The Interpersonal Needs Questionnaire: Statistical Considerations for Improved Clinical Application

Abstract

The interpersonal theory of suicide (ITS) has accumulated empirical support; however, less research has investigated the clinical utility of ITS constructs in suicide risk assessment. The current study sought to increase the clinical utility of the Interpersonal Needs Questionnaire (INQ), an assessment of thwarted belongingness (TB) and perceived burdensomeness (PB), among 318 adult psychiatric outpatients while considering statistical methodology (i.e., multicollinearity and partialling). Results emphasized PB in the prediction of concurrent desire for death/suicide when TB was simultaneously considered. The interaction between TB and PB did not enhance prediction of concurrent desire for death/suicide. Independently, PB was a stronger predictor than TB of concurrent desire for death/suicide in the total sample and gender subsamples. Estimated probabilities of concurrent desire for death/suicide across INQ scores and preliminary INQ clinical cutoff scores are provided to enhance clinical application. These findings suggest the INQ could provide valuable information for suicide risk assessment and conceptualization.

Using categorical data analyses in suicide research: Considering clinical utility and practicality

“…Next, we provide an overview of an example of these categorical methods in the suicide literature. Mitchell et al (2020) tested thwarted belonging and perceived burden (continuous x variables) as predictors of desire for death and desire for suicide ( y ; coded 0 = no desire, 1 = some level of desire) among 318 psychiatric outpatients. To partially describe their results as they pertain to this paper (see Mitchell et al, 2020 for a complete description), they found a positive relation between thwarted belonging and desire for suicide (logit = 0.08, OR = 1.08, p < 0.001); however, to allow a more direct comparison of the OR s for thwarted belonging and perceived burden, they also conducted their analyses with z‐score transformed thwarted belonging and perceived burden scores.…”

“…Note that this standardized OR ( x is in SD units) is larger than the unstandardized OR ( x is in the scale of the measure) because of the change in the meaning of a one‐unit increase when standardizing x scores. To provide practical results that would allow clinicians to calculate and interpret the predicted probability of some level of suicidal desire from patients’ thwarted belonging scores, Mitchell et al (2020) provided predicted probability figures and noted that these figures were derived from the unstandardized logistic regression estimates because the unstandardized assessment scores would likely be used in clinical settings. They also offered sample interpretations of the predicted probability figures.…”

“…For example, a thwarted belonging score of 63 (the highest score) corresponded with a 66% chance of desire for suicide. A clinician could use the figures and this information to inform their clinical decisions, which may not have been possible if only logits or OR s were presented (see Mitchell et al, 2020, for further discussion).…”

“…The following is an example from the suicide literature where ROC curve analyses and AUC statistics were examined. Mitchell et al (2020) provided ROC curve analyses and AUC statistics for thwarted belonging and perceived burden as predictors of desire for death and desire for suicide among psychiatric outpatients, in addition to their logistic regression analyses and predicted probability figures. For example, the ROC curve analyses provided information related to the sensitivity and specificity of the thwarted belonging as a predictor of desire for suicide.…”

“…As an applied example, Mitchell et al (2017, 2020) used identical methods to determine clinical cutoff scores for thwarted belonging and perceived burden when predicting their suicide‐related outcomes. As an example, Mitchell et al (2020) used Youden's J index to identify cutoff scores for thwarted belonging and perceived burden when predicting the desire for suicide. Youden's J index, as mentioned above, places equal emphasis on balancing the false‐positive and false‐negative rates.…”