Attitudes and practices of pediatric oncologists regarding methadone use in the treatment of cancer-related pain: results of a North American Survey

Methadone for Cancer Pain Management in Children: A Review of Literature

Pain associated with cancer is a common feature among children and adolescents. Among opioids, methadone is a unique drug for its multiple mechanisms of action. Methadone is currently underutilized in children. The use of methadone for cancer pain management in children was assessed in a systematic review. Altogether, 141 children receiving methadone were examined, and another 126 children were assessed for QT prolongation. In the clinical studies, modalities of use, dosing, and duration of assessment were highly variable. In general, methadone was effective and well tolerated with a limited tendency for dose increases. QT prolongation was reported in a percentage of patients independently of the dosages or other variables. The majority of studies considered the use of methadone to be safe and effective in children. Despite methadone possessing interesting properties that make this drug unique in a pediatric context, data is limited, and the literature available is based on retrospective studies. Methadone could be an effective, inexpensive, and versatile medication in children with cancer who have pain. This drug deserves more interest and should prompt studies of better quality with a larger number of patients.

Methadone for Cancer Pain in Pediatric End-of-Life Care

BACKGROUND

The goal of adequate pain control becomes increasingly salient for children with cancer and their families as the patients approach the end of life. Methadone is one option that is particularly desirable in end-of-life care given its long duration of action and NMDA antagonism that may help in controlling pain refractory to conventional opioids. The purpose of this study was to describe a single institution's experience with methadone for the treatment of cancer pain in pediatric end-of-life care.

METHODS

This retrospective, observational, single-center study included all patients during a 9-year period who died in the inpatient setting and were receiving methadone in their last 30 days of life.

RESULTS

Twenty patients were identified, 18 (90%) of whom received methadone for nociceptive pain. The median duration of methadone use was 32 days (range 2-323 days). Methadone doses ranged from 0.09 to 7.76 mg/kg per day. There were no instances of discontinuing methadone due to an increased QTc interval. No episodes of torsades de pointes were observed.

CONCLUSION

In patients with pediatric cancer who are nearing the end of life, methadone is a valuable adjunctive therapy to treat nociceptive and neuropathic pain and to prevent opioid-induced hyperalgesia and opioid tolerance. An individualized approach to dosage and route should be considered based on specific clinical circumstances.

Corrected QT Interval Prolongation in Pediatric and Young Adult Patients on Methadone for Cancer-Related Pain

CONTEXT

Methadone has been reported to prolong the corrected QT (QTc) interval and increase the risk of torsades de pointes.

OBJECTIVES

Our study examined the frequency of QTc prolongation among pediatric and young adult patients starting methadone for cancer pain.

METHODS

All patients followed a standardized protocol. Electrocardiograms (ECGs) were obtained at baseline (methadone starting day to 14 days prior), 1-2 weeks, and 4-6 weeks later. QTc values were manually calculated using the Bazett formula. QTc prolongation was defined as ≥460 milliseconds (ms) for prepubertal children, ≥470 ms for pubertal males, and ≥480 ms for pubertal females.

RESULTS

Baseline ECGs were completed in 42 patients. Follow-up ECGs were completed in 38 of 42 (91%) and 31 of 42 (74%) patients at 1-2 weeks and 4-6 weeks, respectively. No patients had prolongation of the QTc at baseline, and 1 of 38 (3%) patients had a prolonged QTc at weeks 1-2. This patient had a history of prolonged QTc that the family did not initially report. No patients had prolongation of the QTc at weeks 4-6. No patients had torsades de pointes or ventricular fibrillation, and none died suddenly. Median (interquartile range [IQR]) baseline QTc was 391 (377-400) ms; median (IQR) 1-2 week follow-up QTc was 399 (374-411) ms (P = .05), and median (IQR) 4-6 week follow-up QTc was 393 (379-423) ms (P = .01).

