Pharmacogenomic testing to prevent aminoglycoside-induced hearing loss in cystic fibrosis patients: potential impact on clinical, patient, and economic outcomes

Aminoglycoside induced ototoxicity risk in the cystic fibrosis population: The utility of large-scale screening

BACKGROUND

MT-RNR1 variants are a well-known cause of aminoglycoside-induced hearing loss (AIHL). Individuals with cystic fibrosis (CF) routinely receive aminoglycosides and are at high risk of AIHL. However, genetic testing before treatment is not routinely performed due to perceived rarity of risk, and cost ineffectiveness with traditional technologies.

AIM

Assess the utility of large-scale screening for AIHL risk in the CF population, using digital droplet polymerase chain reaction (ddPCR), a novel and scalable low-cost molecular technique.

METHODS

Using a clinically validated ddPCR assay, we performed retrospective testing on 122 and prospective testing on 32 individuals with CF for the two most common pathogenic variants associated with AIHL, MT-RNR1 m.1555 A > G and m.1494 C > T. Our study screened the largest known cohort of pediatric cases of CF (94/154) for these specific alterations.

RESULTS

We identified two individuals positive for MT-RNR1 m.1555 A > G and no positives for m.1494 C > T. Of 32 prospective cases, 17 had aminoglycoside exposure. The positive case in our prospective group recently began inhaled tobramycin and denied hearing issues. The clinician adjusted to care for both the patient and sibling with CF (not included in cohort) who is presumed positive for m.1555 A > G due to the nature of mitochondrial inheritance.

CONCLUSION

Our findings demonstrate the utility of pretreatment screening in the cystic fibrosis population for AIHL risk using ddPCR, a scalable and robust testing methodology at a fraction of the cost as compared to other sequencing-based methods. Therefore, the use of large-scale screening for AIHL risk in the cystic fibrosis community should be re-visited.

Cost Effectiveness of Pharmacogenetic Testing for Drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines: A Systematic Review

The objective of this study was to evaluate the evidence on cost-effectiveness of pharmacogenetic (PGx)-guided treatment for drugs with Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. A systematic review was conducted using multiple biomedical literature databases from inception to June 2021. Full articles comparing PGx-guided with nonguided treatment were included for data extraction. Quality of Health Economic Studies (QHES) was used to assess robustness of each study (0-100). Data are reported using descriptive statistics. Of 108 studies evaluating 39 drugs, 77 (71%) showed PGx testing was cost-effective (CE) (N = 48) or cost-saving (CS) (N = 29); 21 (20%) were not CE; 10 (9%) were uncertain. Clopidogrel had the most articles (N = 23), of which 22 demonstrated CE or CS, followed by warfarin (N = 16), of which 7 demonstrated CE or CS. Of 26 studies evaluating human leukocyte antigen (HLA) testing for abacavir (N = 8), allopurinol (N = 10), or carbamazepine/phenytoin (N = 8), 15 demonstrated CE or CS. Nine of 11 antidepressant articles demonstrated CE or CS. The median QHES score reflected high-quality studies (91; range 48-100). Most studies evaluating cost-effectiveness favored PGx testing. Limited data exist on cost-effectiveness of preemptive and multigene testing across disease states.

Evidence gaps in economic analyses of hearing healthcare: A systematic review

BACKGROUND

Hearing loss is a common and costly medical condition. This systematic review sought to identify evidence gaps in published model-based economic analyses addressing hearing loss to inform model development for an ongoing Lancet Commission.

METHODS

We searched the published literature through 14 June 2020 and our inclusion criteria included decision model-based cost-effectiveness analyses that addressed diagnosis, treatment, or prevention of hearing loss. Two investigators screened articles for inclusion at the title, abstract, and full-text levels. Data were abstracted and the studies were assessed for the qualities of model structure, data assumptions, and reporting using a previously published quality scale.

FINDINGS

Of 1437 articles identified by our search, 117 unique studies met the inclusion criteria. Most of these model-based analyses were set in high-income countries (n = 96, 82%). The evaluated interventions were hearing screening (n = 35, 30%), cochlear implantation (n = 34, 29%), hearing aid use (n = 28, 24%), vaccination (n = 22, 19%), and other interventions (n = 29, 25%); some studies included multiple interventions. Eighty-six studies reported the main outcome in quality-adjusted or disability-adjusted life-years, 24 of which derived their own utility values. The majority of the studies used decision tree (n = 72, 62%) or Markov (n = 41, 35%) models. Forty-one studies (35%) incorporated indirect economic effects. The median quality rating was 92/100 (IQR:72-100).

INTERPRETATION

The review identified a large body of literature exploring the economic efficiency of hearing healthcare interventions. However, gaps in evidence remain in evaluation of hearing healthcare in low- and middle-income countries, as well as in investigating interventions across the lifespan. Additionally, considerable uncertainty remains around productivity benefits of hearing healthcare interventions as well as utility values for hearing-assisted health states. Future economic evaluations could address these limitations.

FUNDING

NCATS 3UL1-TR002553-03S3.

