Interventions for preventing weight gain after smoking cessation
Jamie Hartmann-Boyce, Annika Theodoulou, Amanda Farley, Peter Hajek, Deborah Lycett, Laura L Jones, Laura Kudlek, Laura Heath, Anisa Hajizadeh, Marika Schenkels, Paul Aveyard, Jamie Hartmann-Boyce, Annika Theodoulou, Amanda Farley, Peter Hajek, Deborah Lycett, Laura L Jones, Laura Kudlek, Laura Heath, Anisa Hajizadeh, Marika Schenkels, Paul Aveyard
Abstract
Background: Most people who stop smoking gain weight. This can discourage some people from making a quit attempt and risks offsetting some, but not all, of the health advantages of quitting. Interventions to prevent weight gain could improve health outcomes, but there is a concern that they may undermine quitting.
Objectives: To systematically review the effects of: (1) interventions targeting post-cessation weight gain on weight change and smoking cessation (referred to as 'Part 1') and (2) interventions designed to aid smoking cessation that plausibly affect post-cessation weight gain (referred to as 'Part 2').
Search methods: Part 1 - We searched the Cochrane Tobacco Addiction Group's Specialized Register and CENTRAL; latest search 16 October 2020. Part 2 - We searched included studies in the following 'parent' Cochrane reviews: nicotine replacement therapy (NRT), antidepressants, nicotine receptor partial agonists, e-cigarettes, and exercise interventions for smoking cessation published in Issue 10, 2020 of the Cochrane Library. We updated register searches for the review of nicotine receptor partial agonists.
Selection criteria: Part 1 - trials of interventions that targeted post-cessation weight gain and had measured weight at any follow-up point or smoking cessation, or both, six or more months after quit day. Part 2 - trials included in the selected parent Cochrane reviews reporting weight change at any time point.
Data collection and analysis: Screening and data extraction followed standard Cochrane methods. Change in weight was expressed as difference in weight change from baseline to follow-up between trial arms and was reported only in people abstinent from smoking. Abstinence from smoking was expressed as a risk ratio (RR). Where appropriate, we performed meta-analysis using the inverse variance method for weight, and Mantel-Haenszel method for smoking.
Main results: Part 1: We include 37 completed studies; 21 are new to this update. We judged five studies to be at low risk of bias, 17 to be at unclear risk and the remainder at high risk. An intermittent very low calorie diet (VLCD) comprising full meal replacement provided free of charge and accompanied by intensive dietitian support significantly reduced weight gain at end of treatment compared with education on how to avoid weight gain (mean difference (MD) -3.70 kg, 95% confidence interval (CI) -4.82 to -2.58; 1 study, 121 participants), but there was no evidence of benefit at 12 months (MD -1.30 kg, 95% CI -3.49 to 0.89; 1 study, 62 participants). The VLCD increased the chances of abstinence at 12 months (RR 1.73, 95% CI 1.10 to 2.73; 1 study, 287 participants). However, a second study found that no-one completed the VLCD intervention or achieved abstinence. Interventions aimed at increasing acceptance of weight gain reported mixed effects at end of treatment, 6 months and 12 months with confidence intervals including both increases and decreases in weight gain compared with no advice or health education. Due to high heterogeneity, we did not combine the data. These interventions increased quit rates at 6 months (RR 1.42, 95% CI 1.03 to 1.96; 4 studies, 619 participants; I2 = 21%), but there was no evidence at 12 months (RR 1.25, 95% CI 0.76 to 2.06; 2 studies, 496 participants; I2 = 26%). Some pharmacological interventions tested for limiting post-cessation weight gain (PCWG) reduced weight gain at the end of treatment (dexfenfluramine, phenylpropanolamine, naltrexone). The effects of ephedrine and caffeine combined, lorcaserin, and chromium were too imprecise to give useful estimates of treatment effects. There was very low-certainty evidence that personalized weight management support reduced weight gain at end of treatment (MD -1.11 kg, 95% CI -1.93 to -0.29; 3 studies, 121 participants; I2 = 0%), but no evidence in the longer-term 12 months (MD -0.44 kg, 95% CI -2.34 to 1.46; 4 studies, 530 participants; I2 = 41%). There was low to very low-certainty evidence that detailed weight management education without personalized assessment, planning and feedback did not reduce weight gain and may have reduced smoking cessation rates (12 months: MD -0.21 kg, 95% CI -2.28 to 1.86; 2 