The effect of warm saltwater and warm water baths on pain, fatigue, sleep quality, and functional capacity in patients with rheumatoid arthritis: a randomized controlled study^✰

Abstract

Background

Pain, fatigue, poor sleep quality and functional capacity are the most common symptoms in patients with rheumatoid arthritis. Complementary and integrative methods to be applied by nurses can be an essential strategy in successfully managing these symptoms. The purpose of this study was to examine the effects of warm salt water and warm water baths applied to the hands and feet on pain, fatigue, sleep quality and functional capacity in patients with rheumatoid arthritis.

Methods

This three-arm and prospective randomized controlled study fifty-four patients were randomly assigned to three groups (warm salt water: 18; warm water: 18; control: 18). Data were collected using the Visual Analog Scale, Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire, Disease Activity Score 28, Pittsburgh Sleep Quality Index, and Health Assessment Questionnaire. The intervention groups received warm saltwater or warm water hand-foot baths for six weeks. In all three groups, the measurements were taken at the beginning of the study and at the end of the last bathing sessions. Data were analyzed with chi-square test, one-way ANOVA, paired sample t-test, and two-way mixed ANOVA with Bonferroni’s test.

Results

Two-way mixed ANOVA revealed significant Group × Time interactions for pain (F = 9.736, p < 0.001, η² = 0.249), fatigue (F = 4.323, p = 0.013, η² = 0.158), and fatigue-related quality of life (F = 3.350, p = 0.043, η² = 0.116). Bonferroni post-hoc analyses indicated that both interventions (warm salt water and warm water) led to significant improvements in pain, fatigue, and sleep quality scores compared to the control group (p < 0.05), Notably, the most significant improvement in pain was observed in the warm saltwater group, while the most pronounced reductions in fatigue and fatigue-related quality of life were observed in the warm water group (p < 0.05). Although significant within-group improvements were observed in both intervention groups for sleep quality and only in the warm saltwater group for functional capacity (p < 0.05), no significant Group × Time interactions were found for either outcome (p > 0.05).

Conclusions

The findings of this study confirmed that warm saltwater and warm water baths applied to the hands and feet improved pain, fatigue, and sleep quality in patients with rheumatoid arthritis. Additionally, warm saltwater baths significantly improved functional capacity. These interventions may serve as safe, accessible, and effective complementary methods for symptom management.

Registration

Retrospectively registered with the ClinicalTrials.gov (Ref. No: NCT05888220). (Registration Date: 24 May 2023).

Background

Rheumatoid Arthritis (RA) is a chronic, systemic, and autoimmune disease characterized by persistent synovial inflammation in the joints, leading to cartilage and bone destruction [1]. Studies indicate that the prevalence of RA varies between 0.5 and 1% [2]. RA often affects symmetrically small joints, such as the hands and feet [1]. Common symptoms such as swelling, pain, tenderness, and stiffness significantly limit the patient’s ability to perform daily activities [3]. If the disease and symptoms are not properly managed, RA can lead to joint and non-joint problems [4, 5]. While pharmacological methods are available to manage the disease and disease-related symptoms in patients with RA, there is a clear need for alternative management options that can facilitate coping with both the disease and the side effects of treatment. At this point, self-management practices involving the active participation of the patient should be an integral component of the treatment. Therefore, recent studies emphasize that complementary and integrative methods (CIM) such as exercise, joint protection, hand-foot care, and patient education can help patients improve their RA-related symptom management and health outcomes [4–7].

Pain is among the main reasons RA patients apply to the hospital and seek medical care [8]. It is reported that patients with RA often suffer from pain ranging from mild to moderate intensity [9]. Previous studies showed that 56% of RA patients experienced unacceptable pain, 77% had widespread pain, and 28% had widespread chronic pain [10]. The pain mostly occurs in the hands (88%) and/or feet (83%) [11]. In addition to creating a negative impact on health-related quality of life (QoL) [12], pain also causes many problems, such as fatigue, functional limitation, depression, and sleep disorders [8]. Moreover, it is reported that RA patients with severe pain have lower sleep quality and, accordingly, experience more fatigue [13].

Another common symptom that negatively affects the physical and psychosocial health of RA patients is fatigue [14]. In addition to the negative effects of fatigue on patients’ quality of life, it also has negative consequences such as more hospital admissions, job loss, deterioration in communication with friends and family members, social isolation, difficulty in managing other RA-related symptoms, and preventing participation in rehabilitation programs [15]. Fatigue is as common (40–80%) as pain in patients with RA [14, 15]. However, in clinical practice, it cannot be adequately evaluated and managed due to its subjective dimension and multifactorial etiology, such as physical, cognitive, and emotional aspects [14, 16].

