Depression, prescription of antidepressant drugs and changes in body weight: A cohort study using electronic health records

Date of ISAC Approval: 
Lay Summary: 
Studies have shown that using antidepressant medications can be associated with changes in body weight. At present, we only know that antidepressant use can change weight in the short term, with most studies looking at the first three months, and little evidence beyond one year. This study will investigate changes in body weight in patients over longer time periods, and look for differences in those who are given antidepressants for a short time compared to those who use them over longer periods. We will also investigate whether patients' whose weight changes after using antidepressants goes back to normal when they stop using them. There has been a huge rise in the use of antidepressants in recent years, and doctors should be aware of the possible side-effects of these drugs on patients' weight. This is particularly important because people with depression are more likely to become obese, and obese people are more likely to become depressed. Both obesity and depression are common conditions that place a great burden on the health system. This research will give us a better understanding of how patients' weight can change when they become depressed and receive treatment for their depression.
Technical Summary: 
Current research evidence on weight change alongside the use of antidepressants is limited by small sample sizes and short term reporting. Existing evidence suggests that antidepressant drugs can be associated with changes in body weight. The association between antidepressant use and weight change is complicated by the bidirectional relationship between depression and obesity. The present study will use the electronic health records of adults with at least three weight measurements to assess both short- and long-term body weight changes in patients who have been prescribed antidepressant drugs acutely and long-term. We will also investigate body weight changes after cessation of antidepressant use. Patients will be divided by their depression status using diagnostic medical codes and prescriptions of antidepressant drugs. In the face of a great need for care relating to both depression and obesity the results of this study will provide valuable information for health service planning and providers.
Health Outcomes to be Measured: 
Body weight BMI values

Professor Martin Gulliford - Chief Investigator - Kings College London
Ms Helen Booth - Collaborator - CPRD
Judith Charlton - Collaborator - Kings College London
Professor Martin Gulliford - Corresponding Applicant - Kings College London

Patient IMD;Practice IMD (Standard)