J. Pieter Noordzij

Creation and Validation of the Singing Voice Handicap Index

Objectives: We developed and validated a disorder-specific health status instrument (Singing Voice Handicap Index; SVHI) for use in patients with singing problems. Methods: Prospective instrument validation was performed. Of 81 original items, those with poor statistical validity were eliminated, resulting in 36 items. The ability to discriminate dysphonic from normal singers, test-retest reliability, internal consistency, and construct validity were assessed. Results: We included 112 dysphonic and 129 normal singers, professional and nonprofessional, of classical, country, rock, choral, and gospel repertoire. Dysphonic singers had worse SVHI scores than normal singers (p ≤ .001, rank sum test). Test-retest reliability was high (Spearman correlation, 0.92; p ≤ .001). Internal consistency demonstrated a Cronbachs α of 97, and the correlation between the SVHI and self-rated singing voice impairment was .63 (p ≤ .001, Spearman correlation). Conclusions: The SVHI is a reliable and valid tool for assessing self-perceived handicap associated with singing problems.

Glottal area waveform analysis of benign vocal fold lesions before and after surgery.

Glottal area waveform (GAW) is the plot of relative glottal area versus time through 1 representative glottal cycle. It is derived from the quantitative analysis of the videostroboscopic image. A GAW analysis was performed on 24 patients before and after microlaryngeal phonosurgery. Patients with vocal fold polyps, polypoid degeneration, cysts, sulcus vocalis, and Reinkes edema were included. From each GAW, 5 parameters were determined and compared: maximum normalized glottal area, maximum opening rate, maximum closing rate, percent open time at 50% glottal opening, and glottal gap size. Statistically significant differences in postoperative states included an increased maximum glottal area, an increased maximum opening rate, and an increased maximum closing rate. Glottal opening and closing rate are objective measures of vocal fold pliability that have clinical relevance. The GAW may be used to quantitate vocal fold vibratory capability.

Laryngeal injury from prolonged intubation: A prospective analysis of contributing factors

The factors leading to laryngeal injury due to intubation are not fully understood. This study sought to determine if duration of intubation, size of endotracheal tube, and/or type of endotracheal tube impact the degree of vocal fold immobility and other laryngeal injury upon extubation.

Prediction of hypocalcemia after using 1- to 6-hour postoperative parathyroid hormone and calcium levels:an analysis of pooled individual patient data from 3 observational studies

Parathyroid hormone (PTH) levels up to 6 hours postthyroidectomy have been shown to have excellent predictive power in determining hypocalcemia. In this study, we investigate the usefulness of combining calcium and PTH to increase the predictive power.

Factors associated with perception of singing voice handicap

Objective This study will determine factors that influence the self-perceived handicap associated with singing voice problems. Study Design A prospective cohort. Subject and Methods Singers presenting to a voice clinic prospectively completed the Singing Voice Handicap Index (SVHI) before evaluation and treatment. Demographic data, singing style, professional status, duration of symptoms, medical problems, and diagnosis were collected. Univariate and multivariate analysis was performed. Results One hundred seventy-one singers completed the SVHI. The duration of symptoms, being an amateur singer or singing teacher, benign vocal fold lesions, and neurologic voice disorders were associated with increased SVHI scores (P > 0.05, multiple linear regression). Age greater than 50 years and gospel singing were predictive of increased SVHI scores only on univariate analysis (P > 0.05, t test). Conclusion Singers experience significant handicap as a result of their singing problems with certain factors associated with greater impairment. Targeting interventions at patients more severely affected may improve outcomes.

Palliative Treatment of Dysphonia and Dysarthria

The focus of this article is the palliative treatment of a variety of dysphonic conditions. Symptomatic relief of hoarseness can be achieved by voice therapy, augmentative alternative communication modalities, and surgery. The causes of dysphonia addressed herein include amyotrophic lateral sclerosis, Parkinsons disease, multiple sclerosis, stroke, head and neck cancers requiring glossectomy or laryngectomy, unilateral vocal fold paralysis, and presbyphonia. Palliative treatment of dysphonia and voice disorders provides symptomatic relief but not a cure of the underlying disease state. For these patients there are a number of palliative interventions that can greatly improve their quality of life.

