Background There is currently a knowledge gap regarding persistent opioid use after hip fracture surgery. Thus, opioid use within a year after hip fracture surgery in patients with/without opioid use before surgery was examined. Methods This population‐based cohort study included all patients (aged ≥ 65) undergoing primary hip fracture surgery in Denmark (2005–2015) identified from the Danish Multidisciplinary Hip Fracture Database. Opioid use was assessed from The Danish National Health Service Prescription Database as redeemed prescriptions. The proportion of patients with ≥1 opioid prescription was computed within 6 months before surgery and each of four 3‐month periods (quarters) after surgery, among patients alive first day in each period. Proportion differences (95% CI) were calculated for each quarter compared to before surgery. Proportions were calculated for users and nonusers before surgery, including initiators after first quarter. Results This study included 69,456 patients. Proportion differences of opioid users were 35.0 (95% CI 34.5–35.5), 7.0 (95% CI 6.5–7.5), 2.9 (95% CI 2.4–3.4) and 1.4 percentage‐points (95% CI 0.9–1.9) the four quarters after surgery compared to before. Among opioid nonusers before surgery, 54.7% (95% CI 54.3–55.1), 21.8% (95% CI 21.4–22.2), 17.8% (95% CI 17.4–18.2) and 16.8% (95% CI 16.4–17.2) were opioid users in 1st‐4th quarter after surgery. However, 8.5% (95% CI 8.2–8.7) of the nonusers before surgery in 4th quarter initiated opioid use more than a quarter after surgery. Conclusions The proportion of opioid users increased after hip fracture surgery and was 1.4 percentage‐points increased in fourth quarter compared to before. Of opioid nonusers before surgery, 16.8% were opioid users fourth quarter after surgery. Significance Opioid use 1 year after hip fracture surgery is common, both in patients who were opioid users and nonusers before the surgery. These significant findings point out the need for indication of benefits and risks of opioid use in the acute and long‐term management of patients undergoing hip fracture surgery.

A frequent empirical observation is that cold-induced counter-irritation may attenuate itch. The aim of this randomized, single-blinded, exploratory study was to evaluate the counter-irritation effects of cold-stimulation and topical application of transient receptor potential TRPA1/M8-agonists (trans-cinnamaldehyde/L-menthol, respectively), on histamine-induced itch, wheals and neurogenic inflammation in 13 healthy volunteers. Histamine 1% was applied to the volar forearms using skin prick-test lancets. Recorded outcome-parameters were itch intensity, wheal reactions, and neurogenic inflammation (measured by laser-speckle perfusion-imaging). Homotopic thermal counter-irritation was performed with 6 temperatures, ranging from 4°C to 37°C, using a 3 × 3-cm thermal stimulator. Chemical "cold-like" counter-irritation was conducted with 40% L-menthol and 10% trans-cinnamaldehyde, while 5% doxepin was used as a positive antipruritic control/comparator. Cold counter-irritation stimuli from 4°C to 22°C inhibited itch in a stimulus-intensity-dependent manner (p < 0.05) and, to a lesser extent, also wheal reactions and neurogenic inflammation. Chemical "cold-like" counter-irritation with both L-menthol and trans-cinnamaldehyde had antipruritic efficacy similar to doxepin (p < 0.05). Cold-induced counter-irritation had an inhibitory effect on histaminergic itch, suggesting that agonists of cold transduction receptors could be of potential antipruritic value.

Participants with blood type B displayed the lowest mechanical pain sensitivity and the blood type AB group exhibited the strongest conditioned pain modulation effect. These findings emphasize the necessity of considering ABO blood types in future pain research.

Background and aimsBariatric surgery remains a mainstay for treatment of morbid obesity. However, long-term adverse outcomes include chronic abdominal pain and persistent opioid use. The aim of this review was to assess the existing data on prevalence, possible mechanisms, risk factors, and outcomes regarding chronic abdominal pain and persistent opioid use after bariatric surgery.MethodsPubMed was screened for relevant literature focusing on chronic abdominal pain, persistent opioid use and pharmacokinetic alterations of opioids after bariatric surgery. Relevant papers were cross-referenced to identify publications possibly not located during the ordinary screening.ResultsEvidence regarding general chronic pain status after bariatric surgery is sparse. However, our literature review revealed that abdominal pain was the most prevalent complication to bariatric surgery, presented in 3–61% of subjects with health care contacts or readmissions 1–5 years after surgery. This could be explained by behavioral, anatomical, and/or functional disorders. Persistent opioid use and doses increased after bariatric surgery, and 4–14% initiated a persistent opioid use 1–7 years after the surgery. Persistent opioid use was associated with severe pain symptoms and was most prevalent among subjects with a lower socioeconomic status. Alteration of absorption and distribution after bariatric surgery may impact opioid effects and increase the risk of adverse events and development of addiction. Changes in absorption have been briefly investigated, but the identified alterations could not be separated from alterations caused solely by excessive weight loss, and medication formulation could influence the findings. Subjects with persistent opioid use after bariatric surgery achieved lower weight loss and less metabolic benefits from the surgery. Thus, remission from comorbidities and cost effectiveness following bariatric surgery may be limited in these subjects.ConclusionsPain, especially chronic abdominal, and persistent opioid use were found to be prevalent after bariatric surgery. Physiological, anatomical, and pharmacokinetic changes are likely to play a role. However, the risk factors for occurrence of chronic abdominal pain and persistent opioid use have only been scarcely examined as have the possible impact of pain and persistent opioid use on clinical outcomes, and health-care costs. This makes it difficult to design targeted preventive interventions, which can identify subjects at risk and prevent persistent opioid use after bariatric surgery. Future studies could imply pharmacokinetic-, pharmacodynamics-, and physiological-based modelling of pain treatment. More attention to social, physiologic, and psychological factors may be warranted in order to identify specific risk profiles of subjects considered for bariatric surgery in order to tailor and optimize current treatment recommendations for this population.