Structured assessment of suicide risk in a psychiatric emergency service: Psychometric evaluation of the Nurses' Global Assessment of Suicide Risk scale (NGASR)

Background: Risk of suicide is notoriously difficult to assess, and no gold standard is available, in terms of an instrument of first choice. Many different instruments are in use, among which are some that are not properly psychometrically investigated.

Aim: The aim of this study is to establish the psychometric properties of the Dutch version of the Nurses' Global Assessment of Suicide Risk scale (NGASR), and the feasibility of its use in assessing suicide risk. Therefore, our research questions are as follows: what is the reliability, validity, interpretability and feasibility of the NGASR?

Methods: A psychometric study of acceptability, reliability and predictive validity among 252 patients making use of a concurrent instrument, the Suicide Intention Scale (SIS), concurrent assessment by a physician and 6-month follow-up.

Results: Factor analysis identified five factors. Cronbach's alpha was .45. Intraclass correlation was .92 (95% confidence interval (CI) = .85-.95). Association between total NGASR and SIS was substantial and significant (B = 0.66, standard error of mean (SE) = 0.19, ß = .66, p = .003). NGASR total score had a significant and moderately strong association with judgement by a physician on 'suicidal thoughts' (odds ratio (OR) = 1.24, p = < .001) or 'suicidal thoughts or plans' (OR = 1.35, p = .001). No significant association of NGASR scores and 6-month follow-up of suicidality was found.

Conclusions: Internal consistency of the NGASR and most of the subscales identified was low. Other indicators of reliability of the NGASR were sufficient, although predictive validity was poor. The NGASR did not outperform other instruments but is easy to use, and may contribute to identification of risk factors, as well as to a more integral assessment of suicide risk.