Emergent biomarker derived from next-generation sequencing to identify pain patients requiring uncommonly high opioid doses

Next-generation sequencing (NGS) provides unrestricted access to the genome, but it produces 'big data' exceeding in amount and complexity the classical analytical approaches. We introduce a bioinformatics-based classifying biomarker that uses emergent properties in genetics to separate pain patients requiring extremely high opioid doses from controls. Following precisely calculated selection of the 34 most informative markers in the OPRM1, OPRK1, OPRD1 and SIGMAR1 genes, pattern of genotypes belonging to either patient group could be derived using a k-nearest neighbor (kNN) classifier that provided a diagnostic accuracy of 80.6±4%. This outperformed alternative classifiers such as reportedly functional opioid receptor gene variants or complex biomarkers obtained via multiple regression or decision tree analysis. The accumulation of several genetic variants with only minor functional influences may result in a qualitative consequence affecting complex phenotypes, pointing at emergent properties in genetics.

Prediction of persistent post-operative pain: Pain-specific psychological variables compared with acute post-operative pain and general psychological variables

BACKGROUND

Psychological variables and acute post-operative pain are of proven relevance for the prediction of persistent post-operative pain. We aimed at investigating whether pain-specific psychological variables like pain catastrophizing add to the predictive power of acute pain and more general psychological variables like depression.

METHODS

In all, 104 young male patients undergoing thoracic surgery for pectus excavatum correction were studied on the pre-operative day (T0) and 1 week (T1) and 3 months (T2) after surgery. They provided self-report ratings (pain-related: Pain Catastrophizing Scale, Pain Anxiety Symptoms Scale = PASS, Pain Vigilance and Awareness Questionnaire = PVAQ; general psychological: Screening for Somatoform Symptoms, State-Anxiety Inventory-X1, Center for Epidemiologic Studies Depression Scale = CES-D). Additional predictors (T1) as well as criterion variables (T2) were pain intensity (Numerical Rating Scale) and pain disability (Pain Disability Index).

RESULTS

Three months after surgery, 25% of the patients still reported clinically relevant pain (pain intensity ≥3) and over 50% still reported pain-related disability. Acute post-operative pain as well as general psychological variables did not allow for a significant prediction of persistent post-operative pain; in contrast, pain-related psychological variables did. The best single predictors were PASS for pain intensity and PVAQ for pain disability.

CONCLUSIONS

Pain-related psychological variables derived from the fear-avoidance model contributed significantly to the prediction of persistent post-operative pain. The best possible compilation of these measures requires further research. More general psychological variables may become relevant predictors later in the medical history.

SIGNIFICANCE

Our results suggest that pain-specific psychological variables such as pain anxiety and pain hypervigilance add significantly to the prediction of persistent post-operative pain and might even outperform established predictors such as acute pain and general psychological variables. Clinicians might benefit from the development of time-economic screening tools based on these variables.

[Patient-controlled analgesia (PCA) in outpatients with cancer pain. Analysis of 1,692 treatment days]

INTRODUCTION

In the home-care setting, cancer pain patients in need of parenteral analgesia have to be switched to patient-controlled analgesia using portable pumps. But there is a paucity on data on the logistic requirements or the success rate of such a cost-intensive therapy performed by specialized home-care services.

METHODS

In a retrospective study we analyzed data on care intensity, logistics and outcome of 46 consecutive palliative cancer patients with patient-controlled analgesia (PCA) in a home-care setting.

RESULTS

On days 1, 2, and 3 of PCA the switch to parenteral analgesia resulted in a significant increase of the median daily opioid dose in comparison to the dose just prior to PCA. Concurrently, pain scores were significantly reduced. The median duration of PCA was 25 days (range 2-189 days). On average, each patient was seen by the home-care team every 7.4 days. The median duration of the home visits was 60 min (range, 10-190 min). Of the visits 20% were unscheduled, most of these visits being due to problems regarding analgesia. Most patients died at home. Insufficient analgesia required prefinal hospitalization in only a single case.

CONCLUSION

If the indications are correct, intravenous PCA for palliative cancer pain patients results in higher opioid consumption and better pain control. Home-care PCA requires a lot of human and financial resources, but pain-related hospitalization can be prevented.