CONCLUSION

Clinically significant prolongation of the QTc interval occurred only in one patient who had a history of prolonged QTc. Prolonged QTc is rare in this population.

Attitudes, Beliefs, and Practices of Pediatric Palliative Care Physicians Regarding the Use of Methadone in Children With Advanced Cancer

CONTEXT

Methadone is a long-acting opioid known for its unique pharmacokinetic and pharmacodynamic properties. Most research on methadone in children is limited to its effect on the prolongation of the corrected QT (QTc) interval.

OBJECTIVES

To better understand the attitudes, beliefs, and practices of pediatric palliative care physicians regarding the use of methadone in children with advanced cancer.

METHODS

A survey was sent to the American Academy of Pediatrics Section of Hospice and Palliative Medicine LISTSERV. Information on demographics, dosing of methadone, and the use of electrocardiograms (ECGs) was collected.

RESULTS

One-hundred and five respondents (91%) provide palliative care to children ≥ 50% of the time, and a majority (81, 77%) prescribe methadone. Most (62, 77%) physicians were board certified in Hospice and Palliative Medicine, and most (39, 63%) certified via the direct pathway ("grandfathering"). Most physicians (57, 70%) do not use loading doses of methadone. Board-certified physicians trended toward decreasing methadone dose more (40% ± 19%) than non-board-certified physicians (28%, ±20%) when changing from the oral to intravenous route (P = 0.07). Respondents defined a QTc interval as "prolonged" (mean ± SD) at 444 milliseconds (±68 milliseconds). The percentage of patients receiving a baseline ECG was 65% (±33%). The most common reason for not performing a baseline ECG was that the patient was on hospice (13, 36%).

CONCLUSIONS

There are consistent practices, attitudes, and beliefs of pediatric palliative care providers with regard to methadone. More education is needed on the accurate value of a prolonged QTc interval.

Practices, Attitudes, and Beliefs of Palliative Care Physicians Regarding the Use of Methadone and Other Long-Acting Opioids in Children with Advanced Cancer

BACKGROUND

Palliative care physicians often assist with pain management in children with cancer, but little is known about how they use long-acting opioids for chronic pain with these patients.

OBJECTIVE

To determine the practices, attitudes, and beliefs of palliative care physicians toward the use of long-acting opioids in children with advanced cancer.

DESIGN

An electronic survey was sent to all members of The American Academy of Pediatrics (AAP) Section of Hospice and Palliative Medicine (SOHPM) and those identified as physicians who provide palliative care to children on the AAP SOHPM LISTSERV^®.

RESULTS

The response rate to the survey was 62% (116/188). A majority (66% [77/116]) of physicians are board certified in both pediatrics and hospice and palliative medicine. This represents 28% of all board-certified pediatric palliative care physicians. Most palliative care physicians report comfort in using long-acting opioids in children (84-94%), with the exception of long-acting hydromorphone (37%). Physicians perceived methadone as least costly (3%) but associated it with a higher perceived family resistance (51%). As compared with pediatric palliative care fellowship-trained physicians, nonpediatric fellowship-trained physicians perceived titration of oxycodone ER and morphine ER to be easier (p = 0.06, p = 0.07) and less likely to agree that the main reason for starting methadone is that the existing formulations of other long-acting opioids are unsuitable for children (p = 0.05).

CONCLUSIONS

Most physicians who provide palliative care to children are comfortable using opioids but there is significant variation in the level of comfort with different opioids. This information will be helpful in developing targeted education for palliative care providers.

Methadone as the Initial Long-Acting Opioid in Children with Advanced Cancer

BACKGROUND

Methadone is an attractive medication for treating children with advanced cancer with pain as it is the only long-acting opioid available as a liquid. However, it is not frequently used due to concerns about potential toxicities and side effects.

OBJECTIVE

Evaluate the efficacy and safety of methadone as the first long-acting opioid in children with advanced cancer.

