The term Peloid refers to all those natural products consisting of a mixture of a mineral-water or mineromedicinal (including sea or salt lake water) with inorganic or organic materials resulting from geological, biological or both processes used simultaneously with a therapeutic purpose and applied as wrapping or bath.1 The external application of all or part of these products is called pelotherapy, it being a therapeutic modality that, despite having defined mechanisms of action, route and site of different application, is still under the umbrella of balneotherapy, hydrotherapy and spa treatment.2

The application of peloids in rheumatic diseases has been widely used since ancient times, constituting an unquestionable reality, even when and despite having proven their therapeutic efficacy in various rheumatic processes,3–7 there are few studies evaluating the clinical effects resulting from its application in knee osteoarthritis (OAR).8

Several studies have analyzed and compared the effectiveness of pelotherapy in patients diagnosed with OA of the knee (OAK)9–11 versus other intervention procedures5,12 in the short and medium term, such as drug or rehabilitation13–15 or,16–18 noticing improvements in perceived pain, functional capacity, quality of life or drug use; however, the effects of peloid treatment are often masked by it not being applied in isolation.7

At present, despite the fact that the main mechanism of action is known to be thermotherapeutic, other studies have shown systemic activity through changes observed in biochemical and molecular parameters, such as reduced plasma α tumor necrosis factor, IL-1β, IL-1, IL-6, PGE2, LTB419–21 responsible for the reduction of pain and inflammatory processes, increases in the synthesis of noradrenaline, cortisol, beta-endorphins and insulin growth factor, due to the thermal stress caused and stimulating the metabolism of chondrocytes producing joint cartilage protective effects9,11 and inhibition in free radical synthesis by influencing antioxidant reactions.21

Given the need to know from a scientific standpoint, the effects reported by peloid therapy, the main objective of this study was to determine the effects of pelotherapy in perceived pain, quality of life related to health (HRQOL) and trends in drug use in patients diagnosed with OAK versus a control group that continues its routine drug treatment.

Mean values±standard deviation of demographic variables analyzed are shown in Table 1, showing equivalence (P≥.05) in the two groups for all of them, except for the subjects consuming nonsteroidal antiinflammatory drugs (NSAIDs), where statistically significant differences were observed.

The patients in the experimental group had statistically significant improvements from baseline to the final assessment (P<.05), both in the variable of perceived pain as in all HRQoL dimensions analyzed, with a medium-large effect size for all them (Table 2). In the control group, there were no statistically significant improvements (P≥.05) in any of the variables under study.

In the final assessment, both parametric Student's t test and the nonparametric Mann–Whitney test showed statistically significant differences between groups (P<.05), highlighting the dimensions seen in “general health” and “body pain” and “perceived pain” as measured by the VAS (Table 2).

Regarding changes in drug consumption, a reduction and a significant absence in the intake was observed for the experimental group (Table 3), who used the most analgesics in both groups, followed by chondroprotective drugs in the experimental group and ‘others’, such as opioid analgesics or topical drugs in the control group (Table 3).

The main objective of this study was to determine the effects derived after application of natural peloid on perceived pain, HRQoL and consumption of drugs in people diagnosed with OAK.

The results showed statistically significant improvements in all parameters analyzed for the experimental group, with a medium-large effect size in all items analyzed.

Until recently, pelotherapy is a procedure used in rheumatic diseases derived from empiricism and intuitive reasoning. This has resulted in its lack of inclusion as an effective intervention in models of care and evidence-based clinical guidelines for the management of OAK.25

At present, studies such as Pnevmatikatos et al.,4 Cantarini et al.,5 or Fraioli et al. have analyzed10 the therapeutic effect reported by different peloids therapy by patients with OAK in spas. Other comparisons have been conducted on the effectiveness of pelotherapy against other measures based on thermotherapy, such as hot-packs,17 and magnetic fields, such as shortwave5,16 or other therapeutic modalities applied in spas,18 with minor works comparing their influence over drug therapy,13,16 like Odabasi et al.,26 a study very similar from the methodological point of view to ours.

Regarding the variables analyzed after applying pelotherapy in OAK highlights perceived pain as the most studied symptom. Rates of improvement achieved match the results reported in previous studies3,10,13,17,26 after being applied in isolation. Other authors also obtained results combining peloid with a thermal bath or exercise.15,18,19

Regarding HRQoL, we agree with several authors in observing the positive influence of this intervention on quality of life.7,15,17 The results are in line with those reported by Forestier et al.,15 after applying Peloids and thermal bath for 3 weeks in a sample 118 subjects, using the same measurement instrument that we used in the present work. Until now the effect of treatment with physical exercise on pain and functional capacity in OAK was well known27,28; however, and after the results are shown, there could be improvements in the dimensions related to the psychobiological field, such as mental health vitality and the emotional role as emerging psychosocial factors in group therapy within the right context in which it is applied and having a decisive influence on the improvement in dimensions related to mental health.29

It is for this reason that future research should explore its potential efficacy in the treatment of depressive symptoms in older people with changes in HRQoL30 and its direct influence on the habitual use of specific drugs; there are currently a very small number of studies analyzing the influence of pelotherapy on these variables.

Likewise, we agree with Fioravanti et al.,11 on the need for longer follow-up periods in order to know the scope of the technique and ensure better medium to long term results as,5,10 being one of the limitations of this study.

In short, peloids therapy in patients diagnosed with OAK obtains immediate effects on perceived pain and HRQOL, reducing the consumption of specific drugs. Studies are needed to evaluate the scientific evidence from the effects of the intervention, establishing uniform criteria applying them as regards the duration, frequency and optimum temperature of peloid.

The authors have no disclosures to make. The undersigning authors state their authorship of this study, accepting the journals publication norms and transfer their rights to Reumatología Clínica, them being original and inedit.