[Practical pain control in pediatric oncology. Recommendations of the German Society of Pediatric Oncology and Hematology, the German Association for the Study of Pain, the German Society of Palliative Care, and the Vodafone Institute of Children's Pain Therapy and Palliative Care]

In pediatric oncology, optimal pain control is still a challenge. A structured pain history and the regular scoring of pain intensity using age-adapted measuring tools are hallmarks of optimal pain control. Psychological measures are as important as drug therapy in the prophylaxis or control of pain, especially when performing invasive procedures. Pain control is oriented toward the WHO multistep therapeutic schedule. On no account should the pediatric patient have to climb up the "analgesic ladder" - strong pain requires the primary use of strong opioids. Give opioids preferably by the oral route and by the clock - short-acting opioids should be used to treat breakthrough pain. Alternatives are i.v. infusion, patient-controlled analgesia, and transdermal applications. Constipation is the adverse effect most often seen with (oral) opioid therapy. Adverse effects should be anticipated, and prophylactic treatment should be given consistently. The assistance of pediatric nurses is of the utmost importance in pediatric pain control. Nurses deliver the basis for rational and effective pain control by scoring pain intensity and documenting drug administration as well as adverse effects. The nurses' task is also to prepare the patient for and monitor the patient during painful procedures. It is the responsibility of both nurse and doctor to guarantee emergency intervention during sedation whenever needed. In our guideline we comment on drug selection and dosage, pain measurement tools, and documentation tools for the purpose of pain control. Those tools may be easily integrated into daily routine.

Opioidtherapie chronischer Schmerzen bei Kindern

Based on 4 case reports we focus on the peculiarities of long-term pediatric opioid based pain control. Case report #1, emphasizing the importance of adequate opioid dosing with reference to body weight, illustrates that with adequate management oral sustained-release opioid therapy is safe even in infants less than one year old. Case report #2 is the first report on the usage of buccal fentanyl citrate for pediatric break-through pain control. Case report #3 focuses on the adverse effects of opioid pain control in an infant with neurological impairment. Case report #4 reports on the successful tumor pain control using transdermal buprenorphine. We conclude that proven therapeutic strategies for opioid pain control as applied in adults may be adopted for the usage on children in pediatrics. However, it is mandatory to take into account both the pharmacokinetic and pharmacodynamic peculiarities of childhood.

Schmerzdiagnostik und -therapie in der Geriatrie

A primary goal of pain treatment in geriatric patients consists of maintaining physical and mental function, which is a precondition of activity and participation. In patients with chronic pain, multidisciplinary treatment without excluding invasive procedures is the most effective approach. The medication ladder, suggested by the WHO initially for cancer pain, provides a guideline for pharmacological treatment. Due to age-dependent alterations in the kinetics and dynamics of pharmaceuticals, the titration of the medication follows the rule "start low and go slow." The same principle holds true for the maintenance or augmentation of physical activity in order to escape from the activity-deconditioning cycle. The training should be based on learning theories, include pain management strategies, and incorporate psychological approaches to facilitate the active participation of the patient in the treatment program. In hospitals and nursing homes, nurses play an important role in defining the need for pain treatment and in supervising the patient in the treatment process. Despite all these endeavors, a significant number of patients remains whose pain cannot be controlled sufficiently. Euthanasia on demand of the patient with untreatable pain is not admitted in Germany.

Schmerztherapie in der Geriatrie

A primary goal of pain treatment in geriatric patients is the maintenance of physical and mental functions. This is a precondition for activity and participation. In patients with chronic pain, multidisciplinary treatment, without excluding invasive procedures, is the most effective approach. The medication ladder, initially suggested by the WHO for cancer pain, provides a guideline for pharmacological treatment. Due to age-dependent alterations in the kinetics and dynamics of pharmaceuticals, the titration of the medication follows the rule "start low-go slow". The same principle holds true for the maintenance or augmentation of physical activity in order to escape from the activity-deconditioning cycle. Training should be based on learning theories, include pain management strategies, and incorporate psychological approaches to facilitate the active participation of the patient in the treatment program. In hospitals and nursing homes, nurses play an important role in defining the need for pain treatment and in supervising the patient in the treatment process. Despite these endeavours, a significant number of patients remain whose pain cannot be controlled sufficiently. Euthanasia on demand for a patient with untreatable pain is not admitted in Germany.

