Citalopram and the Risk of Serious Adverse Events

Inclusion Criteria: * Older adult aged 66 years or greater with low kidney function (an eGFR \<45 mL/min per 1.73 m2 ) who have filled a new oral prescription for Citalopram at an outpatient pharmacy under the Ontario Drug Benefit (ODB) program with a dose of 10 or 20 mg/day and a day supply of ≥7 days from January 1, 2008, to January 1, 2025 for Ontario (if needed, dates in Alberta to be finalized based on data availability). The investigators will exclude individuals undergoing dialysis or those who have received a kidney transplant. The age criterion is set to guarantee that individuals in this population had at least one year of prior universal outpatient prescription drug coverage. The date when the prescription was filled will serve as the patient's entry or index date for the cohort, with each patient entering the cohort only once. Exclusion Criteria: 1. Individuals with missing administrative database number, missing or invalid age (\<0 or \>105 years), missing or invalid sex, death on or before the index date, non-Ontario resident (for Ontario data). 2. Individuals less than 66 years of age on the index date. 3. Those with evidence of any study drug prescription 180 days before the index date (to restrict to new users only). 4. Individuals with other Selective Serotonin Reuptake Inhibitors (Escitalopram, Fluoxetine, Fluvoxamine, Paroxetine, Sertraline) prescription in the previous 180 days before the index date or on the index date. 5. Individuals with more than one study drug prescription on the index date, as this complicates the ability to ascertain the prescribed dose accurately. 6. Individuals with end-stage renal disease, chronic dialysis, or a kidney transplant prior to the index date. 7. Evidence with hospital discharge or emergency department visit in the two days prior to or on the index date to ensure a new outpatient prescription. 8. Individuals with no serum creatinine lab value in the 0-365 days prior to the index date. 9. Individuals with unstable baseline kidney function:• If the most recent serum creatinine test prior to the index date was an inpatient test \[ER or hospitalization\] (refer to this as test date 1), and there is not at least one 'outpatient' serum creatinine in the year before test date 1, OR• If the most recent prior serum creatinine test prior to the index date was an inpatient test \[ER or hospitalization\] (refer to this as test date 1), and while there is at least 'outpatient' serum creatinine test in the year before (test date 1), the most recent outpatient test prior to (test date 1) differs by an eGFR 10 mL/min/1.73 m2 or more from the value on (test date 1). In Ontario, it has been shown that an outpatient serum creatinine measurement in the province, conducted on a single occasion, usually represents a stable value. 10. Individuals receiving palliative care in the year prior to the index date, as in this setting dosing is less relevant; rather, the focus is comfort care. The investigators will restrict to the first prescription in individuals with more than one eligible prescription. Date of this prescription will be the index date (the date from which the outcomes start being assessed).