Looking at a Systematic Review, Part 1: How Much Peer Support?
A recent systematic review by Dale and colleagues examined the effect of peer support on diabetes outcomes with adults. The authors concluded that “Peer support appears to benefit some adults living with diabetes, but the evidence is too limited and inconsistent to support firm recommendations.” These conclusions were drawn from 25 studies that met inclusion criteria, including 14 RCTs. Of particular interest was the conclusion that peer support was associated with statistically significant improvements in glycaemic control in three out of 13 trials that measured HBA1C (It is noted that 1 of these 3 studies was a publication by Peers for Progress Grantee Michelle Heisler).
This blog is the first in a series that will examine these 13 studies and identify some factors that may have led to the low number of statistically significant reductions in HBA1C. This first blog will examine the dosage of “peer support” delivered in some of the RCTs while a future blog will discuss whether what was actually delivered was peer support.
The amount of peer support in one of these studies (Smith et al, 2011) was previously addressed by Peers for Progress in a 2011 rejoinder by Fisher and Boothroyd, posted on the website of the British Medical Journal. This review noted:
“Average attendance was only five of the nine meetings schedule over two years. Eighteen percent attended none. If an intervention was intended to provide peer support but was only modestly attended, one might question whether peer support has been provided sufficiently to be tested.”
With such low exposure to the intervention, it is difficult to confirm the role of peer support on HBA1C. What about the other RCT’s with no statistically significant improvement in glycaemic control analyzed by Dale and colleagues? How much peer support was delivered in them? The following table summarizes the dose of/exposure to peer support of each of these 10.
In general, participation in these interventions was modest. Exceptions include the paper of Glasgow et al., 2003 and Baksi et al., 2008. In both of these, low baseline HbA1c values (7.5% and 7.4% respectively) militated against finding significant benefits of peer support on this variable. Additionally, the paper of Baksi et al. compared group classes led by peers with those led by diabetes nurse specialists, a highly conservative control condition.
In contrast, the following table presents the attendance/delivery/dose/exposure data for the three RCTs in which Dale et al. identified peer support as having a “statistically significant beneficial impact.”
Our next blog in this series will focus on what was actually delivered in these studies and how much it agreed with the Peers for Progress definition of peer support.
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Baksi AK, Al-Mrayat M, Hogan D, Whittingstall E, Wilson P, Wex J. Peer advisers compared with specialist health professionals in delivering a training programme on self-management to people with diabetes: a randomized controlled trial. Diabet Med 2008; 25: 1076–1082.
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Dale, J. R., Williams, S. M., & Bowyer, V. (2012). What is the effect of peer support on diabetes outcomes in adults? A systematic review. Diabetic Medicine : A Journal of the British Diabetic Association, doi:10.1111/j.1464-5491.2012.03749.x; 10.1111/j.1464-5491.2012.03749.x
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Smith SM, Paul G, Kelly A, Whitford DL, O’Shea E, O’Dowd T. Peer support for patients with type 2 diabetes: cluster randomised controlled trial. Br Med J 2011; 342: 715.
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