Stefan Elbers

96 Chapter 4 Self-Efficacy. Ten studies reported post-intervention comparisons for self-efficacy. However, due to the statistical heterogeneity ( I 2 = 65%, χ 2 (7965) = 17.39, p = 0.02), an overall effect was not calculated. Four comparisons showed statistically significant differences, favouring the experimental group (Lefort et al., 1998; Asenlof et al., 2005; Ersek et al., 2008; Nicholas et al., 2013) with SMD ranging from −0.74 to −0.32. Furthermore, Taal et al. (1993) reported an effect favouring the self-management intervention, with a change score of the experimental group (0.17) that significantly differed from the change score of the control group (−0.13), p < 0.05. Burckhardt et al. (1994) also found a statistically significant difference between both groups, with the self-management group reporting higher scores on the function subscale of the self-efficacy scale (620.7), than the control group (467.5). Four comparisons did not show an effect, (King et al., 2002; Stuifbergen et al., 2010; Manning et al., 2014; Knittle et al., 2015). The unpooled comparisons, indicating a trend favouring self-management, are shown in Figure 3. Figure 3. Post Treatment Comparison of Self-Management Intervention Versus Control on Self-Efficacy. Pain Intensity. Eight studies reported comparisons for pain intensity. Although the four studies that reported endpoint data showed substantial overlap of their confidence intervals, the I 2 was 55%. As a sensitivity analysis showed that the heterogeneity was contributable to only one study, a meta-analysis was performed. The results indicate a statistically significant difference favouring the self-management group, SMD = −0.28 [−0.56, −0.01], z = 2.03, p = 0.04 (see Figure 4). We re-calculated this effect on an 11-point NRS scale (0–10), using the baseline standard deviation of the control group in Nicholas et al. (2013). This effect corresponds to a 0.48 difference in pain intensity, measured on a 0–10 NRS, which is lower than the minimal clinically important difference (MCID) of 2.0 (Salaffi et al., 2004). Manning et al. (2014) reported a similar result: SMD = −0.44 [−0.86, −0.02], z = 2.05, p = 0.04. Burckhardt et al. (1994), Dworkin et al. (2002) and Taal et al. (1993) reported no statistically significant post-intervention differences for pain intensity between the self-management and control groups.