Poor sleep quality is also reported as a serious problem with very high rates (57.6-81.5%) in RA patients [4, 14, 15]. Factors reported to contribute to sleep quality impairment in RA include pain, fatigue, disease activity, inflammation, mood disorders such as depression, and side effects of disease-modifying drugs [4]. While these factors cause poor sleep quality, sleep impairment also triggers the emergence of these problems [7].

Considering the multidimensional and multifactorial effects of these RA-related problems on patients, effective disease and symptom management are essential. Preference for only medical and surgical approaches often limits disease and symptom management [8]. Therefore, apart from these approaches, simple, easily applicable, accessible, and cost-effective CIMs can be useful for managing RA and RA-related symptoms. One of these CIMs is water therapies used in symptom management of different inflammatory and non-inflammatory rheumatic diseases [17, 18]. Warm water and warm saltwater baths are complementary therapeutic methods involving the immersion of part or all the body in water. These applications exert mechanical, thermal, and chemical effects through heat transfer and mineral absorption via the skin, thereby playing a role in symptom management [19–21]. The primary goals of RA treatment are to achieve remission, suppress inflammation, slow joint destruction, manage pain, and maintain functional independence in daily activities [22, 23]. Water baths are valuable adjunct therapies that can complement standard pharmacological treatments [24]. These baths provide significant relief across a range of RA symptoms, particularly in reducing inflammation and pain, enhancing circulation, and supporting joint mobility [25]. Additionally, it is reported that water baths may regulate key pathophysiological processes involved in RA, such as oxidative stress, thereby reducing disease activity [26]. By restoring the balance between oxidants and antioxidants, they exert positive effects on symptoms [27].

The combined effects of water baths include reduced pain and inflammation, improved mobility, increased muscle tone, and enhanced psychosocial well-being [28]. Thermal stress induced by warm water baths stimulates the release of hormones such as adrenocorticotropic hormone, cortisol, prolactin, and growth hormone, which act via the hypothalamic-pituitary-adrenal axis to reduce inflammation and edema [29]. The buoyant force of water reduces the load on painful joints, while hydrostatic pressure and water temperature regulate circulation, decrease edema, and promote muscle relaxation [30]. The impact of water temperature and pressure on the skin is among the core mechanisms underlying pain relief [31]. Moreover, warm water therapy reduces muscle spasms, raises pain thresholds, and stimulates the release of insulin-like growth factor-1 (IGF-1), which supports the metabolic processes of cartilage tissue [31]. These effects demonstrate the holistic benefits of water baths in alleviating pain, improving joint mobility, and restoring functional activity, thereby enhancing overall patient well-being [32].

Water baths not only address physical symptoms but also exert beneficial effects on the psychological well-being of patients. They may reduce stress levels, improve sleep quality, and enhance overall quality of life [33]. It has been suggested that warm water baths stimulate thermoreceptors in the skin, thereby activating the parasympathetic nervous system. Through this mechanism, they promote relaxation, reduce fatigue, and improve sleep quality [18]. WSW baths contribute to symptom relief not only through heat but also through the hypertonic environment created by salt, which draws out fluid through the skin and reduces edema. This is particularly beneficial for reducing swelling in distal joints, improving mobility, and alleviating pain [34]. In addition, Piezo1 and Piezo2 ion channels in the skin are activated by salt and water temperature, generating electrical signals that regulate both the somatosensory and autonomic nervous systems. As a result, these applications promote relaxation, suppress pain, induce a sense of well-being, and reduce fatigue, thereby helping to relieve RA symptoms. Due to the sensitivity of Piezo1 channels to external stimuli such as temperature and salt, it is thought that such interventions can reduce pain perception at a neurophysiological level, facilitate the onset of sleep, and improve sleep quality [35, 36]. Considering physiological effects of the interventions made with the warm water (WW) method on the body, it is stated that an average temperature of 40–45 °C can cause an increase in heat on the skin by contacting the skin. With this temperature created on the skin, muscle contraction decreases while collagen tissue elasticity, blood flow and metabolic rate increase. At the same time, pain is reduced by creating a feeling of relaxation with the sedative effect on the skin [37, 38].

In warm interventions, some methods such as hot pack, paraffin, infrared, WW are used as superficial temperature agents. Superficial temperature agents show their effect in two ways: first, the primary mechanism is based on the gate control theory. Here, cutaneal temperature receptors are activated and act on nociceptors. A temperature above 40 °C is required for the activation of these receptors. Thus, the pathways that transmit pain are suppressed, and analgesia is achieved by pain blockade. In the secondary mechanism, vasodilation occurs with WW intervention, and blood flow increases. With the increase in blood flow, toxic substances are removed, and oxygen is increased in the tissue. An increase in the rate of healing is achieved by contracting the muscles and reducing ischemia [37, 38]. Saltwater increases the excretion of excess fluid and inflammation from the extremities with the osmotic gradient created along the skin [39]. It also shows its effect by acting on piezo ion channels, which are densely located in the skin. With the opening of piezo ion channels, nerve receptors in the skin are stimulated, and a neurological response that affects the brain occurs [35].

