Hydrotherapy on exercise capacity, muscle strength and quality of life in patients with heart failure: A meta-analysis

Mansueto Gomes Neto, Cristiano Sena Conceição, Fabio Luciano Arcanjo de Jesus , Vitor Oliveira Carvalho

Heart failure (HF) is clinically characterized by exercise intolerance, poor health related quality of life (HRQOL) and high mortality. Exercise training is a well-established method to improve exercise intolerance and to restore HRQOL in patients with HF. However, the most efficient modality is unknown. In this context, hydrotherapy (i.e. exercise in warm water) has been proposed as an alternative tool in the rehabilitation of patients with HF. There is no meta-analysis of the efficacy of this intervention in HF patients. The aim of this systematic review with meta-analysis was to analyze the published randomized controlled trials (RCTs) that investigated the effects of hydrotherapy on exercise capacity and HRQOL in HF patients. This review was planned and conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We searched for references on MEDLINE, EMBASE, CINAHL, PEDro, and the Cochrane Library up to May 2014 without language restrictions. This systematic review included all RCTs that studied the effects of hydrotherapy in aerobic capacity, muscle strength and/or HRQOL of the HF patients. Two authors independently evaluated and extracted data from the published reports. Methodological quality was also independently assessed by two researchers. Studies were scored on the PEDro scale a useful tool for assessing the quality of physical therapy trials based on a Delphi list that consisted of 11 items with a score range of 0 to 10.

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Pooled-effect estimates were obtained by comparing the least square mean percentage change from baseline to study end for each group. Two comparisons were made: hydrotherapy versus control group (non exercise) and hydrotherapy versus aerobic exercise group. All analyses were conducted using Review Manager Version 5.0 (Cochrane Collaboration). Six papers met the eligibility criteria. Fig. 1 shows the PRISMA flow diagram of studies in this review. The results of the assessment of the PEDro scale are presented individually in Table 1. The final sample size for the selected studies ranged from 14 to 25 and mean age of participants ranged from 51 to 75 years. All studies analyzed in this review included outpatients with documented HF and New York Heart Association (NYHA) classes II–III. Table 2 summarizes the characteristics. Hydrotherapy was considered as aerobic and strength exercises in warm water and the duration of the programs ranged from 3 to 24 weeks. Regarding the time of the session, there was a variation from 30  to 90 minutes. The frequency of sessions was three times per week in three studies and five times per week in others. Four studies assessed peak VO2 as an outcome, two compared hydrotherapy versus no exercise [10,11] and two hydrotherapy versus conventional aerobic exercise in land. The meta-analyses showed a significant improvement in peak VO2 of 2.97 mL·kg−1 ·min−1 (95% CI: 1.99, 3.94, N = 42) for participants in the hydrotherapy group compared with the no exercise group (Fig. 2A). A non significant change in peak VO2 of −0.66 mL·kg−1 ·min−1 (95% CI: −2.05, 0.72, N = 48) was found for participants in the hydrotherapy group compared with conventional aerobic exercises (Fig. 2B). Three studies assessed the 6-minute walk test (6WMT) as an outcome [10,11,14], two compared hydrotherapy versus no exercise and one hydrotherapy versus aerobic exercises in land. Significant improvements were found when comparing hydrotherapy with no exercise controls. The meta-analyses showed (Fig. 3) a significant improvement in 6WMT of 43.8 m (95% CI: 7.36, 80.16, N = 42) for participants in the hydrotherapy group compared with the no exercise group. Three studies assessed muscle strength as an outcome, two compared hydrotherapy versus no exercise and one hydrotherapy versus aerobic exercise in land. Significant improvements were found when comparing hydrotherapy with no exercise controls. The meta-analyses showed (Fig. 4) a significant improvement in muscle strength of 23.7 Nm (95% CI: 4.49, 42.89, N = 42) for participants in the hydrotherapy group compared with the no exercise group. Two studies measured HRQOL. The meta-analyses showed non significant improvement in HRQOL of −4.5 (95% CI: −14.40, 5.49, N = 42) for participants in the hydrotherapy group compared with the no exercise group (Fig. 5). Meta-analysis demonstrated a significant difference in peak VO2, distance in the six-minute walking test, muscle strength and DBP between patients with HF submitted to hydrotherapy and controls. Moreover, hydrotherapy was as efficient as conventional aerobic exercise in land for peak VO2. It is now known that cardiac function actually improves during water immersion due to the increase in early diastolic filling and decrease in heart rate, resulting in improvements in stroke volume and ejection fraction. These data created a positive scenario to discuss hydrotherapy as a potential tool in cardiovascular rehabilitation. This systematic review with meta-analysis is important because it analyzes the hydrotherapy as a potential co-adjutant modality in the rehabilitation of patients with HF. The mean of peak VO2 in the analyzed studies was 17.05 at the beginning and 18.3 mL·kg−1 ·min−1 at the end of the intervention. It has been demonstrated that improvements above 10% after a cardiovascular rehabilitation program represent a good prognosis in patients with HF. It has also been demonstrated that a minimum VO2 peak of 15 mL·kg−1 ·min−1 in women and 18 mL·kg−1 ·min−1 in men aged 55–86 years seems to be necessary for full and independent living. Thus the improvement generated by the hydrotherapy program can contribute to those patients with CHF to have better conditions to carry out their everyday activities.

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Quadriceps mass and strength are related to maximal exercise capacity in HF. Moreover, changes in muscle performance with exercise training have been demonstrated to be related to changes in physical function and quality of life. In the present systematic review, our meta-analysis demonstrated a significant difference in muscle strength between patients with HF submitted to hydrotherapy and sedentary controls. Despite the fact that hydrotherapy was shown to be efficient in improving peak VO2 and muscle strength, it is not possible to conclude about the benefits of hydrotherapy compared to no exercise in HRQOL. Considering the available data, our meta-analysis showed that hydrotherapy was efficient to improve exercise capacity in patients with HF. Well controlled RCTs are needed to understand the potential bene- fits of hydrotherapy in patients with HF.

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