Effect of Dill (Anethum graveolens) Oil on Pruritus and Quality of Life of Hemodialysis Patients: A Randomized Double-Blind Three-Arm Controlled Trial

Introduction Anethum graveolens (AG), commonly known as dill, is a plant from the Apiaceae family that has been traditionally used as a skin softener and purifying agent in Persian medicine. In a previous study conducted on male rats, dill was found to have anti-inflammatory effects. The current study aimed to examine the efficacy of topical application of Anethum graveolens oil on pruritus severity, skin dryness, sleep quality, and quality of life in patients undergoing hemodialysis. Methods In the current clinical trial, the participants were randomly assigned to one of these groups: topical AG preparation, sesame oil, or a control group receiving no treatment. The study was double-blind and placebo-controlled. The topical treatment was applied twice a day for one month to areas of the skin affected by pruritus. The outcome measures included the severity of skin dryness, the Pittsburgh Sleep Quality Index, Duo's Uremic Pruritus Severity Scale, and the Itchy QoL questionnaire. Results This study involved 106 hemodialysis patients, and after intervention for one month, the medication group had a significantly lower mean score of sleep quality (3.24 ± 2.41) than the placebo (4.54 ± 3.11) and control (5.05 ± 3.21) groups (P=0.032). The mean change in pruritus severity was significantly greater in the medication group (−17.28 ± 8.938) than the placebo (−5.91 ± 5.398) and control (−3.43 ± 3.228) groups (P < 0.001). Moreover, a significant difference was observed in the mean changes in quality of life between the medication, placebo, and control groups, with values of −14.88 ± 7.89, −5.34 ± 4.50, and −1.92 ± 2.86, respectively (P < 0.001). Furthermore, both the medication and placebo groups showed improvement in skin dryness compared to the control group having the values of −1.65 ± 0.91, −1.11 ± 0.79, and −0.38 ± 0.54, respectively (P < 0.001). Conclusion Topical Anethum graveolens preparation significantly improved the sleep quality and quality of life and reduced skin pruritus and dryness in hemodialysis patients. It could be considered as a simple therapeutic modality to control pruritus in hemodialysis patients. This trial is registered with IRCT2017022032671N1.

Introduction.Anethum graveolens (AG), commonly known as dill, is a plant from the Apiaceae family that has been traditionally used as a skin softener and purifying agent in Persian medicine.In a previous study conducted on male rats, dill was found to have anti-infammatory efects.Te current study aimed to examine the efcacy of topical application of Anethum graveolens oil on pruritus severity, skin dryness, sleep quality, and quality of life in patients undergoing hemodialysis.Methods.In the current clinical trial, the participants were randomly assigned to one of these groups: topical AG preparation, sesame oil, or a control group receiving no treatment.Te study was double-blind and placebo-controlled.Te topical treatment was applied twice a day for one month to areas of the skin afected by pruritus.Te outcome measures included the severity of skin dryness, the Pittsburgh Sleep Quality Index, Duo's Uremic Pruritus Severity Scale, and the Itchy QoL questionnaire.Results.Tis study involved 106 hemodialysis patients, and after intervention for one month, the medication group had a signifcantly lower mean score of sleep quality (3.24 ± 2.41) than the placebo (4.54 ± 3.11) and control (5.05 ± 3.21) groups (P � 0.032).Te mean change in pruritus severity was signifcantly greater in the medication group (−17.28 ± 8.938) than the placebo (−5.91 ± 5.398) and control (−3.43 ± 3.228) groups (P < 0.001).Moreover, a signifcant diference was observed in the mean changes in quality of life between the medication, placebo, and control groups, with values of −14.88 ± 7.89, −5.34 ± 4.50, and −1.92 ± 2.86, respectively (P < 0.001).Furthermore, both the medication and placebo groups showed improvement in skin dryness compared to the control group having the values of −1.65 ± 0.91, −1.11 ± 0.79, and −0.38 ± 0.54, respectively (P < 0.001).Conclusion.Topical Anethum graveolens preparation signifcantly improved the sleep quality and quality of life and reduced skin pruritus and dryness in hemodialysis patients.It could be considered as a simple therapeutic modality to control pruritus in hemodialysis patients.Tis trial is registered with IRCT2017022032671N1.