Vakilina et al. (2020) found that a foot bath with warm saltwater (WSW) was effective in reducing pain in patients with painful diabetic neuropathy [39]. Kudo and Sasaki (2020) reported that hand massage with warm hand baths had a significant effect on subjective sleep quality, comfort, and relaxation in older women with sleep disorders [18]. In a randomized controlled trial by Dias et al. (2017), it was found that patients with knee osteoarthritis in the hydrotherapy group had better results in terms of pain and functionality and better scores in terms of knee flexor and extensor strength, and knee extensor endurance [17]. Rout et al. (2020) evaluated the effect of hydrotherapy on pain intensity and QoL in arthritis patients. The affected joints of the patients were kept in WW at 33–36 °C for 15–20 min once a day for one month and the pain intensity and quality of life of the patients were re-evaluated one month, after the intervention. They found that there was a significant decrease in the pain intensity of the patients and an increase in their QoL [40].

Nurses, who have many roles ranging from disease and treatment management to coordination of general care of RA patients, can significantly contribute to effective symptom management with proactive, evidence-based, and patient preference-based care practices. While the evidence confirming that patients benefit from nurse-led interventions continues to increase in the literature [17, 18], there is a need for more high-quality and evidence-based research to strengthen this evidence further. When the literature was reviewed in patients with RA, no study evaluating the effect of WSW baths on patients was found. The current study was planned to determine the effect of a similar application in patients with rheumatoid arthritis, a disease that starts with severe pain and brings other symptoms (fatigue, deterioration in sleep quality, deterioration in functional capacity), considering a study in which warm saltwater bath was effective on pain in patients with diabetic neuropathy [39]. From this point of view, the aim of the present randomized controlled trial aimed to examine the effect of WW and WSW baths applied to the hands and feet of patients with RA on pain, fatigue, sleep quality, and functional capacity.

Methods and materials

Study design and participants

This three-arm study was carried out in a pretest-posttest randomized controlled design. Patients were randomized into one control and two intervention groups. Data collection and interventions were done simultaneously. This study was registered on ClinicalTrials.gov (Ref. No: NCT05888220). The study was reported based on the CONSORT guidelines and TIDieR checklist. The study population comprised patients with RA who applied to Rheumatology Division a university training and research hospital outpatient clinic between January 2022 and October 2022 (N = 78). The minimum sample size was calculated with the G-Power program 3.1.9.4. Based on a randomized controlled clinical trial conducted by vakilinia et al. (2020) on 60 patients [39], it was determined that a total of 48 patients (16 per group) should be included in the study, setting effect size at 0.27, for a significance level of 0.05 and a power of 0.8. Including a potential dropout rate of 10%, the target sample size was determined as 53. However, 54 eligible patients volunteered during the recruitment period, all meeting the inclusion criteria and willing to participate. Therefore, all 54 were included in the study to enhance statistical power and ensure group balance.

Patients were included: (a) aged 18 and over, (b) followed-up with a diagnosis of RA for at least one year, (c) having five and above pain scores from VAS, (d) having low-to-moderate (DAS28 < 5.1) disease activity scores, (e) receiving active treatment (corticosteroid, non-steroidal anti-inflammatory, disease-modifying antirheumatic drugs) for the last three months, (f) having volunteered to participate. Patients were excluded if they (a) had any comorbidity (active malignancy, heart failure or symptomatic ischemic heart disease, severe lung disease, neurologic disease impairing mobility, uncontrolled thyroid disease, diabetes mellitus), (b) had a recent injury or major surgery (within six months before enrollment), (c) had joint replacement surgery plan, (d) had any acute infection, fever, or vascular disease in upper and/or lower extremity, (e) had impaired skin integrity on hands and feet, (f) participating in a regular physical therapy or exercise program, (g) were pregnant, and (h) were diagnosed with sleep apnea.

Randomization and prevention of bias

The researchers created a patient list by evaluating 78 eligible patients between January and August 2022. Of these, 24 patients were excluded (because they did not meet inclusion criteria or declined to participate). To provide homogeneity in each group based on pain scores, two strata were created as pain scores between 5 and 7 (strata 1) and 8 and 10 (strata 2) by the second author. In addition, blocking was used to balance between the strata. Accordingly, nine blocks of six each were formed using a randomization method. Following blocking, the intervention and control groups were randomly assigned to the strata using a table of random numbers. Following the determination of the block rows consisting of the letters A, B, and C, the groups were assigned as follows: A = warm saltwater group (WSWG):18, B = warm water group (WWG):18, and C = control group (CG):18 (Fig. 1). Then, the primary investigator (PI) was given an ordinal numbered list defined by A, B, and C in the Excel sheet. The PI learned the group that the patient would be in through this list. Until the last patient was recruited, the PI was blind for the assignment. All data collection was performed by the PI. The data underwent analysis by an external statistician who had access solely to the group codes, with no knowledge of the specific group affiliations of the patients. This provided blinding to avoid bias at all stages of data collection, implementation, and reporting.

