Efficacy of Zinc on Concurrent Chemo-radiotherapy Induced Taste Alterations

Consecutive Sampling was used. It was a two-stage sampling method. Data was collected from patients visiting the Oncology Section at Atomic Energy Medical Centre Karachi from September 2017 to March 2018 on a proforma after being examined by the section head oncologist for the tumor. A standard proforma was used to record the taste acuity of the participants. Furthermore, the proforma also had details about patient's site of tumor, stage of tumor, daily fraction of dose, total dose of radiotherapy, chemotherapeutic drug and duration of the treatment for the record.

The international Standard Organization ISO 3972:2011/Cor 1:2012 provides guidelines for Method of investigating sensitivity of taste. Therefore, all solutions were prepared in accordance with the ISO. The solutions were prepared with deionized water in grams/litre and stored in 1000ml glass bottles at room temperature. All solutions were colorless and odorless. Eight increasing concentration of each taste (salty, sweet, sour and bitter; altogether 32 bottles), zinc capsules and placebo (filled with cornstarch) were prepared by ATCO pharmaceuticals. Sodium chloride was used as a stimulus for salty, sucrose for sweet, citric acid for sour and caffeine for bitter.

Patients were instructed to refrain from eating or drinking 30 mins to 1 hour before the procedure. If any patient was wearing denture it was taken off before the procedure and mouth was thoroughly rinsed with water before each trial. Each subject was given single 15ml of each solution in a cup and asked to hold the solution for 30 seconds in their mouth and gargle out to make sure the whole of oral cavity will be exposed to the taste solution (sip and spit procedure). After each presentation, patient mouth was thoroughly rinsed with water to remove any after taste and to avoid the residual effect of the previous taste solution. The water used for rinsing was identical with that used for preparing solutions. Each trial was spaced at least 15 seconds apart. The time spent for each data collection tool was 20-30 mins.

Taste function of each patient for four basic taste (salty, sweet, sour and bitter) was assessed by detection and recognition threshold which were noted on a proforma. The proforma had three columns (baseline, end chemoradiation and follow-up a month after chemoradiation) for each taste and marking from 1 to 8 corresponding to the increasing concentration of the taste solutions (D8-D1) for each taste. D1 was considered as the highest concentration whereas D8 was the lowest concentration of each taste solution.

The cut-off values that were set for each patient for detection and recognition threshold were:

1-8 = able to identify and recognize the taste 0 = unable to identify and recognize any response For Detection threshold (DT) A sample of deionized water and a taste sample was presented to the patient. The order of presentation was randomized for every subject. Participants were asked to indicate which of the sample contains the taste. Detection threshold (DT) was considered as the lowest level at which a subject can perceive a stimulus. This was the minimum concentration at which the subject can detect that there is something different from water, but may not identify its quality. D1 was the highest concentration of solution for each taste and was marked on proforma as 1 and D8 was the minimum concentration and was marked as 8.

For Recognition threshold (RT) Participants were also asked to describe the taste of the solution either salty, sweet, sour or bitter. Recognition threshold was considered as the lowest level of a solution at which a subject can correctly recognize its taste, i.e., sucrose for sweet, sodium chloride (NaCl) for salty, citric acid for sour and caffeine for bitter. D1 was the highest concentration of solution for each taste and was marked as 1 whereas D8 was the minimum concentration and was marked as 8.

Solutions were presented in the increasing order of their concentration and the lowest concentration of solution was marked for each taste that was perceived by the patient. Any subject who was unable to detect the difference between the water and the tastant, the concentration of the taste solution was increased.

Data was entered and analyzed by the IBM SPSS software for windows version 20. Data is shown as mean ± SD for descriptive statistics and as median [IQR] for intervention statistics. First, the normality was assessed of all four taste variables by Shapiro-Wilk test. The normality tests are given below.

The baseline characteristics of the test and control group were compared by Chi square and independent t test. To observe difference within the two groups, Wilcoxon Signed Ranks test was applied. To observe the difference between the two groups, Mann-Whitney U test was used. P-value was calculated by Friedman test. Statistical significance was accepted at P < 0.05.