Design
Participants who agreed to participate in the study and had no contraindications to electrotherapy in the neck area were selected or excluded from participation in the study through a computer-generated randomization list. Qualified participants were subjected to ultrasonography of the thyroid gland and had hormone levels (TSH, FT3 and FT4) determined. Thereafter, two study groups assigned to two different interventions (galvanization – group G /iontophoresis – group I) were formed by subsequent randomization. The participants of the study were not informed to which group they were assigned to. A double-blinded, 1:1 parallel-group, randomized controlled trial was conducted.
Participants
The students of the third, fourth and fifth year of physiotherapy were invited to participate in the study. They were given written information about the purpose and course of the study and the possibility of withdrawing from participation at every stage of the study.
Inclusion criteria were:
- informed written consent of the patient to participate in the study;
- no contraindications to electrotherapy in the area of the throat and larynx;
- normal results of ultrasonography of the thyroid and hormone levels (TSH, FT3, FT4);
- no neoplastic diseases and thyroid diseases in the examined person and in the immediate family.
Exclusion criteria were:
- poor tolerance of electrotherapy treatments;
- breaks between consecutive treatments longer than 3 days;
- failure to complete a series of iontophoresis / galvanization treatments;
- use of any stimulants during the observation period.
The members of Scientific Circle of Physical Energy Used in Physiotherapy were therapists.
The study was conducted in Centre for Innovative Research in Medical and Natural Sciences, University of Rzeszow.
Intervention
Participants were subjected to a series of 10 electrotherapy treatments (galvanization or iontophoresis) according to the result of randomization.
Methodology of cathodic galvanization treatment:
- distilled water (placebo) was used for the treatment
- current 2 mA
- treatment time 30 min
Methodology of cathodic iontophoresis treatment:
- 10 ml of 2% KI solution (200 mg of KI) was used
- current 2 mA
- treatment time 30 min
After each treatment, the condition of the skin in the treatment area was assessed in order to exclude any symptoms of iodine allergy.
During the iontophoresis procedure, 6.1927461 mg of potassium iodide, including 4.73409324 mg of iodine was introduced into the tissues (Appendix A).
The following were used for electrotherapy:
- a 4 cm x 5 cm active electrode placed in the throat area (current density was 0.1 mA / cm2)
- a 5 cm x 6 cm passive electrode placed in the nape (current density was 0.066 mA / cm2)
Outcome measures:
Before the study, all students had an ultrasonography examination of the thyroid gland performed by a radiologist.
The outcomes were the levels of TSH, FT3, FT4 hormones (Appendix B). Hormone levels were tested before a series of 10 electrotherapy treatments (test 1), two weeks after the end of the electrotherapy series (test 2), and after 6 months (test 3) (Fig. 1). All hormone tests were performed in the same laboratory.
Data analysis
In the first stage of the analysis, the data obtained from the 50 participants who participated in test 1 and test 2 were analyzed. The level of TSH, FT3 and FT4 was compared before electrotherapy (test 1), after electrotherapy (test 2), as well as the effect of electrotherapy between group G (galvanization) and group I (iontophoresis). The statistical significance of the electrotherapy effect was also assessed in each group separately.
In the next stage, the data obtained from 36 participants who took part in three subsequent tests were analyzed. The significance of changes in individual parameters was assessed in the period between the first and second tests (1-2), between the second and third tests (2-3), and between the first and third tests (1-3) (electrotherapy effects) - separately for group G and group I. The level of individual parameters was compared between groups I and G for each study, as well as for the observed changes (effects of different electrotherapy treatments).
As the distributions of the studied values did not differ significantly from normality, parametric tests were used:
- t-test for independent samples to evaluate differences between groups;
- t-test for paired samples to assess the significance of changes in parameters between studies within groups.
The chi-square test of independence was used to assess the differences in the frequency of decreases or increases in the values of individual parameters in both groups.
The sample size was determined for one of the laboratory parameters, namely TSH. On the basis of the preliminary examination (for 10 people), the mean TSH value was determined at the level of 2.6 µIU / ml with the standard deviation amounting to about 1.2 µIU / ml. It was assumed that the sample size should detect a change between tests at 50% of the variation in the first test (i.e. 0.6 µIU / mL) at a significance level of 0.05 and 80% of test power. Such assumptions for the t-test for dependent samples give a minimum sample size of 21. Some assumptions taken into account might seem debatable therefore groups of 25 were included in the analysis.
In the analysis and interpretation of results, statistical significance was determined at p≤0.05 (*p<0.05 **p<0.01; ***p<0.001). STATISTICA software was used for all calculations.