Table 2 Meta-analysis and subgroup analysis of the effects of lifestyle interventions for SMI on quality of life, severity of depression and severity of anxiety compared to the control condition

Post-intervention effect sizes

N

Hedges' g

95% CI

I²

p

Quality of life

 Outcomes combined

19

0.13

(−0.02 to 0.27)

68.7*

0.09

 Outcomes combined, outliers removed

17

0.03

(−0.08 to 0.14)

46.0*

0.56

 Outcomes with lowest effect size

19

0.10

(−0.05 to 0.24)

67.4*

0.19

 Outcomes lowest, outliers removed

17

0.00

(−0.1 to 0.1)

39.6

0.99

 Outcomes with highest effect size

19

0.18

(0.02 to 0.33)

73.0*

0.03**

 Outcomes highest, outliers removed

17

0.09

(−0.04 to 0.22)

59.8*

0.18

Severity of depression

9

0.292

(0.00 to 0.58)

65.2*

0.047**

Severity of anxiety

4

0.559

(0.16 to 0.95)

0

0.006**

Subgroup analyses for QoL

N

Hedges' g

95% CI

I²

p

 Duration of intervention

  1-3 months

6

0.20

(−0.07 to 0.47)

73.4*

0.05

  4-8 months

6

0.37

(0.09 to 0.66)

65.9*

  12 months

7

−0.05

(− 0.25 to 0.15)

49.2

 Region

  Europe

10

0.12

(−0.08 to 0.33)

80.9*

0.94

  North America

3

0.07

(−0.34 to 0.49)

0

  Asia/ Pacific

4

0.23

(−0.12 to 0.58)

24.1

  South America

2

0.10

(−0.43 to 0.62)

20.1

 Type of intervention

  Group-based

10

0.30

(−0.07 to 0.53)

73.7*

0.08

  Combination

6

−0.07

(−0.29 to 0.16)

37.8

  Individual-based

3

0.18

(−0.16 to 0.51)

40.7

 Attendance to sessions

  High

8

0.46

(0.19 to 0.72)

75.0*

0.01**

  Low

8

−0.02

(−0.21 to 0.17)

0

  Unknown

3

0.02

(−0.30 to 0.33)

79.1*

 Risk of bias

  Lower risk of bias

6

−0.06

(− 0.25 to 0.12)

31.9

0.01**

  Higher risk of bias

13

0.27

(0.09 to 0.45)

65.7*

Explorative analysis (intervention modalities)

N

Hedges’ g

95% CI

I²

 Mainly structured high intensity PA

5

0.92

(0.31 to 1.53)

65.2*

 Including skill training for healthy diet (i.e. buying groceries, cooking or meal preparation)

4

−0.11

(−0.27 to 0.05)

44.2

 Mainly behavioural therapy components (Motivational interviewing, CBT)

6

0.01

(−0.09 to 0.12)

0