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Study flow diagram
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Figure 1

Study flow diagram

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
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Figure 2

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Comparison 1 Primary outcome (adherence), Outcome 1 Adherence ‐ Dichotomous outcomes.
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Analysis 1.1

Comparison 1 Primary outcome (adherence), Outcome 1 Adherence ‐ Dichotomous outcomes.

Comparison 1 Primary outcome (adherence), Outcome 2 Adherence ‐ Continuous outcomes.
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Analysis 1.2

Comparison 1 Primary outcome (adherence), Outcome 2 Adherence ‐ Continuous outcomes.

Comparison 2 Secondary outcomes, Outcome 1 Short‐term abstinence < 6 months.
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Analysis 2.1

Comparison 2 Secondary outcomes, Outcome 1 Short‐term abstinence < 6 months.

Comparison 2 Secondary outcomes, Outcome 2 Long‐term abstinence ≥ 6 months.
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Analysis 2.2

Comparison 2 Secondary outcomes, Outcome 2 Long‐term abstinence ≥ 6 months.

Summary of findings for the main comparison. Interventions to increase adherence compared to standard care for improving adherence to medications for tobacco dependence and abstinence from smoking

Interventions to increase adherence compared to standard care for improving adherence to medications for tobacco dependence and abstinence from smoking

Patient or population: Adult smokers
Settings: Typically in‐person clinical settings
Intervention: Interventions to increase adherence through providing information and facilitating problem‐solving
Comparison: Standard care

Outcomes

Relative effect (95% CI)

Illustrative comparative risks (95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Assumed risk

Corresponding risk

Standard care

Interventions to increase adherence

Adherence to medications for tobacco dependence (dichotomous outcomes)

RR 1.14
(1.02 to 1.28)

Study population

1630
(5 RCTs)

⊕⊕⊕⊝
MODERATE 1

368 per 1000 achieve a specified satisfactory level of adherence

419 per 1000 (375 to 471) achieve a specified satisfactory level of adherence

Adherence to medications for tobacco dependence (continuous outcomes)

SMD 0.07

(‐0.03 to 0.17)

The mean level of adherence is 0

The mean level of adherence is 0.07 standard deviations higher (0.03 lower to 0.17 higher)

1529
(4 RCTs)

⊕⊕⊝⊝
LOW 1,2

Short‐term abstinence from smoking (<6 months)

RR 1.07
(0.95 to 1.21)

Study population

1755
(4 RCTs)

⊕⊕⊝⊝
LOW 1,3

363 per 1000 achieve abstinence

389 per 1000 (345 to 439) achieve abstinence

Long‐term abstinence from smoking (≥6 months)

RR 1.16
(1.01 to 1.34)

Study population

3049
(4 RCTs)

⊕⊕⊝⊝
LOW 1,4

171 per 1000 achieve abstinence

198 per 1000 (173 to 229) achieve abstinence

The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1All studies are judged to be at high or unclear risk of bias which lowers confidence in estimate of effect

2Includes sufficient sample size for single adequately powered trial but 95% CI overlaps no effect and ranges from very small harm to small benefit

3Includes sufficient sample size for single adequately powered trial but 95% CI overlaps no effect and ranges from small harm to substantial benefit

4Substantial heterogeneity with inconsistency in point estimates and limited overlap of confidence intervals

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Summary of findings for the main comparison. Interventions to increase adherence compared to standard care for improving adherence to medications for tobacco dependence and abstinence from smoking
Table 1. Brief descriptions of adherence interventions

Study

Brief description of specific intervention components intended to increase adherence*

Additional contact time relative to standard care?

Medication for which adherence was targeted

Chan

2010

Added counselling contact time to standard behavioural support, focusing specifically on medication adherence

Yes

NRT

Chan

2011

Added counselling contact time to standard behavioural support, focusing specifically on medication adherence

Yes

NRT

Marteau

2012

Tailored and communicated about NRT dosage using a more potent rationale (genotype versus phenotype)

No

NRT

Mooney

2005

Personalised feedback of questionnaire responses regarding medication

No

NRT

Mooney

2007

Personalised feedback of externally validated medication adherence

Yes

Bupropion

Nollen

2011

Added counselling contact time to standard behavioural support, focusing specifically on medication adherence

Yes

Varenicline

Schmitz

2005

Personalised feedback of externally validated medication adherence

Yes

Bupropion

Smith

2013

Added counselling contact time to standard behavioural support, focusing specifically on medication adherence

Yes

NRT

* For further details see Characteristics of Included Studies

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Table 1. Brief descriptions of adherence interventions
Comparison 1. Primary outcome (adherence)

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Adherence ‐ Dichotomous outcomes Show forest plot

5

1630

Risk Ratio (M‐H, Fixed, 95% CI)

1.14 [1.02, 1.28]

2 Adherence ‐ Continuous outcomes Show forest plot

4

1529

Std. Mean Difference (IV, Fixed, 95% CI)

0.07 [‐0.03, 0.17]

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Comparison 1. Primary outcome (adherence)
Comparison 2. Secondary outcomes

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Short‐term abstinence < 6 months Show forest plot

4

1755

Risk Ratio (M‐H, Fixed, 95% CI)

1.07 [0.95, 1.21]

2 Long‐term abstinence ≥ 6 months Show forest plot

4

3049

Risk Ratio (M‐H, Fixed, 95% CI)

1.16 [1.01, 1.34]

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Comparison 2. Secondary outcomes