Tablet and web-based audiometry to screen for hearing loss in adults with cystic fibrosis

INTRODUCTION

Individuals with chronic lung disease (eg, cystic fibrosis (CF)) often receive antimicrobial therapy including aminoglycosides resulting in ototoxicity. Extended high-frequency audiometry has increased sensitivity for ototoxicity detection, but diagnostic audiometry in a sound-booth is costly, time-consuming and requires a trained audiologist. This cross-sectional study analysed tablet-based audiometry (Shoebox MD) performed by non-audiologists in an outpatient setting, alongside home web-based audiometry (3D Tune-In) to screen for hearing loss in adults with CF.

METHODS

Hearing was analysed in 126 CF adults using validated questionnaires, a web self-hearing test (0.5 to 4 kHz), tablet (0.25 to 12 kHz) and sound-booth audiometry (0.25 to 12 kHz). A threshold of ≥25 dB hearing loss at ≥1 audiometric frequency was considered abnormal. Demographics and mitochondrial DNA sequencing were used to analyse risk factors, and accuracy and usability of hearing tests determined.

RESULTS

Prevalence of hearing loss within any frequency band tested was 48%. Multivariate analysis showed age (OR 1.127; (95% CI: 1.07 to 1.18; p value<0.0001) per year older) and total intravenous antibiotic days over 10 years (OR 1.006; (95% CI: 1.002 to 1.010; p value=0.004) per further intravenous day) were significantly associated with increased risk of hearing loss. Tablet audiometry had good usability, was 93% sensitive, 88% specific with 94% negative predictive value to screen for hearing loss compared with web self-test audiometry and questionnaires which had poor sensitivity (17% and 13%, respectively). Intraclass correlation (ICC) of tablet versus sound-booth audiometry showed high correlation (ICC >0.9) at all frequencies ≥4 kHz.

CONCLUSIONS

Adults with CF have a high prevalence of drug-related hearing loss and tablet-based audiometry can be a practical, accurate screening tool within integrated ototoxicity monitoring programmes for early detection.

Pulmonary Mycobacterium abscessus complex in children with cystic fibrosis: A practical management guideline

The treatment of Mycobacterium abscessus complex (MABSC) pulmonary infections is an emerging challenge in patients with cystic fibrosis (CF). Multidrug therapy for prolonged durations is required and carries the significant burden of drug-related toxicity, cost and selective pressure for multiresistant bacteria. International guidelines acknowledge that clinical and in vitro data to support treatment regimens are limited, particularly in children. As part of a collaboration between the infectious diseases and respiratory units at our institution, we have developed a modified treatment guideline that aims to balance the aims of MABSC eradication and slowing disease progression with minimising drug toxicity and resistance. The outcomes of this treatment approach will be monitored and reported. In this manuscript, we discuss the available evidence for treatment choices and present our treatment guideline for paediatric patients with CF and MABSC infection.

Chirp-Evoked Otoacoustic Emissions and Middle Ear Absorbance for Monitoring Ototoxicity in Cystic Fibrosis Patients

OBJECTIVES

The goal of this study was to investigate the use of transient-evoked otoacoustic emissions (TEOAEs) and middle ear absorbance measurements to monitor auditory function in patients with cystic fibrosis (CF) receiving ototoxic medications. TEOAEs were elicited with a chirp stimulus using an extended bandwidth (0.71 to 8 kHz) to measure cochlear function at higher frequencies than traditional TEOAEs. Absorbance over a wide bandwidth (0.25 to 8 kHz) provides information on middle ear function. The combination of these time-efficient measurements has the potential to identify early signs of ototoxic hearing loss.

DESIGN

A longitudinal study design was used to monitor the hearing of 91 patients with CF (median age = 25 years; age range = 15 to 63 years) who received known ototoxic medications (e.g., tobramycin) to prevent or treat bacterial lung infections. Results were compared to 37 normally hearing young adults (median age = 32.5 years; age range = 18 to 65 years) without a history of CF or similar treatments. Clinical testing included 226-Hz tympanometry, pure-tone air-conduction threshold testing from 0.25 to 16 kHz and bone conduction from 0.25 to 4 kHz. Experimental testing included wideband absorbance at ambient and tympanometric peak pressure and TEOAEs in three stimulus conditions: at ambient pressure and at tympanometric peak pressure using a chirp stimulus with constant incident pressure level across frequency and at ambient pressure using a chirp stimulus with constant absorbed sound power across frequency.

RESULTS

At the initial visit, behavioral audiometric results indicated that 76 of the 157 ears (48%) from patients with CF had normal hearing, whereas 81 of these ears (52%) had sensorineural hearing loss for at least one frequency. Seven ears from four patients had a confirmed behavioral change in hearing threshold for ≥3 visits during study participation. Receiver operating characteristic curve analyses demonstrated that all three TEOAE conditions were useful for distinguishing CF ears with normal hearing from ears with sensorineural hearing loss, with an area under the receiver operating characteristic curve values ranging from 0.78 to 0.92 across methods for frequency bands from 2.8 to 8 kHz. Case studies are presented to illustrate the relationship between changes in audiometric thresholds, TEOAEs, and absorbance across study visits. Absorbance measures permitted identification of potential middle ear dysfunction at 5.7 kHz in an ear that exhibited a temporary hearing loss.

CONCLUSIONS

The joint use of TEOAEs and absorbance has the potential to explain fluctuations in audiometric thresholds due to changes in cochlear function, middle ear function, or both. These findings are encouraging for the joint use of TEOAE and wideband absorbance objective tests for monitoring ototoxicity, particularly, in patients who may be too ill for behavioral hearing tests. Additional longitudinal studies are needed in a larger number of CF patients receiving ototoxic drugs to further evaluate the clinical utility of these measures in an ototoxic monitoring program.

