The Mini-CAARMS: Development and Validation of a Short Version of the Comprehensive Assessment of AT Risk Mental States to Facilitate Preventive Psychiatry

Background and Hypothesis Accurate detection of individuals at risk for psychosis with established psychometric instruments such as the Comprehensive Assessment of At-Risk Mental States (CAARMS/2006) is crucial to implement effective preventive strategies. However, the CAARMS/2006's scalability is limited by its lengthy administration. This study developed and validated a shorter CAARMS/2006 version: the mini-CAARMS.Study Design A total of 490 participants (mean age 23.8 +/- 5 years) underwent the full CAARMS/2006 interview (60 items, all individually scored). The development and validation of the mini-CAARMS employed advanced statistical methods: regularized logistic regression with a LASSO penalty within a nested cross-validation framework to retain core items; Cohen's kappa, Harrell's C index, sensitivity, specificity, balanced accuracy, positive (PPV) and negative (NPV) predictive values to assess performance; Monte Carlo simulations to assess the 2-year prognostic accuracy for predicting psychosis onset. A sensitivity analysis developed and validated an ultra-mini-CAARMS.Study Results The mini-CAARMS retained only 23 items and demonstrated excellent accuracy compared to the full version: Cohen's kappa 0.90; Harrell's C index 0.93, sensitivity 95.6%, specificity 100%, balanced accuracy 97.8%, PPV 100%, and NPV 86.3%. The prognostic sensitivity and specificity of the mini-CAARMS were 82.2% and 55.1%, respectively. Sensitivity analyses further developed and validated an ultra-mini-CAARMS (based on 12 items only), which achieved comparable performance, with kappa 0.90, C index 0.91, sensitivity 94.4%, balanced accuracy 97.2%, PPV 100%, NPV 82.2%, and prognostic sensitivity and specificity 81.2% and 55.1%, respectively.Conclusions The mini-CAARMS maintains high accuracy while substantially reducing administration time, and it could facilitate scalability of preventive psychiatry in low-resource settings.