Cost-effectiveness of noninvasive fetal RhD blood group genotyping in nonalloimmunized and alloimmunized pregnancies

BACKGROUND

We sought to determine the cost-effectiveness of noninvasive fetal RhD blood group genotyping in nonalloimmunized and alloimmunized pregnancies in Canada.

STUDY DESIGN AND METHODS

We developed two probabilistic state-transition (Markov) microsimulation models to compare fetal genotyping followed by targeted management versus usual care (i.e., universal Rh immunoglobulin [RhIG] prophylaxis in nonalloimmunized RhD-negative pregnancies, or universal intensive monitoring in alloimmunized pregnancies). The reference case considered a healthcare payer perspective and a 10-year time horizon. Sensitivity analysis examined assumptions related to test cost, paternal screening, subsequent pregnancies, other alloantibodies (e.g., K, Rh c/C/E), societal perspective, and lifetime horizon.

RESULTS

Fetal genotyping in nonalloimmunized pregnancies (at per-sample test cost of C$247/US$311) was associated with a slightly higher probability of maternal alloimmunization (22 vs. 21 per 10,000) and a reduced number of RhIG injections (1.427 vs. 1.795) than usual care. It was more expensive (C$154/US$194, 95% Credible Interval [CrI]: C$139/US$175-C$169/US$213) and had little impact on QALYs (0.0007, 95%CrI: -0.01-0.01). These results were sensitive to the test cost (threshold achieved at C$88/US$111), and inclusion of paternal screening. Fetal genotyping in alloimmunized pregnancies (at test cost of C$328/US$413) was less expensive (-C$6280/US$7903, 95% CrI: -C$6325/US$7959 to -C$6229/US$7838) and more effective (0.19 QALYs, 95% CrI 0.17-0.20) than usual care. These cost savings remained robust in sensitivity analyses.

DISCUSSION

Noninvasive fetal RhD genotyping saves resources and represents good value for the management of alloimmunized pregnancies. If the cost of genotyping is substantially decreased, the targeted intervention can become a viable option for nonalloimmunized pregnancies.

Noninvasive Fetal RhD Blood Group Genotyping: A Systematic Review of Economic Evaluations

OBJECTIVE

Noninvasive fetal rhesus D (RhD) blood group genotyping may prevent unnecessary use of anti-D immunoglobulin (RhIG) in non-alloimmunized RhD-negative pregnancies and can guide management of alloimmunized pregnancies. We conducted a systematic review of the economic literature to determine the cost-effectiveness of this intervention over usual care.

DATA SOURCES

Systematic literature searches of bibliographic databases (Ovid MEDLINE, Embase, and Cochrane) until February 26, 2019, and auto-alerts until October 30, 2020, and of grey literature sources were performed to retrieve all English-language studies.

STUDY SELECTION

We included studies done in serologically confirmed non-alloimmunized or alloimmunized RhD-negative pregnancies, comparing costs and effectiveness of the intervention versus usual care.

DATA EXTRACTION AND SYNTHESIS

Two reviewers extracted data from the eligible studies and assessed their methodological quality (risk of bias) using the Quality of Health Economic Studies (QHES) and Drummond tools. We narratively synthesized findings. Our review included 8 economic studies that evaluated non-invasive fetal RhD genotyping followed by targeted RhIG prophylaxis in non-alloimmunized pregnancies. Five studies further considered a subsequent alloimmunized pregnancy. The cost-effectiveness of the intervention versus usual care (e.g., universal RhIG or prophylaxis conditional on results of paternal testing) for non-alloiummunized pregnancies was inconsistent. Two studies indicated greater benefits and lower costs for the intervention, and another 2 suggested a trade-off. In 4 studies, the intervention was less effective and costlier than alternatives. Three studies were determined to be of high quality by both tools. Two of these studies favoured the intervention, and one assessed benefits in quality-adjusted life-years. No study clearly examined the cost-effectiveness of repetitive use of fetal genotyping in multiple non-alloimmunized or alloimmunized pregnancies. The cost of genotyping was the most influential parameter.

CONCLUSION

The cost-effectiveness of noninvasive fetal RhD genotyping for non-alloimmunized pregnancies varies between studies. Potential savings from targeted management of alloimmunized pregnancies requires further research.

Cost-effectiveness of genome-wide sequencing for unexplained developmental disabilities and multiple congenital anomalies

PURPOSE

Genetic testing is routine practice for individuals with unexplained developmental disabilities and multiple congenital anomalies. However, current testing pathways can be costly and time consuming, and the diagnostic yield low. Genome-wide sequencing, including exome sequencing (ES) and genome sequencing (GS), can improve diagnosis, but at a higher cost. This study aimed to assess the cost-effectiveness of genome-wide sequencing in Ontario, Canada.

METHODS

A cost-effectiveness analysis was conducted using a discrete event simulation from a public payer perspective. Six strategies involving ES or GS were compared. Outcomes reported were direct medical costs, number of molecular diagnoses, number of positive findings, and number of active treatment changes.

RESULTS

If ES was used as a second-tier test (after the current first-tier, chromosomal microarray, fails to provide a diagnosis), it would be less costly and more effective than standard testing (CAN$6357 [95% CI: 6179-6520] vs. CAN$8783 per patient [95% CI: 2309-31,123]). If ES was used after standard testing, it would cost an additional CAN$15,228 to identify the genetic diagnosis for one additional patient compared with standard testing. The results remained robust when parameters and assumptions were varied.

CONCLUSION

ES would likely be cost-saving if used earlier in the diagnostic pathway.

Noninvasive Prenatal Testing for Trisomies 21, 18, and 13, Sex Chromosome Aneuploidies, and Microdeletions in Average-Risk Pregnancies: A Cost-Effectiveness Analysis

OBJECTIVE

The cost effectiveness of noninvasive prenatal testing (NIPT) has been established for high-risk pregnancies but remains unclear for pregnancies at other risk levels. The aim was to assess the cost effectiveness of NIPT in average-risk pregnancies from the perspective of a provincial public payer in Canada.

METHODS

A model was developed to compare traditional prenatal screening (TPS), NIPT as a second-tier test (performed only after a positive TPS result), and NIPT as a first-tier test (performed instead of TPS) for trisomies 21, 18, and 13; sex chromosome aneuploidies; and microdeletions in a hypothetical annual population cohort of average-risk pregnancies (142 000 to 148,000) in Ontario, Canada. A probabilistic analysis was conducted with 5000 repetitions.

RESULTS

Compared with TPS, NIPT as a second-tier test detected more affected fetuses with trisomies 21, 18, and 13 (188 vs. 158), substantially reduced the number of diagnostic tests (i.e., chorionic villus sampling and amniocentesis) performed (660 vs. 3107), and reduced the cost of prenatal screening ($26.7 million vs. $27.6 million) annually. Compared with second-tier NIPT, first-tier NIPT detected an additional 80 cases of trisomies 21, 18, and 13 at an additional cost of $33 million. The incremental cost per additional affected fetus detected was $412 411. Extending first-tier NIPT to include testing for sex chromosome aneuploidies and 22q11.2 deletion would increase the total screening cost.

CONCLUSIONS

NIPT as a second-tier test is cost-saving compared with TPS alone. Compared with second-tier NIPT, first-tier NIPT detects more cases of chromosomal anomalies but at a substantially higher cost.

Cost-Effectiveness of Magnetic Resonance-Guided Focused Ultrasound for Essential Tremor

BACKGROUND

Radiofrequency thalamotomy and deep brain stimulation are current treatments for moderate to severe medication-refractory essential tremor. However, they are invasive and thus carry risks. Magnetic resonance-guided focused ultrasound is a new, less invasive surgical option. The objective of the present study was to determine the cost-effectiveness of magnetic resonance-guided focused ultrasound compared with standard treatments in Canada.

