Our study cohort included 146 095 patients with a first prescription for an antidepressant for depression. These patients contributed 62 224 person years of follow up to the cohort (see bmj.com
). lists the characteristics of the participants, classified according to the first antidepressant prescribed. Almost twice as many women as men received antidepressants. SSRIs were the most commonly prescribed antidepressants. People prescribed SSRIs tended to be younger and more often had a history of self harm and referral to psychiatrists than those prescribed tricyclic antidepressants.
Characteristics of study cohort according to first antidepressant class prescribed. Values are numbers (percentages) unless otherwise indicated
shows data on exposures to antidepressants by age group. The strongest predictors of non-fatal self harm were a history of self harm, referral to a psychiatrist, alcohol misuse, and drug misuse. The strongest predictors for suicide were a history of non-fatal self harm, antipsychotic therapy, number of antidepressants prescribed in the previous year, alcohol misuse, and referral to a psychiatrist ().
Age and sex distribution of cases of non-fatal self harm and suicide and their matched controls
Odds ratios for the association of potential confounders with non-fatal self harm and completed suicides
Over the study period, 1968 people had a recorded an episode of non-fatal self harm: 1344 were exposed to antidepressant medication at the time, and 624 had stopped treatment before the episode. Drug overdose accounted for most episodes of non-fatal self harm (81%). The incidence rate of non-fatal self harm, standardised by age and sex, per 100 000 person years of follow up among people prescribed antidepressants was 2894 (95% confidence interval 2618 to 3170). The rate per 100 000 person years for men was 2834 (2579 to 3089) and for women was 2952 (2471 to 3432).
Overall, 69 suicides took place (56 men, 13 women); 36 of those people were taking antidepressants at the time of death. The overall standardised incidence rate for suicide was 62 (40 to 85) per 100 000 person years; in men this was 117 (72 to 163) and in women 9 (1 to 18).
shows the association of current antidepressant use with non-fatal self harm and suicide for all ages. The adjusted odds ratio for non-fatal self harm among SSRI users compared with users of tricyclic antidepressants was 0.99 (0.86 to 1.14). We found no evidence that the risk of non-fatal self harm varied among the different individual SSRIs or tricyclic antidepressants (P = 0.35 and P = 0.69, respectively) and no evidence of an increased risk of suicide associated with use of SSRIs compared with tricyclic antidepressants (odds ratio 0.57, 0.26 to 1.25).
Table 4 Risk of non-fatal self harm and completed suicide in people prescribed SSRIs, other antidepressants, or exposed to more than one antidepressant compared with people prescribed tricylic antidepressants and among specific SSRIs compared with paroxetine (more ...)
We found borderline evidence that the risk of non-fatal self harm (P for interaction = 0.05), but not suicide (P for interaction = 0.73), differed between the different antidepressant categories in relation to time since starting therapy (). This association showed no clear pattern.
Risk of non-fatal self harm and suicide in relation to time since starting tricyclic antidepressant monotherapy or SSRI monotherapy (all ages)*
We found evidence of a difference in risk of non-fatal self harm for current SSRI users compared with current users of tricyclic antidepressants in relation to age (P for interaction = 0.02), with an increased risk associated with SSRI use among those aged 18 or younger (odds ratio 1.59, 1.01 to 2.50), but not in 19 to 30 year olds (1.04, 0.82 to 1.31) or those younger than 30 (0.86, 0.71 to 1.04; ).
Risk of non-fatal self harm in people prescribed SSRIs compared with tricyclic antidepressants in relation to age
In people aged 18 or younger, we found no evidence of any difference in risk of non-fatal self harm between individual tricyclic antidepressants, but among SSRIs (), the greatest risk was in relation to paroxetine use.
Risk of non-fatal self harm in patients aged 10-18 currently exposed to citalopram, fluoxetine, fluvoxamine, and sertraline compared with paroxetine
The risk of non-fatal self harm or suicide did not seem to differ between or within antidepressant classes according to the time since stopping treatment (see bmj.com