Of apples and oranges: Lessons learned from the preparation of research protocols for systematic reviews exploring the effectiveness of Specialist Palliative Care

BACKGROUND

Agreed terminology used in systematic reviews of the effectiveness of specialist palliative care ((S)PC)) is required to ensure consistency and usability and to help guide future similar reviews and the design of clinical trials. During the preparation of protocols for two separate systematic reviews that aimed to assess the effectiveness of SPC, two international research groups collaborated to ensure a high degree of methodological consensus and clarity between reviews. During the collaboration, it became evident that close attention is needed to (i) avoid ambiguity in the definition of advanced illness, (ii) capture the specialist expertise and prerequisites for SPC interventions, and (iii) the multi-professional and multi-dimensional nature of PC. Also, (iv) the exclusion of relevant studies or (v) impracticality of meta-analyses of the obtained data must be avoided. The aim of this article is to present the core issues of the discussion to help future research groups to easily identify potential pitfalls and methodologic necessities.

CORE ISSUE DISCUSSION

Core issues that arose from the discussion are presented along the research questions according to the PICO process: Population (P): Authors should refer to existing definitions of PC to ensure that, even if the review aims to investigate specific patients (e.g. cancer patients), it is important to make clear that PC is applicable for all life-limiting diseases and not limited to end-of-life or cancer. Intervention (I): PC is a core responsibility of all disciplines (general PC). In contrast, SPC demands further training and expertise. Therefore, core tenets of SPC interventions are that they are (i) multi-professional and (ii) aim at the multi-dimensional nature of suffering. Outcome (O): The main goal of PC is multi-dimensional (quality of life, suffering or distress). Yet, meta-analysis may be complex to conduct due to the heterogeneity of the multi-dimensional outcomes. Therefore, the assessment of uni-dimensional measures such as pain can also provide clinically relevant information that is easier to obtain.

DISCUSSION AND CONCLUSION

Recommendations for future systematic reviews and clinical trials include: (i) Appraise the experience of other research groups who have produced similar systematic reviews or clinical trials. (ii) Include studies that meet the multi-professional and multi-dimensional nature of PC and the specialization requirements for SPC. (iii) Thoroughly weigh relevance and practicability of the primary outcome. Multi-dimensional tools such as quality-of-life questionnaires assess the different dimensions of suffering (the true scope of PC), but uni-dimensional measures such as pain are easier to assess in meta-analyses.

Patient reported outcomes in randomized controlled cancer trials in advanced disease: a structured literature review

INTRODUCTION

In advanced cancer quality of life (QoL) is the most important goal of care. It is measured by patient-reported-outcomes (PRO). This structured review evaluated how randomized controlled trials (RCTs) on anti-cancer therapy in advanced cancer reported PRO.

METHODS

Search was performed in MEDLINE via PubMed for RCTs with median patient survival of ≤2 years. Reporting was rated with the Consolidated Standards of Reporting Trials (CONSORT) PRO extension.

RESULTS

Of 370 retrieved publications, 117 were eligible, but only 30/117 (26%) reported PRO. QoL was most frequently measured (29/30). On average, 4.4 (SD 2.5) of the 14 CONSORT items were met.

CONCLUSION

PRO are insufficiently reported in advanced cancer trials. Yet, this is paramount to enable an informed and patient-oriented decision making process.

Breathlessness and opioid therapy: A retrospective chart analysis in 2,958 patients

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Background: Breathlessness is a common and distressing symptom, which increases in many diseases as they progress and is difficult to manage. It is widely accepted that opioids are safe and effective for treating dyspnea, although no single opioid has an authorization for the treatment of breathlessness. The aims of the study were to assess prevalence rates of breathlessness as well as the treatment approaches especially with respect to opioid therapy in all patients cared by a hospital palliative care team in a university hospital over a period of five years. Methods: A systematic review of all electronically available records of patients under palliative care service from April 2010 – April 2015 was performed. Results: Breathlessness was the third most common symptom in our patient group behind fatigue and pain. Furthermore it was classified as the utmost distressing symptom of all. Many patients suffering from breathlessness were opioid-naive before contact with our palliative care team. Many of these patients were put on prolonged-release opioids together with short-acting opioids (mucosal fentanyl) as rescue medication for breathlessness. Opioid therapy was judged to be very effective by the majority of patients suffering from breathlessness however caused (cancer-related or due to a benign disease e.g. chronic obstructive pulmonary disease). Conclusions: In a large cohort of patients breathlessness is a major topic and is clearly positively influenceable by opioids. In our opinion it is longtime overdue to strive for an authorization for opioids against breathlessness.

