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Research

Antidepressant utilisation and incidence of weight gain during 10 years’ follow-up: population based cohort study

BMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k1951 (Published 23 May 2018) Cite this as: BMJ 2018;361:k1951

Linked Editorial

Antidepressant induced weight gain

Linked Opinion

Antidepressant therapy and risk of weight gain
  1. Rafael Gafoor, research associate1,
  2. Helen P Booth, senior researcher1 2,
  3. Martin C Gulliford, professor of public health1 3
  1. 1School of Population Health and Environmental Sciences, King’s College London, London SE1 1UL, UK
  2. 2Clinical Practice Research Datalink, Medicines and Healthcare products Regulatory Agency, London, UK
  3. 3NIHR Biomedical Research Centre at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, Guy’s Hospital, London, UK
  1. Correspondence to: R Gafoor Rafael.gafoor{at}kcl.ac.uk
  • Accepted 13 April 2018

Abstract

Objective To evaluate the long term association between antidepressant prescribing and body weight.

Design Population based cohort study.

Setting General practices contributing to the UK Clinical Practice Research Datalink, 2004-14.

Participants 136 762 men and 157 957 women with three or more records for body mass index (BMI).

Main outcome measures The main outcomes were antidepressant prescribing, incidence of ≥5% increase in body weight, and transition to overweight or obesity. Adjusted rate ratios were estimated from a Poisson model adjusting for age, sex, depression recording, comorbidity, coprescribing of antiepileptics or antipsychotics, deprivation, smoking, and advice on diet.

Results In the year of study entry, 17 803 (13.0%) men and 35 307 (22.4%) women with a mean age of 51.5 years (SD 16.6 years) were prescribed antidepressants. During 1 836 452 person years of follow-up, the incidence of new episodes of ≥5 weight gain in participants not prescribed antidepressants was 8.1 per 100 person years and in participants prescribed antidepressants was 11.2 per 100 person years (adjusted rate ratio 1.21, 95% confidence interval 1.19 to 1.22, P<0.001). The risk of weight gain remained increased during at least six years of follow-up. In the second year of treatment the number of participants treated with antidepressants for one year for one additional episode of ≥5% weight gain was 27 (95% confidence interval 25 to 29). In people who were initially of normal weight, the adjusted rate ratio for transition to overweight or obesity was 1.29 (1.25 to 1.34); in people who were initially overweight, the adjusted rate ratio for transition to obesity was 1.29 (1.25 to 1.33). Associations may not be causal, and residual confounding might contribute to overestimation of associations.

Conclusion Widespread utilisation of antidepressants may be contributing to long term increased risk of weight gain at population level. The potential for weight gain should be considered when antidepressant treatment is indicated.

Footnotes

  • Contributors: HPB and MCG wrote the protocol for the study. HPB did the initial data analysis. RG completed the analysis and drafted the paper. MCG checked and replicated the analysis. All authors contributed to and approved the final draft of the paper. MCG is the guarantor.

  • Funding: MCG was supported by the NIHR Biomedical Research Centre at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London. The funders were not involved in the design, conduct, or reporting of this study.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf. HPB is now employed by CPRD; there are no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the Independent Scientific Advisory Committee (reference No 15-243), consistent with the broad research ethics approval for observational research using CPRD data. All data were fully anonymised, and no participant consent was required.

  • Data sharing: Data were analysed under licence from CPRD and are not available for sharing.

  • Transparency: The lead author (MCG) affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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