METHODS

We conducted a cost-utility analysis using a Markov cohort model. We compared magnetic resonance-guided focused ultrasound with no surgery in people ineligible for invasive neurosurgery and with radiofrequency thalamotomy and deep brain stimulation in people eligible for invasive neurosurgery. In the reference case analysis, we used a 5-year time horizon and a public payer perspective and discounted costs and benefits at 1.5% per year.

RESULTS

Compared with no surgery in people ineligible for invasive neurosurgery, magnetic resonance-guided focused ultrasound cost $21,438 more but yielded 0.47 additional quality-adjusted life years, producing an incremental cost-effectiveness ratio of $45,817 per quality-adjusted life year gained. In people eligible for invasive neurosurgery, magnetic resonance-guided focused ultrasound was slightly less effective but much less expensive compared with the current standard of care, deep brain stimulation. The results were sensitive to assumptions regarding the time horizon, cost of magnetic resonance-guided focused ultrasound, and probability of recurrence.

CONCLUSIONS

In people ineligible for invasive neurosurgery, the incremental cost-effectiveness ratio of magnetic resonance-guided focused ultrasound versus no surgery is comparable to many other tests and treatments that are widely adopted in high-income countries. In people eligible for invasive neurosurgery, magnetic resonance-guided focused ultrasound is also a reasonable option. © 2018 International Parkinson and Movement Disorder Society.

Some issues for the evaluation of noninferiority trials

Although published noninferiority trials (NITs) generally conclude that the experimental intervention being studied is noninferior compared with standard therapy or active control, NIT quality is often not satisfactory. We have proposed 14 questions to assist in evaluating the clinical evidence of the experimental versus standard therapy. The aim of these questions is to critically appraise NITs and support proper interpretation of study results. Readers should not only consider whether the confidence interval of the primary effect measure falls within the prespecified noninferiority margin (thus concluding noninferiority), but also assess the similarities between primary and secondary outcomes for the experimental and standard therapy. To conclude noninferiority conceptually is to synthesize evidence from both the current NIT comparing experimental therapy with standard therapy and historical data comparing standard therapy with placebo control. Therefore, readers should use external data sources (e.g., historical data) to validate the study design (e.g., selection of standard therapy, effect measure and the noninferiority margin), and assess the uncertainty of findings due to differences between the observed and expected incidence rates, follow-up time, effects of adjuvant therapy and the secondary outcomes of therapies. Following an explanation of the 14 questions, we then apply the questions to a NIT on intraoperative radiation therapy for early stage breast cancer, as an example.

Mechanical Thrombectomy in Acute Ischemic Stroke: A Systematic Review

Although intravenous thrombolysis increases the probability of a good functional outcome in carefully selected patients with acute ischemic stroke, a substantial proportion of patients who receive thrombolysis do not have a good outcome. Several recent trials of mechanical thrombectomy appear to indicate that this treatment may be superior to thrombolysis. We therefore conducted a systematic review and meta-analysis to evaluate the clinical effectiveness and safety of new-generation mechanical thrombectomy devices with intravenous thrombolysis (if eligible) compared with intravenous thrombolysis (if eligible) in patients with acute ischemic stroke caused by a proximal intracranial occlusion. We systematically searched seven databases for randomized controlled trials published between January 2005 and March 2015 comparing stent retrievers or thromboaspiration devices with best medical therapy (with or without intravenous thrombolysis) in adults with acute ischemic stroke. We assessed risk of bias and overall quality of the included trials. We combined the data using a fixed or random effects meta-analysis, where appropriate. We identified 1579 studies; of these, we evaluated 122 full-text papers and included five randomized control trials (n=1287). Compared with patients treated medically, patients who received mechanical thrombectomy were more likely to be functionally independent as measured by a modified Rankin score of 0-2 (odds ratio, 2.39; 95% confidence interval, 1.88-3.04; I2=0%). This finding was robust to subgroup analysis. Mortality and symptomatic intracerebral hemorrhage were not significantly different between the two groups. Mechanical thrombectomy significantly improves functional independence in appropriately selected patients with acute ischemic stroke.

Mechanical thrombectomy in patients with acute ischemic stroke: a cost-utility analysis

BACKGROUND

The beneficial effects of endovascular treatment with new-generation mechanical thrombectomy devices compared with intravenous thrombolysis alone to treat acute large-artery ischemic stroke have been shown in randomized controlled trials (RCTs). This study aimed to estimate the cost utility of mechanical thrombectomy compared with the established standard of care.

METHODS

We developed a Markov decision process analytic model to assess the cost-effectiveness of treatment with mechanical thrombectomy plus intravenous thrombolysis versus treatment with intravenous thrombolysis alone from the public payer perspective in Canada. We conducted comprehensive literature searches to populate model inputs. We estimated the efficacy of mechanical thrombectomy plus intravenous thrombolysis from a meta-analysis of 5 RCTs, and we used data from the Oxford Vascular Study to model long-term clinical outcomes. We calculated incremental cost-effectiveness ratios (ICER) using a 5-year time horizon.

RESULTS

The base case analysis showed the cost and effectiveness of treatment with mechanical thrombectomy plus intravenous thrombolysis to be $126 939 and 1.484 quality-adjusted life-years (QALYs), respectively, and the cost and effectiveness of treatment with intravenous thrombolysis alone to be $124 419 and 1.273 QALYs, respectively. The mechanical thrombectomy plus intravenous thrombolysis strategy was associated with an ICER of $11 990 per QALY gained. Probabilistic sensitivity analysis showed that the probability of treatment with mechanical thrombectomy plus intravenous thrombolysis being cost-effective was 57.5%, 89.7% and 99.6% at thresholds of $20 000, $50 000 and $100 000 per QALY gained, respectively. The main factors influencing the ICER were time horizon, extra cost of mechanical thrombectomy treatment and age of the patient.

INTERPRETATION

Mechanical thrombectomy as an adjunct therapy to intravenous thrombolysis is cost-effective compared with treatment with intravenous thrombolysis alone for patients with acute large-artery ischemic stroke.

Caesarean Delivery Rate Review: An Evidence-Based Analysis

BACKGROUND

In 2007, caesarean deliveries comprised 28% of all hospital deliveries in Ontario. Provincial caesarean delivery rates increased with maternal age and varied by Local Health Integration Network. However, the accepted rate of caesarean delivery in a low-risk maternal population remains unclear.

OBJECTIVES

To review the literature to assess factors that affect the likelihood of experiencing a caesarean delivery, and to examine Ontario caesarean delivery rates to determine whether there is rate variation across the province.

DATA SOURCES

Data sources included publications from OVID MEDLINE, OVID MEDLINE In-Process and Other Non-Indexed Citations, OVID Embase, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), and EBM Reviews, as well as data from the Canadian Institute for Health Information Discharge Abstracts Database and the Better Outcomes and Registry Network.

REVIEW METHODS

A mixed-methods approach was used, which included a systematic review of the literature to delineate factors associated with the likelihood of caesarean delivery and an analysis of administrative and clinical data on hospital deliveries in Ontario to determine provincial caesarean delivery rates, variation in rates, and reasons for variation.

RESULTS

Fourteen systematic reviews assessed 14 factors affecting the likelihood of caesarean delivery; 7 factors were associated with an increased likelihood of caesarean delivery, and 2 factors were associated with a decreased likelihood. Five factors had no influence. One factor provided moderate-quality evidence supporting elective induction policies in low-risk women. The overall Ontario caesarean delivery rate in a very-low-risk population was 17%, but varied significantly across Ontario hospitals.

LIMITATIONS

The literature review included a 5-year period and used only systematic reviews. The determination of Robson class for women is based on care received in hospital only, and the low-risk population may have included data from women with obstetrical conditions that warranted a caesarean delivery.

