Prognosis of acute acoustic trauma: a retrospective study using multiple logistic regression analysis (original) (raw)

Abstract

Objective: The prognosis for acute acoustic trauma (AAT) is difficult to predict. Multiple logistic regression analysis was used in this study to determine which factors were most strongly related to outcome for patients with AAT. Methods: The study group was comprised of 52 patients (52 ears). Separate analyses were performed on the no change and partial recovery groups, and on the no change and full recovery groups. The following eight factors were examined as explanatory variables, age; number of days before the start of treatment; use of earplugs; drug therapy (adrenocortical hormones, low molecular weight dextrans, and vitamin B12), mean hearing levels at 0.5, 1, and 2 kHz (pure tone average, PTA), and mean hearing levels at 4 and 8 kHz (high tone average, HTA). Results: Factors determined to be most strongly related to outcome were the number of days before the start of treatment, PTA, and HTA. No significant relation to outcome was determined for the five following factors, age; use of earplugs; and drug therapy (adrenocortical hormones, low molecular weight dextrans, and vitamin B12). Conclusion: Our results will increase the ability to prognosticate the outcome for AAT.

Introduction

The prognosis for acute acoustic trauma (AAT) caused by loud noises such as gun shots has been reported to range from total recovery to no change. Thus, the prognosis for this injury is difficult to predict. Previous reports on AAT have associated prognosis with the number of days between injury and the start of therapy, the hearing level at presentation, and the method of treatment [1], [2], [3]. Although previous investigations have assessed the relation between individual factors and outcome for AAT, to our knowledge no study has used multivariate analysis, which can adjust for the effects of other factors, to evaluate the contribution of multiple factors to outcome. Logistic regression analysis provides a model for multivariate analyses that can examine at regular intervals the relation between several factors and disease (or all events), after adjusting for the influence of other factors.

Multiple logistic regression analysis was used in this study to determine which factors were most strongly related to outcome for patients with AAT.

Section snippets

Subjects and methods

The study group was comprised of 52 patients (52 ears) observed between July 1988 and April 1999 with AAT. All subjects were members of the Japanese Self Defense Force. They ranged in age from 18 to 53 years (mean, 26.0 years). All but one were male. Hearing loss was caused by trauma due to small arms in 40 patients, blank firing of small arms in seven, machine guns in two, firecrackers in two, and rock music in one. All patients presented within 14 days of the trauma. Twenty-one were admitted

Results

The outcome for the 52 patients with AAT was a full recovery in 15, partial recovery in 25, and no change in 12. The results of logistic regression analyses are shown in Table 2, Table 3. The odds ratio expresses the degree of change in odds associated with a 1-unit change in an explanatory variable.

Discussion

The outcome for patients with AAT was found to be related to the number of days before the start of treatment, HTA, and PTA. A longer interval between the time of acoustic injury and the start of treatment, and poor HTA levels at presentation were associated with a poor outcome. Conversely, poor mean hearing levels at 0.5, 1, and 2 kHz (PTA) were associated with a good outcome. Although an association between poor PTA and good outcome appears contradictory, it could be attributed to an

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