Clinical and genetic associations for carboplatin-related ototoxicity in children treated for retinoblastoma: A retrospective noncomparative single-institute experience

BACKGROUND

Children with retinoblastoma treated with carboplatin chemotherapy risk moderate to severe, irreversible hearing loss. Based on published evidence, we hypothesized that ototoxicity risk is associated with clinical parameters and variants in candidate genes in drug metabolism pathways (methyltransferases [thiopurine S-methyltransferase, TPMT] and [catechol-O-methyltransferase, COMT], and drug transporter ABCC3).

PROCEDURE

We retrospectively reviewed clinical records of patients with retinoblastoma treated with carboplatin chemotherapy regarding age (at diagnosis and chemotherapy initiation), chemotherapy sessions (cycles number, drug doses, and cumulative carboplatin dose), and hearing loss (defined as ototoxicity ≥grade 2 by at least one classification system). Blood samples were genotyped for genetic variants in TPMT (rs12201199, rs1800460), COMT (rs4646316, rs9332377), and ABCC3 (rs1051640) by quantitative PCR and confirmed by allele-specific PCR. Univariate statistical tests, receiver-operating characteristic analysis, and Kaplan-Meier curves were used to examine the association between hearing loss, clinical factors, and variants in candidate genes.

RESULTS

Audiometric data and stored DNA were available for 71 patients with retinoblastoma (88% carried an RB1 pathogenic variant allele). Median carboplatin cumulative dose was 1,400 mg/m² (260-5,148 mg/m² ). Ototoxicity occurred in 18 patients (25%), strongly associated with age at diagnosis (P = 0.01) and age at chemotherapy initiation (OR = 4.99, P = 0.008). The highest likelihood ratio of hearing loss was associated with chemotherapy initiation <4.25 months of age. Ototoxicity was not associated with any tested genetic variants.

CONCLUSIONS

We observed a 25% prevalence of ototoxicity in patients with retinoblastoma treated with carboplatin, higher than previously published. Age at chemotherapy initiation was associated with carboplatin-induced ototoxicity, with children <4.25 months of age at highest risk.

Newborn Screening of Genetic Mutations in Common Deafness Genes With Bloodspot-Based Gene Chip Array

PURPOSE

This study screens for deafness gene mutations in newborns in the Northwest China population.

METHOD

The 9 sites of 4 common deafness genes (GJB2, GJB3, SLC26A4, and mt 12S rRNA) were detected by bloodspot-based gene chip array in 2,500 newborns.

RESULTS

We detected mutations of the 4 genes in 101 (4.04%) newborns; particularly, 0.20% detected the double mutations. In the Hui population, 4.58% of the newborns tested positive for mutations, whereas 4.01% of Han newborns tested positive for mutations. The detective rates are as follows: 1.44% for GJB2 235delC, 1.08% for SLC26A4 IVS7-2A>G, 0.48% for GJB2 299_300delAT, 0.28% for SLC26A4 2168A>G, 0.2% for mt 12S rRNA 1555A>G, and 0.16% for GJB3 538C>T. The 31.25% (5/16) of infants with GJB2 235delC, 50% (3/6) with GJB2 299_300delAT, and 25% (3/12) with SLC26A4 IVS7-2A>G showed abnormal hearing when tested; only 1 double mutation case received the hearing test, and this infant showed abnormality in both ears on the hearing test.

CONCLUSIONS

High mutation rates in the common deafness genes were detected in newborns in Northwest China. Our study is helpful in understanding the deafness genomic epidemiology and also provides evidence for prenatal and postnatal care as well as policy making on population health in the region.

A Systematic Review of Economic Evaluations of Pharmacogenetic Testing for Prevention of Adverse Drug Reactions

BACKGROUND

Pharmacogenetics offers the potential to improve health outcomes by identifying individuals who are at greater risk of harm from certain medicines. Routine adoption of pharmacogenetic tests requires evidence of their cost effectiveness.

OBJECTIVE

The present review aims to systematically review published economic evaluations of pharmacogenetic tests that aim to prevent or reduce the incidence of ADRs.

METHODS

We conducted a systematic literature review of economic evaluations of pharmacogenetic tests aimed to reduce the incidence of adverse drug reactions. Literature was searched using Embase, MEDLINE and the NHS Economic Evaluation Database with search terms relating to pharmacogenetic testing, adverse drug reactions, economic evaluations and pharmaceuticals. Titles were screened independently by two reviewers. Articles deemed to meet the inclusion criteria were screened independently on abstract, and full texts reviewed.

RESULTS

We identified 852 articles, of which 47 met the inclusion criteria. There was evidence supporting the cost effectiveness of testing for HLA-B*57:01 (prior to abacavir), HLA-B*15:02 and HLA-A*31:01 (prior to carbamazepine), HLA-B*58:01 (prior to allopurinol) and CYP2C19 (prior to clopidogrel treatment). Economic evidence was inconclusive with respect to TPMT (prior to 6-mercaptoputine, azathioprine and cisplatin therapy), CYP2C9 and VKORC1 (to inform genotype-guided dosing of coumarin derivatives), MTHFR (prior to methotrexate treatment) and factor V Leiden testing (prior to oral contraception). Testing for A1555G is not cost effective before prescribing aminoglycosides.