CONCLUSIONS

There is moderate-quality evidence that-compared with expectant management-an induction policy is associated with a decrease in caesarean delivery rates in low-risk women. There is significant caesarean delivery rate variation among Ontario hospitals.

Cost-effectiveness of interventions for chronic obstructive pulmonary disease (COPD) using an Ontario policy model

In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions. After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses. The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html. Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework. Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Pulmonary Rehabilitation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Long-Term Oxygen Therapy for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Hospital-at-Home Programs for Patients With Acute Exacerbations of Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Home Telehealth for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Cost-Effectiveness of Interventions for Chronic Obstructive Pulmonary Disease Using an Ontario Policy Model. Experiences of Living and Dying With COPD: A Systematic Review and Synthesis of the Qualitative Empirical Literature. For more information on the qualitative review, please contact Mita Giacomini at: http://fhs.mcmaster.ca/ceb/faculty_member_giacomini.htm. For more information on the economic analysis, please visit the PATH website: http://www.path-hta.ca/About-Us/Contact-Us.aspx. The Toronto Health Economics and Technology Assessment (THETA) collaborative has produced an associated report on patient preference for mechanical ventilation. For more information, please visit the THETA website: http://theta.utoronto.ca/static/contact.

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation throughout the airways, parenchyma, and pulmonary vasculature. The inflammation causes repeated cycles of injury and repair in the airway wall— inflammatory cells release a variety of chemicals and lead to cellular damage. The inflammation process also contributes to the loss of elastic recoil pressure in the lung, thereby reducing the driving pressure for expiratory flow through narrowed and poorly supported airways, in which airflow resistance is significantly increased. Expiratory flow limitation is the pathophysiological hallmark of COPD. Exacerbations of COPD contribute considerably to morbidity and mortality, and impose a burden on the health care system. They are a leading cause of emergency room visits and hospitalizations, particularly in the winter. In Canada, the reported average cost for treating a moderate exacerbation is $641; for a major exacerbation, the cost is $10,086.

OBJECTIVE

The objective of this study was to evaluate the cost-effectiveness and budget impact of the following interventions in moderate to very severe COPD, investigated in the Medical Advisory Secretariat Chronic Obstructive Pulmonary Disease Mega-Analysis Series: smoking cessation programs in moderate COPD in an outpatient setting: – intensive counselling (IC) versus usual care (UC). – nicotine replacement therapy (NRT) versus UC. – IC + NRT versus placebo. – bupropion versus placebo; multidisciplinary care (MDC) teams versus UC in moderate to severe COPD in an outpatient setting; pulmonary rehabilitation (PR) versus UC following acute exacerbations in moderate to severe COPD; long-term oxygen therapy (LTOT) versus UC in severe hypoxemia in COPD in an outpatient setting; ventilation: – noninvasive positive pressure ventilation (NPPV) + usual medical care versus usual medical care in acute respiratory failure due to an acute exacerbation in severe COPD in an inpatient setting. – weaning with NPPV versus weaning with invasive mechanical ventilation in acute respiratory failure due to an acute exacerbation in very severe COPD in an inpatient setting.

METHODS

A cost-utility analysis was conducted using a Markov probabilistic model. The model consists of different health states based on the Global Initiative for Chronic Obstructive Lung Disease COPD severity classification. Patients were assigned different costs and utilities depending on their severity health state during each model cycle. In addition to moving between health states, patients were at risk of acute exacerbations of COPD in each model cycle. During each cycle, patients could have no acute exacerbation, a minor acute exacerbation, or a major exacerbation. For the purposes of the model, a major exacerbation was defined as one that required hospitalization. Patients were assigned different costs and utilities in each model cycle, depending on whether they experienced an exacerbation, and its severity. Starting cohorts reflected the various patient populations from the trials analyzed. Incremental cost-effectiveness ratios (ICERs)—that is, costs per quality-adjusted life-year (QALY)—were estimated for each intervention using clinical parameters and summary estimates of relative risks of (re)hospitalization, as well as mortality and abstinence rates, from the COPD mega-analysis evidence-based analyses. A budget impact analysis was also conducted to project incremental costs already being incurred or resources already in use in Ontario. Using provincial data, medical literature, and expert opinion, health system impacts were calculated for the strategies investigated. All costs are reported in Canadian dollars.

RESULTS

All smoking cessation programs were dominant (i.e., less expensive and more effective overall). Assuming a base case cost of $1,041 and $1,527 per patient for MDC and PR, the ICER was calculated to be $14,123 per QALY and $17,938 per QALY, respectively. When the costs of MDC and PR were varied in a 1-way sensitivity analysis to reflect variation in resource utilization reported in the literature, the ICER increased to $55,322 per QALY and $56,270 per QALY, respectively. Assuming a base case cost of $2,261 per year per patient for LTOT as reported by data from the Ontario provincial program, the ICER was calculated to be $38,993 per QALY. Ventilation strategies were dominant (i.e., cheaper and more effective), as reflected by the clinical evidence of significant in-hospital days avoided in the study group. Ontario currently pays for IC through physician billing (translating to a current burden of $8 million) and bupropion through the Ontario Drug Benefit program (translating to a current burden of almost $2 million). The burden of NRT was projected to be $10 million, with future expenditures of up to $1 million in Years 1 to 3 for incident cases. Ontario currently pays for some chronic disease management programs. Based on the most recent Family Health Team data, the costs of MDC programs to manage COPD were estimated at $85 million in fiscal year 2010, with projected future expenditures of up to $51 million for incident cases, assuming the base case cost of the program. However, this estimate does not accurately reflect the current costs to the province because of lack of report by Family Health Teams, lack of capture of programs outside this model of care by any data set in the province, and because the resource utilization and frequency of visits/follow-up phone calls were based on the findings in the literature rather than the actual Family Health Team COPD management programs in place in Ontario. Therefore, MDC resources being utilized in the province are unknown and difficult to measure. Data on COPD-related hospitalizations were pulled from Ontario administrative data sets and based on consultation with experts. Half of hospitalized patients will access PR resources at least once, and half of these will repeat the therapy, translating to a potential burden of $17 million to $32 million, depending on the cost of the program. These resources are currently being absorbed, but since utilization is not being captured by any data set in the province, it is difficult to quantify and estimate. Provincial programs may be under-resourced, and patients may not be accessing these services effectively. Data from the LTOT provincial program (based on fiscal year 2006 information) suggested that the burden was $65 million, with potential expenditures of up to $0.2 million in Years 1 to 3 for incident cases. From the clinical evidence on ventilation (i.e., reduction in length of stay in hospital), there were potential cost savings to the hospitals of $42 million and $12 million for NPPV and weaning with NPPV, respectively, if the study intervention were adopted. Future cost savings were projected to be up to $4 million and $1 million, respectively, for incident cases.

CONCLUSIONS

Currently, costs for most of these interventions are being absorbed by provider services, the Ontario Drug Benefit Program, the Assistive Devices Program, and the hospital global budget. The most cost-effective intervention for COPD will depend on decision-makers’ willingness to pay. Lack of provincial data sets capturing resource utilization for the various interventions poses a challenge for estimating current burden and future expenditures.