Implementing a home-based exercise program for patients with advanced, incurable diseases after discharge and their caregivers: lessons we have learned

BACKGROUND

Palliative care (PC) patients experience loss of physical function which usually impedes mobility, autonomy and quality of life. We aimed at examining the feasibility of a home-based exercise program for patients with advanced, incurable diseases after discharge.

RESULTS

This was a single-arm pilot study (WHO-ICTRP: DRKS00005048). The 12-week home-based program comprised strength, balance, flexibility and endurance components. Patients with a presumed life expectancy of 6-12 months were recruited during a 6-months period on a specialized PC and a radiation therapy ward. We chose the De Morton Mobility Index as primary outcome. Secondary outcomes were quality of life, 6-min walk test and others. A total of 145 patients were screened, 103 (98%) out of 105 patients on the specialized PC ward could not be included, mostly because of a low performance status [n = 94; 90%; Eastern Cooperative Oncology Group (ECOG) >2]. The only two eligible patients declined to participate. Eleven out of 40 patients (28%) were eligible on the radiation therapy ward. However, only one patient (9%) participated but dropped out 2 days later (upcoming surgery). Distance to the hospital (n = 3; 30%) and considering additional tasks as "too much" (n = 3; 30%) were most common reasons for non-participation.

CONCLUSIONS

Establishing a home-based exercise program for inpatients after discharge was not feasible mainly due to non-eligibility and lack of demand. For future trials, we suggest that choosing (1) outpatients with (2) an ECOG of ≤2 and (3) an estimated survival of ≥9 months could enhance participation in home-based exercise programs.

Specialist palliative care services for adults with advanced, incurable illness in hospital, hospice, or community settings--protocol for a systematic review

BACKGROUND

Specialist palliative care (SPC) interventions aim to relieve and prevent suffering in the physical, psychological, social, and spiritual domain. Therefore, SPC is carried out by a multi-professional team with different occupations (e.g., physician, nurse, psychologist, and social worker). Remaining skepticism concerning the need for SPC may be based on the scarcity of high-quality evaluations about the external evidence for SPC. Therefore, we will conduct a systematic review according to Cochrane standards to examine the effects of SPC for adults with advanced illness.

METHODS/DESIGN

The comprehensive systematic literature search will include randomized controlled trials (RCTs) and cluster RCTs. We will search the databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and PsycINFO. Patients must be adults suffering from life-limiting diseases. Proxy and caregiver outcomes will not be assessed in order to ensure a clear and well-defined research question for this review. Interventions may be in an in- or outpatient setting, e.g., consulting service, palliative care ward, and palliative outpatient clinic. In line with the multi-dimensional scope of palliative care, the primary outcome is quality of life (QoL). Key secondary outcomes are patients' symptom burden, place of death and survival, and health economic aspects. Subgroup analysis will assess results according to cancer type, age, early vs not early SPC, site of care, and setting. Analysis will be performed with the current RevMan software. We will use the Cochrane Collaboration risk of bias assessment tool. The quality of evidence will be judged according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DISCUSSION

The available evidence will be summarized and discussed to provide a basis for decision-making among health care professionals and policy makers. For SPC, we believe that multi-professional care is of utmost importance. Therefore, single-profession interventions such as physician consultations will not be included. Based on the multi-dimensional scope of palliative care, we chose QoL as the primary outcome, despite an expected heterogeneity among the QoL outcomes. We consider unidimensional endpoints such as "pain" for the physical domain to be inadequate for capturing the true scope of (S)PC (i.e., QoL) as defined by the World Health Organization.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015020674.

The Role of End-of-Life Issues in the Design and Reporting of Cancer Clinical Trials: A Structured Literature Review

BACKGROUND

Randomized controlled trials (RCTs) are important sources of information on the benefits and harms patients may expect from treatment options. The aim of this structured literature review by the German Institute for Quality and Efficiency in Health Care was to explore whether and how the end-of-life (EoL) situation of patients with advanced cancer is considered in RCTs investigating anti-cancer treatments.

