Investigation of the relationship between antidepressant medication use and weight change in australian adults
Creators: name: Paige, Ellie
Publisher: name: The Australian National University
Year: 2015

description: Background: Weight gain is a commonly reported side-effect of antidepressant use but empirical evidence for this relationship is limited. Results from randomised clinical trials suggest that some antidepressants are associated with weight gain, but the magnitude of weight gain differs by the type of antidepressant used and duration of use. While most antidepressants are prescribed for ongoing use, clinical trials typically assess only short-term antidepressant use. Population-based studies are useful for examining the relationship between long-term antidepressant use and weight change in 'real-world' populations, where prescribing patterns are complex and co-morbidities are common. To date, only three population-based studies have examined the antidepressant-weight change relationship, finding that people using antidepressants gain slightly more weight than non-users ({u0303}0.1-0.3 kg/year). The aim of this thesis was to investigate the relationship between antidepressant use and weight change within an Australian population-based sample, and whether this relationship varies by antidepressant class, recency of use, duration of use or dose. Methods: The study population consisted of participants from the 45 and Up Study - a population-based cohort study of 267 153 men and women aged 45 years or older from New South Wales, Australia. Data from the baseline and follow-up questionnaires were linked to medication dispensing data from the Pharmaceutical Benefits Scheme. Weight change was calculated based on self-reported weight at baseline and follow-up, and was modelled as a continuous and categorical (loss, maintenance, gain) variable. Antidepressant use (current, past-only, non-persistent and non-use) from 19 months before baseline until follow-up was ascertained from Pharmaceutical Benefits Scheme data. Linear and multinomial logistic regression models were used to estimate the association between antidepressant medication use and weight change. Results: The final study population included 20 751 participants of whom 23% (n=4748) had been dispensed antidepressants during the study period. Current antidepressant users were 19% more likely to gain &gt;3% body weight on average per year than non-users (adjusted relative risk ratio=1.19 (95% CI: 1.03-1.38)), and the risk of weight gain increased with increasing dose. This increased risk of weight gain among current users translates into average annual gains of more than 2.6 and 2.1 kg for the average Australian man and woman, respectively. The risk of weight gain among current users did not significantly differ by class, recency or duration of use; however, compared to non-users, the risk of weight gain was higher in those using SSRIs and those using more recently or for longer periods of time. Conclusion: There is some evidence that antidepressant use, particularly current use, is associated with weight gain, and this risk of weight gain is higher in people dispensed higher doses. While there was no strong evidence that the risk of weight gain varied by recency or duration of use, the observed patterns were consistent with those that would be expected of a causal relationship. These findings provide important quantitative information on the risks of weight gain in antidepressant users and should be used to inform the doctor-patient discussion on the risks and benefits of antidepressants.