Aminoglycosides are powerful broad-spectrum antibiotics used for gram-negative i

Question

Aminoglycosides are powerful broad-spectrum antibiotics used for gram-negative infections often in seriously ill patients. For example, the drugs are often prescribed for drug-resistant tuberculosis as recommended by the World Health Organization. However, these drugs have serious side effects, including irreversible hearing loss referred to as ototoxicity. The most commonly prescribed aminoglycoside is gentamicin. A clinical trial was set up in China to assess whether the addition of aspirin to a standard regimen of gentamicin would have an effect on the incidence of ototoxicity. There were 195 patients enrolled in a prospective, randomized, double-blind clinical trial. Of these, 106 patients were randomized to a twice daily regimen of 80-160 mg of gentamicin plus placebo and 89 patients were randomized to receive the same regimen of gentamicin + 3 g of aspirin ASA daily.

i. What is a prospective study? What are its advantages? ii. What is a double-blind study? Are there advantages s. other approaches?

After 2 weeks of treatment, 14 of the placebo patients and 3 of the ASA patients developed clinically significant hearing loss.

Implement a test to assess whether the incidence of hearing loss is different between the groups. State clearly which test you are using, and report a two-sided p-value. Interpret the results of your test problem.

Explanation / Answer

let p1 denote the proportion of gentamicin plus placebo patients = 14/106 = 0.1321

let p2 denote the proportion of gentamicin + 3 g of aspirin ASA = 3/89 = 0.0337

Ho: there is no significant difference in the incidence of hearing loss is between the groups.

against,

H1: there is a significant difference in the incidence of hearing loss is between the groups.

under Ho, the test statistic is given by

Z = (p1-p2)/(PQ(1/n1+1/n2))

here n1 = 106, n2 = 89

P = (n1p1+n2p2)/n1+n2

P = 0.0872 and Q = 1-P

Q = 1-0.0872 = 0.9128

substituting the above mentioned values in Z we get calculated value of Z

Z cal = 2.46

Now we obtain the tabulated value of Z at 5 % level of significance.

the tabulated value of two-sided is Z tab = 1.96

Now we compare Z cal and Ztab value

but Zcal Ztab therefore we reject the null hypothesis i.e Ho

the conclusion for difference of proportions test is there is a significant difference in the incidence of hearing loss is between the groups.

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