Fig. 1.

CONSORT diagram of the study

Instruments

Data were collected using the Visual Analog Scale (VAS), Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire (BRAFMDQ), Disease Activity Score 28- (DAS-28), Pittsburgh Sleep Quality Index (PSQI), and Health Assessment Questionnaire (HAQ).

Pain was assessed using VAS, consisting of a 100 mm horizontal line anchored with “0: no pain” on one end and “10: unbearable/severe pain” on the other. Patients marked the point that best represented their current pain intensity. Similarly, fatigue severity was evaluated using a VAS with anchors “0: I am not tired at all” and “10: I am unbearably/severely tired.” These scales were administered at baseline and after the intervention.

BRAFMDQ was developed by Nicklin et al. (2010) to measure the effect of fatigue on four different dimensions in patients with RA [41]. A Turkish validity and reliability study was conducted by Sari et al. (2018). They found that the questions in the questionnaire were compatible with each other to assess RA-specific fatigue. The highest score is 70, and the lowest score is 0. As the score increases, the fatigue level also increases [42]. Cronbach’s alpha value was found to be 0.95. In the present study, the Cronbach’s alpha value was 0.978.

To calculate the DAS-28 score, the number of swollen joints, the number of tender joints, erythrocyte sedimentation, C-reactive protein values, and the global VAS value are needed. In the current study, the DAS-28 value was calculated by the physician based on his findings obtained from the examination. The scores are interpreted as follows: ≥ 5.1 high disease activity; >3.2 and < 5.1 moderate disease activity; >2.6 and ≤ 3.2 low disease activity; ≤ 2.6 remission period.

PSQI was developed by Buysse et al. (1989) to evaluate the sleep quality of an individual in the last month [43]. The Turkish validity and reliability study was conducted by Ağargün et al. (1996), and Cronbach’s alpha value was found to be 0.80. The scale has a total of 19 items and seven components. These seven components include subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, sleep medication use, and daytime dysfunction. The total score obtained from the scale varies between 0 and 21 points. A score of 4 and below is defined as “good sleep quality,” and a score of 5 and above is described as “poor sleep quality” [44]. Cronbach’s alpha value was found to be 0.843 in the present study.

HAQ was developed by Fries et al. (1980) to assess the functional status of patients with rheumatoid arthritis daily [45]. Turkish validity and reliability study was conducted by Küçükdeveci et al. (2004), and Cronbach’s alpha value was found to be 0.97. The scale includes a total of 8 sections and 20 items. Each item is scored between 0 (without difficulty) and 3 (unable to do). The scale score is calculated by dividing the total score by the number of items marked. A maximum of 3 points can be obtained. Scale scores are interpreted as follows: 0–1 is a mild and moderate functional disability, 1–2 is a moderate and severe functional disability, and 2–3 is a severe functional disability [46]. Higher scores indicate low health status. Cronbach’s alpha value was found to be 0.990 in this study.

Procedure and measurements

The baseline data were gathered through the patient information form, VAS, BRAFMDQ, DAS-28, PSQI, and HAQ during the first interview (before any intervention was administered) at the outpatient clinic. Patients were called by phone once a week, and their practices were asked and recorded on the patient compliance scale by the researcher. Patients re-answered the VAS, BRAFMDQ, PSQI, and HAQ at the end of the sixth week of the study.

Warm saltwater procedure

The temperature of the water for hand and foot baths and how to prepare and apply the salt ratio (280 g of rock salt for 8 L of water) were explained to the patients through video-based demonstration training. The video training was done in a room with the patient and the researcher in a quiet environment in the hospital via a tablet. The temperature of the water and the duration of the application were determined based on a previous study examining the effectiveness of WW and WSW baths [47]. The content of the video training steps is given in detail in Fig. 2.

Fig. 2.

The content of the video training steps

For the intervention, natural rock salt was used, obtained from a certified local supplier. The product was labeled as unrefined, food-grade quality, and according to the manufacturer, it contained approximately 95–98% sodium chloride (NaCl) along with trace minerals such as magnesium and calcium. Although no formal chemical analysis was carried out, the product was commercially available and safe for human use.

Bathing hours were determined to be between 21:00–22:00 to prevent patients from doing any activity after baths and to ensure relaxation after bathing. Starting one day after the training, each patient applied a WSW hand-foot bath of 41 °C for 20 min. Standard tap water was used in both intervention groups, and the water temperature was measured with a calibrated thermometer to ensure a consistent 41 °C for each application. The patients performed the application in their own homes for six weeks between 21:00–22:00 h thrice a week, every other day, with the same steps.

