the 100-point HRQOL measure, where a higher number indicates higher disease burden. Overall, these hydrotherapies produced a moderate reduction of pain on the VAS (9 trials; N5318, SMD -0.78; 95% CI, -1.42 to -0.13; I 2 583%) and largely improved quality of life on the HRQOL (4 trials; SMD5-1.67; 95% CI, -2.91 to -0.43; I 2 590%). These effects were sustained at follow-up (follow-up was at 6-36 weeks, median 14), with a large pain reduction persisting on the VAS (4 trials; N5160, SMD -1.27; 95% CI, -2.15 to -0.38; I 2 584%) and a large improvement in quality of life persisting on the HRQOL (4 trials; N5202, SMD -1.16; 95% CI, -1.96 to -0.36; I 2 584%). Subgroup analysis for pain improvement indicated statistical significance only in the RCTs involving bathing in thermal or mineral water (5 trials; N5184; P,.0001; SMD -1.63; 95% CI, -.231 to -0.96; I 2 573%), whereas trials with whirl baths, mud baths, and Stanger bath did not (3 trials; N5134, SMD 0.01; 95% CI, -0.45 to 0.47; I 2 512). Only one RCT reported side effects, with a 10% incidence of slight "flushing." This paper was limited by the absence of intention-totreat analysis or adequate blinding in any studies, by only three RCTs having sample sizes of at least 25 per group, and by the method of randomization generally not being reported.The opinions and assertions contained herein are those of the authors and are not to be construed as official or as reflecting the views of the US Army Medical Department, the Army at large, or the Department of Defense.