Introduction
Uremic pruritus is a commonly occurring symptom that afects around 52% of the population in Iran [1].Te exact cause of uremic pruritus is unknown; however, various factors, such as skin dryness, infammatory immune responses, pruritus cytokines, secondary hyperparathyroidism, and uremic neuropathy, are believed to contribute to its development [2][3][4].Skin dryness is closely linked to pruritus severity in patients undergoing hemodialysis, and its incidence varies from 76.2% to 83% across diferent regions of the world, with an estimated prevalence of 51% in Iran [1,3].Uremic pruritus can lead to sleep disorders, negatively affecting the quality of life [4,5].Additionally, it may increase the likelihood of depression and mortality [6,7].
Tere are various treatments, both pharmacological and nonpharmacological, that have been suggested benefcial for improving the sleep quality in patients with uremic pruritus.Some medications, including gabapentin, pregabalin, ketotifen, nalbuphine, and montelukast, are efective in controlling pruritus [8].Topical products like moisturizing creams and baby oil can alleviate pruritus caused by skin dryness [9].Other nonpharmacological remedies consist of enhancing blood fow in the hemodialysis machines, as well as utilizing acupuncture, acupressure, aromatherapy, and narrowband ultraviolet phototherapy [10,11].Additionally, modifying nutritional status, vitamin D levels, and employing cold hemodialysis are among other helpful strategies [12,13].
Te utilization of traditional medicine can be considered as a novel mechanism for managing various diseases in an evidence-based integrative approach [14,15].Persian medicine (PM), which has been practiced for thousands of years, provides numerous efective treatments for various ailments [16,17].PM encompasses various therapeutic modalities, including dietary, pharmaceutical, and manual interventions.Herbal medicine has been particularly emphasized [18,19].
It possesses various medicinal properties, including analgesic, antioxidant, and anti-infammatory efects [34].Pruritus has been accounted as a type of pain in Avicenna's masterpiece, Canon of Medicine.In the second book of Canon, which is dedicated to Materia Medica, dill oil has been introduced as a strong skin softener with analgesic and hypnotic properties [35].Dill oil has also been used as a relieving agent for neural pains, arthralgia, arthritis, otalgia, and anal ulcers [36].
AG essential oil is composed of various major components, such as carvone, limonene, dihydrocarvone, carvacrol, p-cymene, α-phellandrene, and dill apiole [37].Phenol and favonoids, which are potent radical scavengers, have recently been considered as possible therapeutics against free radical mediated diseases, such as infammatory disorders [38,39].Boiled AG seeds have been found to be helpful in the labor process [40,41] and recommended for sleep disorders [42].In our previous animal study, AG oil was found to have signifcant anti-infammatory efects on formalin-induced infammation in male rats [43].Tis clinical trial was conducted to study the impact of AG oil on pruritus and quality of life factors in hemodialysis patients.Tis study is the frst of its kind and was carried out due to the belief that infammation contributes signifcantly to pruritus development.

Study Design.
Adopting a randomized, double-blind, and placebo-controlled design, the current trial was conducted on hemodialysis patients in hemodialysis centers of Golestan University of Medical Sciences in Golestan province, Iran.Following the CONSORT guideline, participants were allocated to three groups of medication (AG oil), placebo (sesame oil), and control (no medication) with equal allocation ratio.Te medication and placebo were completely similar in appearance and their contents were unknown to both patients and the investigator.

Inclusion and Exclusion Criteria.
Te criteria for including participants in the study were as follows: being 18 years or older, having undergone hemodialysis in the last three months, experiencing at least three episodes of pruritus lasting fve minutes or more in the last two weeks, and scoring a minimum of 3 on the Visual Analogue Scale (VAS) for pruritus.Participants were excluded if they had liver problems, open wounds, cellulitis, infections, deep vein thrombosis, epilepsy, bleeding disorders, paraplegia, a pacemaker, hearing or speech difculties, had undergone kidney transplantation, or had allergies.