Warm water procedure

The only difference with this procedure was that no salt was added to the water. Patients were trained by video training on all other steps, identical to the WSW procedure.

Control group procedure

This group did not receive any intervention except for the usual treatment or care. They were only followed up at baseline and at the end of the sixth week to assess outcome measures.

Data analysis

The data were analyzed with the IBM SPSS 23.0 software program (IBM Corp., Armonk, New York). The Shapiro-Wilk test, histograms, and normal Q-Q plots were used to check the normality assumption. One-Way ANOVA and Chi-squared test were used to compare the difference between groups in demographic and medical characteristics. A paired sample t-test was used to investigate within-group differences in pain, fatigue, sleep quality, and functional capacity assessments. To examine the changes in outcomes over time and across groups, a two-way mixed ANOVA was performed with “Time” (pre- and post-intervention) as the within-subjects factor and “Group” (WSW, WW, control) as the between-subjects factor. When significant Group × Time interactions were observed, pairwise comparisons between groups were conducted using Bonferroni correction to control for multiple testing. F and P values were adjusted with the Greenhouse-Geisser correction for degrees of freedom (df) when the sphericity assumption was not met. The effect of intervention was assessed using the partial eta-squared (η²). The η² values indicate the following effects: 0.01 is a small effect, 0.06 is a medium effect, and 0.14 is a large effect.

Ethical considerations

The study was approved by the Health Sciences University Gulhane Training and Research Hospital Clinical Research Ethics Committee (decision number: 2021/56) and the training and administrative officer of the rheumatology department. The study was also conducted in accordance with the Helsinki Declaration. The participants were informed about the purpose of the study and that their acceptance or refusal to participate would not affect their treatment or care procedures. All the participants provided signed, informed written consent before data collection.

Results

The descriptive and medical characteristics of the three groups are presented in Table 1. In all three groups, most participants were women. The mean ages of the participants were 53.9 (SD = 13.01), 51.6 (SD = 14.82) and 52.9 (SD = 15.43) years in the WSWG, WWG, and CG, respectively. The mean DAS 28 varied between 3.6 (SD = 0.78) and 3.9 (SD = 0.8). The mean duration of diagnosis was 12.9 (SD = 10.63), 10.7 (SD = 9.35), and 11.7 (SD = 11.66) years in the three groups, respectively. All three groups were homogeneous in terms of descriptive and medical characteristics (p > 0.05).

Table 1.

Distribution of descriptive characteristics of patients in groups and comparison between groups

	WSWG (n = 18)		WWG (n = 18)		CG (n = 18)
Characteristics	M ± SD		M ± SD		M ± SD		pa
Age	53,9 ± 13,01		51,6 ± 14,82		52,9 ± 15,43		0,903
DAS 28	3,7 ± 0,85		3,9 ± 0,8		3,6 ± 0,78		0,644
Time of diagnosis (year)	12,9 ± 10,63		10,7 ± 9,35		11,7 ± 11,66		0,697
Gender	n	%	n	%	n	%	pb
Female	14	77,8	13	72,2	12	66,7	0,758
Male	4	22,2	5	27,8	6	33,3

Abbreviations WSWG Warm Saltwater Group WWG Warm Water Group, CG Control Group, M Mean, SD Standart Deviation DAS 28 Disease Activity Score, p significance level (p < 0.05 is significant)

^a One-Way Anova

^b Chi-square test

Pain scores in the WSWG significantly decreased from 7.0 (SD = 1.50) at baseline to 5.2 (SD = 1.52) at the end of 6th week after the intervention. Similarly, participants in the WWG also showed a decrease in their relevant pain scores from 6.9 (SD = 1.30) at baseline to 5.3 (SD = 1.42) in the 6th week. Regarding the CG, there was no significant change in pain scores at baseline (6.9) and 6th week (6.7). Within-group changes were statistically significant for both intervention groups (t = −4.973, p < 0.001; t = −6.710, p < 0.001, respectively). There was a significant Group × Time interaction for pain (F (1,51) = 9.736, p < 0.001, η² = 0.249). The Bonferroni post-hoc analysis showed that pain scores were significantly lower in the WSWG (p < 0.001) compared to WWG (p < 0.001) and CG (p > 0.05) (Table 2).

Table 2.

