Posted on

A tonic heat test stimulus yields a larger and more reliable conditioned pain modulation effect compared to a phasic heat test stimulus

imageIntroduction:
The interest in conditioned pain modulation (CPM) as a clinical tool for measuring endogenously induced analgesia is increasing. There is, however, large variation in the CPM methodology, hindering comparison of results across studies. Research comparing different CPM protocols is needed in order to obtain a standardized test paradigm.
Objectives:
The aim of the study was to assess whether a protocol with phasic heat stimuli as test-stimulus is preferable to a protocol with tonic heat stimulus as test-stimulus.
Methods:
In this experimental crossover study, we compared 2 CPM protocols with different test-stimulus; one with tonic test-stimulus (constant heat stimulus of 120-second duration) and one with phasic test-stimuli (3 heat stimulations of 5 seconds duration separated by 10 seconds). Conditioning stimulus was a 7°C water bath in parallel with the test-stimulus. Twenty-four healthy volunteers were assessed on 2 occasions with minimum 1 week apart. Differences in the magnitude and test–retest reliability of the CPM effect in the 2 protocols were investigated with repeated-measures analysis of variance and by relative and absolute reliability indices.
Results:
The protocol with tonic test-stimulus induced a significantly larger CPM effect compared to the protocol with phasic test-stimuli (P < 0.001). Fair and good relative reliability was found with the phasic and tonic test-stimuli, respectively. Absolute reliability indices showed large intraindividual variability from session to session in both protocols.
Conclusion:
The present study shows that a CPM protocol with a tonic test-stimulus is preferable to a protocol with phasic test-stimuli. However, we emphasize that one should be cautious to use the CPM effect as biomarker or in clinical decision making on an individual level due to large intraindividual variability.

A tonic heat test stimulus yields a larger and more reliable conditioned pain modulation effect compared to a phasic heat test stimulus


Orginally Published At: PAIN Reports

Posted on

Evidence that dry eye is a comorbid pain condition in a U.S. veteran population

imageIntroduction:
Recent evidence suggests that dry eye (DE) may be comorbid with other chronic pain conditions.
Objectives:
To evaluate DE as a comorbid condition in the U.S. veteran population.
Methods:
Retrospective review of veterans seen in the Veterans Administration Healthcare System (Veteran Affairs) between January 1, 2010, and December 31, 2014. Dry eye and nonocular pain disorders were ascertained by International Classification of Diseases, Ninth Revision (ICD-9) codes. Dry eye was further separated into ICD-9 codes representing tear film dysfunction or ocular pain. χ2 and logistic regression analyses were used to examine frequency and risk of DE, ocular pain, and tear film dysfunction by pain disorders.
Results:
Of 3,265,894 veterans, 959,881 had a DE diagnosis (29.4%). Dry eye frequency increased with the number of pain conditions reported (P < 0.0005). Ocular pain was most strongly associated with headache (odds ratio [OR] 2.98; 95% confidence interval [CI] 2.95–3.01), tension headache (OR 2.64; 95% CI 2.58–2.71), migraine (OR 2.58; 95% CI 2.54–2.61), temporomandibular joint dysfunction (OR 2.39; 95% CI 2.34–2.44), pelvic pain (OR 2.30; 95% CI 2.24–2.37), central pain syndrome (OR 2.24; 95% CI 1.94–2.60), and fibromyalgia/muscle pain (OR 2.23; 95% CI 2.20–2.26), all P < 0.0005. Tear film dysfunction was most closely associated with osteoarthritis (OR 1.97; 95% CI 1.96–1.98) and postherpetic neuralgia (OR 1.95; 95% CI 1.90–2.00), both P < 0.0005.
Conclusions:
Dry eye, including both ocular pain and tear film dysfunction, is comorbid with pain conditions in this nationwide population, implying common mechanisms.

Evidence that dry eye is a comorbid pain condition in a U.S. veteran population


Orginally Published At: PAIN Reports

Posted on

Pharmacoeconomics of genotyping-based treatment decisions in patients with chronic pain

