A 3-year randomized trial of lifestyle intervention for cardiovascular risk reduction in the primary care setting: the Swedish Björknäs study

Abstract

Background: Successfully transferring the findings of expensive and tightly controlled programmes of intensive lifestyle modification to the primary care setting is necessary if such knowledge is to be of clinical utility. The objective of this study was to test whether intensive lifestyle modification, shown previously in tightly-controlled clinical trials to be efficacious for diabetes risk-reduction among high-risk individuals, can reduce cardiovascular risk factor levels in the primary care setting.

Methodology / principal findings: The Swedish Björknäs study was a randomized controlled trial conducted from 2003 to 2006 with follow-up on cardiovascular risk factors at 3, 12, 24 and 36 months. A total of 151 middle-aged men and women at moderate- to high-risk of cardiovascular disease from northern Sweden were randomly assigned to either an intensive lifestyle intervention (n = 75) or control (n = 76) group. The intervention was based broadly on the protocol of the Diabetes Prevention Program. The three-month intervention period was administered in the primary care setting and consisted of supervised exercise sessions and diet counselling, followed by regular group meetings during three years. The control group was given general advice about diet and exercise and received standard clinical care. Outcomes were changes in anthropometrics, aerobic fitness, self-reported physical activity, blood pressure, and metabolic traits. At 36 months post-randomisation, intensive lifestyle modification reduced waist circumference (-2.2 cm: p = 0.001), waist-hip ratio (-0.02: p<0.0001), systolic blood pressure (-4.9 mmHg: p = 0.036), and diastolic blood pressure (-1.6 mmHg: p = 0.005), and improved aerobic fitness (5%; p = 0.038). Changes in lipid or glucose values did not differ statistically between groups. At 36 months, self-reported time spent exercising and total physical activity had increased more in the intervention group than in the control group (p<0.001).

Conclusion / significance: A program of intensive lifestyle modification undertaken in the primary health care setting can favourably influence cardiovascular risk-factor profiles in high-risk individuals.

Trial registration: ClinicalTrials.gov NCT00486941.

Figure 1. Participants flow Diagram.

Figure 2. (A–D) Changes in anthropometrics.

Data are adjusted means (95% confidence intervals) for each time point derived from generalised line ar models with repeated measures. Adjustments are made for the baseline value for the respective outcome variable. Blood pressure values are also adjusted for medication load. Statistical significance at each follow-up time point generated from univariate analysis of variance, * p<0.05, ** p<0.01, *** p<0.001.

Figure 3. (A–D) Changes in clinical characteristics.

Data are adjusted means (95% confidence intervals) for each time point derived from generalised linear models with repeated measures. Adjustments are made for the baseline value for the respective outcome variable. Blood pressure values are also adjusted for medication load. Statistical significance at each follow-up time point generated from univariate analysis of variance, * p<0.05, ** p<0.01, *** p<0.001.

Figure 4. (A–F) Changes in laboratory characteristics.

Data are adjusted means (95% confidence intervals) for each time point derived from generalised linear models with repeated measures. Adjustments are made for the baseline value for the respective outcome variable. Blood pressure values are also adjusted for medication load. Statistical significance at each follow-up time point generated from univariate analysis of variance, * p<0.05, ** p<0.01, *** p<0.001.

Figure 5. (A–C) Changes in physical activity level.

Proportion of participants reporting the level of each variable, total physical activity, leisure time physical activity and exercise and ordered as follows: TPA; sedentary, minimally active, moderately active and very active. LTPA and exercise; ‘none’ = 0, ‘<30 min/day’ = 1, ‘30–60 min/day’ = 2, and ‘>60 min/day’ = 3. P values from general linear model repeated measures analysis.