This three-group, single-blind, clinical trial was conducted on 93 patients attending the dialysis wards of two hospitals affiliated to Zahedan University of Medical Sciences (Ali Ibn Abi Talib and Khatam-al Anbia hospitals) in 2017. The standard sample size was calculated at 22 for each group based on the formula for sample size determination of interventional studies considering confidence level of 95% and test power of 90%, and according to the values of similar studies on pain intensity reduction. Since this study consists of three groups, the sample size was multiplied by square root of 2; thus, 31 subjects were assigned to each group (
Figure 1) (
19).
Once the proposal was approved by the Ethics Committee of the university (code of ethics: IR.ZAUMS.REC.1396.288) and after making the necessary coordination with the head of the hospitals and hemodialysis wards, the eligible patients were included in the study after receiving an explanation regarding the study objectives and signing an informed consent form. The participants were selected using the convenience sampling method. The inclusion criteria were age above 18 years, consciousness, ability to communicate, need for hemodialysis at least twice a week, not receiving any analgesics or drugs six hours before hemodialysis, absence of severe pain in other organs, and no skin problems or numbness at the site of access to the veins of diabetic patients. The exclusion criteria comprised lack of cooperation, kidney transplantation and termination of hemodialysis treatment, development of wound at the site of fistula at any stage of the disease, misplacement of the fistula needle at the first time, and death.
First, a demographic-clinical information form including items on age, gender, ethnicity, site of fistula, frequency of dialysis per week, and time of initiation of dialysis with fistula was completed by the patients. In case of inability to read and write, the form was completed through interview by the researcher.
In order to assign the patients to each of the intervention groups (distraction, Arnica ointment, and placebo), randomization method was used. For this purpose, 93 colored balls placed inside a vase were provided to the patients. Every patient randomly picked up a ball (red ball: Representing Arnica ointment group; white ball: Representing the distraction group; and green ball: Representing the placebo group), and the patients were assigned to three equal groups accordingly. In the distraction group, in order to distract the patients during insertion of fistula needle, images related to nature alongside music were presented using a laptop and headphone for 30 minutes. Specifically, the patients lied in a semi-seated position, the laptop was placed on the table ahead of the patients, and its monitor was opened towards them. Then, a headphone was provided to the patients, and music and images were presented to them. The music and images were presented for half an hour. Ten minutes after beginning the music, fistula needle insertion was performed and the pain score was assessed and recorded after needle insertion.
In the two groups of Arnica ointment and the group, identical materials were employed by the researcher for 60 minutes before fistula insertion by as large as around 5 cm2 on the needle insertion site. A bandage was then placed on it. Next, Arnica ointment or Vaseline cream was cleared off the skin surface, the needle placement site was disinfected with Betadine, and then arterial needle insertion was performed. Following arterial needle insertion and before venous needle insertion, pain intensity was assessed and recorded by the researcher without knowing the type of applied medication on the skin surface. Needle No. 16 (SUPA) was used for vascular access in all the patients. The arterial needle was inserted to the vessel at a distance of at least 5 cm off the fistula at 30 - 45°. Pain intensity was measured only the first time the patient’s skin was punctured by the nurse to insert the arterial needle. In case of misplacement of fistula needle and second attempt by the nurse to perform this procedure (re-perforation of the skin), the patient was excluded from the study in that session, and the pain resulting from subsequent times was not measured. Across all the three groups, arterial needle insertion was performed by the same nurse.
Visual analogue scale (VAS) was used for evaluating the patients’ pain. This scale is a horizontal line measuring the level of pain on a scale of 0 - 10. VAS was devised in 1975 by Mezlak, and it has been used in various studies ever since. In this method, using a questionnaire and through numerical gradation, among different factors ranked in association with pain, separation between the sensory part and cognitive, motivational, and emotional factors was done. This scale was used to measure the patients’ pain immediately after insertion of fistula needle. The scientific validity and reliability of this scale has been confirmed in various studies. In this regard, Wiliamson in a study entitled “reviewing three pain grading scales which are typically used”, he reported that this scale is valid, reliable, and suitable to be used in clinical practice (with correlation coefficient of 0.97 - 0.99) (
20,
21). Pain assessment was performed by a trained nurse who was blind to the group allocations. Pain assessment in all the three groups was performed during two consecutive hemodialysis sessions (intervention with placebo, Arnica, or distraction). Eventually, the obtained data including demographic and clinical information and pain score were analyzed by using Chi-square, ANOVA, and Bonferroni post hoc tests at the significance level of less than 0.05 in SPSS, version 22.