Comparison of pain, fatigue, sleep quality, and functional capacity scores between the intervention and control groups

Variables	Time	WSWG (n = 18)	WWG (n = 18)	CG (n = 18)	Source	F	p a	η2
		M ± SD	M ± SD	M ± SD
Pain (VAS)	Pre-test Post-test t: pb	7,0 ± 1,50 5,2 ± 1,52 −4,973;0,000*	6,9 ± 1,30 5,3 ± 1,42 −6,71;0,000*	6,9 ± 1,43 6,7 ± 1,84 −0,846;0,409	Group Time Group*Time	1.617 56.100 9.736	0.208 0.000 0.000	- 0.524 0.249
Fatigue (VAS)	Pre-test Post-test t: pb	5,6 ± 2,14 4,5 ± 1,47 −2,872;0,011*	6,7 ± 1,32 5,2 ± 1,53 −3,790;0,001*	6,0 ± 1,94 6,0 ± 1,97 0,000;1,000	Group Time Group*Time	1.887 16.922 4.323	0.162 0.000 0.013	- 0.253 0.158
BRAF-MDQ	Pre-test Post-test t: pb	37,0 ± 13,41 31,1 ± 16,14 −2,225;0,026*	32,3 ± 19,91 24,8 ± 17,33 −3,265;0,001*	30,5 ± 15,86 30,3 ± 16,45 −0,468;0,640	Group Time Group*Time	0.496 14.213 3.350	0.612 0.000 0.043	- 0.218 0.116
PSQI	Pre-test Post-test t: pb	9,3 ± 4,30 7,9 ± 4,07 −3,047;0,002*	8,22 ± 4,02 7,00 ± 3,05 −2,251;0,024*	8,4 ± 4,31 8,5 ± 4,40 −0,214;0,831	Group Time Group*Time	0.246 0.642 1.934	0.783 0.427 0.155	-
HAQ	Pre-test Post-test t: pb	1,1 ± 0,70 0,9 ± 0,65 −2,227;0,026*	0,7 ± 0,77 0,6 ± 0,73 −1,725;0,084	0,8 ± 0,88 0,8 ± 0,88 −0,905;0,366	Group Time Group*Time	0.386 1.370 1.413	0.681 0.247 0.253	-

AbbreviationsWSWG Warm Saltwater Group, WWG Warm Water Group, CG Control Group, BRAF-MDQ Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire, VAS Visual Analog Scale, Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire, PSQI Pittsburgh Sleep Quality Index, HAQ Health Assessment Questionnaire, M Mean SD Standart Deviation, η2 eta-squared, F ANOVA test value, p significance level (p < 0.05 is significant)

^a Mixed Model ANOVA (M-MANOVA)

^b Paired sample t test

Regarding fatigue, significant within-group changes were observed in the WSWG and WWG (t = −2.872, p = 0.011; t = −3.790, p = 0.001, respectively). Scores decreased from 5.6 ± 2.14 to 4.5 ± 1.47 in the WSWG and from 6.7 ± 1.32 to 5.2 ± 1.53 in the WWG. There was a significant Group × Time interaction for fatigue (F (1,50) = 4.323, p = 0.013, η² = 0.158). Bonferroni analysis indicated that the WWG had significantly lower fatigue scores (p < 0.001), compared to the WSWG (p = 0.002) and CG (p > 0.05) (Table 2).

The total BRAF-MDQ scores significantly decreased in the WSWG (t = −2.225, p = 0.026) and WWG (t = −3.265, p = 0.001), while no significant change was observed in the CG (t = −0.468, p = 0.640). The scores decreased from 37.0 ± 13.41 to 31.1 ± 16.14 in the WSWG and from 32.3 ± 19.91 to 24.8 ± 17.33 in the WWG. The mixed-model ANOVA indicated a significant Group × Time interaction (F (1,51) = 3.350, p = 0.043, η² = 0.116). Bonferroni tests revealed that the WWG had significantly lower (p < 0.001) BRAF-MDQ scores than the WSWG (p = 0.004 and CG (p = 0.934) (Table 2).

PSQI scores significantly improved within both the WSWG (t = −3.047, p = 0.002) and the WWG (t = −2.251, p = 0.024), decreasing from 9.3 ± 4.3 to 7.9 ± 4.07 and from 8.22 ± 4.02 to 7.00 ± 3.05, respectively. However, the mixed-model ANOVA showed no significant Group × Time interaction for PSQI (p > 0.05), and therefore no post-hoc comparisons were conducted (Table 2).

Regarding HAQ scores, a significant improvement was observed only in the WSWG (t = −2.227, p = 0.026), whereas no significant changes occurred in the WWG or CG. Since the Group × Time interaction was not significant (p > 0.05), Bonferroni comparisons were not applied for HAQ scores (Table 2).

Discussion

This study is the first RCT examining the effect of WSW and WW baths on the hands and feet on pain, fatigue, sleep quality, and functional capacity in patients with RA. The study data revealed that both WSW and WW baths applied three times a week for six weeks could reduce pain and fatigue and ameliorate sleep quality. In addition, the findings also supported the idea that a WSW bath could improve functional capacity.

