A New Measure of Psychiatric Severity Using Administrative Data: the Manifestations of Psychiatric Severity Index (MoPSI)

Background: Health care managers rely heavily on measures derived from administrative data to monitor and manage their enrollees’ health. There are very few administrative measures of psychiatric illness severity, however, and most either comingle demographics and medical comorbidities or do not have ordinal properties.Objective: To assess the construct, concurrent, and predictive validity of a novel, 6-item, ordinal, administrative measure of psychiatric severity, the Manifestations of Psychiatric Severity Index (MoPSI).Methods: Panel study of 960 gender-stratified, nationally representative Operations Enduring Freedom, Iraqi Freedom, or New Dawn Veterans who had a pending disability claim for posttraumatic stress disorder (PTSD). The 6 input items for the MoPSI were number of mental health clinic visits, emergency department visits or psychiatric hospitalizations in the past 6 months; and the presence of any diagnosis for alcohol use, substance use, or self-harm in the past 6 months. We used 4 scoring approaches based on classical test theory, item-response theory, joint probability density (JPD) method, and a linear approximation of the JPD method. With all approaches, higher MoPSI scores indicate severer psychiatric severity.Results: The four scoring approaches correlated 0.976 – 0.999. Regardless of scoring approach, in terms of construct validity, Veterans who were unmarried or had low income had higher MoPSI scores than Veterans who were married or had higher incomes, respectively (Ps <.03). In terms of concurrent validity, Veterans with serious mental illness or a PTSD diagnosis also had higher MoPSI scores than their respective counterparts (Ps ≤ .0001). In terms of predictive validity, higher MoPSI scores predicted cigarette use, street drug use, and PTSD and depression/anxiety symptom severity six months later, as well as disability award status approximately 1 year later (Ps ≤ .05). Conclusions: The MoPSI appears to be a very well calibrated set of 6 input variables with evidence of construct, concurrent, and predictive validity. Because it has interval and ordinal properties, it is suitable for use as either a predictor variable or an outcome variable in regression analyses, and it avoids collinearity with sociodemographic variables or with medical comorbidities. The MoPSI may be a useful administrative measure of mental health.Trial Registration: Not applicable. Key Words: Manifestations of Psychiatric Severity Index; Psychometrics; Validity; Administrative Data; Population Health; Mental Health