Community-based multidisciplinary care for patients with stable chronic obstructive pulmonary disease (COPD): an evidence-based analysis

In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions. After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses. The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html. Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework. Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Pulmonary Rehabilitation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Long-term Oxygen Therapy for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Hospital-at-Home Programs for Patients With Acute Exacerbations of Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Home Telehealth for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis. Cost-Effectiveness of Interventions for Chronic Obstructive Pulmonary Disease Using an Ontario Policy Model. Experiences of Living and Dying With COPD: A Systematic Review and Synthesis of the Qualitative Empirical Literature. For more information on the qualitative review, please contact Mita Giacomini at: http://fhs.mcmaster.ca/ceb/faculty_member_giacomini.htm. For more information on the economic analysis, please visit the PATH website: http://www.path-hta.ca/About-Us/Contact-Us.aspx. The Toronto Health Economics and Technology Assessment (THETA) collaborative has produced an associated report on patient preference for mechanical ventilation. For more information, please visit the THETA website: http://theta.utoronto.ca/static/contact. OBJECTIVE: The objective of this evidence-based analysis was to determine the effectiveness and cost-effectiveness of multidisciplinary care (MDC) compared with usual care (UC, single health care provider) for the treatment of stable chronic obstructive pulmonary disease (COPD). CLINICAL NEED: CONDITION AND TARGET POPULATION: Chronic obstructive pulmonary disease is a progressive disorder with episodes of acute exacerbations associated with significant morbidity and mortality. Cigarette smoking is linked causally to COPD in more than 80% of cases. Chronic obstructive pulmonary disease is among the most common chronic diseases worldwide and has an enormous impact on individuals, families, and societies through reduced quality of life and increased health resource utilization and mortality. The estimated prevalence of COPD in Ontario in 2007 was 708,743 persons. TECHNOLOGY: Multidisciplinary care involves professionals from a range of disciplines, working together to deliver comprehensive care that addresses as many of the patient’s health care and psychosocial needs as possible. Two variables are inherent in the concept of a multidisciplinary team: i) the multidisciplinary components such as an enriched knowledge base and a range of clinical skills and experiences, and ii) the team components, which include but are not limited to, communication and support measures. However, the most effective number of team members and which disciplines should comprise the team for optimal effect is not yet known. RESEARCH QUESTION: What is the effectiveness and cost-effectiveness of MDC compared with UC (single health care provider) for the treatment of stable COPD? RESEARCH METHODS: LITERATURE SEARCH: SEARCH STRATEGY: A literature search was performed on July 19, 2010 using OVID MEDLINE, OVID MEDLINE In-Process and Other Non-Indexed Citations, OVID EMBASE, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Wiley Cochrane Library, and the Centre for Reviews and Dissemination database, for studies published from January 1, 1995 until July 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. INCLUSION CRITERIA: health technology assessments, systematic reviews, or randomized controlled trials; studies published between January 1995 and July 2010; COPD study population; studies comparing MDC (2 or more health care disciplines participating in care) compared with UC (single health care provider). EXCLUSION CRITERIA: grey literature; duplicate publications; non-English language publications; study population less than 18 years of age. OUTCOMES OF INTEREST: hospital admissions; emergency department (ED) visits; mortality; health-related quality of life; lung function. QUALITY OF EVIDENCE: The quality of each included study was assessed, taking into consideration allocation concealment, randomization, blinding, power/sample size, withdrawals/dropouts, and intention-to-treat analyses. The quality of the body of evidence was assessed as high, moderate, low, or very low according to the GRADE Working Group criteria. The following definitions of quality were used in grading the quality of the evidence: [Table: see text] SUMMARY OF FINDINGS: Six randomized controlled trials were obtained from the literature search. Four of the 6 studies were completed in the United States. The sample size of the 6 studies ranged from 40 to 743 participants, with a mean study sample between 66 and 71 years of age. Only 2 studies characterized the study sample in terms of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPD stage criteria, and in general the description of the study population in the other 4 studies was limited. The mean percent predicted forced expiratory volume in 1 second (% predicted FEV₁) among study populations was between 32% and 59%. Using this criterion, 3 studies included persons with severe COPD and 2 with moderate COPD. Information was not available to classify the population in the sixth study. Four studies had MDC treatment groups which included a physician. All studies except 1 reported a respiratory specialist (i.e., respiratory therapist, specialist nurse, or physician) as part of the multidisciplinary team. The UC group was comprised of a single health care practitioner who may or may not have been a respiratory specialist. A meta-analysis was completed for 5 of the 7 outcome measures of interest including: health-related quality of life, lung function, all-cause hospitalization, COPD-specific hospitalization, and mortality. There was only 1 study contributing to the outcome of all-cause and COPD-specific ED visits which precluded pooling data for these outcomes. Subgroup analyses were not completed either because heterogeneity was not significant or there were a small number of studies that were meta-analysed for the outcome. QUALITY OF LIFE: Three studies reported results of quality of life assessment based on the St. George’s Respiratory Questionnaire (SGRQ). A mean decrease in the SGRQ indicates an improvement in quality of life while a mean increase indicates deterioration in quality of life. In all studies the mean change score from baseline to the end time point in the MDC treatment group showed either an improvement compared with the control group or less deterioration compared with the control group. The mean difference in change scores between MDC and UC groups was statistically significant in all 3 studies. The pooled weighted mean difference in total SGRQ score was −4.05 (95% confidence interval [CI], −6.47 to 1.63; P = 0.001). The GRADE quality of evidence was assessed as low for this outcome. LUNG FUNCTION: Two studies reported results of the FEV₁ % predicted as a measure of lung function. A negative change from baseline infers deterioration in lung function and a positive change from baseline infers an improvement in lung function. The MDC group showed a statistically significant improvement in lung function up to 12 months compared with the UC group (P = 0.01). However this effect is not maintained at 2-year follow-up (P = 0.24). The pooled weighted mean difference in FEV₁ percent predicted was 2.78 (95% CI, −1.82 to −7.37). The GRADE quality of evidence was assessed as very low for this outcome indicating that an estimate of effect is uncertain. HOSPITAL ADMISSIONS: ALL-CAUSE: Four studies reported results of all-cause hospital admissions in terms of number of persons with at least 1 admission during the follow-up period. Estimates from these 4 studies were pooled to determine a summary estimate. There is a statistically significant 25% relative risk (RR) reduction in all-cause hospitalizations in the MDC group compared with the UC group (P < 0.001). The index of heterogeneity (I²) value is 0%, indicating no statistical heterogeneity between studies. The GRADE quality of evidence was assessed as moderate for this outcome, indicating that further research may change the estimate of effect. COPD-SPECIFIC HOSPITALIZATION: Three studies reported results of COPD-specific hospital admissions in terms of number of persons with at least 1 admission during the follow-up period. Estimates from these 3 studies were pooled to determine a summary estimate. There is a statistically significant 33% RR reduction in all-cause hospitalizations in the MDC group compared with the UC group (P = 0.002). The I² value is 0%, indicating no statistical heterogeneity between studies. The GRADE quality of evidence was assessed as moderate for this outcome, indicating that further research may change the estimate of effect. EMERGENCY DEPARTMENT VISITS: ALL-CAUSE: Two studies reported results of all-cause ED visits in terms of number of persons with at least 1 visit during the follow-up period. There is a statistically nonsignificant reduction in all-cause ED visits when data from these 2 studies are pooled (RR, 0.64; 95% CI, 0.31 to −1.33; P = 0.24). The GRADE quality of evidence was assessed as very low for this outcome indicating that an estimate of effect is uncertain. COPD-SPECIFIC: One study reported results of COPD-specific ED visits in terms of number of persons with at least 1 visit during the follow-up period. There is a statistically significant 41% reduction in COPD-specific ED visits when the data from these 2 studies are pooled (RR, 0.59; 95% CI, 0.43−0.81; P < 0.001). The GRADE quality of evidence was assessed as moderate for this outcome. MORTALITY: Three studies reported the mortality during the study follow-up period. Estimates from these 3 studies were pooled to determine a summary estimate. There is a statistically nonsignificant reduction in mortality between treatment groups (RR, 0.81; 95% CI, 0.52−1.27; P = 0.36). The I² value is 19%, indicating low statistical heterogeneity between studies. All studies had a 12-month follow-up period. The GRADE quality of evidence was assessed as low for this outcome. CONCLUSIONS: Significant effect estimates with moderate quality of evidence were found for all-cause hospitalization, COPD-specific hospitalization, and COPD-specific ED visits (Table ES1). A significant estimate with low quality evidence was found for the outcome of quality of life (Table ES2). All other outcome measures were nonsignificant and supported by low or very low quality of evidence.

