A Cochrane review [Abstract] 2 included 83 studies with 29 563 smokers. Studies were pooled to compare more versus less support. When all studies of additional behavioural therapy were pooled, there was a statistically significant benefit from additional support (RR 1.15, 95% CI 1.08 to 1.22; 65 trials, n=23 331, I²=8%) for abstinence at longest follow-up, and this effect was not different when we compared subgroups by type of pharmacotherapy or intensity of contact. Increasing the amount of behavioural support increased the chance of success by about 10% to 20%. This effect was similar in the subgroup of 8 studies in which the control group received no behavioural support (RR 1.20, 95% CI 1.02 to 1.43; n=4018, I²=20%).
A systematic review 5 included 54 RCTs. The MI interventions were delivered alone or in combination with other interventions, and varied in mode of delivery (e.g. face-to-face, phone), exposure level (duration, number of sessions), and provider characteristics (profession, training). Medication adherence showed significant improvement in 23 RCTs, and other clinical outcomes were improved in 19 RCTs (e.g. risky behaviors, disease symptoms).
A systematic review and meta-analysis 3 investigated whether integrated motivational interviewing and cognitive behaviour therapy leads to changes in lifestyle mediators of overweight and obesity in community-dwelling adults. 10 RCTs involving 1949 participants were included. Integrated motivational interviewing and cognitive behaviour therapy had a significant effect in increasing physical activity levels in community-dwelling adults (SMD 0.18, 95% CI 0.06 to 0.31, p < 0.05). The combined intervention resulted in a small, non-significant effect in body composition changes (SMD -0.12, 95% CI -0.24 to 0.01, p=0.07).
Another meta-analysis 4 assessing motivational interviewing for increased physical activity, cardiorespiratory fitness or functional exercise capacity in people with chronic health conditions included 10 RCTs. There was a small effect in increasing physical activity levels relative to comparison groups (standardized mean differences 0.19, 95% CI 0.06 to 0.32, p=0.004). Sensitivity analysis based on trials that confirmed treatment fidelity produced a larger effect. No conclusive evidence was observed for cardiorespiratory fitness or functional exercise capacity.
A systematic review and meta-analysis 6 assessing behavioural interventions including motivational interviewing on physical activity outcomes in adults included 97 randomised controlled trials totallingwith a total of 27 811 participants. Interventions including MI were superior to comparators for increases in total physical activity (SMD 0.45, 95% CI 0.33 to 0.65, equivalent to 1323 extra steps/day; low certainty evidence) and moderate to vigorous physical activity (0.45, 0.19 to 0.71, equivalent to 95 extra min/week; very low certainty evidence) and for reductions in sedentary time (-0.58, -1.03 to -0.14, equivalent to -51 min/day; very low certainty evidence). The magnitude of effect diminished over time. Most interventions involved patients with a specific health condition.
Yet another systematic review and meta-analysis 7 included 30 RCTs with a total of 4214 participants with type 2 diabetes. The transtheoretical model-based MI intervention significantly reduced HbA1c (MD -0.92, 95% CI -1.08 to -0.75, p < 0.001, I²=65%), fasting plasma glucose (SMD -1.06, 95% CI -1.38 to -0.73, p < 0.001, I²=93%), and 2hPGplasma glucose (MD -1.42 mmol/L, 95% CI -1.83 to -1.00, p < 0.001, I²=89%), with high, moderate, and low certainty of evidence, respectively. The intervention also improved self-management (and self-efficacy. Meta-analysis revealed that MI treatment dose and initial glycemic status contributed to the high heterogeneity.
Comment: The quality of evidence is downgraded by study limitations and heterogeneity.
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