imageAbstractIntroduction:Genotyping-based treatment decisions may optimize treatment response and minimize adverse drug events (ADEs) in patients with chronic pain.Objectives:To estimate the financial impact of genotyping-based treatment decisions in patients with moderate to severe chronic pain in a managed care setting.Methods:A budget impact model was built with a 1-year time horizon to estimate costs of genotyping-based treatment decisions in a 1000-patient cohort. The model includes drug costs, type and cost of ADEs, distribution of treatments used, and genotyping costs. Event rates and health care costs were derived from primary literature. Three patient cohorts were assessed with and without genotyping-based treatment decisions: no genetic testing; 50% genetic testing; and 100% genetic testing. Sensitivity analysis was performed varying costs, adherence, and the percentage of patients treated according to genotyping results.Results:Medical and ADE costs varied by patient severity and genotyping rates. Without genotyping, drug and ADE costs ranged from $1,544,377 to $24,313,844. With genotyping-based treatment, total costs ranged from $1,780,922 to $18,868,032. Sensitivity analysis, varying costs, adherence, and genotyping rates suggested genotyping improves outcomes and is cost saving in patients with chronic pain.Conclusion:Genotyping-based treatment costs are offset by reduced medication utilization and adverse event costs. Genotyping should be considered for patients with chronic pain in clinical practice and within clinical trials.
Introduction:
Genotyping-based treatment decisions may optimize treatment response and minimize adverse drug events (ADEs) in patients with chronic pain.
Objectives:
To estimate the financial impact of genotyping-based treatment decisions in patients with moderate to severe chronic pain in a managed care setting.
Methods:
A budget impact model was built with a 1-year time horizon to estimate costs of genotyping-based treatment decisions in a 1000-patient cohort. The model includes drug costs, type and cost of ADEs, distribution of treatments used, and genotyping costs. Event rates and health care costs were derived from primary literature. Three patient cohorts were assessed with and without genotyping-based treatment decisions: no genetic testing; 50% genetic testing; and 100% genetic testing. Sensitivity analysis was performed varying costs, adherence, and the percentage of patients treated according to genotyping results.
Results:
Medical and ADE costs varied by patient severity and genotyping rates. Without genotyping, drug and ADE costs ranged from $1,544,377 to $24,313,844. With genotyping-based treatment, total costs ranged from $1,780,922 to $18,868,032. Sensitivity analysis, varying costs, adherence, and genotyping rates suggested genotyping improves outcomes and is cost saving in patients with chronic pain.
Conclusion:
Genotyping-based treatment costs are offset by reduced medication utilization and adverse event costs. Genotyping should be considered for patients with chronic pain in clinical practice and within clinical trials.

Pharmacoeconomics of genotyping-based treatment decisions in patients with chronic pain


Orginally Published At: PAIN Reports

Posted on

Interpersonal behavior in anticipation of pain: a naturalistic study of behavioral mimicry prior to surgery

imageAbstractIntroduction:Social relationships facilitate coping with pain, but research suggests that it may be difficult to galvanize social support during an episode of acute pain.Objectives:The current research examined whether social connections are optimized in the anticipation of pain by observing patients’ mimicry of an interaction partner prior to surgery. We hypothesized that when controlling for their current experience of pain, patients’ anticipation of pain would be associated with greater mimicry of an interaction partner.Methods:Sixty-five patients were interviewed in the waiting room of a maxillofacial surgery unit prior to the removal of an impacted wisdom tooth. Patients’ spontaneous mimicry of an interviewer was observed. Patients then rated the quality and intensity of their anticipated pain, as well as the intensity of their current pain and their affective distress.Results:Anticipated pain, current pain, and affective distress were positively correlated. Current pain was associated with less frequent mimicry of an interaction partner. The zero-order correlation between anticipated pain and mimicry did not reach conventional levels of significance; however, when controlling for current pain, anticipated pain predicted more frequent mimicry of an interaction partner. The relationship between anticipated pain and mimicry was not explained by affective distress.Conclusion:This is the first study to demonstrate that anticipated and current pain relate to behavioral mimicry in divergent ways. Further research is needed to investigate whether the current pattern of results generalizes to other interpersonal behaviors that facilitate social bonds.
Introduction:
Social relationships facilitate coping with pain, but research suggests that it may be difficult to galvanize social support during an episode of acute pain.
Objectives:
The current research examined whether social connections are optimized in the anticipation of pain by observing patients’ mimicry of an interaction partner prior to surgery. We hypothesized that when controlling for their current experience of pain, patients’ anticipation of pain would be associated with greater mimicry of an interaction partner.
Methods:
Sixty-five patients were interviewed in the waiting room of a maxillofacial surgery unit prior to the removal of an impacted wisdom tooth. Patients’ spontaneous mimicry of an interviewer was observed. Patients then rated the quality and intensity of their anticipated pain, as well as the intensity of their current pain and their affective distress.
Results:
Anticipated pain, current pain, and affective distress were positively correlated. Current pain was associated with less frequent mimicry of an interaction partner. The zero-order correlation between anticipated pain and mimicry did not reach conventional levels of significance; however, when controlling for current pain, anticipated pain predicted more frequent mimicry of an interaction partner. The relationship between anticipated pain and mimicry was not explained by affective distress.
Conclusion:
This is the first study to demonstrate that anticipated and current pain relate to behavioral mimicry in divergent ways. Further research is needed to investigate whether the current pattern of results generalizes to other interpersonal behaviors that facilitate social bonds.