Intervention.
During the study, patients were instructed to apply 2.5 g of either AG or sesame oil topically to the skin twice a day for one month.Tey were provided with instructions on avoiding contact with eyes and washing their hands with cold water after each use and cautioned against using the oils on areas with open wounds.

Outcomes.
Te outcome measures comprised the severity of skin dryness, the Pittsburgh Sleep Quality Index, Duo's Uremic Pruritus Severity Scale, and the Itchy QoL questionnaire.Before and after the intervention, the blood samples were collected from participants and sent to the 2 Evidence-Based Complementary and Alternative Medicine laboratory for analysis.Te tests included measuring levels of phosphorus, calcium, alkaline phosphatase, creatinine, blood urea nitrogen, hemoglobin, hematocrit, and platelet count, as well as the levels of C-reactive protein (CRP) and parathormone.Participants were randomly assigned to groups receiving either the medication (AG oil) or placebo.Te control group received routine therapeutic measures.Te skin sensitivity was frst checked with the content of the package before the intervention.First, a hand without fstula was washed with soap and water and dried.At the beginning of hemodialysis, a small amount of the content of package was applied to the skin.During the hemodialysis, the site was observed for any type of reaction.Te patient was then asked to report any kind of reaction during the study period.Ensuring that no complication occurred in the frst session, the patient was trained for the correct manner of taking the topical oil at the presence of a physician who was a member of the research team.Te patients were also asked to share any question or problem immediately via phone numbers that were given to them and their family members.
After the end of a one-month period, the tests were repeated and questionnaires were completed under the supervision of one of the researchers.

Randomisation.
In this research, the samples were selected by the available sampling method.In order to generate the random allocation sequence, the samples were randomly assigned.Considering the inclusion criteria, the participants were chosen using the convenience sampling method and then divided into three groups using a computer-generated block randomization method.Te block size was four.Next, 111 patients undergoing hemodialysis were selected and randomly assigned to three groups: drug, placebo, and control (without intervention).

Blinding.
Te packages containing either the AG oil or the placebo (sesame oil) were identical in color, size, and shape and were randomly labeled with codes that remained confdential by an independent individual until the trial ended.During the study, a nurse who was unaware of the allocation of the packages administered the medication (AG oil) and placebo packages to the patients.

Data Collection
Instruments.Demographic and clinical characteristics of patients as well as laboratory parameters, including calcium, phosphorus, parathormone, CRP, blood urea nitrogen, creatinine, hemoglobin, hematocrit, alkaline phosphatase, and platelets were recorded.We used a grading method to evaluate skin dryness which had been explained in a previous study [44].According to this method, score 0 indicates the absence of skin dryness; score 1: mild skin pruritus (involving legs); score 2: moderate skin dryness (involving all organs); and score 3: severe skin dryness (involving the whole body).
Te Pittsburgh Sleep Quality Index (PSQI-P) in Persian version was utilized to evaluate the patients' quality of sleep [45].It includes diferent dimensions of sleep disorders questioning about problem in getting to sleep, during the sleep, and in waking up.Four questions are considered for each type of sleep disorder.Te score of 0 or 1 is considered for each question depending on the existence of the problem.Te mean score of all four questions is named as PSQI-P.Patients with the PSQI-P less than 4 are assumed to have a good sleep, but those with PSQI-P of 4 or greater are considered to have a sleep disorder.
In addition, Duo's uremic pruritus scale was applied to the pruritus severity assessment.Tis questionnaire investigates the frequency, severity, and dispersion of pruritus and the resulting sleep disorder.Pruritus severity is evaluated by a score range of 0-48.A higher score indicates higher severity of the problems [46].
Te ItchyQoL questionnaire, which has 26 questions evaluating symptoms, functions, and feelings of patients with pruritus, was used to assess the clinical status of the participants in terms of their quality of life.Te answers were scored on a scale of 1 to 5. Te scores of each participant were calculated on each axis and the total score.A previous study had confrmed the reliability and validity of the Persian version of the questionnaire.Tere were no modifcations made to the trial outcomes [47].