METHODS

Our journal pool comprised 19 medical journals, namely five preselected key general medical journals as well as 14 specialist journals (mainly cancer) identified via a scoping search. We systematically searched these journals in MEDLINE to identify RCTs investigating anti-cancer treatments for the following four cancer types: glioblastoma, lung cancer (stage IIIb-IV), malignant melanoma (stage IV), and pancreatic cancer (search via OVID; November 2012). We selected a representative sample of 100 publications, that is, the 25 most recent publications for each cancer type. EoL was defined as a life expectancy of ≤ two years. We assessed the information provided on (1) the descriptions of the terminal stage of the disease, (2) the therapeutic goal (i.e. the intended therapeutic benefit of the intervention studied), (3) the study endpoints assessed, (4) the authors' concluding appraisal of the intervention's effects, and (5) the terminology referring to the patients' EoL situation.

RESULTS

Median survival was ≤ one year for each of the four cancer types. Descriptions of the terminal stage of the disease were ambiguous or lacking in 29/100 publications. One or more therapeutic goals were mentioned in 51/100 publications; these goals were patient-relevant in 38 publications (survival alone: 30/38; health-related quality of life (HRQoL) or HRQoL and survival: 6/38; symptom control or symptom control and survival: 2/38). Primary endpoints included survival (50%), surrogates (44%), and safety (3%). Patient-reported outcomes (PROs) were assessed in 36/100 RCTs. The implications of treatment-related harms for the patients were discussed in 22/100 appraisals. Terminology referring to the patients' EoL situation (e.g. "terminal") was scarce, whereas terms suggesting control of the disease (e.g. "cancer control") were common.

CONCLUSIONS

The EoL situation of patients with advanced cancer should be more carefully considered in clinical trials. Although the investigation and robust reporting of PROs is a prerequisite for informed decision-making in healthcare, they are rarely defined as endpoints and HRQoL is rarely mentioned as a therapeutic goal. Suggestions for improving standards for study design and reporting are presented.

Early Palliative Care-Health services research and implementation of sustainable changes: the study protocol of the EVI project

Background

International medical organizations such as the American Society of Medical Oncology recommend early palliative care as the “gold standard” for palliative care in patients with advanced cancer. Nevertheless, even in Comprehensive Cancer Centers, early palliative care is not yet routine practice. The main goal of the EVI project is to evaluate whether early palliative care can be implemented—in the sense of “putting evidence into practice”—into the everyday clinical practice of Comprehensive Cancer Centers. In addition, we are interested in (1) describing the type of support that patients would like from palliative care, (2) gaining information about the effect of palliative care on patients’ quality of life, and (3) understanding the economic burden of palliative care on patients and their families.

Methods/design

The EVI project is a multi-center, prospective cohort study with a sequential control group design. The study is a project of the Palliative Care Center of Excellence (KOMPACT) in Baden-Württemberg, Germany, which was recently established to combine the expertise of five academic, specialist palliative care departments. The study is divided into two phases: preliminary phase (months 1–9) and main study phase (months 10–18). In each of all five participating academic Comprehensive Cancer Centers, an experienced palliative care physician will be hired for 18 months. During the preliminary phase, the physician will be allowed time to establish the necessary structures for early palliative care within the Comprehensive Cancer Center. In the main study phase, patients with metastatic cancer will be offered a consultation with the palliative care physician within eight weeks of diagnosis. After the initial consultation, follow-up consultations will be offered as needed. The study is built upon a convergent parallel design. In the quantitative arm, patients will be surveyed in both the preliminary and main study phase at three points in time (baseline, 12 weeks, 24 weeks). Standardized questionnaires will be used to measure patients’ quality of life, symptom burden and mood. Using interviews with palliative care physicians, oncologists, department heads, patients and their caregivers, the qualitative arm will explore (1) what factors encourage and hinder the early integration of palliative care into standard oncology care, (2) what support patients and their caregivers would like from palliative care, and (3) what effect palliative care has on the economic disease burden of patients and their families.

Discussion

The study proposed is meant to serve as a catalyzer. Local palliative care teams should be put in position to routinely cooperate with the primary treating department at their respective cancer center. The long-term goal of this project is to create sustainable improvements in the care of patients with incurable cancer.

