Development of the C4 inventory: a measure of common characteristics that complicate care in outpatient psychiatry

BACKGROUND Psychiatric syndromes are complicated by comorbidity and other factors that burden patients, making guideline-informed psychiatric care challenging, and negatively affecting outcome. A comprehensive intake tool could improve the quality of care. Existing tools to quantify these characteristics do not identify specific complications and may not be sensitive to phenomena that are common in psychiatric outpatients. OBJECTIVE To develop a practical inventory to capture observations related to complex care in psychiatric outpatients and quantify the overall burden of complicating factors. DESIGN We developed a checklist inventory through literature review and clinical experience. The inventory was tested and compared with related measures in a cross-sectional study of 410 consenting outpatients at the time of initial assessment. RESULTS The summed score of inventory checklist items was significantly correlated with patient-assessed measures of distress (K10, r=0.36) and function (WHODAS 2.0, r=0.31), and physician-assessed measures of function (GAF, r=-0.42), number of psychiatric diagnoses [F(df3)=33.6], and most complex diagnosis [F(df3)=37.4]. In 53 patients whose assessment was observed by two clinicians, inter-rater reliability was acceptable for both total inventory score (intraclass correlation, single measures = 0.74) and agreement on specific items (mean agreement score = 90%). CONCLUSIONS The Psychiatric C4 Inventory is a reliable instrument for psychiatrists that captures information that may be useful for quality improvement and resource planning. It demonstrates convergent validity with measures of patient distress, function, and complexity. Further tests of validity and replication in other settings are warranted.