Pain
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Randomized Controlled Trial
Side effects can enhance treatment response through expectancy effects: an experimental analgesic randomized controlled trial.
In randomized controlled trials, medication side effects may lead to beliefs that one is receiving the active intervention and enhance active treatment responses, thereby increasing drug-placebo differences. We tested these hypotheses with an experimental double-blind randomized controlled trial of a nonsteroidal anti-inflammatory drug with and without the addition of atropine to induce side effects. One hundred healthy volunteers were told they would be randomized to either combined analgesics that might produce dry mouth or inert placebos. ⋯ A chain of mediation analysis demonstrated that the addition of atropine increased dry mouth symptoms, which increased beliefs that one had received the active medication, which, in turn, increased analgesia. In addition to this indirect effect of atropine on analgesia (via dry mouth and beliefs), analyses suggest that among those who received diclofenac, atropine directly increased analgesia. This possible synergistic effect between diclofenac and atropine might warrant future research.
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Multicenter Study
Prevalence and incidence of chronic pain with or without neuropathic characteristics in patients with cancer.
This prospective national multicenter study was carried out to estimate the prevalence and incidence of chronic pain with or without neuropathic characteristics in patients with cancer in France. All consecutive outpatients (n = 1885) seen over 2 weeks for cancer treatment in 12 oncology units were invited to participate in the study, and 1805 were included. Patients underwent a clinical examination during visit 1, and a questionnaire was completed to detect chronic pain (defined as daily pain for at least 3 months), and to characterize its intensity, location, and neuropathic characteristics (ie, DN4 score ≥4). ⋯ Pain intensity and interference were higher in patients with neuropathic characteristics. In total, 1285 patients were included in the incidence study, 873 of whom were seen at least once, 3, or 6 months after the first visit. The incidence of chronic pain during the 6-month follow-up period ranged from 13% to 28%, depending on primary tumor location, and neuropathic characteristics were found in 19.9% of patients with chronic pain.
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Although the most widely agreed neurophysiological tool for investigating small fiber damage is laser-evoked potential (LEP) recording, no study has documented its diagnostic accuracy. In this clinical, neurophysiological, and skin biopsy study, we collected age-corrected LEP normative ranges, verified the association of LEPs with pinprick sensory disturbances in the typical diabetic mixed fiber polyneuropathy, and assessed the sensitivity and specificity of LEPs in diabetic small fiber neuropathy. From 288 LEP recordings from the face, hand, and foot in 73 healthy subjects, we collected age-corrected normative ranges for LEPs. ⋯ By applying age-corrected normative ranges for LEPs, we found that LEPs were strongly associated with pinprick sensory disturbances. In relation to the skin biopsy findings, LEPs yielded 78% sensitivity and 81% specificity in the diagnosis of diabetic small fiber neuropathy. Our study, providing age-corrected normative ranges for the main LEP data and their diagnostic accuracy, helps to make LEPs more reliable as a clinical diagnostic tool, and proposes this technique as a less invasive alternative to skin biopsy for diagnosing diabetic small fiber neuropathy.
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A primary goal in managing pain is to reduce pain and increase physical function (PF). This goal is also tied to continuing payment for treatment services in many practice guidelines. Pain interference (PI) is often used as a proxy for measurement and reporting of PF in these guidelines. ⋯ A parallel process latent growth curve model analysis showed a weak, unidirectional relationship (β = 0.18) between average PF scores and changes in PI over the course of 90 days of care, and no relationship between average PI scores and changes in PF across time. Although PI and PF seem moderately related when measured concurrently, they do not cluster closely together across time. The differential pathways between these 2 domains suggest that therapies that target both the consequences of pain on relevant aspects of persons' lives, and capability to perform physical activities are likely required for restoration of a vital life.
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Pain evaluation in large community studies is difficult. Analgesics can be a useful tool in estimating pain-related conditions in which analgesic use is highly regulated. In this study, we evaluated analgesics consumption patterns of regular Israel Defense Force soldiers. ⋯ Chronic analgesic use was associated with a significant increase in health care utilization cost per year (911$ per soldier vs 199$ for nonusers), increased sick leave days per year (7.09 vs 0.67 for nonusers), and higher dropout rate from combat units (25% vs 9.2% for nonusers). Chronic use of analgesics is common among young adults, and it is an important predictor for unsuccessful military service and high health care utilization costs. Further studies in other setups are indicated.