Validity and Reliability of Instruments. Te Visual
Analogue Scale (VAS) tool has already been used for itching severity in clinical trials in Iran and around the world [9,48,49].It is a visual, numerical single-item tool that can be easily translated and shown to the patients.Te validity of the tool for measuring skin dryness was proven in a study by Akhyani et al. [44].In order to check the sleep quality of patients, the postsleep inventory (PSI) questionnaire, designed by Webb et al. [50], has been used by researchers to evaluate the subjective responses to the last period of sleep [51,52].Janabi et al. translated, validated, and used the modifed version of PSI (modifed postsleep inventory) questionnaire to investigate the relationship between Creactive protein serum level and sleep disorders in chronic hemodialysis patients [53].
Te itch intensity questionnaire used in this research was originally designed by Duo [46] and then modifed by Mettang et al. [54].It was then modeled by Yosipovitch et al.'s [55] questionnaire and was frst translated into Persian before being used by Panahi et al.In the current Evidence-Based Complementary and Alternative Medicine study, the researchers adopted and used this Persian version by Panahi et al. [49].
Te questionnaire for the quality of life of patients sufering from itching (ItchyQoL) is related to the research of Desai et al. in 2008 [47].Tari et al. translated the ItchyQoL questionnaire and checked its reliability and validity [56].To check the reliability and validity of the Persian translation of the ItchyQoL questionnaire, it was frst translated into Persian by two bilingual experts and then back-translated into English by two other bilingual experts.Finally, by matching the original and translated versions and revising the questions of the Persian version of the questionnaire, it was presented to the patients.Te questionnaire was flled in by 44 patients with pruritic skin disease in two occasions with an interval of 72 hours.Ten, the answers were statistically analyzed to check the reliability and structural validity of the questionnaire.Te reliability of the questionnaire was determined by calculating the internal correlation coefcient (Cronbach's alpha correlation coefcient) and the test-retest method.

Statistical Analysis.
Te analysis of the data was performed using the Statistical Package for the Social Sciences software (version 18.0).Using the one-sample Kolmogorov-Smirnov test, the normality of continuous variables was checked.Te chi-square as well as Fisher's exact tests were also used for nominal variables, while the Kruskal-Wallis and Mann-Whitney tests were performed for categorical variables.One-way ANOVA and Tukey's post hoc test were used in the case of continuous variables with a normal distribution.Statistical signifcance was considered as a p value of less than 0.05.

Herbal Medicine Preparation.
Te AG fresh plant was procured from a local market in Tehran and confrmed as authentic at the Herbarium of the Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran, with the voucher number 1702.To prepare the topical oil, 40 ml juice was extracted from 100 grams of AG fresh aerial parts, which was then mixed with sesame oil obtained from the Saman Company.Te mixture was boiled at a gentle temperature, so that all existing water in the mixture evaporated within 2 hours and the oil phase was remained.In the end, 44 g of AG oil in sesame oil base was obtained.Te mentioned preparation as "AG oil" was used in the medication group while the sesame oil was used in the placebo group.

Total Fatty Acid Content.
Te AG oil fatty acid content was determined using the gas chromatography and mass spectrometry (GC-MS) method.In brief, trans-methylation of fatty acids was carried out by accurately weighing 500 mg of AG oil into a screw-capped tube, to which 3 mL of heptane was added and mixed until the oil was completely dissolved.Methylation was then performed using a 2 N methanolic potassium hydroxide solution (2 mL).Te tube was shaken for 30 seconds, and the aqueous and organic layers were allowed to separate.A 2 μL sample from the top layer (heptane) was then injected into the gas chromatograph for analysis.
A gas chromatograph which was coupled with a mass spectrometer, specifcally the Agilent 6890 system, was employed in the analysis.Separation of the compound mixture was carried out on a BPX5 column (30 m × 0.25 mm × 0.25 mm flm thickness) using a program of temperature that ramped from 50 (held for 1 minute) to 133 °C (held for 0.2 minutes) at a rate of 3 °C per minute.Te temperature of the injector was set at 290 °C, and injection was performed in the splitless mode.Helium was used as the carrier gas, at a fow rate of 1 ml/min.

