Table 1.

Baseline Characteristics According to Exposure Group, Clinical Practice Research Datalink, United Kingdom, 1998–2017

	AD Prescription at Cohort Entry
Variable	Citalopram (n = 137,791)		Fluoxetine (n = 108,712)
	No.	%	No.	%
Agea, years	43.4 (18.2)		40.7 (16.3)
Age group, years
18–24	20,665	15.0	17,950	16.5
25–34	31,382	22.8	27,248	25.1
35–44	29,927	21.7	25,564	23.5
45–54	22,309	16.2	17,523	16.1
≥55	33,508	24.3	20,427	18.8
Female sex	87,561	63.6	71,826	66.1
Year of cohort entry
1998–2005	40,077	29.1	56,502	52.0
2006–2011	65,297	47.4	38,780	35.7
2012–2017	32,417	23.5	13,430	12.4
Comorbidities
Smoking status
Ever	70,033	50.8	52,910	48.7
Never	46,795	34.0	34,010	31.3
Unknown (further multiply imputed)	20,963	15.2	21,792	20.1
BMIb
<18.5	2,296	1.7	1,725	1.6
18.5–24.9	37,957	27.5	29,652	27.3
≥25.0	50,285	36.5	38,538	35.4
Unknown (further multiply imputed)	47,253	34.3	38,797	35.7
Index of Multiple Deprivation (quintile)
1 (least deprived)	26,592	19.3	19,922	18.3
2	27,454	19.9	21,026	19.3
3	28,410	20.6	22,874	21.0
4	27,999	20.3	22,536	20.7
5 (most deprived)	27,182	19.7	22,188	20.4
Missing (further multiply imputed)	154	0.1	166	0.2
No. of psychiatric admissions or hospitalizations for self-harm in previous 6 monthsa	0.046 (0.274)		0.030 (0.478)
0	132,749	96.3	106,329	97.8
1	4,203	3.1	1,980	1.8
2–5	814	0.6	387	0.4
>5	25	0.0	16	0.0
Alcohol abuse	11,008	8.0	7,130	6.6
Psychiatric diagnosis
Schizophrenia	1,968	1.4	1,177	1.1
Bipolar disorder	1,033	0.8	720	0.7
Anxiety/generalized anxiety disorder	41,979	30.5	24,019	22.1
Autism spectrum disorder	209	0.2	135	0.1
Obsessive-compulsive disorder	736	0.5	618	0.6
Drug use
Lipid-lowering drugs	10,487	7.6	5,385	5.0
Antipsychotics	16,078	11.7	11,499	10.6
Benzodiazepine or other psychotropic drugs	27,169	19.7	18,579	17.1

Abbreviations: AD, antidepressant drug; BMI, body mass index.

^a Values are expressed as mean (standard deviation).

^b Weight (kg)/height (m)².