Two clinicians rated 18 cases independently and blind to each other. The Kappa statistic could be calculated for 7 of the 11 items and was greater than 0.85 for each (p < 0.001 for each). For all 11 items, Spearman's rank correlation coefficient was greater than 0.75, (p < 0.001). The total score for the eleven items correlated 0.959 (p < 0.001).
Ratings were available for 316 people assessed using the DUNDRUM-1 security triage scale [16
]. Exploratory factor analysis yielded a first factor with Eigen value 7.48 which accounted for 67.9% of the variance. This loaded positively on all nine items other than the two items concerning self harm or suicide. The second factor had an Eigen value of 1.5 and accounted for 13.7% of the variance and loaded positively only on the two self harm/suicide items.
A measure of internal consistency, Cronbach's Alpha was 0.949 for the eleven-item scale. Table shows that the corrected item-total correlation was greater than 0.8 for 9 of the eleven items. Only the two items relating to self harm had low item-total correlations but removing either of these items increased the Alpha statistic only from 0.949 to 0.957.
The HCR-20 [21
] ratings for historical and clinical (current) items were available for 32 individuals. The HCR-20 historical items correlated with the DUNDRUM-1 security triage scale using Spearman rank correlation coefficient r = 0.329 (NS) and the HCR-20 current items correlated r = 0.166 (NS).
Triage for Court Diversion
For the three month period April to June 2009 table shows that of 246 persons assessed 159 were discharged to the prison GP for follow up, 57 were followed in the psychiatric in-reach clinic and 30 were admitted to a psychiatric hospital. The total score on the DUNDRUM-1 triage security scale differed significantly for the three groups (ANOVA F = 360.1, df = 2, p < 0.001). The 95% confidence intervals did not overlap and post-hoc tests using Bonferroni's method showed that each of the three groups differed significantly from the other two.
Total DUNDRUM-1 score by outcome for those assessed following screening over a three month period
The receiver operating characteristic for the threshold between discharge to the GP (n = 159) and either psychiatric follow-up or admission (n = 87) yields an area under the curve (AUC) = 0.893 (95% confidence interval 0.843 to 0.943) with sensitivity at a score of 1 = 0.782 and specificity = 0.922.
The receiver operating characteristic for the distinction between those admitted to any psychiatric hospital during this three month period (n = 30) and those not admitted (n = 216) yields area under the curve = 0.984 (95% confidence interval 0.971 to 0.977) (figure ). At a cut off score of 6, sensitivity was 0.95 and specificity 0.92.
DUNDRUM-1 Triage Security score. April to June 2009, those not transferred from prison to hospital (n = 216) v transferred from prison to any hospital (n = 30) Area Under the Curve = 0.984 (95% confidence interval 0.971 to 0.997)
Triage for Various Levels of Therapeutic Security
Table shows that for the two year period January 2008 to December 2009 100 individuals were either diverted from the remand prison to local psychiatric hospitals in open wards or locked low secure intensive care units (PICUs), or transferred from the prison to the forensic hospital, the Central Mental Hospital at medium/high security. The total scores on the DUNDRUM-1 triage security 11-item scale differed significantly according to the level of security to which the person was admitted (ANOVA F = 75.2, df = 2, p < 0.001) and as before each group differed significantly from the other two as assessed by the Bonferroni test for post hoc differences.
Total score by outcome for those admitted to hospital following screening over a two year period
To calculate receiver operating characteristics, those admitted were divided into three groups and the area under the curve calculated for adjacent pairs of groups - open wards -v- psychiatric intensive care units, psychiatric intensive care units -v- medium/high security. These comparisons yield conservative estimates of the receiver operating characteristics. Larger areas under the curve are generated and better sensitivity and specificity calculated if all those above or below a level of security are compared.
For those admitted to open wards (n = 27) compared to those admitted to psychiatric intensive care units (n = 26), the receiver operating characteristic yielded an area under the curve of 0.805 (95% confidence interval 0.680 to 0.930) (figure ) and at a threshold score of 13 sensitivity was 0.78, specificity 0.71.
DUNDRUM-1 Triage Security score. Two year period 2008 to 2009, those transferred to open wards (n = 27) compared to those transferred to psychiatric intensive care units (n = 26) Area Under the Curve = 0.805 (95% confidence interval 0.680 to 0.930)
For those admitted to psychiatric intensive care units (locked low secure units, n = 26) compared to those admitted to a forensic medium/high secure unit (n = 47) the receiver operating characteristic area under the curve was 0.866 (95% confidence interval 0.784 to 0.949) (figure ) and at a threshold score of 20 sensitivity was 0.728, specificity 0.827.
Figure 4 DUNDRUM-1 Triage Security score. Two year period 2008 to 2009, those transferred to psychiatric intensive care units (n = 26) compared to those transferred to forensic medium and high security at Central Mental Hospital (n = 47) Area Under the Curve = (more ...)
Re-analysing the differences between levels of security for a nine item scale omitting the two items for seriousness of self harming history and immediacy of self-harm made no significant difference to any of these results.
Items and Outcomes
Table shows that the Spearman rank correlation between items and outcomes for nine violence related items ranged between 0.755 and 0.874. The two suicide-related items had the weakest item to outcome correlations at 0.270 and 0.248, though these were still statistically significant.
Item to outcome correlations and exact agreement with outcome
The measurement of exact agreement between the rating and the level of therapeutic security to which an individual was allocated is also shown in table . The proportion of agreement in table is the sum of those rated '0' who had a corresponding outcome 'not admitted', those rated '1' who were admitted to an open ward, those rated '2' who were admitted to a PICU and those rated '3' or '4' who were admitted to the forensic hospital (medium and high security). Agreement for items ranged between 61% and 92%. The two suicide related items had agreement with outcome of 61% and 67%, comparable to the agreement for the violence related items. The 'legal procedure' item had the strongest agreement with outcome at 92%, while several items related to patient focused issues and social context rated higher than simple violence related items, including absconding risk (80%), victim sensitivities (80%), preventing access to contraband (78%) and specialist forensic treatment needs (78%).
Table shows the relationship between item scores and the level of therapeutic security to which the person was eventually allocated where agreement was rated if the allocation was at the corresponding level of therapeutic security or higher. Those allocated to a lower level of therapeutic security than the rating indicated were regarded as non-corresponding.
Item to outcome agreement where outcome is matched to appropriate level or higher.
Tables and show the relationship between the ratings and the actual placement for each item. Table shows the percentages of agreement between each rating for each item and the actual placement, where the placement matches the rating or is at a higher (safer) level of therapeutic security. Table shows the percentages of those placed at each level of therapeutic security who were rated on each item as appropriate for that placement or a less secure placement.
Matching of rating for each item and eventual placement.
Matching of eventual placements with ratings for each item