Therapeutic Benefit of Balneotherapy and Hydrotherapy in the Management of Fibromyalgia Syndrome

A Qualitative Systematic Review and Meta-analysis of Randomized Controlled Trials

Johannes Naumann; Catharina Sadaghiani


Arthritis Res Ther. 2014;16(R141) 

In This Article


This systematic review was performed according to the statement, preferred reporting items for systematic reviews and meta-analyses (PRISMA)[16] and the recommendations of the Cochrane Collaboration.[17]

Literature Search

Electronic bibliographic databases (Medline via Pubmed, Cochrane Central Register of Controlled Trials, EMBASE, and CAMBASE) were screened up to April 2013. The search strategy was constructed around a broad range of balneotherapeutic and hydrotherapeutic treatments: BT, HT, thalassotherapy, spa therapy, cryotherapy, thermotherapy, and phytothermotherapy combined with FMS. The search filter was restricted to randomized controlled trials (RCTs). Reference lists of relevant articles and reviews were examined for additional studies.

The search strategy for Pubmed was as follows: ("FMS" OR "fibromyal*") AND "RCT" AND ("BT" OR "HT" OR "thalassotherapy" OR "spa therapy" OR "thermotherapy" OR "phytothermotherapy" OR "aquatic" OR "hydrogalvanic" OR "cryo" OR "pool exercise" OR "water-based" OR "pool-based" OR "stanger" OR "mud" OR "thermal water" OR "bath" OR "peloid" OR "natural therapeutic gas" OR "radon"). The search strategy applied a combination of text and keywords (medical subject heading (MeSH) terms) and was adapted for each database if necessary.

Inclusion and Exclusion Criteria

The criteria were as follows: 1) types of study: RCTs were only eligible if they were published as full paper articles. No language restrictions were made; 2) types of participants: patients of any age diagnosed with FMS on recognized criteria were included; 3) types of intervention: studies that compared any kind of BT (mineral/thermal water, spa treatment, thalassotherapy, thermotherapy, peloids, natural therapeutic gas) or HT (treatment in plain water with or without exercise) with no treatment or any active treatment. Studies were excluded if BT/HT treatments were not the main intervention or if the intervention in treatment and control group were the same and only the co-therapies differed; and 4) types of outcome: studies assessing at least one symptom-specific outcome of the major FMS symptoms,[18] such as pain (for example, tender point count (TPC), visual analog scale (VAS)), fatigue, sleep disturbances, depressive symptoms, health-related quality of life (HRQOL) and/or relevant pain-related psychological issues such as self-efficacy pain and/or objective tests of physical fitness, were included.

Data Extraction

The authors (JN, CS) of the review presented here independently extracted relevant study information (for example, participants, characteristics of the intervention and control, outcome measures, results) using predefined data fields, including risk-of-bias indicators. If necessary, existing inconsistencies were solved by discussion, and consensus achieved. For quantitative analysis the mean post-test values, or change scores when available, were used.

Risk of Bias Assessment

The risk of bias for each study was determined independently by the same two authors (assessment of information in study reports) using the criteria of the Cochrane risk-of-bias tool. Disagreements were resolved by discussion to achieve consensus.

Summary assessment of risk-of-bias key domains (selection, performance, detection, attrition and reporting bias), was based on the three-tiered rating style as proposed by Higgins et al..[19] Performance bias was not considered a key domain due to the required participatory nature of BT and HT. Studies with a high risk of bias in one of the key domains or unclear risk in at least two key domains were considered to be at high risk of bias. Studies with unclear risk in one of the key domains were considered to have unclear risk of bias. Only studies with low risk of bias in all key domains were graded as having low risk of bias. Analysis was done with the Review Manager (RevMan) version 5.2 risk-of-bias tool from the Cochrane Collaboration.[21]

Missing Data

In the case of reported median, low and high end of range and sample size only, we estimated the mean and variance using the appropriate formula as mentioned by Hozo et al..[20]

Data Analysis and Assessment of Heterogeneity

RevMan version 5.2[21] was used to analyze the data and perform testing of heterogeneity, using the I2 statistic, with the following categories: I2 = 25%, no heterogeneity; I2 = 50%, moderate heterogeneity; I2 = 75%, strong heterogeneity,[22] and P ≤0.1 for the Chi2 test showing significant heterogeneity. We used Cohen's categories to evaluate the magnitude of the effect size, calculated by standardized mean difference (SMD), with g >0.2 to 0.5, small effect size; g >0.5 to 0.8, medium effect size; and g >0.8, large effect size. We used the following modified levels of evidence descriptors to classify the results: (1) strong, if there were consistent findings among multiple (≥3) RCTs with low risk of bias; (2) moderate, if there were consistent findings among multiple high-risk RCTs and/or one low-risk RCT; (3) limited, with one high-risk RCT; (4) conflicting, with inconsistent findings among multiple RCTs; and (5) no evidence, no RCTs.[23] Whenever possible we used the results from intention-to-treat analysis. Negative SMDs indicate a beneficial effect of the experimental intervention.

Subgroup and Sensitivity Analysis

Where at least two studies were available, subgroup analyses were pre-specified for different types of intervention. Additionally, control groups were compared (no treatment/active treatment). Waiting list or treatment-as-usual were classified as non-intervention control. The subgroup analyses were also used to examine potential sources of heterogeneity. Sensitivity analyses were performed for studies with high versus low risk of bias, respectively, for studies with serious flaws in one or more key domains and for sample size per treatment arm.