studies, 61 participants; I2 = 0%; RR for smoking cessation 0.66, 95% CI 0.48 to 0.90; 2 studies, 522 participants; I2 = 0%). Part 2: We include 83 completed studies, 27 of which are new to this update. There was low certainty that exercise interventions led to minimal or no weight reduction compared with standard care at end of treatment (MD -0.25 kg, 95% CI -0.78 to 0.29; 4 studies, 404 participants; I2 = 0%). However, weight was reduced at 12 months (MD -2.07 kg, 95% CI -3.78 to -0.36; 3 studies, 182 participants; I2 = 0%). Both bupropion and fluoxetine limited weight gain at end of treatment (bupropion MD -1.01 kg, 95% CI -1.35 to -0.67; 10 studies, 1098 participants; I2 = 3%); (fluoxetine MD -1.01 kg, 95% CI -1.49 to -0.53; 2 studies, 144 participants; I2 = 38%; low- and very low-certainty evidence, respectively). There was no evidence of benefit at 12 months for bupropion, but estimates were imprecise (bupropion MD -0.26 kg, 95% CI -1.31 to 0.78; 7 studies, 471 participants; I2 = 0%). No studies of fluoxetine provided data at 12 months. There was moderate-certainty that NRT reduced weight at end of treatment (MD -0.52 kg, 95% CI -0.99 to -0.05; 21 studies, 2784 participants; I2 = 81%) and moderate-certainty that the effect may be similar at 12 months (MD -0.37 kg, 95% CI -0.86 to 0.11; 17 studies, 1463 participants; I2 = 0%), although the estimates are too imprecise to assess long-term benefit. There was mixed evidence of the effect of varenicline on weight, with high-certainty evidence that weight change was very modestly lower at the end of treatment (MD -0.23 kg, 95% CI -0.53 to 0.06; 14 studies, 2566 participants; I2 = 32%); a low-certainty estimate gave an imprecise estimate of higher weight at 12 months (MD 1.05 kg, 95% CI -0.58 to 2.69; 3 studies, 237 participants; I2 = 0%).
Authors' conclusions: Overall, there is no intervention for which there is moderate certainty of a clinically useful effect on long-term weight gain. There is also no moderate- or high-certainty evidence that interventions designed to limit weight gain reduce the chances of people achieving abstinence from smoking.
Trial registration: ClinicalTrials.gov NCT02453659 NCT01867983 NCT01199185 NCT03528304 NCT00755716 NCT00921388 NCT01305447 NCT02906644 NCT02044874 NCT01401569 NCT01010204 NCT00666978 NCT00935818 NCT01370356 NCT00689611 NCT00794573 NCT01509547 NCT03553173 NCT00918307 NCT02859142 NCT01860924 NCT01303861 NCT01517022 NCT02521662 NCT00985985 NCT01694732 NCT03156660 NCT00943618 NCT02417467 NCT02162849 NCT03722966 NCT04088942.
Conflict of interest statement
JHB: co‐applicant on an award from the Cochrane Review Support Programme. JHB also writes and publishes frequently on the evidence for smoking cessation interventions, and to a lesser extent about evidence on weight management. None of these represent a conflict with what is covered in this review.
AT: None
AF: co‐applicant on a researcher‐led grant from Ethicon (Johnson and Johnson).
PH: research grants, last held in 2015 from Pfizer (funds were received by the institution); Recieved payment for assessing grant applications (GRAND initiative) and attending global advisory board meeting (last attended in 2017); provides invited commentaries, usually concerning an article on e‐cigarettes for journals (The Lancet, Tobacco Control, Lancet Respiratory and Addiction); was involved in the conduct of a study that was eligible for inclusion in this work which was funded by NIHR.
DL: published a press release following publication of a research report; was involved in the conduct studies that were eligible for inclusion in this work: The DeMist Trial: UKCTCS, VLCD provided by Lipotrim (2010) and The SWISSS Trial: NIHR‐SPCR, Slimming Word vouchers for intervention provide by Slimming World (2013)
LLJ: None
LK: None
LH: None
AH: None
MS: None
PA: was involved in the conduct of a study that was eligible for inclusion in this work funded by the School for Primary Care Research.
PA and AF (nee Parsons) are also authors of a study included in this review testing the effect of St John's wort and chromium supplements on smoking cessation and post‐cessation weight gain. The trial was funded by Cancer Research UK and the supplements were bought from the manufacturer. Paul Aveyard has done consultancy work for pharmaceutical and biotechnology companies that has led to payments to him and his institution. This includes work for companies providing smoking cessation medication, including McNeil, Xenova and Pfizer.
Copyright © 2021 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
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Source: PubMed