Table 1. Description of the Sex-Stratified, Age-Matched Cohort for Self-Harm Eventsa.
| Characteristic | Individuals, No. (%) | Standardized differenceb | Individuals, No. (%) | Standardized differenceb | ||
|---|---|---|---|---|---|---|
| Autistic females (n = 19 800) | Nonautistic females (n = 79 200) | Autistic males (n = 56 126) | Nonautistic males (n = 224 504) | |||
| Age of first autism diagnosis claim, median (IQR), y | 12 (6-25) | NA | NA | 8 (4-14) | NA | NA |
| Age at maximum follow-up, median (IQR), y | 22 (16-38) | 22 (16-38) | 0 | 19 (14-27) | 19 (14-26) | 0.01 |
| Follow-up duration, median (IQR), y | 11 (6-16) | 11 (5-16) | 0 | 9 (5-16) | 9 (5-16) | 0.01 |
| Neighborhood income quintile | ||||||
| Q1 (lowest) | 4187 (21.1) | 14 957 (18.9) | 0.06 | 11 478 (20.5) | 41 107 (18.3) | 0.05 |
| Q2 | 3924 (19.8) | 14 791 (18.7) | 0.03 | 10 933 (19.5) | 41 081 (18.3) | 0.03 |
| Q3 | 3805 (19.2) | 15 912 (20.1) | 0.02 | 11 019 (19.6) | 45 398 (20.2) | 0.01 |
| Q4 | 3999 (20.2) | 16 436 (20.8) | 0.01 | 11 436 (20.4) | 47 749 (21.3) | 0.02 |
| Q5 (highest) | 3802 (19.2) | 16 823 (21.2) | 0.05 | 11 036 (19.7) | 48 408 (21.6) | 0.05 |
| Missing | 83 (0.4) | 281 (0.4) | 0.01 | 224 (0.4) | 761 (0.3) | 0.01 |
| Rural index | ||||||
| Urban | 17 775 (89.8) | 69 948 (88.3) | 0.05 | 50 417 (89.8) | 198 666 (88.5) | 0.04 |
| Rural | 2002 (10.1) | 9185 (11.6) | 0.05 | 5635 (10.0) | 25 670 (11.4) | 0.05 |
| Missing | 23 (0.1) | 67 (0.1) | 0.01 | 74 (0.1) | 168 (0.1) | 0.02 |
| Diagnoses ever recorded | ||||||
| Intellectual disabilities | 3216 (16.2) | 239 (0.3) | 0.6 | 7943 (14.2) | 1057 (0.5) | 0.54 |
| Mood and anxiety disorders | 14 820 (74.8) | 41 216 (52.0) | 0.49 | 36 265 (64.6) | 82 674 (36.8) | 0.58 |
| Schizophrenia spectrum and other psychotic disorders | 3097 (15.6) | 1376 (1.7) | 0.51 | 7833 (14.0) | 3644 (1.6) | 0.47 |
| Substance-related and addictive disorders | 1836 (9.3) | 4183 (5.3) | 0.15 | 4346 (7.7) | 14 041 (6.3) | 0.06 |
| Personality disorders | 2695 (13.6) | 2180 (2.8) | 0.4 | 5373 (9.6) | 4361 (1.9) | 0.33 |
| Ever had self-harm events leading to emergency health care | 1586 (8.0) | 1762 (2.2) | 0.26 | 2080 (3.7) | 2627 (1.2) | 0.16 |
| Age at first self-harm event leading to emergency health care, if present, median (IQR), y | 17.9 (15.4-25.6) | 17.5 (15.4-22.2) | 0.08 | 20.1 (16.6-26.5) | 19.6 (16.7-24.8) | 0.04 |
Abbreviations: NA, not applicable; Q, quintile.
a
Accrual period from 10th birthday (or from April 1, 2005, for those older than 10 years at this date) to March 31, 2020. Most autistic individuals, across sexes, were identified via autism diagnoses recorded in outpatient and/or inpatient settings; 2.4% of autistic females (481 of 19 800) and 2.4% of autistic males (1370 of 56 126) were identified exclusively via records in emergency department visits.
b
Standardized difference of 0.1 or more implies clinical meaningfulness.37