Journal of Human Hypertension (2015), 1 © 2015 Macmillan Publishers Limited All rights reserved 0950-9240/15 www.nature.com/jhh

LETTER TO THE EDITOR

Transcendental meditation and blood pressure Journal of Human Hypertension advance online publication, 9 July 2015; doi:10.1038/jhh.2015.74 We read the systematic review and meta-analysis by Bai et al.1 on the effect of transcendental meditation (TM) on blood pressure (BP) with interest. They concluded that TM might decrease both systolic and diastolic BP, and subgroup analyses showed that TM had greater effects on BP reduction in some populations. However, we think that there are some methodological and clinical concerns. First, many of the studies included were susceptible to attrition bias. The completion rate was lower than 75% in 6 of 11 included studies, as Bai et al. noted in their discussion. A further concern is the incomplete reporting of outcome in these six studies. Only one study reported on all primary and secondary outcomes with intention-to-treat analysis,2 and some others3,4 reported and analyzed only participants who completed the interventions. One trial did not show the reasons for dropouts.5 If participants who withdrew from the study might not have benefitted by TM, then such a trial might have shown a tendency to favor TM. Thus, a sensitivity analysis by attrition should be considered. Second, the efficacy of TM on BP tended to decrease with the study durations, as Bai et al. discussed. If TM and usual care, such as an education program, are similar in terms of the efficacy on BP, then there should be a rationale for preferring TM. TM is a special practice and needs educated instructors. TM is also an expensive practice costing $960 per course for one individual.6 When the long-term efficacy of TM on BP is finally demonstrated, a cost analysis should be conducted. Finally, the participants in the included studies were clinically heterogeneous. For example, three trials focused on adolescents with high normal BP,3,4,7 and one focused on students with normal BP.5 Another looked at patients with at least one coronary lesion with 450% stenosis.2 These findings suggest that the target populations are at different risks of developing cardiovascular events. Future research should investigate the efficacy of TM on clinically relevant populations.

We agree with the potential of TM for lowering BP, but question the applicability of TM in our clinical practice. Long-term and methodologically sound trials of TM on clinically important populations are still needed. CONFLICT OF INTEREST The authors declare no conflict of interest.

S Urushidani1 and A Kuriyama2 Department of- Emergency Medicine, Kurashiki Central Hospital, Okayama, Japan and 2 Department of General Medicine, Kurashiki Central Hospital, Okayama, Japan E-mail: [email protected]

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REFERENCES 1 Bai Z, Chang J, Chen C, Li P, Yang K, Chi I. Investigating the effect of transcendental meditation on blood pressure: a systematic review and meta-analysis. J Hum Hypertens e-pub ahead of print 12 February 2015. 2 Schneider RH, Grim CE, Rainforth MV, Kotchen T, Nidich SI, Gaylord-King C et al. Stress reduction in the secondary prevention of cardiovascular disease: randomized, controlled trial of transcendental meditation and health education in Blacks. Circ Cardiovasc Qual Outcomes 2012; 5(6): 750–758. 3 Barnes VA, Kapuku GK, Treiber FA. Impact of transcendental meditation on left ventricular mass in african american adolescents. Evid Based Complement Alternat Med 2012; 2012: 923153. 4 Barnes VA, Treiber FA, Johnson MH. Impact of transcendental meditation on ambulatory blood pressure in African-American adolescents. Am J Hypertens 2004; 17(4): 366–369. 5 Nidich SI, Rainforth MV, Haaga DA, Hagelin J, Salerno JW, Travis F et al. A randomized controlled trial on effects of the Transcendental Meditation program on blood pressure, psychological distress, and coping in young adults. Am J Hypertens 2009; 22(12): 1326–1331. 6 Transcendal Meditation. http://www.tm.org/course-fee Last access on April 15, 2015. 7 Barnes VA, Treiber FA, Davis H. Impact of Transcendental Meditation on cardiovascular function at rest and during acute stress in adolescents with high normal blood pressure. J Psychosom Res 2001; 51(4): 597–605.

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