Interpersonal behavior in anticipation of pain: a naturalistic study of behavioral mimicry prior to surgery


Orginally Published At: PAIN Reports

Posted on

Differences in opioid prescribing in low back pain patients with and without depression: a cross-sectional study of a national sample from the United States

imageAbstractIntroduction:Low back pain (LBP) is among the leading indications for the prescription of opioid analgesics in clinical practice. There is increasing evidence suggesting that these agents may have diminished efficacy in the treatment of LBP.Objectives:We evaluated the relationship between depression, the probability of receiving an opioid prescription, and the amount of morphine equivalent amounts prescribed per year among patients with LBP using nationwide data.Methods:A cross-sectional analysis was performed on existing data from the Medical Expenditure Panel Survey data set from the period 2004 to 2009. Demographic, medical condition, Patient Health Questionnaire-2 responses, and prescription drug information were obtained on 56,811,864 weighted person-years of data from individuals aged 18 to 65 with an ICD-9 code specific to LBP.Results:Increases in PHQ-2 score, as well a positive screen for depression, were associated with an increased probability of being prescribed opioid therapy and more morphine equivalents per year.Conclusion:Analysis of a nationwide sample of patients with LBP shows an association between depression and higher rates of opioid prescribing after controlling for several known cofounders. Clinicians prescribing opioids in LBP populations that rely on clinical trial results that exclude depressed patients may misjudge the risks and benefits of this class of therapy.
Introduction:
Low back pain (LBP) is among the leading indications for the prescription of opioid analgesics in clinical practice. There is increasing evidence suggesting that these agents may have diminished efficacy in the treatment of LBP.
Objectives:
We evaluated the relationship between depression, the probability of receiving an opioid prescription, and the amount of morphine equivalent amounts prescribed per year among patients with LBP using nationwide data.
Methods:
A cross-sectional analysis was performed on existing data from the Medical Expenditure Panel Survey data set from the period 2004 to 2009. Demographic, medical condition, Patient Health Questionnaire-2 responses, and prescription drug information were obtained on 56,811,864 weighted person-years of data from individuals aged 18 to 65 with an ICD-9 code specific to LBP.
Results:
Increases in PHQ-2 score, as well a positive screen for depression, were associated with an increased probability of being prescribed opioid therapy and more morphine equivalents per year.
Conclusion:
Analysis of a nationwide sample of patients with LBP shows an association between depression and higher rates of opioid prescribing after controlling for several known cofounders. Clinicians prescribing opioids in LBP populations that rely on clinical trial results that exclude depressed patients may misjudge the risks and benefits of this class of therapy.

Differences in opioid prescribing in low back pain patients with and without depression: a cross-sectional study of a national sample from the United States


Orginally Published At: PAIN Reports

Posted on

Phonetic characteristics of vocalizations during pain

imageIntroduction and Objectives:
There have, yet, been only few attempts to phonetically characterize the vocalizations of pain, although there is wide agreement that moaning, groaning, or other nonverbal utterance can be indicative of pain. We studied the production of vowels “u,” “a,” “i”, and “schwa” (central vowel, sounding like a darker “e” as in hesitations like “ehm”)—as experimental approximations to natural vocalizations.
Methods:
In 50 students vowel production and self-report ratings were assessed during painful and nonpainful heat stimulation (hot water immersion) as well as during baseline (no-stimulation). The phonetic parameters extracted were pitch (mean F0), phonatory fluctuations (range F0) and loudness (acoustic energy level).
Results:
Only for the vowels “u” and “schwa,” which might be considered best approximations to moaning and groaning, did pitch and loudness increase during pain. Furthermore, changes from nonpainful to painful stimulations in these parameters also significantly predicted concurrent changes in pain ratings.
Conclusion:
Vocalization characteristics of pain seem to be best described by an increase in pitch and in loudness. Future studies using more specific and comprehensive phonetic analyses will surely help to provide an even more precise characterization of vocalizations because of pain.

Phonetic characteristics of vocalizations during pain


Orginally Published At: PAIN Reports

Posted on

Influence of opioid-related side effects on disability, mood, and opioid misuse risk among patients with chronic pain in primary care

imageBackground:
There is increasing concern among primary care practitioners about the use of opioids for chronic pain, including their adverse effects, but little attention has been given to how reports of side effects from prescription medication can contribute to outcomes among patients with chronic pain. The aim of this study was to investigate the impact of frequently reported side effects on mood, disability, and opioid misuse in patients with chronic pain prescribed opioids within primary care.
Methods:
Two hundred (N = 200) patients with chronic pain taking opioids for pain were recruited into the study. All patients completed baseline measures and a monthly side effects checklist once a month for 6 months. Patients were divided evenly based on a median split of the number of endorsed side effects over 6 months. The subjects repeated the baseline measures at the end of the study period.
Results:
Over time, reports of medication side effects tended to decrease, but differences in frequency of reported side effects from baseline to follow-up (6-month time) were not significant, and the order of the frequency of the reported side effects remained similar. Patients who reported significant medication-related adverse effects reported significantly greater activity interference, negative affect, and catastrophizing compared with those with fewer side effects (P < 0.01). In addition, those patients with pain who reported more side effects showed significantly higher scores on opioid misuse risk (P < 0.001).
Discussion:
This study demonstrates the important role of monitoring medication-related side effects among patients with chronic pain who are prescribed opioid medication for pain within primary care.

Influence of opioid-related side effects on disability, mood, and opioid misuse risk among patients with chronic pain in primary care


Orginally Published At: PAIN Reports