Pain is among the main reasons for RA patients’ hospital admission and medical care-seeking behaviors [8]. Besides medical approaches to relieve and manage pain, CIMs are also recommended to provide effective symptom management in patients with RA [5]. These methods usually include exercise, yoga, reiki, aromatherapy, energy-saving practices, nutritional interventions, massage, and water therapies. In the present study, while there was no significant change in pain scores in the CG, there was a significant decrease in WSWG and WWG. A previous randomized controlled trial examining the effect of hydrotherapy on pain, functionality, and muscle function in older women with knee osteoarthritis found that the hydrotherapy group had less knee pain than the CG [17]. In a different randomized controlled study evaluating the effect of WSW bath on pain due to diabetic neuropathy, WSW intervention significantly reduced pain compared to WW and CG [39]. Similarly, the WSW bath had a higher effect on reducing the pain score than the WW in the current study. While WW shows its positive effect in relieving RA-related joint pain by affecting the sympathetic system, WSW may have helped to further reduce pain due to the edema-dissolving effect of salt.

Patients with RA experience not only pain but also a significant proportion (over 50%) of fatigue [7]. Although the etiology is not clear, fatigue can also be triggered by pain [5]. Therefore, methods to control pain may also facilitate the management of fatigue. One of these methods, water-based interventions, helps manage fatigue by dilating blood vessels to increase and improve blood flow to the affected body area, relieving spasms, relaxing, and strengthening muscles, or increasing muscle strengthen [37]. In this study, the mean fatigue scores in WSWG and WWG decreased significantly compared to the CG. Although both WSW and WW interventions had ameliorative effects on fatigue, WW was more effective in reducing fatigue than WSW. In addition to patient-reported fatigue scores, the BRAFMDQ was also used as an objective measurement method to reveal the effects of WSW and WW on fatigue and fatigue-related multidimensions. Similarly, as a result of this evaluation, it was determined that the mean BRAFMDQ scores in the WSWG and WWG in the sixth week decreased significantly compared to the CG, and WW intervention was more effective in alleviating fatigue. Although there is no study specifically evaluating the effect of WSW and WW on fatigue in patients with RA, it has been investigated in several studies in different populations. For example, in a randomized controlled study evaluating the effect of a WSW bath on chemotherapy-induced fatigue, no significant difference was found between the groups in terms of the mean total fatigue scores. In contrast, reduction in fatigue level in the intervention group was significantly higher than in the CG [47]. In another study investigating the effect of foot baths on comfort, fatigue, and dialysis symptoms in patients receiving hemodialysis, it was determined that foot baths reduced fatigue [48]. In support of the results of these studies, improvements in fatigue levels can be attributed to the improving effect of the water on circulation and muscles, as well as the reduction in pain following the intervention. In addition, the literature indicates that warm water baths may alleviate fatigue through both physiological and psychological mechanisms. The activation of the parasympathetic nervous system by warm water supports muscle relaxation and overall comfort, potentially reducing the perception of fatigue [49]. Enhanced circulation facilitated by warm water also promotes the removal of metabolic waste accumulated in muscles, thereby reducing muscle-related fatigue [50, 51]. Furthermore, the regulatory effects of thermal stress on hormonal secretion help relieve both pain and stress, while improving sleep quality and thereby enabling more effective fatigue management [27]. Taken together, these effects suggest that warm water baths can be considered an effective complementary approach for alleviating physical and mental fatigue [52].

Moreover, some studies have shown that mineral-rich baths can also reduce fatigue. In one study involving balneotherapy with radon-enriched mineral baths at temperatures up to 37 °C, a significant reduction in fatigue levels was observed. The researchers attributed this effect to the calming influence of both water temperature and mineral content, which promoted muscle relaxation and pain relief, thereby regulating the nervous system, improving mood, and reducing fatigue [53]. When considered alongside these findings, it becomes clear that chemical composition, duration, and method of application are critical factors in determining the effectiveness of water-based interventions.

Patients with RA are reported to have poor sleep quality compared to the general population [5, 7]. In fact, it is emphasized that there is a vicious cycle with a bidirectional relationship between pain, fatigue, and sleep quality in people with RA [54]. Bestaş et al. (2022) showed that balneotherapy and water-based exercise significantly improved sleep latency in patients with ankylosing spondylitis [55]. In another previous study exploring the effects of balneotherapy and physical therapy on sleep quality in patients with osteoarthritis, patients reported significant improvement in sleep, pain, stiffness, and functional status after interventions [56]. It is reported that there is an opposite relationship between central body temperature and sleep desire. It is also emphasized that hydrotherapy applied before bedtime may facilitate the onset of sleep and improve sleep quality by increasing blood flow and temperature to the peripheral parts of the body without increasing or decreasing the central body temperature. In the present study, WSW and WW interventions improved the sleep quality of the patients. Considering that the hand and foot bath was applied before sleep in this study, it can be said that it contributed to improving the sleep quality of the patients due to the physiological effects mentioned above.