CONCLUSIONS

Our systematic review identified robust evidence of the cost effectiveness of genotyping prior to treatment with a number of common drugs. However, further analyses and (or) availability of robust clinical evidence is necessary to make recommendations for others.

Impact of pulmonary exacerbations and lung function on generic health-related quality of life in patients with cystic fibrosis

BACKGROUND

The analysis aimed to examine the impact of pulmonary exacerbations (PEs) and lung function on generic measures of HRQL in patients with cystic fibrosis (CF) using trial-based data.

METHODS

In a 48-week randomized, placebo-controlled study of ivacaftor in patients ≥12 years with CF and a G551D-CFTR mutation the relationship between PEs, PE-related hospitalizations and percent predicted forced expiratory volume in one second (ppFEV1) with EQ-5D measures (index and visual analog scale [VAS]) was examined in post-hoc analyses. Multivariate mixed-effects models were employed to describe the association of PEs, PE-related hospitalizations, and ppFEV1 on EQ-5D measures.

RESULTS

One hundred sixty one patients (age: mean 25.5 [SD 9.5] years; baseline ppFEV1: 63.6 [16.4]) contributed 1,214 observations (ppFEV1: no lung dysfunction [n = 157], mild [n = 419], moderate [n = 572], severe [n = 66]). Problems were most frequently reported on pain/discomfort, anxiety/depression, and usual activities EQ-5D items. The mean (SE) EQ-5D index nominally decreased (worsened) with worsening severity of lung dysfunction (P = 0.070): 0.931 (0.023); mild: 0.923 (0.021); moderate: 0.904 (0.018); severe: 0.870 (0.020). 146 PEs were experienced by 72 patients, including 52 PEs (35.6 %) that required hospitalization. Mean EQ-5D index and VAS scores were lowest (worst) within 1 week (before or after PE start) for PEs requiring hospitalization. Pulmonary exacerbations, PE-related hospitalizations, and ppFEV1 were significant predictors of EQ-5D index and VAS.

CONCLUSIONS

In a clinical study of patients with CF (≥12 years of age and a G551D-CFTR mutation), PEs, primarily those requiring hospitalization, were associated with low EQ-5D index and VAS scores. The impact of ppFEV1 was relatively smaller. Reducing PEs, in particular those requiring hospitalization, would likely improve HRQL among these patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00909532 ; URL: clinicaltrials.gov, May 26, 2009.

Systematic review, meta-analysis and economic modelling of molecular diagnostic tests for antibiotic resistance in tuberculosis

BACKGROUND

Drug-resistant tuberculosis (TB), especially multidrug-resistant (MDR, resistance to rifampicin and isoniazid) disease, is associated with a worse patient outcome. Drug resistance diagnosed using microbiological culture takes days to weeks, as TB bacteria grow slowly. Rapid molecular tests for drug resistance detection (1 day) are commercially available and may promote faster initiation of appropriate treatment.

OBJECTIVES

To (1) conduct a systematic review of evidence regarding diagnostic accuracy of molecular genetic tests for drug resistance, (2) conduct a health-economic evaluation of screening and diagnostic strategies, including comparison of alternative models of service provision and assessment of the value of targeting rapid testing at high-risk subgroups, and (3) construct a transmission-dynamic mathematical model that translates the estimates of diagnostic accuracy into estimates of clinical impact.

REVIEW METHODS AND DATA SOURCES

A standardised search strategy identified relevant studies from EMBASE, PubMed, MEDLINE, Bioscience Information Service (BIOSIS), System for Information on Grey Literature in Europe Social Policy & Practice (SIGLE) and Web of Science, published between 1 January 2000 and 15 August 2013. Additional 'grey' sources were included. Quality was assessed using quality assessment of diagnostic accuracy studies version 2 (QUADAS-2). For each diagnostic strategy and population subgroup, a care pathway was constructed to specify which medical treatments and health services that individuals would receive from presentation to the point where they either did or did not complete TB treatment successfully. A total cost was estimated from a health service perspective for each care pathway, and the health impact was estimated in terms of the mean discounted quality-adjusted life-years (QALYs) lost as a result of disease and treatment. Costs and QALYs were both discounted at 3.5% per year. An integrated transmission-dynamic and economic model was used to evaluate the cost-effectiveness of introducing rapid molecular testing (in addition to culture and drug sensitivity testing). Probabilistic sensitivity analysis was performed to evaluate the impact on cost-effectiveness of diagnostic and treatment time delays, diagnosis and treatment costs, and associated QALYs.

RESULTS

A total of 8922 titles and abstracts were identified, with 557 papers being potentially eligible. Of these, 56 studies contained sufficient test information for analysis. All three commercial tests performed well when detecting drug resistance in clinical samples, although with evidence of heterogeneity between studies. Pooled sensitivity for GenoType® MTBDRplus (Hain Lifescience, Nehren, Germany) (isoniazid and rifampicin resistance), INNO-LiPA Rif.TB® (Fujirebio Europe, Ghent, Belgium) (rifampicin resistance) and Xpert® MTB/RIF (Cepheid Inc., Sunnyvale, CA, USA) (rifampicin resistance) was 83.4%, 94.6%, 95.4% and 96.8%, respectively; equivalent pooled specificity was 99.6%, 98.2%, 99.7% and 98.4%, respectively. Results of the transmission model suggest that all of the rapid assays considered here, if added to the current diagnostic pathway, would be cost-saving and achieve a reduction in expected QALY loss compared with current practice. GenoType MTBDRplus appeared to be the most cost-effective of the rapid tests in the South Asian population, although results were similar for GeneXpert. In all other scenarios GeneXpert appeared to be the most cost-effective strategy.

