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Can Fam Physician
Vol. 54, No. 12, December 2008, pp.1706 - 1713
Copyright © 2008 by The College of Family Physicians of Canada
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Research

Lifestyle interventions in primary care

Systematic review of randomized controlled trials

Patrick Fleming
Research Assistant in the Primary Healthcare Research Unit

Marshall Godwin, MD MSc
Professor of Family Medicine, both at Memorial University of Newfoundland in St John’s

Correspondence: Dr Marshall Godwin, Room 1776, Health Science Centre, 300 Prince Philip Dr, St John’s, NL A1B 3V6; telephone 709 777-8373; fax 709 777-6118; e-mailgodwinm{at}mun.ca

Elements of lifestyle, such as exercise, diet, smoking, and stress, are known to affect health and risk of cardiovascular disease. Various studies have identified relationships between lifestyle and health status, health care use, and costs to the health care system.1–4 Interventions aimed at improving patients’ lifestyles have resulted in improvements in health outcomes.5–7 The best known study of these interventions was conducted by the Diabetes Prevention Program research group.6 They found that lifestyle interventions prevented progression to diabetes in patients with pre-diabetes. Most of these interventions, however, involved intense exercise and diet programs delivered by exercise physiologists and dietitians.

The objective of this study was to determine whether lifestyle interventions delivered in primary care settings by primary care providers to their adult patients were effective in changing factors related to cardiovascular risk. Only patients without known cardiovascular disease or diabetes were included in the study (primary prevention situations only). Lifestyle interventions were limited to those related to exercise and diet. Outcomes of interest were cardiovascular risk scores, blood pressure, lipid levels, weight or body mass index, and morbidity and mortality.


   DATA SOURCES
TOP
 DATA SOURCES
SYNTHESIS
 DISCUSSION
 Footnotes
 References
 
Literature search
We searched MEDLINE (PubMed), EMBASE, and CINAHL from January 1985 to December 2007 for all randomized controlled trials (RCTs) and systematic reviews of lifestyle counseling in primary care for primary prevention of cardiovascular disease. Search terms used included lifestyle counseling, dietary advice, exercise, physical activity, lifestyle intervention, behaviour modification, primary care, general or family practice, and primary prevention. The reference lists of all articles retrieved were checked to ensure that all suitable RCTs had been included. The search was limited to English-language articles involving human subjects.

Study selection
We considered only RCTs that reported on outcomes at 12 months or longer of patients who did not have pre-existing cardiovascular disease or diabetes. Study participants had to be 18 years or older and could be of either sex. Trials involving drug treatment in combination with lifestyle counseling were excluded.

Interventions had to be lifestyle orientated and focused on healthy eating or increased physical activity. Smoking could not be a main focus of the trial. Trials must have been conducted within the context of primary care and carried out by primary care providers, such as family physicians or practice nurses. Trials had to have had control groups who were managed with usual care. Usual care could include distribution of basic lifestyle messages, such as the literature on healthy living typically handed out by health professionals.

Both authors reviewed the articles independently using the criteria outlined in the users guides by Guyatt et al.8 Criteria used to assess the validity of the articles included randomization, accountability and follow-up after the study, intention-to-treat analysis, blinding and concealment, homogeneity, similarity of study and control groups, and evidence of contamination or simultaneous interventions. The reviewers were not blinded to the authors of the articles nor to the citation sources, but it turns out they were not familiar with any of the authors of the articles included. Reviewers considered both overall study validity and applicability to general practice. Overall assessment included details of studies’ methodology, patient populations, interventions and controls, and clinical aspects. Agreement as to whether an article would be included was settled by consensus after the independent reviews.

As shown in the flow diagram (Figure 1), our initial literature search identified 37 articles of which 24 were excluded. The remaining 13 articles9–21 were reviewed in more detail. Among these 13 articles, 4 were excluded because the study populations lacked homogeneity9–12 (eg, they included primary and secondary prevention patients), 1 was excluded because it lacked a control group,13 and another because of a lack of consistency in data reporting.14 In the end, 7 studies were included in the review (Table 1).15–21


Figure 10541706
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  		Figure 1 Study selection

 

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  		Table 1 Articles included in this review

 
Because data were reported in various ways in the studies and because some information was missing (eg, no standard deviations, percentages without numbers), we could not adequately conduct a meta-analysis. We report outcome data in Table 2.15–21 In addition to determining the statistical significance of the outcomes, we assessed the relevance or importance of differences, when they were found, using the definitions shown in Table 3.


