The primary goal of this study was to test the effect of tailored, computerized physical activity reports on patients' physical activity at six months. This study used an innovative computer program adapted from previous successful work.47
Our study targeted patients directly as a strategy to attempt to overcome patient-clinician counseling barriers to physical activity promotion in primary care visits.
Contrary to our hypotheses, we did not find significant changes in physical activity between intervention and control groups, contrasting with studies that have shown improvements.47-50
There are several possible reasons for the lack of effect. It is possible that participants under-reported physical activity on the initial telephone screen, over-reported on the baseline assessment, and/or actually changed their activity level from screening to baseline assessment. Other studies (Jumpstart47
, Project STRIDE48;49
) excluded those with greater than 90 minutes per week on the baseline assessment, to maximize enrollment of sedentary individuals. Our study chose a less restrictive exclusion criterion of 150 minutes per week in an effort to access a broader population and be consistent with recent evidence-based guidelines recommending 150 minutes per week of physical activity.51;52
Unfortunately, the higher cutoff resulted in more above-threshold individuals enrolled than anticipated. Though we instructed participants not to increase their activity between their initial screen and baseline assessment, many participants did so despite our efforts to use procedures similar to other studies' protocols.47-49
With more sedentary individuals, we might have detected a larger intervention effect.
Given the relatively active participants in this study, we were surprised how markedly participants increased their physical activity (133 minutes in the intervention group and 99 minutes in the control group). We considered whether participants were unwittingly prompted to change activity with questions from the baseline assessment or other unintentional physical activity prompts in study procedures. We attempted to embed physical activity questions in other general health questions to reduce their emphasis. However, it is possible that answering multiple surveys during the study period led to reactivity that enhanced physical activity. Participants, through informed consent and enrollment, were likely aware that the purpose of the study related to preventive health and was endorsed by their physician. It is possible that participants wanted to “please their doctor” during the study period by increasing their physical activity. Given the high percentage of participants with obesity and other chronic diseases amenable to physical activity who expressed motivation to change, participation in the study itself may have been motivating for both groups to change their activity. Clinical trial participants often increase their physical activity more than what would likely be observed in “real world” populations, especially for short-term studies (6 months or less).15;16;21
Previous studies have also shown control group participants typically increase their physical activity to some degree along with intervention groups.15;20 22;53;30;31
While our participants reported high rates of receiving and reading the computerized tailored reports, the frequency of discussing them with their physician was low overall, and lowest for the participants who were least active. The control group was significantly more likely to show and discuss them with their primary care provider than the intervention group. It is possible that the control group participants, having received information on specific preventive screening tests, found this information easier or more routine to bring up with their physician. Though these reports were not physical activity specific, perhaps the other preventive health information increased health promotion discussions that contributed to the change in the control group.
The present study, by design, had limited physician involvement and expectation to change their clinical counseling or provide study-specific activities. Minimizing clinician burden is advantageous to more feasibly recruit and retain a robust sample of physicians and their patients, given real-world constraints. Consequently, we were able to assess whether patients respond to direct targeting and whether direct targeting activates patients to discuss exercise with their physician. However, because of the low levels of discussion of the intervention materials with the physicians, our study cannot address the issue of whether physician counseling is effective. Other work54
examining tailored physician advice found no significant difference in patients' physical activity, perhaps because physicians did not uniformly distribute the written materials or discuss physical activity as intended by the study protocol. Similarly, our intervention may have been less effective due to less frequent discussion than intended with physicians.
Finally, since the intervention was developed and tailored based on the transtheoretical model, our null results raise the question of possible limitations of this model. Given the limitations of this study, we cannot be definitive on this point. However, the results do call into question the role of the transtheoretical model in this intervention.
Limitations and strengths
There are limitations of our study. First, our participants had higher baseline activity levels than anticipated and reported in previous studies; perhaps the intervention would have been more effective with a different (more sedentary) population. Since the intervention materials were geared towards sedentary patients, the intervention may not have been sufficiently matched to our participants' physical activity levels. Another important limitation is that cluster randomization was used, randomizing at the level of the physician; thus, some patient baseline characteristics were unbalanced in this sample. Randomization at the patient level would likely have resulted in more comparable distributions of patient demographics. We do not have the primary care provider's perspective on the degree to which the participants discussed their intervention materials with them. Therefore, clinician involvement may have been less robust than anticipated which also would have reduced the effect of the intervention.
Despite the limitations, there are several strengths of this study. First, it had a randomized controlled design and recruited patients from a relatively large (n=22) group of primary care practices. The study had a higher representation of African Americans than usually reported in this type of research. The high retention rate (89.6%) suggests that the intervention was well received. Despite not seeing differences between groups on physical activity, participants had large increases in physically activity within groups; we saw the largest increase in the most sedentary individuals at baseline which may be clinically significant and worthy of further study. This study also had a well-designed tracking mechanism to verify the dose received of intervention, and was designed to be more patient driven than clinician dependent.
Recommendations for research
Research on physical activity interventions in primary care should evaluate additional patient-clinician interventions for diverse groups and practice settings to discover effective strategies to target sedentary individuals. Research should also endeavor to develop optimal content of messages and/or channels (print-based, internet based) most likely to be effective, and engage clinicians to the fullest extent possible given their real-world constraints and competing demands.
A theoretically based, tailored computerized physical activity intervention targeting adult primary care patients was feasible to accomplish with a high retention rate. However, computerized tailored physical activity reports did not significantly increase physical activity levels among ethnically and socioeconomically diverse adults in primary care. Further research is needed to determine optimal intervention content, delivery channel, dose, and the role of clinician involvement in primary care.