[A structured pain interview for geriatric patients]

BACKGROUND

In old age, assessment of pain often is hampered by sensory and cognitive deficits that do not allow the patients to fill in standardized questionnaires without help from significant others. Therefore, as an alternative, we developed a structured pain interview, and examined its properties and acceptance in a sample of geriatric patients with pain.

METHODS

The interview covers site of pain, intensity of pain, its duration and persistency, pain related disability and, finally, emotional and cognitive variables. In addition, the interviewer addresses significant others to get information about medication, previous treatment, and residence, and administers the Mini-Mental-State-Examination (MMSE). The analysis includes 128 patients of pain centers older than 74 years, of whom 80% are female.

RESULTS

Forty percent of the subjects score below the critical MMSE value < or =23 indicative of cognitive impairment. These patients are responsible for 36 out of a total of 39 missing values. A significant increase of missing values is observed in patients with a MMSE score below 10. Cognitive impairment goes along with greater functional and social disability. On the other hand, cognitive impairment is unrelated to localization, intensity, and duration of pain. The memory item of the MMSE can be used as a screening tool for cognitive impairment. Patients, who are unable to recall any of the three objects, comprise 80% of the total of missing values and demonstrate a low MMSE score.

CONCLUSION

As long as geriatric patients are able to communicate verbally, they are most likely to profit from the structured pain interview in spite of existing cognitive impairment. A MMSE score <10 indicates that the interpretation of the data obtained may be difficult, especially due to a high frequency of missing values.

[Monitoring of patient-controlled analgesia by the nursing staff]

OBJECTIVE

Patient-controlled analgesia (PCA) is employed successfully on surgical wards. Continuous monitoring is important for the safety of the patient and the efficiency of this form of pain therapy. In the study we evaluated the regularity and completeness of monitoring data which had been collected by the nursing staff on the surgical wards.

METHODS

Data on pain intensity, vital signs, and side effects were collected. Additionally, in the case of epidural analgesia, sensory and motor function were tested. In the first four hours after starting the PCA-pump, the nursing staff was instructed to document this data hourly (phase I), followed by a two hour interval until 8 am the next day (phase II). In general, monitoring was continued every four hours up to the discontinuation of the PCA; whereas in our study only forty hours (10 measurements) were included (phase III). Documentation protocols of 637 patients were evaluated and tested for the completeness of the data.

RESULTS

In phase I, the data of 128 patients (20%) were complete. In 173 patients (27%) less than 50% of the data were documented. During phase II, only in 98 patients (15%) the data collection was complete. In 237 patients (37%) less than 50% of the measurements were determined. In phase III, in 205 patients (32%) all measurements, and in 104 patients (16%) less than 50% of the measurements were documented.

CONCLUSION

Complications during PCA become manifest mainly during the first hours after starting the PCA-pump. Especially during these phases, documentation was found to be quite poor. This underlines the importance of an intense cooperation between acute-pain service and nursing staff with periodical training of the staff.

[Management of postoperative pain in children]

TREATMENT OF PAIN: Undertreatment of postoperative pain in children is a problem in clinical practice. This is due to a lack of both knowledge about age-specific aspects of physiology and pharmacology, and routine pain assessment. For example, the fear of side-effects prevents the adequate usage of opioids. It is of major importance to select a route of drug administration where the child feels comfortable with (avoid intramuscular injections). NON-OPIOID ANALGESICS: Non-opioid analgesics are recommended for basic pain treatment after minor surgical procedures. Instead of using the whole multitude of drugs available, the doctor should stick to those drugs he is familiar with (acetaminophen, ibuprofen, diclofenac, dipyrone).

OPIOIDS

Opioid usage requires individual dose titration and careful monitoring of side-effects (respiratory monitoring, sedation score). The strong opioids piritramide and morphine may advantageously be administered as either continuous, or patient-controlled iv- infusion (PCA).

