Analytical approach:
The authors used a state-transition model, with a cycle length of one year, to compare the costs and effects of using hearing aids compared with no hearing aid, over a 30-year period. The authors stated that the perspective was societal.
Effectiveness data:
The probabilities of hearing decline or stability were from a systematic review of the published literature. The probability of going to visit a physician was from one study, as was the probability of patient satisfaction. The probability of using a hearing aid after a consultation with the audiologist was from observational data that were appropriate to the setting. The key data were assigned distributions for a Bayesian analysis.
Monetary benefit and utility valuations:
The utility estimates were derived from a systematic review of published studies that used the visual analogue scale or the Hearing Handicap Inventory for the Elderly.
Measure of benefit:
The measure of benefit was quality-adjusted life-years (QALYs) gained and these were discounted at a rate of 3% per annum.
Cost data:
The costs included those of visits to a physician about hearing loss and to evaluate hearing status, hearing aids and consultation, and maintenance of hearing aids, such as battery replacement and repair. The costs of consultations were from the National Health Insurance reimbursements schedule for Taiwan and those of hearing aids were estimated from observational data on patients who were using hearing aids. The indirect costs of lost productivity, from the gross national product per capita in Taiwan, and travel (an arbitrary estimate) were also included. The costs were in US dollars ($) and in Euros (EUR), in 2004 values, and discounted at a rate of 3%.
Analysis of uncertainty:
The impact on the results of variations in the key model parameters, across ranges identified in the literature, was assessed using probabilistic sensitivity analysis.