CONCLUSIONS

Rapid molecular tests for rifampicin and isoniazid resistance were sensitive and specific. They may also be cost-effective when added to culture drug susceptibility testing in the UK. There is global interest in point-of-care testing and further work is needed to review the performance of emerging tests and the wider health-economic impact of decentralised testing in clinics and primary care, as well as non-health-care settings, such as shelters and prisons.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42011001537.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Value within otolaryngology: Assessment of the cost-utility analysis literature

Objective

To assess the characteristics and quality of cost utility analyses (CUA) related to otolaryngology within the CEA registry and to summarize their collective results.

Methods

All cost-utility analyses published between 1976 and 2011 contained in the Cost-Effectiveness Analysis Registry (CEA Registry) were evaluated. Topics that fall within the care of an otolaryngologist were included in the review regardless of the presence of an otolaryngologist author. Potential associations between various study characteristics and CEA registry quality scores were evaluated using the Pearson product moment correlation coefficient.

Results

Sixty-one of 2913 (2.1%) total CUA publications screened were related to otolaryngology. Eighteen of 61 (29.5%) publications included an otolaryngologist as an author. Fourteen studies agreed on the cost effectiveness of at least unilateral cochlear implantation and six of seven (85.7%) studies demonstrated the cost effectiveness of continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA). Forty-six percent (28 of 61) of all manuscripts were published between 2008 and 2011. A more recent publication year was associated with a higher CEA registry quality score while the presence of an otolaryngologist author and journal impact factor had no significant correlation with the quality of the CUA.

Conclusion

Based on current evidence in the CEA registry, unilateral cochlear implantation for hearing loss and CPAP for OSA are both cost-effective therapeutic interventions. Although CUAs in otolaryngology have increased in quantity and improved in quality in more recent years, there is a relative lack of CUAs in otolaryngology in comparison to other subspecialties.

Economic Evaluations of Pharmacogenetic and Pharmacogenomic Screening Tests: A Systematic Review. Second Update of the Literature

Objective

Due to extended application of pharmacogenetic and pharmacogenomic screening (PGx) tests it is important to assess whether they provide good value for money. This review provides an update of the literature.

Methods

A literature search was performed in PubMed and papers published between August 2010 and September 2014, investigating the cost-effectiveness of PGx screening tests, were included. Papers from 2000 until July 2010 were included via two previous systematic reviews. Studies’ overall quality was assessed with the Quality of Health Economic Studies (QHES) instrument.

Results

We found 38 studies, which combined with the previous 42 studies resulted in a total of 80 included studies. An average QHES score of 76 was found. Since 2010, more studies were funded by pharmaceutical companies. Most recent studies performed cost-utility analysis, univariate and probabilistic sensitivity analyses, and discussed limitations of their economic evaluations. Most studies indicated favorable cost-effectiveness. Majority of evaluations did not provide information regarding the intrinsic value of the PGx test. There were considerable differences in the costs for PGx testing. Reporting of the direction and magnitude of bias on the cost-effectiveness estimates as well as motivation for the chosen economic model and perspective were frequently missing.

Conclusions

Application of PGx tests was mostly found to be a cost-effective or cost-saving strategy. We found that only the minority of recent pharmacoeconomic evaluations assessed the intrinsic value of the PGx tests. There was an increase in the number of studies and in the reporting of quality associated characteristics. To improve future evaluations, scenario analysis including a broad range of PGx tests costs and equal costs of comparator drugs to assess the intrinsic value of the PGx tests, are recommended. In addition, robust clinical evidence regarding PGx tests’ efficacy remains of utmost importance.

Acquired Hearing Loss in Children

Hearing loss is the most common congenital sensory impairment. According to National Health and Nutrition Examination Survey data from 2001 to 2008, 20.3% of subjects aged greater than or equal to 12 had unilateral or bilateral hearing loss. The World Health Organization notes that, worldwide, there are 360 million people with disabling hearing loss, with 50% preventable. Although many hearing losses are acquired, many others are manifestations of preexisting conditions. The purpose of a pediatric hearing evaluation is to identify the degree and type of hearing loss and etiology and to outline a comprehensive strategy that supports language and social development and communication.

Normal hearing in a child with the m.1555A>G mutation despite repeated exposure to aminoglycosides. Has the penetrance of this pharmacogenetic interaction been overestimated?

The mtDNA m.1555A>G mutation causes increased susceptibility to aminoglycoside ototoxicity resulting in significant hearing loss in 100% of reported exposed cases. Genetic and audiological assessments were conducted in a sample of 59 children with cystic fibrosis (CF) undergoing aminoglycoside treatment. Of the two m.1555G patients identified one had severe-profound deafness. Surprisingly, the second m.1555G patient exhibited well-preserved hearing despite repeated exposure. This may be a rare case of intact hearing in an m.1555G individual with aminoglycoside use. Alternatively, its penetrance may have been previously overestimated due to recruitment bias. Further studies are required to determine the true penetrance to inform m.1555A>G genetic testing in similar clinical scenarios.