FORMS OF THERAPY

In addition to infiltration anesthesia, intraoperatively applied nerve blocks provide excellent pain relief. Epidural analgesia with local anesthetics and/or opioids via a thoracic or lumbar epidural catheter is a therapeutic option after thoracic or abdominal surgery, or after extensive orthopedic or urological interventions. Adjuvant analgesics and nonpharmacologic interventions, i. e. transcutaneous electrical nerve stimulation (TENS), are primarily indicated in patients suffering from neuropathic pain.

CONCLUSION

The establishment of pain services and the comprehensive education of both the nursing and the medical staff should help to improve postoperative pediatric pain therapy.

[Practice of pain control in paediatric oncology--recommendations of the quality-monitoring group of the German Society for Paediatric Oncology and Haematology (GPOH)]

In paediatric oncology, optimal pain control is still a challenge.A structured pain history and the regular scoring of pain intensity using age-adapted measuring tools are hallmarks of optimal pain control. Psychological measures are as important as drug therapy in prophylaxis or control of pain, especially when performing invasive procedures. Pain control is oriented on the WHO analgesic ladder. On no account the paediatric patient should have to climb up the 'analgesic ladder'- strong pain requires the primary use of strong drugs. Opioids should be given by the oral route and by the clock - short acting opioids should be used to treat break-through pain. Alternatives are IV infusion and patient-controlled analgesia. Constipation is the adverse effect most often seen with (oral) opioid therapy. Adverse effects should be anticipated, and prophylactic treatment should be given consistently. The assistance of paediatric nurses is of utmost importance in paediatric pain control. Nurses' deliver the basis for rational and effective pain control by scoring pain intensity and documenting drug administration as well as adverse effects. The nurses task is also to prepare the patient for and monitor the patient during painful procedures. It is the responsibility of both nurse and doctor to guarantee emergency intervention during sedation whenever needed. In our paper we comment on drug selection and dosage, pain measurement tools, and documentation tools for the purpose of pain control. Those tools may be easily integrated into daily routine.

[Complex regional pain syndrome. Clinical and autonomic disorders during acute and chronic illness stages]

In order to describe autonomic dysfunction and clinical outcome in complex regional pain syndrome (CRPS) 20 patients were followed-up. First investigation was performed in the acute stage of CRPS and the second investigation two years later after therapy (individual, not standardized). Skin temperature and sudomotor function (thermoregulatory sweating (TST) and quantitative sudomotor axon reflex (QSART)) were assessed, and a clinical follow-up was performed carefully. Skin temperature was warmer on the affected side at first investigation (p < 0.001) and colder at follow-up (p < 0.02). Sudomotor output was enhanced on the affected side both after TST (p < 0.005) and QSART (p < 0.05) at first investigation. At follow-up, however, while thermoregulatory sweating was still increased (p < 0.04) QSART was not different. While autonomic failure improves as assessed by clinical examination, therapy failed to alleviate pain significantly. But patients' self-assesment of therapy was mostly positive (16 of 20, p < 0.001). The present study has shown that the autonomic failure may be probably the result of central disturbances of thermoregulation, but secondary peripheral mechanisms also contribute to our findings. Individual based therapy seems to be efficacious for long term treatment, but for final judge controlled studies are required.

[Tramadol infusion for pain therapy following bladder exstrophy surgery in pediatric wards]

We investigated in 17 children (mean 7.1 years) the continuous administration of tramadol following augmentation cystoplasty or exstrophy reconstruction. Mean duration of the tramadol administration on the pediatric ward was 3.8 +/- 1.1 days (initial dosage 0.25 mg/kg/per hour, dose adjustment by the nursing staff). Mean tramadol consumption was 0.21 mg/kg/h on day 1 and was reduced to 0.08 mg/kg/per hour on day 4. Median pain score (assessed with ten-step scales) was 5 before treatment and between 2.5 (day 1) and 0.5 (day 5) during therapy. Lowest oxygen saturations (mean) ranged from 93.8% to 95.2%. Three patients (17.6%) suffered from nausea/vomiting on 3 of 64 treatment days (4.7%). Pruritus and extreme sedation did not occur. The continuous administration of tramadol is a simple and safe procedure following major urological surgery in children.