Functional capacity, which indicates people’s ability to perform tasks and activities necessary or desired in daily life, is often adversely affected by pain, fatigue, and poor sleep quality. Considering these three symptoms, which are the major complaints of patients with RA, it may be an inevitable problem that their functional capacity is generally low [54]. Although there are several studies investigating the effect of water-based interventions on functional capacity in patients with rheumatologic problems, there is no study examining their effects in patients with RA. In contrast to our results, Kaya et al. (2016) found that balneotherapy and physical therapy improved the functional status of patients with knee osteoarthritis [56]. Similarly, Bestaş et al. (2022) reported that physical functions improved significantly after water-based exercise in patients with fibromyalgia [55]. Interestingly, in the present study, functional capacity significantly improved in the WSWG, whereas there was no significant change in the WWG. Similarly, a recent meta-analysis supporting the study results showed that water-based exercises did not lead to a significant improvement in functional capacity [57]. Various factors may contribute to the emergence of these discrepancies. The type of intervention (passive vs. active modalities), patient population (RA vs. osteoarthritis/fibromyalgia), and the assessment tools used (self-reported measures like HAQ vs. performance-based tests) are important in explaining the variability in study outcomes. Recent studies also support this perspective. In a study conducted by Milenković et al. (2025), balneotherapy with radon mineral baths at temperatures up to 37 °C resulted in a significant improvement in functional capacity as measured by the HAQ questionnaire (p < 0.01). The authors suggested that this effect may be attributed to the normalization of synovial membrane permeability and the myogenic and metabolic regulation of blood flow to the joints, capsules, and muscles induced by radon [53].

Similarly, Silva et al. (2023) reported a significant improvement in functional capacity following a 14-day balneotherapy program in individuals with musculoskeletal disorders [58]. Furthermore, a randomized controlled study evaluating the effects of balneological treatment in patients with osteoarthritis found that the combination of hydrotherapy and peloidotherapy led to long-term improvements in functional capacity. These effects were attributed not only to thermal mechanisms but also to the chemical composition of the peloid. This finding highlights the potential of topically applied mineral-rich muds (peloids) to enhance functional capacity [59]. In our current study, the increase in functional capacity observed WSW bath group can be explained by the additional physiological effects offered by salt water. Mechanisms such as the reduction of edema through osmotic gradient, suppression of inflammation, and neurological modulation of fatigue and pain via the activation of piezo ion channels may have contributed not only to symptom relief but also to the improvement of functional independence [35, 39, 60]. All these findings suggest that the type of intervention, its composition (e.g., salt, radon, peloid), duration, and method of application play a role in shaping the effects on functional capacity. Therefore, further studies examining these intervention-related variables may be considered to better clarify their impact on functional recovery in patients with RA.

Limitations

The limitations of the study include the relatively short duration of the intervention (six weeks), which may have limited the ability to assess long-term effects. Future studies with extended follow-up periods may help determine the sustainability of symptom management over time.

Conclusion

The present study confirmed that WSW bath reduced the pain scores and improved the functional capacity, whereas WW bath reduced the fatigue scores in patients with RA. The findings also support the hypothesis that WSW and WW baths applied to the hands and feet can improve sleep quality. In addition, both WSW and WW baths can be used as cheap, easy, safe, and effective CIMs to provide symptom management in patients with RA. RA patients can perform these interventions independently at home after training given by nurses.

Abbreviations

BRAFMDQ

Bristol rheumatoid arthritis fatigue multidimensional questionnaire

CG

Control group

CIM

Complementary and integrative methods

CONSORT

Consolidated standards of reporting trials

DAS-28

Disease activity score 28

HAQ

Health assessment questionnaire

M-MANOVA

Mixed-model ANOVA

PI

Primary investigator

PSQI

Pittsburgh sleep quality index

QoL

Quality of life

RA

Rheumatoid arthritis

TIDieR

Template for intervention description and replication

VAS

Visual analog scale

WSW

Warm saltwater

WSWG

Warm saltwater group

WW

Warm water

WWG

Warm water group

Authors’ contributions

O.A. Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Validation, Visualization, Writing - original draft, review & editing. A.A.D. Conceptualization, Data curation, Formal analysis, Methodology, Project administration Supervision, Validation, Visualization, Writing - original draft, review & editing. S.K. Conceptualization, Methodology, Supervision, Validation, Visualization, Writing – original draft, review & editing. M.Ç. Conceptualization, Methodology, Writing - original draft, review & editing.

Funding

This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

The data for this study is available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The study was approved by the Health Sciences University Gulhane Training and Research Hospital Clinical Research Ethics Committee (decision number: 2021/56) and the training and administrative officer of the rheumatology department. The study was also conducted in accordance with the Helsinki Declaration. The participants were informed about the purpose of the study and that their acceptance or refusal to participate would not affect their treatment or care procedures. All the participants provided signed, informed written consent before data collection.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.