Early economic evaluation of MRI-guided laser interstitial thermal therapy (MRgLITT) and epilepsy surgery for mesial temporal lobe epilepsy

Background

MRI-guided laser interstitial thermal therapy (MRgLITT) is a new minimally invasive treatment for temporal lobe epilepsy (TLE), with limited effectiveness data. It is unknown if the cost savings associated with shorter hospitalization could offset the high equipment cost of MRgLITT. We examined the cost-utility of MRgLITT versus surgery for TLE from healthcare payer perspective, and the value of additional research to inform policy decision on MRgLITT.

Methods

We developed a microsimulation model to evaluate quality adjusted life years (QALYs), costs, and incremental cost-effectiveness ratio (ICER) of MRgLITT versus surgery in TLE, assuming life-time horizon and 1.5% discount rate. Model inputs were derived from the literature. We conducted threshold and sensitivity analyses to examine parameter uncertainties, and expected value of partial perfect information analyses to evaluate the expected monetary benefit of eliminating uncertainty on probabilities associated with MRgLITT.

Results

MRgLITT yielded 0.08 more QALYs and cost $7,821 higher than surgery, with ICER of $94,350/QALY. Influential parameters that could change model outcomes include probabilities of becoming seizure-free from disabling seizures state and returning to disabling seizures from seizure-free state 5 years after surgery and MRgLITT, cost of MRgLITT disposable equipment, and utilities of disabling seizures and seizure-free states of surgery and MRgLITT. The cost-effectiveness acceptability curve showed surgery was preferred in more than 50% of iterations. The expected monetary benefit of eliminating uncertainty for probabilities associated with MRgLITT was higher than for utilities associated with MRgLITT.

Conclusions

MRgLITT resulted in more QALYs gained and higher costs compared to surgery in the base-case. The model was sensitive to variations in the cost of MRgLITT disposable equipment. There is value in conducting more research to reduce uncertainty on the probabilities and utilities of MRgLITT, but priority should be given to research focusing on improving the precision of estimates on effectiveness of MRgLITT.

Bridging health technology assessment (HTA) with multicriteria decision analyses (MCDA): field testing of the EVIDEM framework for coverage decisions by a public payer in Canada

BACKGROUND

Consistent healthcare decision making requires systematic consideration of decision criteria and evidence available to inform them. This can be tackled by combining multicriteria decision analysis (MCDA) and Health Technology Assessment (HTA). The objective of this study was to field-test a decision support framework (EVIDEM), explore its utility to a drug advisory committee and test its reliability over time.

METHODS

Tramadol for chronic non-cancer pain was selected by the health plan as a case study relevant to their context. Based on extensive literature review, a by-criterion HTA report was developed to provide synthesized evidence for each criterion of the framework (14 criteria for the MCDA Core Model and 6 qualitative criteria for the Contextual Tool). During workshop sessions, committee members tested the framework in three steps by assigning: 1) weights to each criterion of the MCDA Core Model representing individual perspective; 2) scores for tramadol for each criterion of the MCDA Core Model using synthesized data; and 3) qualitative impacts of criteria of the Contextual Tool on the appraisal. Utility and reliability of the approach were explored through discussion, survey and test-retest. Agreement between test and retest data was analyzed by calculating intra-rater correlation coefficients (ICCs) for weights, scores and MCDA value estimates.

RESULTS

The framework was found useful by the drug advisory committee in supporting systematic consideration of a broad range of criteria to promote a consistent approach to appraising healthcare interventions. Directly integrated in the framework as a "by-criterion" HTA report, synthesized evidence for each criterion facilitated its consideration, although this was sometimes limited by lack of relevant data. Test-retest analysis showed fair to good consistency of weights, scores and MCDA value estimates at the individual level (ICC ranging from 0.676 to 0.698), thus lending some support for the reliability of the approach. Overall, committee members endorsed the inclusion of most framework criteria and revealed important areas of discussion, clarification and adaptation of the framework to the needs of the committee.

CONCLUSIONS

By promoting systematic consideration of all decision criteria and the underlying evidence, the framework allows a consistent approach to appraising healthcare interventions. Further testing and validation are needed to advance MCDA approaches in healthcare decisionmaking.