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  		Table 2 Summaries of outcome data in the 7 articles included in this study

 

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  		Table 3 Definitions of effect size for each outcome

 

   SYNTHESIS
TOP
 DATA SOURCES
 SYNTHESIS
DISCUSSION
 Footnotes
 References
 
Overall, the studies found little benefit from lifestyle- orientated interventions compared with usual care. Three of the 6 studies that assessed blood pressure as an outcome found a small but significant benefit to lifestyle counseling versus usual care.16,18,20 Two of the 5 studies that assessed cholesterol levels as an outcome found a small but significant benefit of lifestyle counseling.16,19 Only 1 of the 5 studies that assessed body mass index showed significant benefit of counseling, but again the effect was small.16 Only 1 of the 7 studies included in this review measured cardiovascular risk scores as an outcome; it showed no significant improvement in risk between intervention and control groups.17 None of the articles included in this review measured mortality or morbidity as an outcome.

The studies used a variety of lifestyle interventions. Two used dietary interventions only.15,19 One study was strictly oriented toward physical activity.17 The remaining 4 studies16,18,20,21 used a combination of healthy-eating and staying-active messages. The interventions varied in duration from 1 to 9 months. There was also variation in who delivered the advice. In 1 study20 it was physicians only, in 2 others17,18 it was a combination of nurses and physicians, and in 4 studies15,16,19,21 it was nurses only. Details of the studies are shown in Tables 1 and 2.15–21


   DISCUSSION
TOP
 DATA SOURCES
 SYNTHESIS
 DISCUSSION
Footnotes
 References
 
Usefulness of lifestyle interventions
This review allows us to answer, or at least get insight into, specific questions about the usefulness of lifestyle counseling interventions delivered in primary care settings.

Were outcomes affected by which primary care provider (physician or practice nurse) delivered the intervention?
Among the 4 studies15,16,19,21 in which a nurse alone delivered the intervention, only 1 showed a consistent positive benefit.16 The benefit was small, however, and the achievement of statistical significance was helped by a large sample size. The 1 study20 in which a primary care physician alone delivered the intervention showed the intervention was not effective at lowering cholesterol or body mass index, but did have a positive effect on diastolic blood pressure in men only. The intervention in this study was, however, complex and not easily generalizable to most practices. The 2 studies in which both physicians and nurses were involved17,18 showed little positive effect of the intervention. One study showed no benefit on any of the outcomes measured; the other looked at blood pressure only and showed a small but significant reduction. It does not appear to matter which primary care provider delivers the intervention. The results are generally not impressive.

Did adding external supports to the provider-delivered intervention improve outcomes?
Two studies17,20 used additional services with the primary care providers’ intervention. One study had exercise specialists follow up patients after initial counseling by physicians and nurses. The other had experts providing physicians with extra training. Neither of these studies showed benefit of the intervention except for a moderate improvement in diastolic blood pressure in men only.

Were overall cardiovascular risk scores affected by the lifestyle interventions?
The 1 study17 that looked at cardiovascular risk scores showed no benefit from the intervention, even though there was a reasonable sample size (N = 878), and the intervention was delivered by physicians and nurses with follow-up by exercise specialists.

Were specific components of risk (blood pressure, weight, lipid levels) affected by the lifestyle interventions?
Only 416,18–20 of the 7 studies in this review showed any positive effect of lifestyle interventions. The main effects were on blood pressure and to a lesser degree on lipids. In general, effects were small.

Were morbidity and mortality affected by the lifestyle interventions?
These outcomes were not measured in any of the 7 studies included in the review.

Limitations
The main limitation of this review was the inability to conduct a meta-analysis because the study populations were not homogeneous and the presentation of results was done in a variety of ways. Since a meta-analysis was not done, we could not assess the likelihood of a negative result bias because we could not construct a funnel plot. We did not search non-English literature; it is possible that valid articles on the topic exist in other languages. We searched the 2 major medical databases (MEDLINE and EMBASE) and the major allied health database (CINAHL). It is unlikely that there is much primary care or family practice literature that has not been captured by the 3 databases we searched.

