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Lifestyle modification and blood pressure

Study
Results
Comment

Lifestyle is the new pink (or black, or whatever). Even governments now witter on about reducing obesity, changing diet, and increasing exercise. That is a wonderful thing to see, but a problem can sometimes be that ordinary folk may not know which part of the message to concentrate on. Should I lose weight, or reduce my salt intake? Take more exercise, or eat more fruit? The answer is that comprehensive lifestyle modification is the key to getting on top of moderately raised blood pressure [1]. Bandolier has always had a dread of antihypertensive medicines, so knowing that a batch of changes can keep them at bay makes good reading.

Study

Participants in this randomised study were generally healthy adults with above optimal blood pressure, and included people with mild hypertension and who were not taking antihypertensive medicines. The systolic BP had to be between 120 and 159 mmHg, and the diastolic BP between 80 and 95 mmHg as a mean over three screening visits. They were 25 years of age or older, and had a body mass index between 18.5 and 45 kg/sq metre. Excluded were those taking drugs likely to affect blood pressure, and people who drank more than 21 units a week, or who had major medical conditions.

Randomisation was to:

The main outcome was blood pressure measured at six months, though many other outcomes were measured by personnel masked to randomisation assignment.

Results

There were 810 participants with a mean age of 50 years and BMI of 33 kg/sq metre, of whom 62% were women and 34% African American. The mean initial systolic blood pressure was 135 mmHg, and diastolic 85 mmHg, with 38% hypertensive (defined as a blood pressure over 140/90 mmHg). Participants in the three groups were well matched at baseline. The majority of patients (70-80%) attended at least 15 of the 18 planned sessions in the active intervention groups.

Blood pressure declined in all three groups over the six months. In the advice-only group the mean reduction in systolic BP was 7 mmHg, and 11 mmHg in both intervention groups. Diastolic BP reductions were 4 mmHg and 6 mmHg respectively. The interventions made the expected changes, with more weight loss (5-6 kg) in the intervention than advice group (1 kg). Participants in the established + DASH group ate more fruit and vegetables, less fat, and less saturated fat, so the interventions could be seen to achieve their dietary goals.

Most interesting was the proportion of participants who, at six months, were hypertensive (BP greater than 140/90 mmHg) or who had optimal BP, at 120/80 mmHg or below). Figure 1 shows that the best results, with most participants with optimal BP and fewest who were hypertensive occurred with established + DASH, and Table 1 shows the numbers needed to treat to achieve these outcomes.



Figure 1: Participants with hypertension or optimum blood pressure







Table 1: NNTs for active therapy versus advice only



Outcome and comparison
NNT
95%CI)
Prevent hypertension
Established vs advice
11 (5 to 55)
Established + DASH vs advice
7 (5 to 13)
Promote optimum BP
Established vs advice
9 (5 to 29)
Established + DASH vs advice
6 (4 to 12)


Behavioural modification plus the DASH diet had numbers needed to treat of 7 (95% CI 5 to 13) to prevent one participant being hypertensive, and 6 (4 to 12) for one participant to have optimal BP. Only one in four of those with blood pressure above 140/90 mmHg still had this degree of elevation after six months of behavioural modification plus the DASH diet, compared with one in two with advice only.

Comment

Behavioural modification plus the DASH minimised the extreme results we don't want (hypertension) and maximised the extreme result we do want (optimal blood pressure). These are substantial and important results for healthcare systems and individuals. For individuals, the message is that reducing weight and salt, and increasing exercise and consumption of fruits and vegetables can keep us from needing to see our doctors, except socially. For healthcare systems, the results highlight a concerted way in which prevention can keep patients away from expensive and possibly harmful medicines, and perhaps reduce cost while improving peoples’ health.

Reference:

  1. Premier Collaborative Research Group. Effects of comprehensive lifestyle modification on blood pressure control. JAMA 2003 289: 2083-2093.

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