Table 1

Characteristics of adults with intellectual and developmental disabilities, stratified on basis of antipsychotic initiation (1 April 2010–31 March 2016)

Initiated antipsychotic
n=6924
No antipsychotic use
n=32 320
Standardised difference*
Demographic characteristics
Age, mean (SD)41.0 (13.9)40.7 (13.2)0.02
 18–29, n (%)1986 (28.7)8805 (27.2)0.03
 30–45, n (%)2135 (30.8)10 885 (33.7)0.06
 46+, n (%)2803 (40.5)12 630 (39.1)0.03
Male, n (%)3886 (56.1)18 329 (56.7)0.01
Urban residence, n (%)5830 (84.2)26 512 (82.0)0.06
Income quintile, n (%)
 12267 (32.7)10 572 (32.7)0.00
 21476 (21.3)6958 (21.5)0.01
 31175 (17.0)5539 (17.1)0.00
 41065 (15.4)4803 (14.9)0.01
 5893 (12.9)4031 (12.5)0.01
 Missing48 (0.7)417 (1.3)0.06
Residing in group home768 (11.1)2933 (9.1)0.07
Medication use
Number of drugs dispensed in past year, median (IQR)5 (1–9)2 (0–6)0.40
Past use of other medications (prior 1 year), n (%)
 Antidepressants2994 (43.2)4876 (15.1)0.65
 Benzodiazepines1997 (28.8)3692 (11.4)0.45
 Lithium or antiepileptic drug622 (9.0)2647 (8.2)0.03
 Stimulant215 (3.1)372 (1.2)0.14
 Cognitive enhancer134 (1.9)108 (0.3)0.15
Health services utilisation
Hospitalised in past 2 years, n (%)1645 (23.8)3338 (10.3)0.36
ED visit in past 2 years, n (%)4767 (68.8)13 776 (42.6)0.55
Mental health hospitalisation in past 2 years, n (%)1669 (24.1)819 (2.5)0.67
Number of physician visits in past year, median (IQR)6 (3–12)3 (1–6)0.66
Specialist visits in past 90 days, n (%)
 Psychiatrists2115 (30.5)648 (2.0)0.84
 Family practice4979 (71.9)15 089 (46.7)0.53
 Neurologist343 (5.0)820 (2.5)0.13
Comorbidities, n (%)
Charlson score (using 3 years of hospitalisation data)
 No hospitalisation4963 (71.7)27 887 (86.3)0.36
 01172 (16.9)2939 (9.1)0.23
 1296 (4.3)759 (2.3)0.11
 2+493 (7.1)735 (2.3)0.23
Psychiatric diagnosis in the past 2 years, n (%)
 Major mental illness2169 (31.3)846 (2.6)0.83
 Other psychiatric diagnosis4654 (67.2)6437 (19.9)1.09
 Both of the above1762 (25.4)494 (1.5)0.75
 Neither of the above1863 (26.9)25 531 (79.0)1.22
Prior diagnosis of diabetes1051 (15.2)4007 (12.4)0.08
Prior diagnosis of hypertension1358 (19.6)5697 (17.6)0.05
Prior myocardial infarction56 (0.8)261 (0.8)0.00
  • *All comparisons with standardised difference >0.10, indicating a meaningful difference between groups, are presented in bold font.