DESIGN

Retrospective chart review of 52 consecutive patients referred to Pediatric Supportive Care for pain management started on methadone as their first long-acting opioid. Data collected at baseline, follow-up visits #1 (F1) and #2 (F2) included child and parent-reported outcomes for various physical and psychological symptoms, opioid side effects and other clinical data. Symptoms were rated on a 0 (not at all) to 4 (a lot) scale.

RESULTS

Pain (mean ± standard deviation [SD]) scored by the child was 3.6 (±0.6)/4 at baseline and 1.8 (±1.1)/4 at F1 (p < 0.0001). Compared to baseline, pain scored by the child at F2 was 1.2 (±1.3)/4 (p < 0.0001). Pain scored by the parent was 3.5 (±0.7)/4 at baseline and 1.4 (±1.3)/4 at F1 (p < 0.0001). Compared to baseline, pain scored by the parent at F2 was 1.0 (±1.2)/4 (p < 0.0001). Thirty-three (70%) patients at F1 and 23 (79%) patients at F2 did not need a change in dose of methadone. No cardiac arrhythmias or opioid neurotoxicity was observed.

CONCLUSIONS

Initiation of methadone was effective and safe as the first long-acting opioid in children with pain.

The frequency of QTc prolongation among pediatric and young adult patients receiving methadone for cancer pain

INTRODUCTION

A prolonged corrected QT (QTc) interval in pediatric patients is defined as ≥470 msec. Methadone can cause a prolonged QTc interval that can lead to ventricular arrhythmias. The risk of methadone-induced prolongation of the QTc interval in children and young adults is unknown. The purpose of the study was to determine the frequency of QTc prolongation among pediatric and young adult patients with cancer pain on methadone treatment.

METHODS

We retrospectively reviewed data for all patients on methadone during the study period. Qualifying patient data were reviewed to determine whether these patients had an electrocardiogram (ECG) while on methadone. The QTc values for analysis were manually calculated using the standard formula described by Bazett.

RESULTS

Twenty-five patients were identified that met eligibility criteria. The median QTc decreased from baseline after initiation of methadone. QTc prolongation occurred in four of 25 (16%) patients and only one patient had a QTc greater than 500 msec. This patient had 17 normal QTc intervals on methadone prior to the prolongation. After resolution of electrolyte abnormalities, six subsequent ECGs on methadone had a normal QTc interval.

CONCLUSIONS

Prolongation of the QTc interval is infrequent. The only observed case was transient during multiple comorbid conditions. A prospective study is justified to better understand what role methadone plays as one of many risk factors for prolongation of the QTc interval in children and young adults.

Very-Low-Dose Methadone To Treat Refractory Neuropathic Pain in Children with Cancer

BACKGROUND

Compared with nociceptive pain, neuropathic pain is a challenging diagnosis to make and successfully treat in children with cancer.

OBJECTIVE

The objective of this case report was to see whether very-low-dose methadone (VLDM) (defined as <50% of accepted starting analgesic dose of methadone for children) would be an effective strategy to treat refractory neuropathic pain due to vincristine in two children with acute lymphoblastic leukemia.

METHODS

This case report is based on the clinical experience and parent-reported outcomes of two children with refractory neuropathic pain who received VLDM.

RESULTS

Based on parent/caregiver-reported outcome scores over a one-year period, both children's refractory neuropathic pain syndrome was successfully treated with the addition of VLDM to their pre-existing regimen of gabapentin. Neither child suffered any adverse effects from methadone.

CONCLUSIONS

VLDM shows promise as an effective, safe, and inexpensive way to treat refractory neuropathic pain in children with cancer.

Methadone prolongs cardiac conduction in young patients with cancer-related pain

OBJECTIVE

Methadone prolongs cardiac conduction, from mild corrected QT (QTc) prolongation to torsades de pointes and ventricular fibrillation, in adults. However, methadone use for pain and its effects on cardiac conduction have not been investigated in pediatric populations.

