The present study was conducted to determine the effects of yoga on BP and quality of life in patients in primary health care. Our results demonstrated a significant reduction in DBP in the patients who practiced yoga at home compared to the control group (p < 0.05). The yoga at home group also showed a greater improvement in quality of life than the control group (p < 0.05). Patients who practiced yoga in a group with an instructor, however, did not experience significant improvements in BP or self-rated quality of life compared to the control group. Only three of the 83 participants failed to attend the follow-up appointment. This means that a sufficient number of patients completed the study according to the power calculation.
The results imply that simple yoga exercises may be useful as a supplementary BP therapy in addition to medical treatment when prescribed by primary care physicians.
It is well known that physical activity has a BP lowering effect. For those patients who are not able or willing to do demanding exercise, an easy yoga program could be an alternative.
It is interesting to note that a relatively small effort for the health care center (in terms of number of visits) had the best effect on BP and quality of life.
The present study contributes to yoga-hypertension research by examining the effects of yoga in a primary health care setting, where most patients with hypertension are treated. The shorter intervention (yoga at home) can easily be taught to the patient by his or her own doctor at the health care center.
Previous studies have shown that yoga reduces BP [6–9, 16–20]. However, the yoga intervention design varied among these studies and the length of the intervention ranged from 3 to 20 weeks, making it difficult to compare the interventions in terms of effectiveness. Furthermore, some of the studies combined the yoga treatment with other measures, such as changes in diet [19, 20].
One of four invited patients (25%) chose to participate in the study. These patients were probably open-minded about complementary and alternative therapy. In view of this selection bias, the results of the study are probably not applicable to all patients in primary care with hypertension. However, this is the case in most other comparable yoga studies. As reported, the yoga at home patients rated their quality of life at baseline higher than the other groups. This fact could indicate a higher motivation among these patients to try something new to further improve their quality of life. On the other hand, one could argue that it is more difficult to improve quality of life when starting from a higher level. Additionally, the fact that the yoga at home group had an early private appointment with a study physician may in itself have had a positive effect on the results . Patients probably adhere more to a doctor’s advice about yoga when yoga is used as a supplementary therapy. However, the patients in the yoga at home group only met the doctor for 20 minutes, while the yoga class group patients met their instructor for 12 hours during the intervention period.
It is unclear why the yoga class group did not have any reduction in BP. One possible explanation lies in the yoga exercises the two groups performed at home. The yoga class group had a more advanced yoga program than the yoga at home group. This may have contributed to the fact that the yoga class group participants performed fewer yoga sessions at home during the intervention than the yoga at home participants. The number of sessions may have influenced the result, but the yoga class group patients spent on average about 50% more time doing yoga than the yoga at home group patients. There might have been additional barriers to the yoga class group members than the advanced exercises, such as travelling to the health care center each week. Being in a class environment with other patients could also make some people feel insecure and uncomfortable. However, one could also argue that these barriers would be balanced by a rewarding interaction with the instructor and other group members.
According to a Swedish literature review, the mean reduction of BP from an antihypertensive drug is 10/5 mmHg, when used alone . The effect of an additional drug is mostly lower. In view of this fact, the mean reduction of DBP of 4.4 mmHg, shows that the effect of the short yoga program could be of clinical relevance and interest when used as a supplement to other treatment.
A weakness of the study concerns the self-reported data (yoga calendar), which is a problem in all studies of this kind. In general, studies on supplementary intervention are difficult to perform, but none the less it is an important study since yoga is increasingly popular and practiced by many people.
The fact that the proportion of women in the different groups varied, with the highest proportion of women in the yoga at home group, may have influenced the results to some extent, since women tended to have a greater SBP-lowering response to yoga than men. However, the differences in age and gender between the groups were not significant.
The participants were matched for SBP at study start. They were not matched regarding the number of medicines. The yoga class group patients had on average more antihypertensive drugs than the yoga at home and control group patients. The differences between the groups were not significant, but more medicines could indicate more severe hypertension.
A 24-hour ambulatory BP measurement would be a more accurate method to measure BP over time, but this was not possible in our study. Moreover, even studies on the effects of medicine on BP are usually not made with 24-hour ambulatory BP measurement.
Randomized allocation is superior to matching in most studies, and this is a limitation of the study. Our rationale for matching the groups was that we wanted to ensure similar SBP values at baseline.