Outcome Study in Hearing Loss
Date Issued
2008
Date
2008
Author(s)
Chao, Ting-Kuang
Abstract
Background: Hearing impairments would cause social isolation and difficulties in communications. Among diseases that cause sudden hearing deterioration, idiopathic sudden sensorineural hearing loss (ISSHL) is still a controversial topic. Although several prognostic factors had been reported, there is lacking of in-depth analysis. Besides, the prediction of recovery in ISSHL with the incorporation of all putative factors has been barely investigated. Only few studies have covered this theme. In addition to ISSHL, most people suffered from age-related hearing loss (ARHL) with aging. The progressive type has been well documented but the disease natural history is poorly understood. In addition, the mainstay treatment for such kind of hearing loss relies on hearing aids fitting. However, the efficacy of such assistance is also lacking of systematic evaluation.bjective: (1) To evaluate the prognostic factors associated with ISSHL, especially focused on the distortion-product otoacoustic emissions (DPOAE), an objective auditory indicator as a potential prognostic factor for ISSHL patients. (2) To establish a predictive model for recovery of ISSHL for clinical application. (3) To develop an appropriate model in quantifying the progression of hearing in ARHL and to establish a new model in performing a probabilistic analysis of cost-effectiveness for hearing aids fitting in elders.ethods: (1) One hundred and eight patients with ISSHL were included. Time-dependent Cox regression model was used in evaluation of DPOAE and other prognostic factors. The average of two series of DPOAE intensity corrected for the noise level in 8 frequencies was coded as dichotomous as U>U6 dB or <6 dB. We selected the most updated DPOAE at 3 days or more before the assessment of recovery into the analysis. (2) Two hundred patients with ISSHL were recruited to build up the predictive model. First, the log-normal accelerated failure time model was applied to investigate the time duration from treatment to a significant recovery of the hearing. Second, the cure rate model was utilized to predict the long-term cumulative recovery rate by taking into account the extent of susceptibility to recovery. Bayesian approaches of both models with WinBUGS program were applied in predicting the median and 95% credible interval of the recovery time or long-term cumulative recovery rate. (3) In ARHL, we modeled the disease process for hearing loss as a four-state continuous-time Markov process. The pooled estimates were obtained and compared with each other. With the estimates, we can also predict all transition probabilities between states. Then a decision model run with different hearing states was used in evaluation of cost-effectiveness for hearing aids fitting. Probabilistic approach with Monte Carlo simulation was performed to produce the cost effectiveness acceptability curve of showing the probabilities of being cost-effective given a series of willingness to pay (WTP). esults: (1) In ISSHL, the results showed that a better DPOAE amplitude was a significant good prognostic indicator both in univariate analysis (recovery rate ratio = 3.626, 95%CI = 2.119~6.205, p<0.0001) and multivariate analysis (recovery rate ratio= 2.94, 95%CI = 1.537~5.624, p=0.0011). Younger age (age<= 40 years), better initial pure tone audiometry (< 65 dB), normal auditory brainstem response and vestibular evoked myogenic potential represented a better prognosis. The configuration of initial audiometry was also a significant prognostic factor. (2) Predicted results were compared with the observed values and the model showed a good internal validity. However, both models have equivalent predictive accuracy within three weeks after onset of ISSHL but the cure rate model had a better long-term prediction than the lognormal model. The overall results predicted by different combinations of covariates were summarized and organized in an Access program file that is convenient for clinical application. (3) In ARHL, the progression of hearing loss increased with the ascending frequencies across all age groups. Males had significantly faster progression rates in all frequencies and age groups except for the age group of 90 years or older. In comparison between ears, the progression of hearing would be slightly faster in left ears initially in early elder life and did not show any difference in further aging and later hearing declines. With the pooled estimates of progression rates, the probabilities of hearing deterioration could be obtained. With regard to the cost-effectiveness of hearing aids fitting, the incremental cost for an additional HQALY gain in women and men were NT$ 461,154 and NT$ 329,010 respectively. Using acceptability curve, the probability of being cost-effective increased up to 52% in women and 64% in men given a WTP of NT $ 400,000. It would reach plateau with 67% in women and 78% in men given a WTP of NT $ 700,000.onclusions: In some kinds of ear diseases, hearing loss might be reversible after treatment. ISSHL is a typical type that treatment might improve the prognosis. The first part of our study could offer an appropriate statistical model in evaluating prognostic factors and different treatment protocols for ISSHL patients. The development of the predictive models could offer a good reference for clinical consultations. On the other side, in some diseases, hearing loss is progressive and can’t be restored with present treatments and techniques. ARHL is a representative type that prevention and rehabilitation are the major issues. In this study, we realize the natural course of the hearing progression and could offer a model in evaluating the effects of risk factors. The establishment of an appropriate model in quantifying the hearing progression in ARHL would be helpful in future researches. By using a multi-state model with different hearing states, hearing aid fitting is demonstrated as a cost-effective strategy in the rehabilitation for hearing-impaired elders. The results could help policy makers in allocating the health resources more appropriately.
Subjects
Cure rate model
Distortion product otoacoustic emissions
Markov chains
Prediction
Presbycusis
Quality of life
Sudden hearing loss
SDGs
Type
thesis
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