Cost-effectiveness of specialized multidisciplinary heart failure clinics in Ontario, Canada

BACKGROUND

Specialized multidisciplinary clinics have been shown to reduce mortality in heart failure (HF). Our objective was to evaluate the cost-effectiveness of this model of care delivery.

METHODS

We performed a cost-effectiveness analysis, with a 12-year time horizon, from the perspective of the Ontario Ministry of Health and Long-term Care, comparing a standard care cohort, consisting of all patients admitted to hospital with HF in 2005, to a hypothetical cohort treated in HF clinics. Survival curves describing the natural history of HF were constructed using mortality estimates from the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study. Survival benefits and resource uptake associated with HF clinics were estimated from a meta-analysis of published trials. HF clinics costs were obtained by costing a representative clinic in Ontario. Health-related costs were determined through linkage to administrative databases. Outcome measures included life expectancy (years), costs (in 2008 Canadian dollars) and the incremental cost-effectiveness ratio (ICER).

RESULTS

HF clinics were associated with a 29% reduction in all-cause mortality (risk ratio [RR] 0.71; 95% confidence interval [CI] 0.56-0.91) but a 12% increase in hospitalizations (RR 1.12; 95% CI 0.92-1.135). The cost of care in HF clinics was $52 per 30 patient-days. Projected life-expectancy of HF clinic patients was 3.91 years, compared to 3.21 years for standard care. The 12-year cumulative cost per patient in the HF clinic group was $66,532 versus $53,638 in the standard care group. The ICER was $18,259/life-year gained.

CONCLUSIONS

HF clinics appear to be a cost effective way of delivering ambulatory care to HF patients.

Severe hemodilutional anemia increases cerebral tissue injury following acute neurotrauma

Anemia may worsen neurological outcomes following traumatic brain injury (TBI) by undefined mechanisms. We hypothesized that hemodilutional anemia accentuates hypoxic cerebral injury following TBI. Anesthetized rats underwent unilateral TBI or sham injury (n > or = 7). Target hemoglobin concentrations between 50 and 70 g/l were achieved by exchanging 40-50% of the blood volume (1:1) with pentastarch. The effect of TBI, anemia, and TBI-anemia was assessed by measuring brain tissue oxygen tension (Pbr(O(2))), regional cerebral blood flow (rCBF), jugular venous oxygen saturation (Sjv(O(2))), cerebral contusion area, and nuclear staining for programmed cell death. Baseline postinjury Pbr(O(2)) values in the TBI and TBI-anemia groups (9.3 +/- 1.3 and 11.3 +/- 4.1 Torr, respectively) were lower than the uninjured controls (18.2 +/- 5.2 Torr, P < 0.05 for both). Hemodilution caused a further reduction in Pbr(O(2)) in the TBI-anemia group relative to the TBI group without anemia (7.8 +/- 2.7 vs. 14.8 +/- 3.9 Torr, P < 0.05). The rCBF remained stable after TBI and increased comparably after hemodilution in both anemia and TBI-anemia groups. The Sjv(O(2)) was elevated after TBI (87.4 +/- 8.9%, P < 0.05) and increased further following hemodilution (95.0 +/- 1.6%, P < 0.05). Cerebral contusion area and nuclear counts for programmed cell death were increased following TBI-anemia (4.1 +/- 3.0 mm(2) and 686 +/- 192, respectively) relative to TBI alone (1.3 +/- 0.3 mm(2) and 404 +/- 133, respectively, P < 0.05 for both). Hemodilutional anemia reduced cerebral Pbr(O(2)) and oxygen extraction and increased cell death following TBI. These results support our hypothesis that acute anemia accentuated hypoxic cerebral injury after neurotrauma.

A phase I, two-center study of the pharmacokinetics and pharmacodynamics of dexmedetomidine in children

BACKGROUND

To investigate dexmedetomidine in children, the authors performed an open-label study of the pharmacokinetics and pharmacodynamics of dexmedetomidine.

METHODS

Thirty-six children were assigned to three groups; 24 received dexmedetomidine and 12 received no drug. Three doses of dexmedetomidine, 2, 4, and 6 microg x kg x h, were infused for 10 min. Cardiorespiratory responses and sedation were recorded for 24 h. Plasma concentrations of dexmedetomidine were collected for 24 h and analyzed. Pharmacokinetic variables were determined using nonlinear mixed effects modeling (NONMEM program). Cardiorespiratory responses were analyzed.

RESULTS

Thirty-six children completed the study. There was an apparent difference in the pharmacokinetics between Canadian and South African children. The derived volumes and clearances in the Canadian children were V1 = 0.81 l/kg, V2 = 1.0 l/kg, Cl1 (systemic clearance) = 0.013 l x kg x min, Cl2 = 0.030 l x kg x min. The intersubject variabilities for V1, V2, and Cl1 were 45%, 38%, and 22%, respectively. Plasma concentrations in South African children were 29% less than in Canadian children. The volumes and clearances in the South African children were 29% larger. The terminal half-life was 110 min (1.8 h). Median absolute prediction error for the two-compartment mammillary model was 18%. Heart rate and systolic blood pressure decreased with time and with increasing doses of dexmedetomidine. Respiratory rate and oxygen saturation (in air) were maintained. Sedation was transient.

CONCLUSION

The pharmacokinetics of dexmedetomidine in children are predictable with a terminal half-life of 1.8 h. Hemodynamic responses decreased with increasing doses of dexmedetomidine. Respiratory responses were maintained, whereas sedation was transient.

β 2 Adrenergic antagonist inhibits cerebral cortical oxygen delivery after severe haemodilution in rats

BACKGROUND

Haemodilution has been associated with neurological morbidity in surgical patients. This study tests the hypothesis that inhibition of cerebral vasodilatation by systemic beta2 adrenergic blockade would impair cerebral oxygen delivery leading to tissue hypoxia in severely haemodiluted rats.

METHODS

Under general anaesthesia, cerebral tissue probes were placed to measure temperature, regional cerebral blood flow (rCBF) and tissue oxygen tension (P(Br)O2) in the parietal cerebral cortex or hippocampus. Baseline measurements were established before and after systemic administration of either a beta2 antagonist (10 mg kg(-1) i.v., ICI 118, 551) or saline vehicle. Acute haemodilution was then performed by simultaneously exchanging 50% of the estimated blood volume (30 ml kg(-1)) with pentastarch. Arterial blood gases (ABGs), haemoglobin concentration (co-oximetry), mean arterial blood pressure (MAP) and heart rate (HR) were also measured. Data were analysed using a two-way anova and post hoc Tukey's test [mean (sd)].

RESULTS

Haemodilution reduced the haemoglobin concentration comparably in all groups [71 (9) g litre(-1)]. There were no differences in ABGs, co-oximetry, HR and MAP measurements between control and beta2 blocked rats, either before or 60 min after drug or vehicle administration. In rats treated with the beta2 antagonist there was a significant reduction in parietal cerebral cortical temperature, regional blood flow and tissue oxygen tension, relative to control rats, 60 min after haemodilution (P<0.05 for each). These differences were not observed when probes were placed in the hippocampus.

CONCLUSION

Systemic beta2 adrenergic blockade inhibited the compensatory increase in parietal cerebral cortical oxygen delivery after haemodilution thereby reducing cerebral cortical tissue oxygen tension.

Development and psychometric evaluation of the pediatric anesthesia emergence delirium scale

BACKGROUND

Emergence delirium has been investigated in several clinical trials. However, no reliable and valid rating scale exists to measure this phenomenon in children. Therefore, the authors developed and evaluated the Pediatric Anesthesia Emergence Delirium (PAED) scale to measure emergence delirium in children.

