To summarise the literature on primary care-based interventions for increasing physical activity, and to make recommendations for future research and for integrating successful strategies into practice.

MEDLINE (from 1980 to 1998), Psychological Abstracts, ERIC and HealthSTAR databases, and the Journal of Family Practice's website (www.jfampract.com), were searched using the following search terms: 'physical activity' and 'randomised controlled trials'; 'physical activity counselling' and 'primary care' or 'medical office'; 'exercise interventions' and 'primary care' or 'medical office'; and 'physical activity' and 'health promotion'. Only studies published in the English language were considered. In addition, bibliographies of selected studies and previous reviews were searched for relevant articles, and three experts in the field of physical activity were contacted for information on unpublished trials.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) and quasi-experimental studies using a comparison group were considered.

Specific interventions included in the review

The interventions varied across the included studies. Intervention elements typically included short (5 minutes) advice from health care professional (MD or nurse), a written exercise prescription, health educational material, and follow-up ranging from 2 weeks to 48 months. The controls were as follows: usual care, mailed physical activity materials, verbal advice only, risk assessment and general practitioner feedback.

Participants included in the review

The authors did not specify any inclusion criteria for participants. The characteristics of the participants varied across studies. Participants were adults aged at least 18 years, and from the limited information provided, most (65%) were female. The interventions were delivered in the primary care setting.

Outcomes assessed in the review

An inclusion criterion was the reporting of at least one measure of physical activity. The assessed outcomes, although variously defined across studies, mainly included self-reported outcomes such as the amount, duration and type of physical exercise, as well as objective outcomes such as physical activity level scores (PASE and PACE) and metabolic rate.

How were decisions on the relevance of primary studies made?

The authors do not state how the papers were selected for the review, or how many of the reviewers performed the selection.

Assessment of the methodological quality of studies was based on the RE-AIM model (see Other Publications of Related Interest), which assessed six criteria; study design, analyses, dependent variable, reach, implementation, and attrition. Scores deriving from this assessment method ranged from 0 to 10. Two independent raters assessed methodological quality, and any disagreements were resolved through discussion with a third reviewer.

The authors do not state how the data were extracted for the review, or how many of the reviewers performed the data extraction. Data were extracted on sample details, study design, intervention details (i.e. length and content), outcome variables, length of follow-up and outcomes. Outcomes were presented in terms of effect sizes for continuous variables, and odds ratios (ORs) for dichotomous variables, for both short-term (less than 12 months) and long-term (at least 12 months) outcomes. Authors of studies were contacted for additional information if necessary.

How were the studies combined?

The studies were combined in a qualitative narrative.

How were differences between studies investigated?

Differences between the studies were investigated through a narrative discussion of factors relating to study design, intervention and participants' characteristics.

Fifteen studies were included (n=25,153): 9 RCTs (n=8,015) and 6 quasi-experimental studies (n=17,138).

Methodological quality: the scores ranged from 4 to 9, with the majority receiving a score of 6 or 7 on the scale of 0 to 10. Most common methodological limitations were not reporting implementation results, and failing to employ intention to treat analyses or imputation procedures to address attrition issues.

Physical activity outcomes: of the 10 studies reporting 0- to 11- month post-intervention outcomes, 7 reported statistically-significant outcomes. Effect sizes ranged from 0.003 to 0.26 and ORs from 1.04 to 3.73 (median=1.88). Of the 7 studies reporting post-intervention outcomes at 12 or more months, 3 reported statistically-significant outcomes. The only study among these from which an effect size could be calculated (d=0.09) reported follow-up ORs ranging from 0.09 to 1.39 (median=1.25).

Differences between studies: none of the following differences were related to effectiveness; interventionist (MD, nurse or student), methodological quality, use of follow-up support, duration of counselling, or whether the intervention was explicitly theory-based. Some between-study differences appeared to be related to effectiveness. Interventions that focused only on physical activity, and those that were tailored to participants' characteristics, were more effective in the short-term. In contrast, all 3 of the studies with significant long-term effects were multiple risk factor interventions.

Well-controlled physical activity interventions have generally produced moderate short-term improvements, but these results are often less encouraging at long-term follow-up. Thus, although brief, primary care-based interventions appear efficacious in producing short-term changes in physical activity, prolonged change or maintenance remains difficult.

This was, on the whole, a methodologically-sound review that is well reported. The review question was clearly stated and well-supported by study inclusion criteria. The literature search was reasonable, though limited to English language papers, and there was a limited attempt to identify unpublished material. The methodological quality of included studies was assessed and results were presented appropriately. Some details of review methodology were not reported, e.g. how papers were selected for the review and how data were extracted. The authors' conclusions do seem to follow from the results presented.

Practice: The authors state that to achieve short-term changes in patient physical activity, the intervention focus should be on physical activity only, consist of tailored interventions with written materials and, since physical activity counselling can be successfully implemented by a variety of health care team members, the person who delivers the intervention should be whomever is most likely to do so consistently, given time, training and interest.

Research: The authors state that identifying methods for long-term maintenance of short-term intervention gains in physical activity is a key issue for future research.

Glasgow RE, Vogt TM, Boles SM. Evaluating the public health impact of health promotion interventions: the RE-AIM framework. Am J Public Health 1999;89:1322-7.

This additional published commentary may also be of interest. Fein SP, Sherman SE. Review: brief primary care interventions are moderately effective for increasing physical activity. Evidence-Nased Nursing 2001;4:45.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.