Future research
More sustained intensive programs of lifestyle counseling, delivered by health educators with backgrounds in nutrition and exercise, might be more effective. This has been shown to be the case outside the primary care setting in the Diabetes Prevention Program7 study. A randomized controlled trial (the PROACTIVE study22) is currently under way in Canada, funded by the Canadian Institutes for Health Research, looking at the use of an intensive program of lifestyle counseling delivered during many visits over a 2-year period. The intervention is being delivered in primary care settings, but by providers referred to as health educators with backgrounds in exercise and health promotion. We await the results of this trial to know whether outcomes will be improved using this approach in primary care.

Conclusion
This review looked at lifestyle counseling interventions delivered by primary care providers in primary care settings to patients at low risk of cardiovascular disease (primary prevention). The effects of the interventions were far from striking. Only 2 of the 7 studies showed consistently positive results, and these were primarily around improvements in blood pressure. The improvements were small, in the range of 2 mm Hg difference between intervention and control groups. While we did not formally look at high-risk patients, several of the studies we encountered looked at both high- and low-risk patients. It appears that patients at higher risk (those with pre-existing ischemic heart disease or diabetes) might benefit more from lifestyle counseling than the low-risk patients we studied. In general, while it is difficult to suggest that primary care providers not counsel all their patients on healthy lifestyles, their time might be better spent focusing on those at higher risk. It is possible that more sustained intensive programs of lifestyle counseling, delivered by health educators with backgrounds in nutrition and exercise, are more effective.



   EDITOR’S KEY POINTS
 
  • This systematic review was conducted to determine whether lifestyle interventions delivered in primary care settings by primary care providers to their adult patients were effective in changing factors related to cardiovascular risk.
  • Overall, for cardiovascular risk scores, blood pressure, lipid levels, weight or body mass index, morbidity, and mortality outcomes, the studies found little benefit from lifestyle-orientated interventions compared with usual care.
  • While it is difficult to suggest that primary care providers not counsel all their patients on how to lead healthy lives, their time might be better spent focusing on those patients at higher risk.

 



   POINTS DE REPÈRE DU RÉDACTEUR
 
  • Cette revue systématique voulait déterminer si les interventions des soignants de première ligne auprès de leurs patients adultes concernant leur mode de vie étaient efficaces pour modifier les facteurs de risque cardiovasculaires.
  • Dans l’ensemble, les études ont montré que par rapport aux soins habituels, les interventions visant le mode de vie avaient peu d’effet bénéfique sur l’indice de risque cardiovasculaire, la tension artérielle, le niveau des lipides, le poids et l’indice de masse corporelle, la morbidité et la mortalité.
  • Même si on peut difficilement suggérer aux intervenants de première ligne de ne pas renseigner leurs patients sur un mode de vie sain, il pourrait être plus avantageux pour eux de consacrer davantage de temps aux patients à haut risque.

 


   Footnotes
TOP
 DATA SOURCES
 SYNTHESIS
 DISCUSSION
 Footnotes
References
 
This article has been peer reviewed.

Competing interests

None declared

Contributors

Mr Fleming and Dr Godwin contributed to concept and design of the study; data gathering, analysis, and interpretation; and preparing the article for submission.


   References
TOP
 DATA SOURCES
 SYNTHESIS
 DISCUSSION
 Footnotes
 References
 

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  7. Ramachandran A, Snehalatha C, Mary S, Mukesh B, Bhaskar AD, Vijay V. Indian Diabetes Prevention Programme (IDPP). The Indian Diabetes Prevention Programme shows that lifestyle modification and metformin prevent type 2 diabetes in Asian Indian subjects with impaired glucose tolerance (IDPP-1). Diabetologia 2006;49(2):289–97.[Medline]
  8. Guyatt GH, Sackett D, Cook DJ. Evidence Based Medicine Working Group. Users guides to the medical literature. II: How to use an article about therapy or prevention. A. Are the results of the study valid? JAMA 1993;270(21):2598–601.[Abstract/Free Full Text]
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