Introduction

Balneotherapy,1 has been frequently used globally as a complementary and/or alternative therapy.2–5 A recent systematic review (SR) showed that balneotherapy (BT) and spa therapy (ST) could significantly improve quality of life of patients with knee osteoarthritis.6 A review that performed a quality assessment of 51 randomized controlled trials (RCTs) based on ST identified each disease based on the International Classification of Diseases (ICD)-10.7 The findings identified 40 studies (78%) that were about “Diseases of the musculoskeletal system and connective tissue” (eg, osteoarthritis, low back pain, fibromyalgia, ankylosing spondylitis, rheumatoid arthritis) and three studies (6%) that were about “Diseases of the skin and subcutaneous tissue” (ie, atopic dermatitis and psoriasis).

An SR based on RCTs is very important to demonstrate evidence of effective intervention, and can help decision-makers interpret the deluge of published biomedical literature. We hoped to formulate a future research agenda for RCTs that would encourage more progress toward implementation of BT worldwide. Our study focused on all treatment and rehabilitation effects and health enhancements using the ICD-11. It is well known in research design that evidence grading is highest for an SR with meta-analysis (MA) of RCTs. Although many studies have reported the effects of BT and ST, there is no global review of SRs based on RCTs.

The objective of this review was to summarize SRs with MA of BT and ST based on RCTs and provide a perspective for future research.

Approach

This was an overview study for which we developed a protocol a priori. The detailed protocol was finalized on 15 November 2019 and is available from the corresponding author upon request.

 

Scope of This Review

We completely reviewed target SRs with MA based on the recommended structured abstracts8 and created a brief summary according to the ICD-11 numbering system. We also summarized the evidence and provided a perspective for future research.

 

Terminology

The terms “balneotherapy (BT)”, “hydrotherapy (HT)”, and “spa therapy (ST)” are frequently confused and tend to be used interchangeably; furthermore, the meaning of these words varies depending on the country and culture.9 We defined these terms as follows: based on terminology from recent studies.1,10,11 BT traditionally involved immersion in mineral and/or thermal waters from natural springs but may have interchangeably been defined as balneological interventions with natural gases (CO2, sulphur, radon, etc.), peloids (mud), and other traditional remedies.1 HT generally employed normal tap water for medical treatment. We excluded HT in which the intervention was only immersion in tap water without aquatic exercise. ST employed a number of different treatment modalities, including HT and BT, often combined with massage, exercise, physical therapy, and/or rehabilitation. We refer to target SRs in this paper as the use of all types of BT and ST for treatment and rehabilitation.

Aquatic exercise has various names such as water exercise, underwater exercise, and aquatic physical therapy, but in principle, it is referred to as aquatic exercise in this manuscript. However, in the structured abstracts of each study, we used the terms as written by the authors.

 

Criteria for Considering Studies Included in This Review

 

Types of Studies

Studies were eligible if they were SRs with MA based on RCT or quasi-RCT. There was no restriction on the basis of language.

 

Types of Participants

This study was a review based on SRs and was therefore restricted to original SRs of participants with any diseases. There were no restrictions on the type of disease to be treated by BA or ST.

 

Comparator(s)/Control

As controls, pre-planned stratified analyses were (a) placebo controls or waiting list controls, and (b) intervention groups that used different types of treatment, rehabilitation, and other therapies.

 

Types of Interventions

Studies that included at least one treatment group in which BA or ST was included.

 

Types of Outcome Measures

We focused on all treatment and rehabilitation effects using ICD-11.12

 

Search Methodology for Identification of Studies

 

Bibliographic Database Search Strategies

We searched the following databases from 2000 up to 20 November 2019: MEDLINE via PubMed, CINAHL, Web of Science, and Ichushi Web (in Japanese). We also searched the Cochrane Database of Systematic Reviews up to 20 November 2019. All searches were performed by a specific searcher (hospital librarian, MM) who was qualified in medical information handling and was sophisticated in searches of clinical trials.

 

Search Strategies

The special search strategies contained the elements and terms for MEDLINE, CINAHL, Web of Science, Ichushi Web, and Cochrane Reviews (supplementary material). Only keywords about intervention were used for the searches. First, titles and abstracts of identified published articles were reviewed in order to determine the relevance of the articles. Next, references in relevant studies and identified SRs were screened.

 

Handsearching and Reference Checking

One author (HK) handsearched original articles in the Journal of Japanese Society of Balneology, Climatology, and Physical Medicine published from 2000 up to 30 November 2019.

