Several reports suggest that zinc, which is involved in several neural transmissions systems throughout the auditory pathway, might help some tinnitus patients. However, previous studies used inadequate experimental designs. Therefore, we tested the effectiveness of zinc to reduce tinnitus.
Randomized, prospective double-blind placebo-controlled design.
Tertiary referral center.
Tinnitus subjects older than 60 years, who are more likely to have a zinc deficiency.
In Phase 1, 58 subjects were randomized to receive 50 mg of zinc per day for 4 months, and 58 subjects received a placebo. After a 1-month washout period, the 2 groups were crossed over to receive the alternative regime (Phase 2).
Main Outcome Measure
Difference scores between before and after measures of the Tinnitus Handicap Questionnaire. Changes on the difference scores 20 or greater were considered as a statistically significant and, therefore, clinically meaningful improvement for THQ.
Five percent (5 of 93 patients) had an improvement of 20 points or greater in THQ scores after zinc treatment, whereas 2% (2 of 94 patients) had an improvement of 20 or greater in THQ scores after placebo. The difference between 2 proportions is 5/93 - 2/94 = 0.03, the estimate of relative improvement is (5/93) / (2/94) = 2.53, with 95% confidence interval from 0.5 to 12.7. From chi-square independent test, there was no significant evidence that patients treated by zinc improved better than those treated by placebo (X2 (1) = 1.4, p > 0.05). The observed power in THQ for zinc is 0.16, and that for placebo is 0.06.
Zinc is not an effective treatment for tinnitus in this subgroup of patients.