METHODS

A list of scale items that were statements describing the emergence behavior of children was compiled, and the items were evaluated for content validity and statistical significance. Items that satisfied these evaluations comprised the PAED scale. Each item was scored from 1 to 4 (with reverse scoring where applicable), and the scores were summed to obtain a total scale score. The degree of emergence delirium varied directly with the total score. Fifty children were enrolled to determine the reliability and validity of the PAED scale. Scale validity was evaluated using five hypotheses: The PAED scale scores correlated negatively with age and time to awakening and positively with clinical judgment scores and Post Hospital Behavior Questionnaire scores, and were greater after sevoflurane than after halothane. The sensitivity of the scale was also determined.

RESULTS

Five of 27 items that satisfied the content validity and statistical analysis became the PAED scale: (1) The child makes eye contact with the caregiver, (2) the child's actions are purposeful, (3) the child is aware of his/her surroundings, (4) the child is restless, and (5) the child is inconsolable. The internal consistency of the PAED scale was 0.89, and the reliability was 0.84 (95% confidence interval, 0.76-0.90). Three hypotheses supported the validity of the scale: The scores correlated negatively with age (r = -0.31, P <0.04) and time to awakening (r = -0.5, P <0.001) and were greater after sevoflurane anesthesia than halothane (P <0.008). The sensitivity was 0.64.

CONCLUSIONS

These results support the reliability and validity of the PAED scale.

Bupivacaine 0.125% produces motor block and weakness with fentanyl epidural analgesia in children

PURPOSE

Epidural infusions of fentanyl (2 micrograms.ml-1) alone or combined with bupivacaine 0.125% were compared for perioperative analgesia, motor block and other side-effects in children who underwent urological surgery.

METHODS

In a prospective, double-blind study, 42 children, ASA I-II, 1-16 yr, were randomly allocated to receive either epidural F (fentanyl bolus 2 micrograms.kg-1 in 0.5 ml.kg-1 saline followed by 2 micrograms.ml-1 fentanyl infusion) or epidural F-B (fentanyl bolus 2 micrograms.kg-1 in 0.5 ml.kg-1 bupivacaine 0.25% followed by 2 micrograms.ml-1 fentanyl infusion in bupivacaine 0.125%) after induction of general anaesthesia. Adequacy of analgesia, lower limb motor block and side-effects were assessed four hourly postoperatively.

RESULTS

Both infusion regimens provided excellent analgesia (median objective pain scores = 0). Epidural infusion rates were similar in the F (0.29 +/- 0.07 ml.kg-1.hr-1) and F-B (0.26 +/- 0.05 ml.kg-1.hr-1) groups. Three children in the F group and all children in the F-B group developed lower limb weakness. (P < 0.05) Bromage scores were different in the F group (median 0, range 0-0.66) compared with the F-B group (median 0.33, range 0-1) (P < 0.001). Other side-effects did not differ.

CONCLUSION

Postoperative epidural fentanyl infusion provides equipotent analgesia to administration of a solution including both fentanyl and bupivacaine 0.125% and causes less lower limb weakness. No reduction in the fentanyl requirement resulted from the addition of bupivacaine 0.125%.

Maintenance and recovery characteristics after sevoflurane or propofol during ambulatory surgery in children with epidural blockade

PURPOSE

To compare the maintenance and recovery characteristics after sevoflurane with those after propofol in children with epidural blockade.

METHODS

Fifty unpremedicated, children ASA I-II, 2-8 yr of age, scheduled for elective urological surgery as outpatients, were randomly allocated to receive either: 1) sevoflurane for induction and maintenance of anaesthesia or 2) propofol for induction (2-3 mg.kg-1 i.v.) and for maintenance (5-10 mg.kg-1.hr-1 i.v.). All children received N2O 70% in oxygen before induction and throughout the anaesthetic, rocuronium for neuromuscular blockade and a lumbar or caudal epidural block before incision. Heart rate (HR), systolic blood pressure (SBP), recovery times and all side effects during maintenance and recovery were recorded by a blinded observer. Adverse events during the first 24 hr were also recorded.

RESULTS

Mean HR increased 5-10% after induction in both groups reaching a maximum by five minutes. Heart rate returned to baseline by skin incision in the sevoflurane group and by 10 min after induction in the propofol group. During maintenance, HR decreased by 10-20% below baseline values by 20 min in the propofol group only, where it remained for the remainder of the anaesthetic. Similarly, SBP increased by 10% after induction of anaesthesia in both groups, but returned to baseline by 10 min. Light anaesthesia occurred in four (16%) children, all in the propofol group. Emergence and recovery indices were similar in the two groups.

DISCUSSION

Sevoflurane and propofol exhibit similar maintenance and recovery profiles when combined with epidural analgesia in children undergoing ambulatory surgery.

Single-breath vital capacity rapid inhalation induction in children: 8% sevoflurane versus 5% halothane

BACKGROUND

The authors compared the speed of induction of anesthesia with sevoflurane with and without nitrous oxide with the speed of halothane and nitrous oxide using a single-breath vital capacity induction.

METHODS

With informed parental consent, 51 healthy unpremedicated children aged 5-12 yr were randomized to inhale a single breath of one of three gas mixtures: 8% sevoflurane in 66% nitrous oxide, 8% sevoflurane in oxygen, or 5% halothane in 66% nitrous oxide. A blinded observer recorded the times to loss of the eyelash reflex, return of conjugate gaze, the presence of airway reflex responses, involuntary movement, and hemodynamic responses.

RESULTS

Forty-two children completed the study. The times (mean +/- SD) to loss of the eyelash reflex with sevoflurane/nitrous oxide, 38+/-8 s, and for sevoflurane-oxygen, 34+/-12 s, were less than that with halothane-nitrous oxide, 58+/-17 s (P < 0.01). Movement occurred less frequently during sevoflurane than during halothane anesthesia (P < 0.05). The times to return of conjugate gaze and the incidence of airway reflex responses were similar among the groups. The incidence of dysrhythmias in the sevoflurane groups was less than that in the halothane group (P < 0.01).

CONCLUSIONS

Induction of anesthesia with a single breath of 8% sevoflurane with or without 66% nitrous oxide is more rapid than with 5% inspired halothane with 66% nitrous oxide in children. The incidence of movement and dysrhythmias during a single-breath induction with sevoflurane are less than they are with halothane.

Recovery characteristics of propofol anaesthesia, with and without nitrous oxide: a comparison with halothane/nitrous oxide anaesthesia in children

Few studies have examined whether nitrous oxide influences the recovery characteristics of propofol anaesthesia. The present study examined the effect of nitrous oxide on the recovery characteristics of propofol anaesthesia, and compared these data with those for halothane/nitrous oxide anaesthesia. Sixty children aged 3-12 years were assigned at random to receive one of three maintenance regimens: propofol with or without nitrous oxide (70%) or halothane/nitrous oxide (70%). During propofol/N2O anaesthesia, the infusion rate of propofol (180 +/- 39 micrograms.kg-1.min-1) required to maintain the mean arterial pressure and heart rate within 20% of the baseline values was significantly less than that during propofol/O2 (220 +/- 37 micrograms.kg-1.min-1; P < 0.005). The time from discontinuation of anaesthesia to eye-opening (11 +/- 6 min), to response to commands (12 +/- 6 min), and to return of full wakefulness (21 +/- 10 min) after propofol/N2O were similar to those after propofol/O2, but significantly less (by approximately 30%) than those after halothane (P < 0.05). The overall incidence of emesis after propofol/N2O (53%) was greater than that after propofol/O2 (17%, P < 0.05) and comparable to that after halothane/N2O (58%). These data suggest that N2O has little effect on the rate of recovery after propofol, but significantly increases the incidence of postoperative emesis, thereby attenuating one of the main attributes of propofol anaesthesia.