Is individualized medicine more cost-effective? A systematic review

BACKGROUND

Individualized medicine (IM) is a rapidly evolving field that is associated with both visions of more effective care at lower costs and fears of highly priced, low-value interventions. It is unclear which view is supported by the current evidence.

OBJECTIVE

Our objective was to systematically review the health economic evidence related to IM and to derive general statements on its cost-effectiveness.

DATA SOURCES

A literature search of MEDLINE database for English- and German-language studies was conducted.

STUDY APPRAISAL AND SYNTHESIS METHOD

Cost-effectiveness and cost-utility studies for technologies meeting the MEDLINE medical subject headings (MeSH) definition of IM (genetically targeted interventions) were reviewed. This was followed by a standardized extraction of general study characteristics and cost-effectiveness results.

RESULTS

Most of the 84 studies included in the synthesis were from the USA (n = 43, 51 %), cost-utility studies (n = 66, 79 %), and published since 2005 (n = 60, 71 %). The results ranged from dominant to dominated. The median value (cost-utility studies) was calculated to be rounded $US22,000 per quality-adjusted life year (QALY) gained (adjusted to $US, year 2008 values), which is equal to the rounded median cost-effectiveness in the peer-reviewed English-language literature according to a recent review. Many studies reported more than one strategy of IM with highly varying cost-effectiveness ratios. Generally, results differed according to test type, and tests for disease prognosis or screening appeared to be more favorable than tests to stratify patients by response or by risk of adverse effects. However, these results were not significant.

LIMITATIONS

Different definitions of IM could have been used. Quality assessment of the studies was restricted to analyzing transparency.

CONCLUSIONS

IM neither seems to display superior cost-effectiveness than other types of medical interventions nor to be economically inferior. Instead, rather than 'whether' healthcare was individualized, the question of 'how' it was individualized was of economic relevance.

Economic Evaluations of Pharmacogenetic Approaches in Infectious Diseases: A Review of Current Approaches and Evaluation of Critical Aspects Affecting their Quality

Pharmacogenetics holds great potential for improving the effectiveness of treatment modalities in infectious diseases by taking into account the genetic determinants of both the host and infectious agents' individuality. Better utilization of resources and improved therapeutic efficiency are the expected outcomes of personalized medicine using pharmacogenetic and pharmacogenomics information made available by technological advances. However, there has been growing concern in the clinical community regarding the evaluation of the true benefits of these approaches. This perception is partly due to the limited number and perceived poor quality of economic evaluations in this field, and initiatives aimed at harmonizing and communicating strategies improving the quality of these studies and their acceptance by the clinical community are greatly needed. This paper reviews current literature of economic evaluations of pharmacogenetics interventions guiding pharmacotherapy in infectious diseases. PubMed and the NHS Centre for Reviews and Dissemination databases were searched using a combination of five broad research terms related to pharmacogenetic approaches, and papers relative to economic evaluations of pharmacogenetic interventions in infectious diseases retained for further analysis. Using these criteria, a total of 14 papers were included in this review. The area of economic evaluation of pharmacogenetic interventions in infectious diseases remains understudied and would benefit from greater harmonization. The main weaknesses of evaluations reviewed in this paper seem to be represented by poor evidence of pharmacogenetic marker validation, inconsistencies in the selection of costs and utility included in the economic models and the choice of sensitivity analysis. All these factors limit the overall transparency of the studies, greater acceptance of their results and applicability to diverse and possibly resourcelimited environments where these approaches could be expected to have the greater impact.

Hearing loss and vestibular dysfunction among children with cancer after receiving aminoglycosides

BACKGROUND

Children undergoing cancer therapy often receive aminoglycosides to treat febrile neutropenia or gram-negative infections. The magnitude of the risk of developing aminoglycoside-induced ototoxicity and the dose threshold at which that risk significantly increases are unknown.

PROCEDURE

Eligible cancer patients received the aminoglycoside amikacin at Children's Medical Center between 2004 and 2007. They were aged 3-8 years; were without prior hearing loss; had no platinum-based chemotherapy, cranial radiation, nor bone marrow transplant; and received no loop diuretics within 6 weeks of testing. Consenting patients underwent complete hearing and vestibular testing.

RESULTS

We tested 23 patients who had significant amikacin exposure. Three (13%) had abnormal hearing tests, and four (17%) had subclinical vestibular dysfunction; none had both. Of those with hearing loss, two were known to have developed hearing loss after aminoglycoside exposure, but the third had moderate to severe high-frequency sensorineural hearing loss bilaterally that had been undiagnosed. We observed clear dose-dependent ototoxicity; of the eight patients who received amikacin for a cumulative total of more than 50 days, five (68%) developed toxicity. Similarly, of the seven who received a cumulative total of more than 1,200 mg/kg, five developed toxicity.

CONCLUSIONS

These data highlight the risks of prolonged aminoglycoside administration and warrant further validation in a larger group of patients. Patients to be treated with prolonged aminoglycoside therapy may benefit from prospective hearing screening.