Summarising and validating test accuracy results across multiple studies for use in clinical practice

Following a meta‐analysis of test accuracy studies, the translation of summary results into clinical practice is potentially problematic. The sensitivity, specificity and positive (PPV) and negative (NPV) predictive values of a test may differ substantially from the average meta‐analysis findings, because of heterogeneity. Clinicians thus need more guidance: given the meta‐analysis, is a test likely to be useful in new populations, and if so, how should test results inform the probability of existing disease (for a diagnostic test) or future adverse outcome (for a prognostic test)? We propose ways to address this. Firstly, following a meta‐analysis, we suggest deriving prediction intervals and probability statements about the potential accuracy of a test in a new population. Secondly, we suggest strategies on how clinicians should derive post‐test probabilities (PPV and NPV) in a new population based on existing meta‐analysis results and propose a cross‐validation approach for examining and comparing their calibration performance. Application is made to two clinical examples. In the first example, the joint probability that both sensitivity and specificity will be >80% in a new population is just 0.19, because of a low sensitivity. However, the summary PPV of 0.97 is high and calibrates well in new populations, with a probability of 0.78 that the true PPV will be at least 0.95. In the second example, post‐test probabilities calibrate better when tailored to the prevalence in the new population, with cross‐validation revealing a probability of 0.97 that the observed NPV will be within 10% of the predicted NPV.

Management of Dysphonic Patients by Otolaryngologists

Objective To investigate common treatment approaches of general otolaryngologists for adult dysphonic patients without obvious laryngeal anatomic abnormalities. Study Design Cross-sectional survey. Setting General otolaryngology community. Subjects and Methods One thousand randomly chosen American Academy of Otolaryngology—Head and Neck Surgery general otolaryngologists were mailed a survey. Results The response rate was 27.8%. Mean years in practice was 19.5. The most common treatments were proton pump inhibitor (PPI), referral to speech pathology, and stroboscopy. Muscle tension dysphonia, vocal fold nodules, and dysphonia of uncertain etiology were the most common reasons for voice therapy referral. Various forms of supraglottic compression and tender extralaryngeal muscles were identified as findings of muscle tension dysphonia. Response to once-daily PPI, laryngeal signs, and throat symptoms were the most common determinants for laryngopharyngeal reflux. When patients failed initial treatment, 58.2% refer for voice therapy, 46.9% obtain stroboscopy, and 33.3% extend or increase duration of PPI treatment. Conclusions Varied treatment approaches to adult dysphonic patients were identified. How practice patterns vary from best practice guidelines, affect patient outcome, and influence health care costs needs examination.

Neurogenic cough: Neurogenic Cough

We review contemporary concepts of the pathophysiology of neurogenic cough, and its evaluation and treatment based on scientific publications addressing neurogenic cough. Neurogenic cough is thought to be the result of sensory neuropathy, most commonly idiopathic. Because it is principally a sensory phenomenon, clinical evaluation is challenging, the diagnosis most often being made by exclusion. Identification of motor paresis, either by laryngoscopy or laryngeal electromyography, may suggest the presence of sensory neuropathy. The utility of amitriptyline and gabapentin has been demonstrated in randomized clinical trials, and retrospective series and case reports have suggested efficacy of pregabalin, baclofen, and botulinum toxin. Sensory neuropathy appears to be an important cause of chronic refractory cough, and appears amenable to treatment with a variety of pharmacologic agents.

Meta-analysis of test accuracy studies: an exploratory method for investigating the impact of missing thresholds

BackgroundPrimary studies examining the accuracy of a continuous test evaluate its sensitivity and specificity at one or more thresholds. Meta-analysts then usually perform a separate meta-analysis for each threshold. However, the number of studies available for each threshold is often very different, as primary studies are inconsistent in the thresholds reported. Furthermore, of concern is selective reporting bias, because primary studies may be less likely to report a threshold when it gives low sensitivity and/or specificity estimates. This may lead to biased meta-analysis results. We developed an exploratory method to examine the potential impact of missing thresholds on conclusions from a test accuracy meta-analysis.MethodsOur method identifies studies that contain missing thresholds bounded between a pair of higher and lower thresholds for which results are available. The bounded missing threshold results (two-by-two tables) are then imputed, by assuming a linear relationship between threshold value and each of logit-sensitivity and logit-specificity. The imputed results are then added to the meta-analysis, to ascertain if original conclusions are robust. The method is evaluated through simulation, and application made to 13 studies evaluating protein:creatinine ratio (PCR) for detecting proteinuria in pregnancy with 23 different thresholds, ranging from one to seven per study.ResultsThe simulation shows the imputation method leads to meta-analysis estimates with smaller mean-square error. In the PCR application, it provides 50 additional results for meta-analysis and their inclusion produces lower test accuracy results than originally identified. For example, at a PCR threshold of 0.16, the summary specificity is 0.80 when using the original data, but 0.66 when also including the imputed data. At a PCR threshold of 0.25, the summary sensitivity is reduced from 0.95 to 0.85 when additionally including the imputed data.ConclusionsThe imputation method is a practical tool for researchers (often non-statisticians) to explore the potential impact of missing threshold results on their meta-analysis conclusions. Software is available to implement the method. In the PCR example, it revealed threshold results are vulnerable to the missing data, and so stimulates the need for advanced statistical models or, preferably, individual patient data from primary studies.