Vomiting after adenotonsillectomy in children: a comparison of ondansetron, dimenhydrinate, and placebo

We compared the effectiveness of ondansetron, dimenhydrinate, and placebo for the prevention of postoperative vomiting in children after adenotonsillectomy. In a randomized, placebo-controlled, double-blind study, 74 children, 2-10 yr of age scheduled for adenotonsillectomy as outpatients were given a single i.v. dose of ondansetron (0.1 mg/kg, n = 26), dimenhydrinate (0.5 mg/kg, n = 25), or placebo (saline, n = 23) at induction of anesthesia. The incidence of retching and vomiting (POV) and side effects observed 24 h after surgery were recorded. Demographic data were similar among the three groups. The 24-h incidence of POV was 42%, 79%, and 82% in the ondansetron, dimenhydrinate, and placebo groups, respectively (ondansetron compared with dimenhydrinate [P < 0.02] or placebo [P < 0.01]). The study was stopped after two children vomited large volumes of bloody fluid 9 and 22 h after surgery without previous signs of occult bleeding. Both children had received ondansetron. We conclude that ondansetron is superior to dimenhydrinate or placebo for the prevention of POV after adenotonsillectomy in children. Antiemetics may mask the signs of bleeding after adenotonsillectomy.

IMPLICATIONS

I.v. ondansetron (0.1 mg/kg) is more effective than both dimenhydrinate and placebo in preventing vomiting after adenotonsillectomy in healthy children. However, antiemetics may also mask the presence of blood in the stomach by preventing vomiting, and this should be appreciated when adenotonsillectomy is performed on an outpatient basis.

Subhypnotic propofol does not treat postoperative vomiting in children after adenotonsillectomy

PURPOSE

To investigate the efficacy of a subhypnotic dose of propofol to treat vomiting in children after adenotonsillectomy.

METHODS

Two hundred and fifty-two children, aged 2-12 yr, underwent a standardized anaesthetic opioid administration, and postoperative care after adenotonsillectomy, adenoidectomy or tonsillectomy. A prospective, double-blinded, placebo-controlled study was performed in 70 of the patients who retched or vomited after surgery and who had intravenous access. Patients were assigned randomly to receive either 0.2 mg.kg-1) propofol (n = 35), or placebo (intralipid 10%, n = 35).

RESULTS

The overall incidence of vomiting during the first 18-24 hr was 50%. Of those who had received propofol after the first episode of vomiting, 63% relapsed requiring a rescue antiemetic compared with 57% of those who had received intralipid (P = NS). Of the children who received propofol, 54% experienced pain on injection and 46% were mildly sedated compared with 3% and 11%, respectively, in the placebo group (P < 0.003).

CONCLUSION

We conclude that an intravenous bolus of 0.2 mg.kg-1 propofolis not effective in the treatment of postoperative vomiting in children after adenotonsillectomy when a standardized anaesthetic with thiopentone, halothane, nitrous oxide, and 1.5 mg.kg-1 codeine phosphate is used, but it does cause sedation and pain on injection.

Anaesthesia for insertion of ear tubes in children: comparison of propofol, thiopentone and halothane

To determine the quality of anaesthesia and speed of recovery after propofol anaesthesia for myringotomy in children, 100 children 2-12 years were randomized to one of four anaesthetic regimens for induction/maintenance: thiopentone (STP) (5 mg.kg-1)/halothane, propofol (3 mg.kg-1)/halothane, halothane/halothane or propofol (3 mg.kg-1)/propofol bolus (0.5 mg.kg-1 every 3 min (10 mg.kg-1.h-1)). Nitrous oxide (70%) in oxygen (30%) was used to facilitate insertion of an intravenous catheter and was continued throughout the anaesthetic. We found that the incidence of intraoperative movement in response to surgical stimulation was significantly greater in the prop/prop group 32%, compared with the three other groups (P < 0.02). Although some recovery variables (time to response to questions, sit unaided, tolerate oral fluids, and discharge with fluids) were achieved more rapidly by the prop/ prop group than the other three groups, the times to open eyes, obey commands and, most importantly, discharge from recovery without fluids did not differ between the prop/prop and the hal/ hal groups. We conclude that there is little benefit in using propofol as an induction agent alone or in combination with a propofol maintenance anaesthetic for paediatric myringotomy and tube surgery.

Parental perceptions, expectations and preferences for the postanaesthetic recovery of children

Improvements in anaesthesia have led to the introduction of rapid-acting agents which quicken recovery and decrease sleepiness. Whether parents believe a rapid postanaesthetic recovery is an advantage is unknown. Therefore, we evaluated the parental perceptions, expectations and preferences for the postanaesthetic recovery of children. One hundred and three parents of children having ambulatory surgery completed a structured questionnaire and the results of 101 are presented. Results indicate that 93% of parents expect their child to be sleepy after surgery. Seventy-four per cent of parents indicated they would prefer their child to be sleepy or tired in the first 24 h postoperatively. Eight-five percent of parents would not be upset if their child's discharge was delayed up to three hours because their child was too sleepy. Finally 45.5% of parents are extremely concerned about their child experiencing postoperative pain and 68% believe that their child would be in more pain if they recovered rapidly from the anaesthetic. These results indicate that rapid recovery from anaesthesia and quick discharge from hospital are not key expectations of parents of children admitted for day surgery. Parents associate a rapid recovery with more pain. Parents need to be more fully informed of the advantages of a rapid recovery and reassured that children can recover quickly and completely but at the same time be comfortable postanaesthetic.

Pharmacokinetics of the active metabolite (MDL 74,156) of dolasetron mesylate after oral or intravenous administration to anesthetized children

BACKGROUND

Dolasetron mesylate is a selective 5-HT3 receptor antagonist under investigation as an antiemetic in children. Published studies indicate that its antiemetic activity results from the active metabolite (MDL 74,156), which is produced within 10 minutes of administration of dolasetron mesylate.

METHODS

The pharmacokinetics of MDL 74,156 and the safety and tolerability of dolasetron mesylate were studied after a single oral or intravenous dose of 1.2 mg.kg-1 dolasetron mesylate to healthy children from 2 to 12 years of age. Oral dolasetron was administered to 12 children 1 to 2 hours before anesthesia. Intravenous dolasteron was administered to 18 children at induction of anesthesia. Serial blood samples were collected for 24 hours after dosing to measure the plasma concentration of MDL 74,156. Indexes of liver and kidney function were determined, and electrocardiograms and adverse events were recorded.

Dimenhydrinate decreases vomiting after strabismus surgery in children

Dimenhydrinate, an H1-receptor antagonist, has been used to both prevent and treat postoperative vomiting (POV) in children for several decades. However, its effectiveness for POV after strabismus surgery remains anecdotal. This study was designed to determine the effectiveness and side effects of dimenhydrinate for the prevention of POV in children after strabismus surgery. Eighty ASA physical status I or II children, ages 1-12 yr inclusive, who were undergoing strabismus surgery, were prospectively and randomly allocated to receive either dimenhydrinate 0.5 mg/kg intravenously (n = 40) or placebo (n = 40) at induction of anesthesia. The incidence of POV and the times to arousal (and discharge from the recovery room and hospital) were recorded postoperatively in a double blinded manner. For 24 h after discharge from the hospital, all emetic episodes and medications given were recorded by the parents. Demographic data did not differ between the groups. Children who received dimenhydrinate had significantly less POV both inhospital (10%) and overall (30%) than those who received placebo (in-hospital 38%, P < 0.008; overall 65%, P < 0.003). The times to arousal and discharge from the hospital did not differ between the two groups. Dimenhydrinate (0.5 mg/kg) is an effective, safe, and inexpensive antiemetic in children undergoing strabismus surgery. It significantly reduces the incidence of vomiting for 24 h postoperatively and is not associated with prolonged sedation or other adverse effects.

