The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
Using multiple daily pain ratings to improve reliability and assay sensitivity: how many is enough?
The Initiative for Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) has reported diminished assay sensitivity in pain treatment trials and recommended investigation of the causes. Specific recommendations included examination of outcome measure reliability and lengthening the baseline measurement period to allow more measurements to be collected. This secondary data analysis evaluated the minimum number of daily pain intensity ratings required to obtain a reliability of at least .90 and whether a composite of this smaller number of ratings was interchangeable with the composite of all ratings. Veterans Affairs medical center patients made 14 daily calls to an automated telephone system to report their average daily pain intensity rating. A single daily rating produced less than adequate reliability (intraclass correlation coefficient = .65), but a composite of the average of 5 ratings resulted in reliability above .90. A Bland-Altman analysis revealed that the differences between a 5-day composite and the composite of all ratings were small (mean .09 points, standard deviation = .45; 95% confidence interval = -.05 to .23) and below the threshold for a clinically meaningful difference, indicating that the 2 measurements are interchangeable. Our results support the IMMPACT recommendations for improving assay sensitivity by collecting a multiple-day baseline of pain intensity ratings. ⋯ This study examined the minimum number of pain ratings required to achieve reliability of .90 and examined whether this smaller subset of ratings could be used interchangeably with a composite of all available ratings. Attention to measure reliability could enhance the assay sensitivity, power, and statistical precision of pain treatment trials.
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Physical function and functional recovery are important aspects of the acute pain experience in children and adolescents in hospitalized settings. Measures of function related to pediatric acute pain do not exist currently, limiting understanding of recovery in youth undergoing acute and procedural pain. To address this gap, we developed and assessed the clinical utility and preliminary validity of the Youth Acute Pain Functional Ability Questionnaire (YAPFAQ). We evaluated psychometric properties of this measure in 159 patients with sickle cell disease, ages 7 to 21 years, who were hospitalized for vaso-occlusive episodes at 4 urban children's hospitals. The YAPFAQ demonstrated strong internal reliability and test-retest reliability. An exploratory factor analysis was conducted to examine the preliminary factor structure and to help reduce the number of items for the final scale. Evidence for moderate construct validity was demonstrated among validated measures of pain burden, motor function, functional ability, and quality of life. The YAPFAQ is a new measure of youth functional ability in the acute pain setting. Further evaluation of this measure in additional pediatric populations is needed to understand applicability across a spectrum of youth experiencing acute pain related to illness, trauma, and medical/surgical procedures. ⋯ Measures of function in response to acute pain are needed in order to more comprehensively evaluate acute pain interventions in pediatrics; however, no specific measures are available. Our preliminary psychometric evaluation of an acute pain functional ability measure for youth indicates that it may be a promising tool for further refinement in additional pediatric acute pain populations.
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Persistent pain following breast cancer surgery is well documented. However, it is not well characterized in terms of the anatomic site affected (ie, breast, arm). In 2 separate growth mixture modeling analyses, we identified subgroups of women (N = 398) with distinct breast pain and arm pain trajectories. The fact that these latent classes differed by anatomic site, types of tissue affected, and neural innervation patterns suggests the need for separate evaluations of these distinct persistent pain conditions. The purposes of this companion study were to identify demographic and clinical characteristics that differed between the 2 arm pain classes and determine if differences existed over time in sensitivity in the upper inner arm and axillary lymph node dissection sites, pain qualities, pain interference, and hand and arm function, as well as to compare findings with persistent breast pain. Higher occurrence rates for depression and lymphedema were found in the moderate arm pain class. Regardless of pain group membership, sensory loss was observed in the upper inner arm and axillary lymph node dissection site. Arm pain was described similarly to neuropathic pain and interfered with daily functioning. Persistent arm pain was associated with sustained impairments in shoulder mobility. ⋯ For persistent breast and arm pain, changes in sensation following breast cancer surgery were notable. Persistent arm pain was associated with sustained interference with daily functioning and upper body mobility impairments. Long-term management of persistent pain following breast cancer surgery is warranted to improve the quality of survivorship for these women.
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Interindividual variability exists in persistent breast pain following breast cancer surgery. Recently, we used growth mixture modeling to identify 3 subgroups of women (N = 398) with distinct persistent breast pain trajectories (ie, mild, moderate, severe) over 6 months following surgery. The purposes of this study were to identify demographic and clinical characteristics that differed among the breast pain classes and, using linear mixed effects modeling, to examine how changes over time and in sensitivity in the breast scar area, pain qualities, pain interference, and hand and arm function differed among these classes. Several demographic and clinical characteristics differentiated the breast pain classes. Of note, 60 to 80% of breast scar sites tested were much less sensitive than the unaffected breast. Significant group effects were observed for pain qualities and interference scores, such that, on average, women in the severe pain class reported higher scores than women in the moderate pain class. In addition, women in the moderate pain class reported higher scores than women in the mild pain class. Compared to women in the mild pain class, women in the severe pain class had significantly impaired grip strength, and women in the moderate and severe pain classes had impaired flexion and abduction. ⋯ Subgroups of women with persistent postsurgical breast pain differed primarily with respect to the severity rather than the nature or underlying mechanisms of breast pain. Pervasive sensory loss and the association between persistent breast pain and sustained interference with function suggest the need for long-term clinical follow-up.
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Disorders of pain neural systems are frequently chronic and, when recalcitrant to treatment, can severely degrade the quality of life. The pain pathway begins with sensory neurons in dorsal root or trigeminal ganglia, and the neuronal subpopulations that express the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel transduce sensations of painful heat and inflammation and play a fundamental role in clinical pain arising from cancer and arthritis. In the present study, we elucidate the complete transcriptomes of neurons from the TRPV1 lineage and a non-TRPV1 neuroglial population in sensory ganglia through the combined application of next-gen deep RNA-Seq, genetic neuronal labeling with fluorescence-activated cell sorting, or neuron-selective chemoablation. RNA-Seq accurately quantitates gene expression, a difficult parameter to determine with most other methods, especially for very low and very high expressed genes. Differentially expressed genes are present at every level of cellular function from the nucleus to the plasma membrane. We identified many ligand receptor pairs in the TRPV1 population, suggesting that autonomous presynaptic regulation may be a major regulatory mechanism in nociceptive neurons. The data define, in a quantitative, cell population-specific fashion, the molecular signature of a distinct and clinically important group of pain-sensing neurons and provide an overall framework for understanding the transcriptome of TRPV1 nociceptive neurons. ⋯ Next-gen RNA-Seq, combined with molecular genetics, provides a comprehensive and quantitative measurement of transcripts in TRPV1 lineage neurons and a contrasting transcriptome from non-TRPV1 neurons and cells. The transcriptome highlights previously unrecognized protein families, identifies multiple molecular circuits for excitatory or inhibitory autocrine and paracrine signaling, and suggests new combinatorial approaches to pain control.