Outcome | No. (%) of adolescents with no self-harm visitsn = 10 731 | No. (%) of adolescents with ≥ 1 self-harm visitsn = 5661 | Time-to-event analyses HR (95% CI) | RR (95% CI) | Positive predictive value | |
---|---|---|---|---|---|---|

Readmissions to emergency department or hospital for self-harm | 637 (5.9) | 1626 (28.7) | 5.52 (5.05–6.04) | 4.84 (4.44–5.27) | 28.7 | |

Overall mortality | 34 (0.3) | 58 (1.0) | 3.25 (2.12–4.96) | 3.23 (2.12–4.93) | 1.0 | |

Suicides | 10 (0.1) | 42 (0.7) | 8.00 (3.99–16.04) | 7.96 (4.00–15.86) | 0.7 | |

Mean ± SD | Mean ± SD | t | p value | D | ||

Lower-bound estimates of 5-year health care costs, $ | 19 055 ± 53 767 | 30 388 ± 61 312 | 31.96 | < 0.001 | 0.20 | N/A |

Note: CI = confidence interval,

*D*= group difference, HR = hazard ratio, N/A = not applicable, RR = relative risk.↵* Hazard ratio is from the Cox proportional regression (meaning, the hazard rate for adolescents with ≥ 1 self-harm visits divided by the rate for the matched controls) for that outcome. The positive predictive value is the proportion of youths with ≥ 1 self-harm visits who have the outcome. Relative risk is the probability of the occurrence of the outcome within 5 years for adolescents with ≥ 1 self-harm visits divided by the probability of the outcome for the matched controls.

*t*statistic is the comparison of the average log-transformed lower-bound costs, with statistical significance*p*.