 

Review Methods

 

Selection of Studies

In order to make the final selection of studies for the review, all criteria were applied by an author (HK) to the full text of articles that had passed the first eligibility screening (Figure 1). Uncertainties were resolved by discussion with other authors (SN, JI). Studies were selected when i) the design was an SR and ii) one of the interventions was a form of spa bathing. Treatment and rehabilitation effects were used as a primary outcome measure. Trials that were excluded are presented with reasons for exclusion (supplementary material).

 

Figure 1

Flowchart of trial process.

Note: *Reduplication.

The literature searches based on databases included potentially relevant articles (Figure 1). Abstracts from those articles were assessed, and 40 papers were retrieved for further evaluation (checks for relevant literature). Twenty-two publications were excluded because they did not meet the eligibility criteria.

 

Quality Assessment of Included Studies

We did not perform a quality assessment of each article.

 

Summary of Studies and Data Extraction

One author (HK) described the summary from each article based on the structured abstracts, and other authors (SN, JI) confirmed the contents of each SR. We used ICD-11 to categorize each target disease in the SRs.

Results

Discussion

This is the first overview of SRs with MA based on only RCTs for treatment and rehabilitation with BT and ST during the last two decades. There was a summary of SRs based on RCTs of water immersion therapies a decade ago,4 but it was limited to just water immersion and did not include as many RCT-designed studies compared with trials from the last decade. The current review strengthened the evidence by covering a broader range of issues. Furthermore, this study was unique in its summary of ICD-11 disease status in each study, and its listing of intervention effects by outcome across diseases.

Current Evidence and Research Challenges

Based on current evidence from SRs, we propose challenges that researchers should undertake in the near future to treat patients with various diseases (Figure 2). First, because the mechanisms of pain relief are well known, it is now necessary to conduct well-designed clinical trials (ie, RCTs) and MA for other chronic diseases with pain. In fact, although there are no SRs that include only RCTs, there have been studies of neck pain42 and multiple sclerosis.43

 

Figure 2

Current evidence and research challenge.

Improvement of symptoms and partial and whole-body functions and symptoms from aquatic exercise are expected to be effective not only for diseases of the musculoskeletal system or connective tissue but also for many other diseases such as those that involve the nervous system44,45 and circulatory system.46 A recent SR without MA reported aquatic exercise was effective for improving motor skills in children with cerebral palsy.47 Depending on the patient’s physical characteristics and symptoms, BT and ST may contribute to pain reduction (including reduction of analgesic and/or NSAID consumption), improved QoL, and improved function in a variety of potential diseases.

Although we have summarized specific effects on outcome across diseases, researchers planning to conduct clinical trials will need to set appropriate outcomes for each intervention while avoiding the error of multiple comparisons.

Limitations

This review had several limitations that should be acknowledged. First, some selection criteria were common across SRs; however, bias remained due to differences in eligibility for participation, which were described in each original article. Furthermore, a weakness of this study is the possibility that important SRs were overlooked because the PICOS setting criterion might not have been fully appropriate. Second, publication bias was a limitation due to inadequate use of multiple databases for each SR. In fact, this study did not use the Physiotherapy Evidence Database (PEDro), a free database of over 47,000 RCTs, SRs, and clinical practice guidelines in physiotherapy that are focused on rehabilitation and non-pharmacological participants. Although there was no linguistic restriction in the eligibility criteria, we searched studies with only English and Japanese keywords. Third, although we defined BT and ST separately, there were slight differences in the definitions in each SR. Fourth, we created a brief summary, but it did not reflect effect size by considering standardized mean difference, mean difference, or relative risk. Fifth, due to differences in the definitions of several words in each SR, BT and ST could sometimes not be strictly distinguished. Sixth, as mentioned earlier (see section on ‘Current problems with SRs’), there were multiple SRs with the same research theme, and they were included without any quality assessment. Last, the purpose of this study was to summarize the characteristics of SRs with MA, but a weak point is that it was difficult to interpret the obtained evidence because it did not evaluate the quality of each SR.

Conclusions

Both BT and ST provide significant pain relief effects and improved QoL in chronic diseases of the musculoskeletal system or connective tissue. Additionally, BT and ST with exercise under water may improve physical fitness and function in patients across diseases.

Researchers need to conduct studies on the treatment of many kinds of potential diseases using the keywords of pain relief and QoL. In addition, depending on patients’ symptoms, physical fitness, and disabilities, conducting exercise under water may improve effects on physical function and fitness.

Acknowledgment

Funding Statement

There is no funding to report.

References