Summary of evidence table for biomarker feedback intervention studies to assist pregnant smokers achieve abstinence
| Population: | Pregnant smokers | |||||
| Setting: | Any setting* | |||||
| Intervention: | Biomarker feedback† | |||||
| Comparison: | Usual care or control‡ | |||||
| Outcome | Anticipated absolute effects (95% CI) | Relative effect (95% CI)§ | No. of participants (studies) | Certainty of evidence (Grading of Recommendations Assessment, Development and Evaluation) | Comments | |
| Effect with usual care or control group | Effect with intervention | |||||
| Biomarker feedback interventions | ||||||
| Biomarker feedback interventions on point prevalence abstinence¶ in late pregnancy | 372 per 1000 | 443 per 1000 | 1.32 (0.75–2.32) | 1878 (4) | ⊕⊕○○** Low | Heterogeneity is moderate to high (ie, 64% p=0.04) |
| Biomarker feedback interventions on point prevalence abstinence at postpartum (1–3 months, 4–6 months and 7–18 months and unspecified) | Not estimatable | No outcome measured to include in meta-analysis | ||||
| Biomarker feedback interventions on continuous abstinence†† in late pregnancy | Not estimatable | No outcome measured to include in meta-analysis | ||||
| Biomarker feedback interventions on continuous abstinence at postpartum (1–3 months, 4–6 months and 7–18 months and unspecified) | 376 per 1000 | 405 per 1000 | 1.05 (0.84–1.30) | 1120 (1) | See comment | Only one study (with two different measurements) could be included for this outcome |
*All included studies were conducted in high income countries (USA, UK and Ireland) in English speaking populations, where recruitment took place through antenatal or maternity clinics and/or hospitals. Included studies may have involved pregnant smokers of various socioeconomic positions.
†Biomarker feedback interventions included two studies measuring urine cotinine or metabolite (Cope et al 2003).9 Patten et al96 and two studies measuring breath carbon monoxide (Hajek et al and Thornton77 99). These measures were used in addition to smoking cessation information material, counselling, self-help or support to help motivate pregnant smoker quit as part of the intervention.
‡Usual care often included brief counselling including the brief use of the 5As (ie, ask, advice, assess, assist and arrange) approach, provision of printed information or simply brief advice.
§Relative effect was calculated as relative risk where risk is treated as effect rather than risk and CI for this calculated relative effect.
¶Point prevalence abstinence was either defined as point prevalence abstinence of various time periods or was abstinence at a point in time that was biochemically validated but was not specifically defined. This type of abstinence did not include continuous abstinence which is understood as abstinence for a period of time rather than a point in time.
**Low certainty in evidence due to high risk of bias in two of the four studies, inconsistency due to moderate to high heterogeneity and limited overlap in CI and imprecision caused by wide CI and CI crossing value of 1. Certainty of evidence was upgraded due to risk of bias not being serious enough.
††Continuous abstinence was defined as abstinence for a period of time rather than at a time point. This definition included both undefined and defined time periods.