Serotonin-norepinephrine reuptake inhibitor antidepressants and the risk of falls in older people: Case-control and case-series analysis of a large UK primary care database

Background: Antidepressant medications have long been implicated as a cause of falls in older people, but there are few data on the risk of falls associated with exposure to serotonin-norepinephrine (noradrenaline) reuptake inhibitors (SNRIs). Objective: The aim of this study was to determine the role of SNRIs in older people with a recorded fall in primary care using a case-control approach and a self-controlled case-series analysis of data from The Health Improvement Network (THIN) UK primary care database. Methods: Cases were 9862 individuals aged >60 years with a first fall recorded between 2003 and 2006. Up to six controls per case were matched by age, sex and primary care practice. For the case-series analysis, we extended our case set to those with a first fall recorded between 2001 and 2008. We estimated odds ratios (ORs) for 'ever', 'current', 'recent', 'previous' or 'never' prescribed SNRIs (and for the other main classes of antidepressants, for comparison) in cases compared with matched controls, using conditional logistic regression.We also examined the effect of the time interval from first prescription to first fall. In the case-series analysis, we compared the rate of occurrence of first falls during episodes of exposure to SNRIs with unexposed periods in our case group. Results: There was an increased risk of current prescribing of SNRIs (adjusted OR 1.79; 95% CI 1.42, 2.25) in first fall cases compared with controls. This was similar in magnitude to that seen with tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). The increase in risk was apparent within the first 28 days after first prescription. The effects were also apparent in the self-controlled case-series analysis, although the magnitudes of effect were slightly smaller; the incidence risk ratio for the period 128 days after initiation of treatment compared with unexposed periods was 1.49 (95% CI 1.15, 1.93). Conclusions: Treatment with SNRIs in older people may be associated with an increased risk of falling. The falls risk profile of SNRIs appears to be similar to that of SSRIs and TCAs.