Determination of Phenol and Flavonoid Contents.
Folin-Ciocalteu reagent was used to determine the total phenolic content of AG oil (based on gallic acid), following a method previously described (36,60).Gallic acid (Sigma) was used as the standard.To extract the sample of AG oil, methanol was used.Ten, 5 ml of reagent (Folin-Ciocalteu reagent diluted with distilled water 1 : 10) as well as 4 ml of Na 2 CO 3 1M were added to both the sample and standard solutions.Te total content of phenolic compounds was determined by colorimetry at 765 nm after 15 minutes.By measuring the absorption of gallic acid solution at 0.0000, 50.0000, 100.000, 200.000, and 250.000 mg/ml concentrations in methanol:water (50 : 50 v/v), a standard curve was prepared.Te tests were repeated three times, and the mean value was presented as gallic acid equivalent (mg/g of AG oil).
Te total favonoid content of AG was measured using the method described by Beketov et al. [57].A mixture of 5 ml of 2% aluminum trichloride in methanol and 5 ml of AG oil was centrifuged at 4000 rpm for 8 minutes.Te upper clear phase was separated, and the total favonoid content was determined by calorimetry at 415 nm, using a blank sample of AG oil and methanol.Te standard curve was prepared using a catechin solution (Sigma, Aldrich), with concentrations of 0.0000, 5.0000, 20.000, 50.000, and 80.000 mg/l.After three measurements, the mean values of the total favonoid content were reported as mg of catechin equivalent per gram of AG oil.  1 and 2 display the demographic characteristics of the patients and the results of laboratory tests.Te data indicate that no signifcant differences between the groups regarding these factors were observed, except for the underlying cause of kidney failure.

Patient Characteristics. Tables
Te result of the Kruskal-Wallis test showed that before the intervention, there were some diferences between the mean creatinine values.Tere were statistically signifcant  diferences between the three groups.Tere was a signifcant diference by entering the creatinine variable into the ANOVA model as the covariate and the ANCOVA was analyzed, and it was observed that the diference in creatinine in the groups did not have any efect on the signifcance of the diferences between the groups for the main purposes.

Pruritus Severity.
Prior to the intervention, signifcant diferences were observed among the mean pruritus severity scores of the placebo, medication, and control groups (Table 3).Terefore, the ANOVA test was employed to compare the changes of pruritus severity between the three groups, which indicated higher decrease in the pruritus severity score in the AG group than the other groups during the study (P < 0.001).
4.4.Skin Dryness.Skin dryness degree was signifcantly diferent before the intervention in the medication, placebo, and control groups (P � 0.036).However, ANOVA test showed that mean changes of skin dryness scores were signifcantly diferent after the intervention among the groups (P < 0.001) (Table 4).

Quality of Life.
Te study found that the quality of life at the beginning of the study was diferent between groups (P � 0.018).After intervention, the ANOVA test was used for comparing the score changes between groups and it showed a signifcant diference (P < 0.001) which is presented in Table 5. Te post hoc test revealed a signifcant diference between medication and placebo groups (P < 0.001), medication and control groups (P < 0.001), and placebo and control groups (P � 0.024) in terms of mean changes in the quality-of-life scores.Te participants did not report any serious side efects.
4.6.Sleep Quality.Table 6 displays the results of the study regarding the mean scores of sleep quality in the three groups before and after the intervention.Te results of the analysis showed that there was no signifcant diference in the mean scores of sleep quality among the groups before the intervention (P � 0.687).However, after the intervention, a signifcant diference was observed among the groups (P � 0.032).At baseline, the PSQI-P score for all groups was above 4, indicating sleep disorders.Nevertheless, after the intervention, only the medication group demonstrated a PSQI-P score below 4, indicating improved sleep quality.

Phytochemical Study of AG Oil.
Te values for fatty acid contents of AG oil are shown in Table 7.Moreover, total phenol and favonoid contents of AG oil were determined as 0.081 ± 0.002 mg gallic acid/g and 0.12 ± 0.04 mg catechin/g, respectively.
4.8.Harms.No adverse efects or hypersensitivity were observed in the study groups of the current clinical trial.