Trial registration

DRKS00006162; date of registration: 19/05/2014

Advances in pharmacotherapy for opioid-induced constipation - a systematic review

INTRODUCTION

Opioid-induced constipation (OIC) is one of the most frequent and burdening adverse events (AE) of opioid therapy. This systematic review aimed to evaluate efficacy and safety of drugs in randomized controlled trials (RCTs) with adult OIC patients.

AREAS COVERED

Efficacy assessment focused on objective outcome measures (OOMs): bowel movement (BM) frequency, BM within 4 h and time to first BM. Twenty-one studies examining seven drugs were identified. Methylnaltrexone showed improvements in all three OOMs. RCTs in naloxone and alvimopan tended to be effective for BM frequency measures. Naloxegol (≥ 12.5 mg) improved all OOMs. Though effectiveness of lubiprostone was demonstrated for all OOMs, group differences were small to moderate. CB-5945 and prucalopride tended to increase BM frequency, especially for 0.1 mg twice daily and 4 mg daily, respectively. Besides nausea and diarrhea, abdominal pain was the most frequent AE for all drugs (risk ratio, range: 1.52 - 5.06) except for alvimopan. Treatment-related serious AEs were slightly higher for alvimopan (cardiac events) and prucalopride (severe abdominal pain, headache). Pain scores for placebo and intervention groups were similar for all drugs.

EXPERT OPINION

Finding a consensus definition and inclusion criteria for OIC plus a rational balance between efficacy and AEs of drugs remain future challenges.

Silent night: retrospective database study assessing possibility of "weekend effect" in palliative care

OBJECTIVE

To compare the mortality of patients in a palliative care unit on working days with that on weekends and public holidays.

DESIGN

Retrospective database study.

SETTING

Palliative care unit in Germany.

POPULATION

All admissions to palliative care unit between 1 January 1997 and 31 December 2008.

MAIN OUTCOME MEASURE

The impact of day type (working days or weekends and public holidays) on mortality was analysed using Poisson regression models.

RESULTS

A total of 2565 admitted patients and 1325 deaths were recorded. Of the deaths, 448 (33.8%) occurred on weekends and public holidays. The mortality rate on weekends and public holidays was 18% higher than that on working days (mortality rate ratio 1.18, 95% confidence interval 1.05 to 1.32; P=0.005).

CONCLUSION

Patients in the palliative care unit were at higher risk of dying on weekends and public holidays. In the absence of a prospective study, the exact reasons for this correlation are unclear.

Dying in cancer centers: do the circumstances allow for a dignified death?

BACKGROUND

Prior research has shown that hospitals are often ill-prepared to provide care for dying patients. This study assessed whether the circumstances for dying on cancer center wards allow for a dignified death.

METHODS

In this cross-sectional study, the authors surveyed physicians and nurses in 16 hospitals belonging to 10 cancer centers in Baden-Wuerttemberg, Germany. A revised questionnaire from a previous study was used, addressing the following topics regarding end-of-life care: structural conditions (ie, rooms, staff), education/training, working environment, family/caregivers, medical treatment, communication with patients, and dignified death.

RESULTS

In total, 1131 surveys (response rate = 50%) were returned. Half of the participants indicated that they rarely have enough time to care for dying patients, and 55% found the rooms available for dying patients unsatisfactory. Only 19% of respondents felt that they had been well-prepared to care for the dying (physicians = 6%). Palliative care staff reported much better conditions for the dying than staff from other wards (95% of palliative care staff indicated that patients die in dignity on their ward). Generally, physicians perceived the circumstances much more positively than nurses, especially regarding communication and life-prolonging measures. Overall, 57% of respondents believed that patients could die with dignity on their ward.

CONCLUSIONS

Only about half of the respondents perceived that a dignified death is possible on their ward. We recommend that cancer centers invest more in staffing, adequate rooms for dying patients, training in end-of-life care, advance-care planning standards, and the early integration of specialist palliative care services.

Fentanyl for the relief of refractory breathlessness: a systematic review

CONTEXT

Fentanyl is a potent opioid that has been proven to provide effective treatment for breakthrough cancer pain. Although opioids are the only drug group with evidence for the symptomatic treatment of breathlessness, evidence about the efficacy of fentanyl for the relief of breathlessness is unknown.