Plasma inorganic fluoride concentrations after sevoflurane anesthesia in children

BACKGROUND

Sevoflurane is degraded in vivo in adults yielding plasma concentrations of inorganic fluoride [F-] that, in some patients, approach or exceed the 50- micron theoretical threshold for nephrotoxicity. To determine whether the plasma concentration of inorganic fluoride [F-] after 1-5 MAC x h sevoflurane approaches a similar concentration in children, the following study in 120 children scheduled for elective surgery was undertaken.

METHODS

Children were randomly assigned to one of three treatment groups before induction of anesthesia: group 1 received sevoflurane in air/oxygen 30% (n = 40), group 2 received sevoflurane in 70% N2O/30% O2 (n = 40), and group 3 received halothane in 70% N2O/30% O2 (n = 40). Mapleson D or F circuits with fresh gas flows between 3 and 61/min were used Whole blood was collected at induction and termination of anesthesia and at 1, 4, 6, 12, and 18 or 24 h postoperatively for determination of the [F-]. Plasma urea and creatinine concentrations were determined at induction of anesthesia and 18 or 24 h postoperatively.

RESULTS

The mean (+/- SD) duration of sevoflurane anesthesia, 2.7 +/- 1.6 MAC x h (range 1.1-8.9 MAC x h), was similar to that of halothane, 2.5 +/- 1.1 MAC x h. The peak [F-] after sevoflurane was recorded at 1 h after termination of the anesthetic in all but three children (whose peak values were recorded between 4 and 6 h postanesthesia). The mean peak [F-] after sevoflurane was 15.8 +/- 4.6 microns. The [F-] decreased to <6.2 microns b 24 h postanesthesia. Both the peak [F-] (r2 = 0.50) and the area under the plasma concentration of inorganic fluoride-time curve (r2 = 0.57) increased in parallel with the MAC x h of sevoflurane. The peak [F-] after halothane, 2.0 +/- 1.2 microns, was significantly less than that after sevoflurane (P<0.00012) and did not correlate with the duration of halothane anesthesia (MAC x h; r2 = 0.007). Plasma urea concentrations decreased 24 h after surgery compared with preoperative values for both anesthetics (P<0.01), whereas plasma creatinine concentrations did not change significantly with either anesthetic.

CONCLUSIONS

It was concluded that, during the 24 h after 2.7 +/- 1.6 MAC x h sevoflurane, the peak recorded [F-] is low (15.8 microns), F- is eliminated rapidly, and children are unlikely to be at risk of nephrotoxicity from high [F-].

Pharmacokinetics of intravenous ondansetron in healthy children undergoing ear, nose, and throat surgery

BACKGROUND

To determine the pharmacokinetics of the 5-HT3 antagonist ondansetron in children, informed written consent was obtained from the parents of 21 healthy children aged from 3 to 12 years scheduled for ear, nose, and throat surgery.

METHODS

The children were stratified according to age: 3 to 7 years and 7.1 to 12 years, and a single intravenous infusion of 2 or 4 mg ondansetron, respectively, was administered over 5 minutes before induction of anesthesia. After completion of the infusion, anesthesia was induced intravenously and maintained with inhalational anesthesia. Whole blood (3 ml) was obtained before administration of ondansetron, at completion of the infusion, at the beginning and end of surgery, and at 3, 4, 6, 8, 10, and 12 hours after start of the infusion. Pharmacokinetic variables were determined with use of standard noncompartmental techniques.

RESULTS

Mean plasma clearance was 0.50 L.hr-1.kg-1 and 0.39 L.hr-1.kg-1, the mean volume of distribution at steady-state was 1.70 L.kg-1 and 1.61 L.kg-1, and the mean plasma terminal half-life was 2.6 hours and 3.1 hours for the 2 mg and 4 mg groups, respectively. On a body surface area basis, mean plasma clearance was 14.0 and 13.7 L.hr-1.m-2 and mean volume of distribution was 47.7 and 55.9 L.m-2 for the 2 and 4 mg groups, respectively. There were no serious adverse events attributable to ondansetron.

CONCLUSIONS

These data indicate that the pharmacokinetics of ondansetron in children from 3 to 12 years old are predictable and similar to those in adults. The elimination half-life of ondansetron increases in parallel with age. However, clearance is constant when normalized to body surface area, but the volume of distribution increases over the age range studied.

The pharmacology of sevoflurane in infants and children

BACKGROUND

Sevoflurane is a new volatile anesthetic with physical properties that should make it suitable for anesthesia (MAC of sevoflurane on oxygen alone and in 60% nitrous oxide, (MAC) of sevoflurane in oxygen alone and in 60% nitrous oxide, the hemodynamic, induction and emergence responses to sevoflurane and the metabolism to inorganic fluoride were studied in 90 ASA physical status 1 or 2 neonates, infants, and children.

METHODS

MAC of sevoflurane in oxygen was determined in six groups of subjects stratified according to age: full-term neonates, infants 1-6 and > 6-12 months and children > 1-3, > 3-5 and > 5-12 yr. MAC in 60% nitrous oxide was determined in a separate group of children 1-3 yr of age. After an inhalational induction, the trachea was intubated (except for neonates in whom an awake intubation was performed). MAC for each age group was determined using the Up-and-Down technique of Dixon.

RESULTS

MAC of sevoflurane in neonates, 3.3 +/- 0.2% and in infants 1-6 months of age, 3.2 +/- 0.1%, were similar; MAC in older infants 6-12 months and children 1-12 yr was constant at approximately 2.5%; MAC of sevoflurane in 60% nitrous oxide in children 1-3 yr of age was 2.0 +/- 0.2%. Systolic arterial pressure decreased significantly at 1 MAC before skin incision compared with awake values in all subjects except children 1-3 yr with 60% nitrous oxide and children 5-12 yr in oxygen, and then returned toward awake values after skin incision. Heart rate was unchanged at approximately 1 MAC sevoflurane before incision compared with awake values in all subjects except children > 3-5 and > 5-12 yr in whom heart rate increased before incision. Induction of anesthesia, particularly with respect to airway irritability, and emergence from sevoflurane anesthesia were not remarkable. The plasma concentration of inorganic fluoride reached maximum values (8.8-16.7 microM) 30 min after discontinuation of anesthesia.

CONCLUSIONS

We conclude that sevoflurane appears to be a suitable anesthetic agent for use in neonates, infants and children undergoing < or = 1 h of anesthesia.

Premedication of children with oral midazolam

In a randomized, double-blind, placebo-controlled study, the safety, efficacy and feasibility of oral midazolam premedication in children were evaluated in an ambulatory surgery unit. Eighty unmedicated children (ASA PS I or II, ages 1-6 yr) were randomly assigned to one of four groups receiving midazolam 0.5, 0.75, or 1.0 mg.kg-1 or a placebo 30 min before separation from parents. Heart rate, systolic blood pressure, arterial oxygen saturation, respiratory rate, sedation and anxiolysis scores were recorded before premedication, every five minutes for 30 min and then during induction of anaesthesia and recovery. We found that heart rate, systolic blood pressure, arterial oxygen saturation and respiratory rate were unchanged during the study. Sedation and anxiolysis scores in the midazolam-treated groups were greater than those in the placebo group and that anxiolysis at the time of separation from the parents was judged excellent in 80-90% of the children who received midazolam. However, sedation and anxiolysis did not differ among the three midazolam groups. Mean times to discharge from hospital were similar for all four groups. The side effects, loss of balance and head control, blurred vision and dysphoric reactions were observed only in the 0.75 and 1.0 mg.kg-1 midazolam groups. We conclude that oral midazolam 0.5 mg.kg-1 is a safe and effective premedication and that 0.75 and 1 mg.kg-1 while offering no additional benefit, may cause more side effects.