The Impact of Thermal Water in Asthma and COPD: A Systematic Review According to the PRISMA Statement

Abstract

Background: Asthma and chronic obstructive pulmonary disease (COPD) are global health challenges leading to substantial morbidity and mortality. While existing guidelines emphasize evidence-based treatments, the potential therapeutic role of thermal water (TW) inhalation remains under-investigated.

Methods: This systematic review followed PRISMA-P guidelines and sought to evaluate the impact of TW in asthma and COPD. A thorough literature search, performed up to May 2023, encompassed in vitro, in vivo, randomized controlled trial (RCT), non-RCT, and observational studies.

Results: The review included 12 studies reporting different findings. In vitro studies suggested TW could enhance antioxidant capacity and cell proliferation. In a murine model of non-atopic asthma, TW inhalation reduced airway hyperresponsiveness and inflammation. RCTs in COPD patients indicated mixed effects, including improved quality of life, reduced airway oxidant stress, and enhanced exercise tolerance. Asthma patients exposed to water aerosols exhibited improved lung function and reduced airway inflammation. Non-RCTs showed improved lung function and antioxidant activity after TW therapy. Additionally, observational studies reported enhanced lung function and reduced airway inflammation.

Conclusion: The current evidence suggests potential benefits of TW therapy in asthma and COPD. However, limited high-quality RCTs and concerns regarding occupational TW exposure necessitate further investigation. While TW therapy offers a non-invasive treatment, its therapeutic potential still needs definitive demonstration. Future research should therefore prioritize well-designed RCTs to thoroughly establish the efficacy and safety of TW as a potential therapeutic intervention for asthma and COPD.

Keywords: COPD; asthma; systematic review; thermal water.

Figure 1

PRISMA flow diagram for the identification of studies included in the systematic review concerning the impact of TW on asthma and COPD. COPD: chronic obstructive pulmonary disease; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; TW: thermal water.

Figure 2

Traffic light plot for assessment of the risk of bias of each included RCT (A) and weighted plot for the assessment of the overall risk of bias (B) via the Cochrane RoB 2 tool (n = 5 studies, from 5 records). Traffic light plot reports five risk-of-bias domains: D1, bias arising from the randomization process; D2, bias due to deviations from intended intervention; D3, bias due to missing outcome data; D4, bias in measurement of the outcome; D5, bias in selection of the reported result. Yellow circle indicates some concerns regarding the risk of bias, green circle represents low risk of bias, and blue circle indicates insufficient information about the risk of bias. RCT: randomized controlled trial; RoB: risk of bias.