OBJECTIVES

We performed a systematic review to evaluate the current evidence for the use of fentanyl for the relief of breathlessness.

METHODS

The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendation for systematic reviews. Four databases (MEDLINE, EMBASE, Cochrane Library, International Pharmaceutical Abstracts) were screened using "fentanyl" and "dyspnoea" (and synonyms) as search terms. Hand search and contact with relevant authors completed the search.

RESULTS

A total of 622 references were retrieved, 13 of which met the inclusion criteria for this review. Two randomized controlled trials (RCTs) evaluated fentanyl for breathlessness, but one only included two patients. The other studies were before-after (n = 2) and case studies (n = 9). All studies reported successful relief of breathlessness after fentanyl application, but the only (pilot-) RCT failed to demonstrate a statistically significant difference compared with placebo. The nature and incidence of adverse events were comparable with other opioids, and no respiratory depression was observed.

CONCLUSION

Descriptive studies yielded promising results for the use of fentanyl for the relief of breathlessness; however, efficacy trials are lacking. Fully powered RCTs are warranted to determine the efficacy of fentanyl for breathlessness relief, but these require pilot studies to evaluate effective size, study procedures, and outcome measures.

Drug interactions in palliative care--it's more than cytochrome P450

OBJECTIVE

This study aims to identify the combination of substances with high potential for drug interactions in a palliative care setting and to provide concise recommendations for physicians.

METHODS

We used a retrospective systematic chart analysis of 200 consecutive inpatients. The recently developed and internationally advocated classification system OpeRational ClAssification of Drug Interactions was applied using the national database of the Federal Union of German Associations of Pharmacists. Charts of patients with potential for severe DDIs were examined manually for clinical relevance.

RESULTS

In 151 patients (75%) a total of 631 potential drug interactions were identified. Opioids (exception: methadone), non-opioids (exception: non-steroidal anti-inflammatory drugs), benzodiazepines, proton-pump inhibitors, laxatives, co-analgesics (exception: carbamazepine) and butylscopolamine were generally safe. High potential for drug interactions included combinations of scopolamine, neuroleptics, metoclopramide, antihistamines, non-steroidal anti-inflammatory drugs, (levo-) methadone, amitriptyline, carbamazepine and diuretics. The manual analyses of records from eight patients with risk for severe drug interactions provided no indicator for clinical relevance in these specific patients. Drug interactions attributed to the cytochrome pathway played a minor role (exception: carbamazepine).

CONCLUSION

Most relevant drug interactions can be expected with: (i) drugs (inter-) acting via histamine, acetylcholine or dopamine receptors; and (ii) Non-steroidal anti-inflammatory drugs. Even in last hours of life the combination of substances (e.g. anticholinergics) may produce relevant drug interactions (e.g. delirium).

PERSPECTIVE

Data on the potential for drug-drug interactions in palliative case is extremely scarce, but drug interactions can be limited if a few facts are considered. A synopsis of the findings of these studies is presented as concise recommendation to minimize drug interactions.

[Management of refractory dyspnoea in patients with advanced diseases - evidence-based update for clinical practice]

Many patients with advanced diseases complain about refractory breathlessness when breathlessness is present although the underlying disease is optimal treated. After exclusion of potential curable causes of breathlessness, management of refractory breathlessness includes general approaches, pharmacological (opioids) and non-pharmacological (e.g. handheld fan, rollator) interventions. Oxygen should be used far less than used in clinical practice at the moment and needs critical appraisal of effectiveness.