METHODS

A retrospective review of QTc intervals in patients receiving methadone analgesia was conducted. Medical records from a 4-year period (September 2006 to October 2010) at a pediatric oncology institution were reviewed, and correlations were tested between cardiac conduction and methadone dosage and duration of therapy, electrolyte levels, renal and hepatic dysfunction, and concurrent medications.

RESULTS

Of the 61 patients who received methadone, 37 met our inclusion criteria and underwent 137 electrocardiograms (ECGs). During methadone treatment, the mean QTc was longer than that at baseline (446.5 vs 437.55 ms). The mean methadone dose was 27.0±24.3 mg/d (range, 5-125 mg/d; median, 20 mg/d) or 0.47±0.45 mg/kg per day (range, 0.05-2.25 mg/kg per day; median, 0.37 mg/kg per day), and the mean duration of therapy was 49 days. The authors identified a correlation between automated and manual ECG readings by two cardiologists (Pearson r=0.649; p<0.0001), but the authors found no correlations between methadone dose or duration and concurrent QTc-prolonging medications, sex, age, electrolyte abnormalities, or renal or hepatic dysfunction.

CONCLUSION

At a clinically effective analgesic dose, methadone dosage and duration were not correlated with QTc prolongation, even in the presence of other risk factors, suggesting that methadone use may be safe in pediatric populations. The correlation between automated and manual ECG readings suggests that automated ECG readings are reliable for monitoring cardiac conductivity during the reported methadone-dosage regimens.

Extreme doses of intravenous methadone for severe pain in two children with cancer

We describe the effect and side effects in two children with cancer treated with intravenous methadone in extreme doses (>10 mg/kg/day) due to vincristine-induced neuropathy where surgical procedures provoked severe neuropathic pain. The maximum daily dose was 33 and 25 mg/kg/day. Methadone remained effective at adjusted doses. Few side effects were reported. No significant changes in paraclinical data were observed. Prolonged QTc-interval occurred only during concomitant treatment with fluconazole. In conclusion, methadone should be seen as a part of the armamentarium against cancer-related pain. Methadone can be used in extreme doses with appropriate monitoring by clinicians experienced in its use.

Adaptation of an evidence-based clinical practice guideline in cancer pain management by medical oncologists: a case vignette study

PURPOSE

Pain is a major problem in all cancer stages. Cancer pain guidelines are developed to improve management of pain. It is unclear whether these recommendations are applied in daily practice. Therefore, the objective of this study was to assess medical oncologists' adherence to an evidence-based clinical practice guideline in cancer pain management and their confidence in treatment choices.

METHODS

A cross-sectional case vignette survey describing a patient with intractable pancreatic cancer and pain was sent to all 268 medical oncologists registered at the Netherlands Association of Internal Medicine. Descriptive statistics were conducted.

RESULTS

Sixty-three of 268 medical oncologists (24 %) completed the survey. Adherence to the different recommendations of the guideline ranged from 18 to 100 %. Confidence for treatment choice ranged from 5.6 to 9.5 on a Numeric Rating Scale (0-10). Most of the responding oncologists (94 %) adhered to prescribing paracetamol as first-line pain treatment, and all prescribed a laxative in combination with opioids to prevent constipation. However, only 24 % of the respondents adhered to the guideline when first-line treatment had insufficient effect. Additionally, only 35 % adhered to the recommendation for insomnia treatment providing psychosocial support or using a multidimensional pain questionnaire besides pharmacological treatment. Finally, only 18 % adhered to the recommendation to perform a multidimensional pain assessment when disease worsens and pain increases.

CONCLUSIONS

The recommendations of the guideline have been partly adopted in cancer pain practice by medical oncologists. Particularly, pain assessment is not applied in the recommended manner. Therefore, implementation strategies should focus on adequate pain assessment in patients with cancer.