluster 1—Low variability (n = 115; 44.9%): low degree of variability among pain intensity, pain unpleasantness, fatigue and affect
  • Cluster 2—High variability (n = 48; 18.8%): high degree of variability among pain intensity, pain unpleasantness, fatigue and affect
  • Cluster 3—Mixed variability (n = 93; 36.3%): low degree of variability in pain unpleasantness, moderate variability in pain intensity, fatigue, and depressed mood, and high variability in anxiety.

“We looked at variability clusters to see if there was a high variability in one domain, would we also find high variability in another. Our findings showed that the majority (approximately 2/3) of patients cluster,” Dr. Staud said.

Fibromyalgia Symptoms Easily Clustered in the Majority of Patients

Most of the variation in symptoms occurred across individuals, but a significant, yet smaller, portion of variance was due to intra-individual fluctuations in pain-related experiences. For example, Dr. Staud indicated that pain intensity, fatigue, and pain unpleasantness decreased over time, while depressed mood and anxiety showed greater long-term stability.1

“Patients who have high symptom burden in one domain have it in others. We assumed variability was yoked with pain, so as pain goes up, people exhibit greater anxiety, are more depressed and have increased fatigue with higher pain levels,” said Dr. Staud, “However, this only didn’t work for cluster 3.”

A Second Opinion on the Relevance the Study Findings

Don Goldenberg, MD, professor emeritus at Oregon Health Services University in Portland, who was not associated with the study, told Practical Pain Management that he considered the most significant finding “that recognizing that the variability of symptoms is important and should be taken into account in treatment planning.”

He added, “the study also reinforces the value that sub-grouping patients as important in prognosis and treatment, and that patients with the greatest burden of psychosocial problems tend to have the most difficulty in responding to care, even with similar levels of pain.” 

Dr. Staud added that there are a couple of other insights for clinicians to consider given the results arising from this study.

“First, pain and fatigue get better over time, which is encouraging for both clinicians and patients. Negative affect is fairly stable over time, which indicates a dissociation between mood and pain. Second, the variance of pain is associated with better outcomes, so the focus of future studies should be to look at whether changing the variance of pain due to activities (ie, exercise) provides a better outcome.”

Understanding the mechanism underlying the variance of pain and its potential for creating better outcomes is a necessary next step in gaining a better handle on fibromyalgia care management.

Last updated on: February 5, 2018
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An Osteopathic Approach to Fibromyalgia

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