Adverse events associated with pyrazinamide and levofloxacin in the treatment of latent multidrug-resistant tuberculosis

BACKGROUND

The current Canadian and US guidelines for the treatment of multidrug-resistant latent tuberculosis infection advocate the use of pyrazinamide and a fluoroquinolone as a first-line treatment option. However, there is very little information in the literature that describes the use of these agents together. This case series describes the probable association between multiple adverse events and the use of pyrazinamide and levofloxacin in the treatment of individuals with suspected latent multidrug-resistant tuberculosis infection.

METHODS

We studied a case series of 17 individuals with suspected latent multidrug-resistant tuberculosis infection in Hamilton, Ont., who were being treated with pyrazinamide and levofloxacin. The Naranjo scale was used to assess patients for musculoskeletal, central nervous system, gastrointestinal and dermatological adverse events. Hepatocellular events were assessed and defined using criteria established by the Council for International Organizations of Medical Sciences. Laboratory abnormalities and adverse events that were documented during combination drug therapy were evaluated to determine the likelihood of an association.

RESULTS

Fourteen individuals developed musculoskeletal adverse effects (11 were deemed to be probably related to combination therapy). There were 8 reports of central nervous system effects (5 of which were assessed as being probably associated with therapy). Hyperuricemia and gastrointestinal and dermatological effects were also common; the use of pyrazinamide and levofloxacin was believed to be probably responsible for the emergence of these adverse effects. There were 5 cases of hepatocellular injury. Therapy was discontinued in all individuals.

INTERPRETATION

The combination of pyrazinamide and levofloxacin appears to be a poorly tolerated regimen. The mechanism of a possible interaction is not yet understood. Given the severity of some of the adverse events, a better understanding of dosing and clearer guidelines for monitoring therapy are imperative if these drugs are to be prescribed together.

Preoperative therapeutic considerations in chronic suppurative otitis media

The present randomized, prospective study of 119 cases of chronic suppurative otitis media compares the effectiveness of inexpensive, atoxic, nonallergenic disinfectants applied locally, to that of a number of occasionally toxic antimicrobial chemotherapeutic agents, administered systemically. Systemic treatment resulted in a cure rate of 53.5% (SEp = 5.9%) while ototopical treatment resulted in a 39.5% cure rate (SEp = 7%). Eradication of pathogens or colonization by a nonpathogen occurred in 50.7% (SEp = 5.9%) with systemic treatment, and in 39.5% (SEp = 7%) with ototopical treatment. Bacteriological modification was 2.5 times more frequent with systemic treatment than with ototopical treatment. No recurrences were noted with ototopical treatment, while 13% to 36% recurrence rates were noted in various subgroups of cases treated systemically. Cure rates achieved with particular drug regimens (administration based on sensitivity tests in vitro) were: Azactam 25% (5%-57% confidence limits), sulfamethoxazole plus trimethoprim 58.6% (38%-76%), ciprofloxacin 87.5% (47%-99%), ciprofloxacin plus metronidazole 90% (55%-99%). Cure rates with other drugs were inconclusive because of the limited number of observations.

Reversible and permanent bone conduction threshold shift in cases of chronic suppurative otitis media

Bone conduction thresholds were measured in sixty-six cases of chronic suppurative otitis media before and after successful oral antimicrobial chemotherapeutic treatment. Comparison of pre- and post-treatment cumulative clinical audiograms of the diseased and the control ears of the same patients disclosed the presence of sensorineural hearing loss with a reversible and a permanent component in the diseased ears. The reversible threshold shift was observed over the higher frequencies, while the permanent threshold shift was equally imposed upon the whole range of the five tested frequencies.

Role of aerobic and anaerobic microorganisms in chronic suppurative otitis media

This study reports results of cultures of drainage from 119 cases with chronic otitis media. Mixed infections were found to occur 30 times more frequently among cholesteatomatous cases compared to noncholesteatomatous. A significant association was found between prior use of gentamicin ear drops and bacterial resistance to the drug. The role of aerobes and anaerobes in mixed infections of cholesteatomatous ears is discussed. The relevant literature is critically reviewed and the mechanisms of synergistic anaerobic infections of the ear are summarized. The need for animal studies of bacterial pathogenicity and parallel human studies of response to rational medicinal treatment is stressed.