Replication of TPMT and ABCC3 genetic variants highly associated with cisplatin-induced hearing loss in children

Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. A serious complication of cisplatin treatment is permanent hearing loss. The aim of this study was to replicate previous genetic findings in an independent cohort of 155 pediatric patients. Associations were replicated for genetic variants in TPMT (rs12201199, P = 0.0013, odds ratio (OR) 6.1) and ABCC3 (rs1051640, P = 0.036, OR 1.8). A predictive model combining variants in TPMT, ABCC3, and COMT with clinical variables (patient age, vincristine treatment, germ-cell tumor, and cranial irradiation) significantly improved the prediction of hearing-loss development as compared with using clinical risk factors alone (area under the curve (AUC) 0.786 vs. 0.708, P = 0.00048). The novel combination of genetic and clinical factors predicted the risk of hearing loss with a sensitivity of 50.3% and a specificity of 92.7%. These findings provide evidence to support the importance of TPMT, COMT, and ABCC3 in the prediction of cisplatin-induced hearing loss in children.

Hearing in 44-45 year olds with m.1555A>G, a genetic mutation predisposing to aminoglycoside-induced deafness: a population based cohort study

Background The mitochondrial DNA mutation m.1555A>G predisposes to permanent idiosyncratic aminoglycoside-induced deafness that is independent of dose. Research suggests that in some families, m.1555A>G may cause non-syndromic deafness, without aminoglycoside exposure, as well as reduced hearing thresholds with age (age-related hearing loss). Objectives To determine whether adults with m.1555A>G have impaired hearing, a factor that would inform the cost-benefit argument for genetic testing prior to aminoglycoside administration. Design Population-based cohort study. Setting UK. Participants Individuals from the British 1958 birth cohort. Measurements Hearing thresholds at 1 and 4 kHz at age 44-45 years; m.1555A>G genotyping. Results 19 of 7350 individuals successfully genotyped had the m.1555A>G mutation, giving a prevalence of 0.26% (95% CI 0.14% to 0.38%) or 1 in 385 (95% CI 1 in 714 to 1 in 263). There was no significant difference in hearing thresholds between those with and without the mutation. Single-nucleotide polymorphism analysis indicated that the mutation has arisen on a number of different mitochondrial haplogroups. Limitations No data were collected on aminoglycoside exposure. For three subjects, hearing thresholds could not be predicted because information required for modelling was missing. Conclusions In this cohort, hearing in those with m.1555A>G is not significantly different from the general population and appears to be preserved at least until 44-45 years of age. Unbiased ascertainment of mutation carriers provides no evidence that this mutation alone causes non-syndromic hearing impairment in the UK. The findings lend weight to arguments for genetic testing for this mutation prior to aminoglycoside administration, as hearing in susceptible individuals is expected to be preserved well into adult life. Since global use of aminoglycosides is likely to increase, development of a rapid test is a priority.

A formal risk-benefit framework for genomic tests: facilitating the appropriate translation of genomics into clinical practice

PURPOSE

Evaluation of genomic tests is often challenging because of the lack of direct evidence of clinical benefit compared with usual care and unclear evidence requirements. To address these issues, this study presents a risk-benefit framework for assessing the health-related utility of genomic tests.

METHODS

We incorporated approaches from a variety of established fields including decision science, outcomes research, and health technology assessment to develop the framework. Additionally, we considered genomic test stakeholder perspectives and case studies.

RESULTS

We developed a three-tiered framework: first, we use decision-analytic modeling techniques to synthesize data, project incidence of clinical events, and assess uncertainty. Second, we defined the health-related utility of genomic tests as improvement in health outcomes as measured by clinical event rates, life expectancy, and quality-adjusted life-years. Finally, we displayed results using a risk-benefit policy matrix to facilitate the interpretation and implementation of findings from these analyses.

CONCLUSION

A formal risk-benefit framework may accelerate the utilization and practice-based evidence development of genomic tests that pose low risk and offer plausible clinical benefit, while discouraging premature use of tests that provide little benefit or pose significant health risks compared with usual care.

Side effects of aminoglycosides on the kidney, ear and balance in cystic fibrosis

Aminoglycoside antibiotics are a central component of the treatment of pulmonary exacerbations of cystic fibrosis (CF) and slow the decline in lung function which ultimately causes the death of most patients. The prognosis of CF has improved, and thus side effects of treatments have become increasingly important. Observational studies suggest that the morbidity from side effects of aminoglycosides is disturbingly common, and that aggressive treatment may lead to more side effects. This review of the current literature on side effects of aminoglycosides considers the pathophysiological mechanisms, epidemiology and risk factors, investigation of side effects and preventative strategies. Treatments which have shown early promise are identified and areas of future research are discussed.

Clinical and public health implications of emerging genetic technologies

The clinical utility of many emerging genetic technologies has yet to be established. For many new genetic tests, no practice guidelines are available to help clinicians decide when and how to use them in practice. The clinical and public health implications of new genetic technologies are easiest to evaluate when these tests are compared with other genetic tests, including those already well established in clinical practice. Genetic tests can be divided into different categories based on their intent as follows: (1) to establish a diagnosis (genetic diagnostic tests), (2) to classify disease processes to assist management (gene expression profiling), (3) to predict drug response or side effects (pharmacogenomic tests), and (4) to predict susceptibility to disease (genetic susceptibility testing). As new genetic tests emerge, their translation into practice will depend on their performance based on laboratory standards, but also on their ability to enhance prevention or assist clinicians in diagnosing and treating patients. This article reviews the clinical and public health implications of different types of genetic tests, the evaluation of genetic tests from a public health perspective, and the need for partnership to achieve the potential for benefit of new genetic technologies.

