The investigators will include gender, age in years at time of first prescription, previous psychiatric illness/consultation, previous use of psychotropic medications such as hypnotics, antipsychotics and antidepressants, previous self-harm, measures of alcohol consumption where appropriate mean/median number of GP visits per year, body mass index, socioeconomic position (deprivation score for area or residence) and major chronic illness (including diabetes, cancer, arthritis) using the Charlson index. Relevant Read codes will be identified either by validated code lists or by searching for each of these events in the Read code dictionaries to identify any missing Read codes. Collider bias could occur if the investigators conditioned on events which happened as a result of the prescription the patient was issued. To prevent this bias from affecting the results, the investigators will define each covariate using data inputted prior to the first prescription.