Suicide risk assessment among psychiatric inpatients: a systematic review and meta-analysis of high-risk categories.

BACKGROUND: The clinical care of psychiatric patients is often guided by perceptions of suicide risk. The aim of this study was to examine the methods and results of studies reporting high-risk models for inpatient suicide. METHODS: We conducted a registered meta-analysis according to PRISMA guidelines. We searched for relevant peer-reviewed cohort and controlled studies indexed in Medline, EMBASE and PsychINFO. RESULTS: The pooled odds ratio (OR) among 18 studies reporting high-risk models for inpatient suicide was 7.1 [95% confidence interval (CI) 4.2-12.2]. Between-study heterogeneity in ORs was very high (range 0-94.8, first quartile 3.4, median 8.8, third quartile 26.1, prediction interval 0.80-63.1, I2 = 88.1%). The meta-analytically derived sensitivity was 53.1% (95% CI 38.2-67.5%, I2 = 95.9%) and specificity was 84.2% (95% CI 71.6-91.9%, I2 = 99.9%) with an associated meta-analytic area under the curve of 0.83. The positive predictive value of risk categorization among six cohort studies was 0.43% (95% CI 0.014-1.3%, I2 = 95.9%). A history of suicidal behavior and depressive symptoms or affective disorder was included in the majority of high-risk models. CONCLUSIONS: Despite the strength of the pooled association between high-risk categorization and suicide, the very high degree of observed heterogeneity indicates uncertainty about our ability to meaningfully distinguish inpatients according to suicide risk. The limited sensitivity and low positive predictive value of risk categorization suggest that suicide risk models are not a suitable basis for clinical decisions in inpatient settings.

The localisation of spectrally restricted sounds by human listeners.

The two principal binaural cues to sound location are interaural time differences (ITDs), which are thought to be dominant at low frequencies, and interaural level differences (ILDs), which are thought to dominate at mid to high frequencies. The outer ear also filters the sound in a location dependent manner and provides spectral cues to location. In these experiments we have examined the relative contribution of these cues to the auditory localisation performance by humans. Six subjects localised sounds by pointing their face toward the perceived location of stimuli presented in complete darkness in an anechoic chamber. Control stimuli were spectrally flat (400 Hz to 16 kHz), while the relative contribution of location cues in the low frequency channels was determined using noise high passed at 2 kHz and in the high frequency channels using stimuli low passed at 2 kHz. The removal of frequencies below 2 kHz had little effect on either the pattern of systematic errors or the distribution of localisation estimates with the exception of an increase in the size of the standard deviations associated with a few rear locations. This suggests considerable redundancy in the auditory localisation information contained within a broadband sound. In contrast, restricting the target spectrum to frequencies below 2 kHz resulted in a large increase in the cone-of-confusion errors as well as a subject dependent biasing of the front-to-back or back-to-front confusions. These biases and the reduction in localisation accuracy for high pass stimuli at some posterior locations are consistent with a contribution of spectral information at low frequencies.

Recognizing silhouettes and shaded images across depth rotation.

Outline-shape information may be particularly important in the recognition of depth-rotated objects because it provides a coarse shape description which gives first-pass information about the structure of an object. In four experiments, we compared recognition of silhouettes (showing only outline shape) with recognition of fully shaded images of objects, by means of a sequential-matching task. In experiments 1 and 2, the first stimulus was always a shaded image, and the second stimulus was either a shaded image or a silhouette. Recognition costs associated with a change in viewpoint were no greater for silhouettes than they were for shaded images. Experiments 3 and 4 replicated the design of the earlier experiments, but showed a silhouette as the initial stimulus, rather than a shaded image. In these cases, recognition costs associated with a change in viewpoint were greater for silhouettes than for shaded images. Combined, these results indicate that, while visual representations clearly include additional information, outline shape plays an important role in object recognition across depth rotation.