No hearing loss after repeated courses of tobramycin in cystic fibrosis patients

CONCLUSION

Our results indicate that repeated treatment courses with tobramycin 10 mg/kg (twice daily for 3 weeks) may be safely applied in cystic fibrosis (CF) patients with respect to ototoxicity. The risk of hearing loss in this patient group is less than expected, which could be explained by either unfavourable baseline audiometry or the use of unidentified protective medication, or both. However, due to large inter-individual variations, audiometry screening remains important with respect to the detection of individual outliers.

OBJECTIVES

Tobramycin is frequently prescribed for CF patients. In this study, hearing loss due to cumulative tobramycin exposure in adult CF patients was investigated.

PATIENTS AND METHODS

We retrospectively investigated 19 patients with both baseline and follow-up audiometry before and after repeated courses of intravenous tobramycin (10 mg/kg/day in twice daily administrations for 3 weeks). Pure tone audiometry was performed at 0.250-16 kHz.

RESULTS

After repeated courses of tobramycin (median 3, range 1-8), the mean increase per frequency was 2.1 dB (median 0.5 dB, SD 12.6) with large (inter-individual) variations (range -23.5 to 34.5 dB). The pure tone averages (PTA) at 1-2-4 kHz and 8-10-12 kHz increased 1.4 dBHL and 2.3 dBHL, respectively, but were neither statistically significant, nor correlated with the cumulative tobramycin exposure.

Cost effectiveness of pharmacogenomics: a critical and systematic review

The use of pharmacogenetic testing in clinical practice is limited thus far. A potential barrier to the widespread implementation of pharmacogenetic testing is the lack of evidence on whether testing provides good value for money. The objective of this review was to provide a systematic and critical review of economic evaluations of pharmacogenetic testing. A literature search using publically available databases was performed for articles published up to October 2009. To be included, studies had to meet the definition of being a pharmacogenomic study (defined as use of information on human genetic variation to target drug therapy) and an economic evaluation (defined as an evaluation of both costs and clinical outcomes). Articles that met these criteria were subsequently reviewed and graded using the Quality of Health Economic Studies (QHES) instrument. Lastly, the evidence for biomarker validity and utility were qualitatively assessed using expert opinion. A total of 34 articles were identified using our defined criteria. The most common disease category was thromboembolic-related diseases (26%), while the most common biomarkers were thiopurine methyltransferase and cytochrome P450 2C9 (18% each). Almost all studies were published after 2004 (91%). Two types of studies were identified: cost-effectiveness studies and cost-utility studies, with roughly half of the overall studies being cost-utility studies (53%) and a majority of these published within the last 3 years. The average quality score was 77 (range 29-99). Of the biomarkers reviewed, it was estimated that most had demonstrated clinical validity, but only two had demonstrated clinical utility. Despite a recent increase in the number of economic evaluations of pharmacogenetic applications, further studies examining the clinical validity and utility of these biomarkers are needed to support cost-effectiveness assessments.

Ethical and social implications of genetic testing for communication disorders

Advances in genetics and genomics have quickly led to clinical applications to human health which have far-reaching consequences at the individual and societal levels. These new technologies have allowed a better understanding of the genetic factors involved in a wide range of disorders. During the past decade, incredible progress has been made in the identification of genes involved in the normal process of hearing. The resulting clinical applications have presented consumers with new information and choices. Many of the same gene identification techniques are increasingly being applied to the investigation of complex disorders of speech and language. In parallel with gene identification, studies of the legal, ethical and psychosocial impacts of the clinical application of these advances and their influence on specific behaviors of individuals with communication disorders are paramount, but often lag behind. These studies will help to ensure that new technologies are introduced into clinical practice in a responsible manner.

LEARNING OUTCOMES

As a result of this activity, the participant will be able to (1) explain the differences between Mendelian and complex forms of inheritance and why these differences complicate the ethical impact of genetic testing, (2) explain how publicly funded genome research through the Human Genome Project, the International HapMap Project and others have examined the ethical, legal and social implications of genome research, (3) list some of the ethical complexities of prenatal, newborn and predictive testing for various genetic disorders and (4) discuss the importance of evidence-based practice to the development of public policy for the introduction and clinical use of genetic tests.

Removing barriers to a clinical pharmacogenetics service

Pharmacogenetics has been proposed as a new discipline to facilitate safer and more effective prescribing by predicting individuals who will have a therapeutic response or develop side effects. Implementation of pharmacogenetic testing into mainstream clinical practice has been slow. However, recent studies provide robust evidence that pharmacogenetics can make real differences to reduce adverse reactions to certain medications. It is therefore important to consider what factors influence the introduction of pharmacogenetics into clinical practice and what requirements must be met to ensure an effective, safe, efficient and equitable pharmacogenetics service.

The contractual genome: how direct-to-consumer genomic services may help patients take ownership of their DNA

The sequencing and genotyping of personal genomes by commercial services outside traditional clinical settings may help to shape the expectations of research subjects and patients regarding control of and responsibility for the information contained in their DNA. A greater sense of individual ownership of personal genomic information could replace overly complex and paternalistic institutional proxies for the protection of personal genotype and sequence data, and also could encourage research participants and patients to become better educated regarding genetic contributors to disease.