Cancer Pain Management and Bone Metastases: An Update for the Clinician

Breast cancer patients with bone metastases often suffer from cancer pain. In general, cancer pain treatment is far from being optimal for many patients. To date, morphine remains the gold standard as first-line therapy, but other pure μ agonists such as hydromorphone, fentanyl, or oxycodone can be considered. Transdermal opioids are an important option if the oral route is impossible. Due to its complex pharmacology, methadone should be restricted to patients with difficult pain syndromes. The availability of a fixed combination of oxycodone and naloxone is a promising development for the reduction of opioid induced constipation. Especially bone metastases often result in breakthrough pain episodes. Thus, the provision of an on-demand opioid (e.g., immediate-release morphine or rapid-onset fentanyl) in addition to the baseline (regular) opioid therapy (e.g., sustained-release morphine tablets) is mandatory. Recently, rapid onset fentanyls (buccal or nasal) have been strongly recommended for breakthrough cancer pain due to their fast onset and their shorter duration of action. If available, metamizole is an alternative non-steroid-anti-inflammatory-drug. The indication for bisphosphonates should always be checked early in the disease. In advanced cancer stages, glucocorticoids are an important treatment option. If bone metastases lead to neuropathic pain, coanalgetics (e.g., pregabalin) should be initiated. In localized bone pain, radiotherapy is the gold standard for pain reduction in addition to pharmacologic pain management. In diffuse bone pain radionuclids (such as samarium) can be beneficial. Invasive measures (e.g., neuroaxial blockage) are rarely necessary but are an important option if patients with cancer pain syndromes are refractory to pharmacologic management and radiotherapy as described above. Clinical guidelines agree that cancer pain management in incurable cancer is best provided as part of a multiprofessional palliative care approach and all other domains of suffering (psychosocial, spiritual, and existential) need to be carefully addressed («total pain»).

Palliative care consultation service and palliative care unit: why do we need both?

BACKGROUND

Palliative care (PC) infrastructure has developed differently around the globe. Whereas some institutions consider the palliative care unit (PCU) a valuable component, others report that the sole provision of a state-of-the art palliative care consultation service (PCCS) suffices to adequately care for the severely ill and dying.

OBJECTIVE

To aid institutional planning, this study aimed at gathering patient data to distinguish assignments of a concomitantly run PCU and PCCS at a large hospital and academic medical center.

METHODS

Demographics, Eastern Cooperative Oncology Group performance status, symptom/problem burden, discharge modality, and team satisfaction with care for all 601 PCU and 851 PCCS patients treated in 2009 and 2010 were retrospectively analyzed.

RESULTS

Patients admitted to the PCU versus those consulted by the PCCS: (a) had a significantly worse performance status (odds ratio [OR], 1.48); (b) were significantly more likely to suffer from severe symptoms and psychosocial problems (OR, 2.05), in particular concerning physical suffering and complexity of care; and (c) were significantly much more likely to die during hospital stay (OR, 11.03). For patients who were dying or in other challenging clinical situations (suffering from various severe symptoms), self-rated team satisfaction was significantly higher for the PCU than the PCCS.

CONCLUSION

This study presents a direct comparison between patients in a PCU and a PCCS. Results strongly support the hypothesis that the coexistence of both institutions in one hospital contributes to the goal of ensuring optimal high-quality PC for patients in complex and challenging clinical situations.

Practicability, safety, and efficacy of a "German model" for opioid conversion to oral levo-methadone

INTRODUCTION

An algorithm to convert from any other opioid to oral levo-methadone was developed in Germany, the German model of levo-methadone conversion (GMLC). According to this GMLC, the pre-existing opioid is stopped, then titration of oral levo-methadone is initiated with a starting dose of 5 mg orally q 4 h (plus prn q 1 h). If necessary, levo-methadone dose is increased (pain) or decreased (side effects) by 30% q 4 h (plus prn q 1 h). After 72 h, the achieved single dose is maintained, but the dosing interval increases twofold to q 8 h (plus prn q 3 h). The aim of this study was to obtain information about the practicability, safety, and efficacy of the GMLC in clinical routine.

METHODS

A retrospective, systematic chart review of levo-methadone conversions for the treatment of pain in inpatient palliative care was performed.

RESULTS

Fifty-two patients were analyzed. The dosing interval was increased correctly after 72 h as demanded by the GMLC in 60% of patients. In 85% of the patients, opioid medication with levo-methadone could be maintained until the end of the inpatient stay. In three patients (6%), levo-methadone administration had to be stopped due to side effects. No serious adverse events could be detected during opioid rotation. Pain intensity was reduced significantly (p < 0.001) after conversion concerning mean (NRS 0.9; range 0-4) and maximum pain over the day (NRS 3.9; range 0-10).

CONCLUSION

The presented study indicates that the GMLC provides a practical and reasonably safe approach to perform opioid rotation to levo-methadone in a palliative care setting.