Discussion
Te clinical treatment of uremic pruritus starts with changing the dialysis method, and improving the quality of dialysis can reduce the prevalence and severity of ESRD pruritus, but these measures have a high cost and treatment complexity, so their application is limited [58,59].A better quality of life can be achieved for these patients through planning and implementing nursing interventions to increase the adequacy of dialysis and to improve some parameters [60].
Te fndings of this study reveal that the medication group experienced signifcant improvement in pruritus, skin dryness, sleep quality, and overall quality of life compared to the other groups.No adverse reactions or hypersensitivity were observed following the use of AG topical preparation.
Essential oils as secondary metabolites of plants have been reported to have diferent functions, such as antimutagenic, antioxidant, antibacterial, antiviral, antifungal, and anti-infammatory properties [61].For example, a randomized controlled clinical trial study demonstrated that topical use of traditional formulation of chamomile oil can decrease the analgesic requests of patients with knee osteoarthritis [62].In another study, Esmaeili et al. demonstrated that cinnamon and clove essential oil nanogels could be regarded as analgesic drugs for preventing the infammation and nociception in rats [63].A recent randomized double-blind, controlled trial investigation disclosed that supplementation with Nigella sativa oil could decrease oxidative stress, infammation, and blood sugar in diabetic patients undergoing hemodialysis [64].In the current study, sesame oil was employed as a common oily vehicle for medicinal oils, which has been recommended for formulation in traditional Persian medicine.Moreover, sesame oil has been reported to have antioxidant and antiinfammatory properties [62].
Given that pruritus afects a high percentage (20-80%) of hemodialysis patients and signifcantly impacts their quality of life, these results are of signifcant importance [65].
AG could probably reduce itching through its antiinfammatory efects; thus, the patients have experienced a better sleep quality in addition to the improved quality of life.Te fndings of the present study are in line with the results of our previous research that stressed the antiinfammatory efect of Anethum graveolens oil [43].Also, given the antidysmenorrhea efects in a study by Mohammadinia et al., the anti-infammatory efects of the AG extract can be taken into consideration [66].
Te results of the current study confrm that our intervention improved the pruritus severity in patients compared with the control and placebo groups.In a crosssectional clinical trial, massage therapy was carried out with/ without aromatic oil.Analysis of research data indicated that the massage with or without aromatic oil signifcantly relieves itching [67].Accordingly, it seems that a portion of our intervention efcacy might be due to the massage efect.
In another double-blind randomized trial, the efect of capsaicin on the uremic pruritus was examined.In this double-blind cross-over clinical trial on 34 hemodialysis Evidence-Based Complementary and Alternative Medicine patients sufering from uremic pruritus, the efect of capsaicin compared to placebo was investigated.Te results showed that the efect of capsaicin and placebo on reducing the severity of itching was the same; so, the researchers recommended that considering that the placebo contained a moisturizer, patients should use topical moisturizers to reduce their itching.It was found that capsaicin reduces the pruritus severity similar to the placebo.Tey showed that the use of capsaicin 0.03 is efective in improving and relieving itching [27].Nevertheless, patients reported burning sensation after using capsaicin while no adverse efect was reported in the current study.
Te study found no signifcant diference in mean changes in skin dryness between the medication and placebo groups.However, diferences which were signifcant were observed between the placebo and control groups, as well as diferences between the medication and control groups, in terms of mean changes in skin dryness.Tis suggests that both the medication and placebo groups experienced improvements in skin dryness compared to the control group, potentially due to the presence of sesame oil.
Improving the efect of AG oil on pruritus and skin dryness can well explain its positive efect on the sleep quality and quality of life of the patients regardless of its traditional use for the sleep disorders [68].
Small sample size, short duration of follow up, and subjective outcome measures may be regarded as the limitation of the present research, which should be considered in future studies.

Conclusion
It can be concluded that Anethum graveolens oil (on the basis of sesame oil) can efectively reduce the pruritus and skin dryness of the hemodialysis patients and thus improve their sleep quality and quality of life.

Figure 1 :
Figure 1: CONSORT diagram of the trial.

Table 1 :
Characteristics related to demographics and clinical information of the participants.

Table 2 :
Laboratory test results of the patients.